PUBLU: DIY Posable Puppet

13,558

58

9

Introduction: PUBLU: DIY Posable Puppet

About: Hi ! My name is Gautam Karve, and I am a Physics teacher by profession. I like to tinker with ideas and dabble in Design and Technology.

Hi !

In this Instructable we will see how to make a posable puppet armature (and body) using DIY methods. This puppet was made with an intent of creating photo-comics, but it could be adopted for stop motion animation as well. I have named it PUBLU due to extensive use of BLUE PU tubes (PU stands for polyurethane) that have been used for its joints and limbs! The key components of this armature design are the 7 distinct types of joints (Three types of hinge joints, three types of ball and socket joints, and a two-axis-translation joint ). With these 7 types of joints and movable eyes (gaze direction can be adjusted), there are 40 points of articulation. I had made previous designs and prototypes of posable puppets, before I came up with the current design. But the previous designs did not meet my expectations/ specifications (The older prototypes are shown at the end of this Instructable).

The current design of the posable puppet is quite satisfactory and meets most of my requirements that I set for myself. I have not found a similar design elsewhere. Out of the 7 types of joints, designing one particular joint -The Magnetic-Ball-and-O-Ring-Joint was quite challenging as it required positioning and attaching the magnets that are size of a few mm, to a position precision of a few 100ths of a mm (or tens of micrometer), in the presence of strong magnetic forces of the order of hundreds of gm weight. The assembly of this particular joint requires measurement of physical quantities- (force and displacements) to be done for each geometry of magnet size, magnet strength, steel ball size etc. I like to describe this particular assembly in the following way- "We are taming the two tiny beasts: One- The strong and restless NdFeB alloy magnet, and the other- the softer, yet firm gripping rubber O-ring, and get them to work as a team !".

Sections in this Instructable: There are 13 steps or sections, excluding this section of ‘Introduction and Supplies’. The last four sections are not really part of the fabrication process, but additional information.

  1. Head and Eyes
  2. Chest and Shoulder blades (two-axis translation joint)
  3. Limb Segment Length Proportions
  4. Ankle, Waist and Neck Joints (ball and socket joint- type 1)
  5. Foot
  6. Fingers and Thumb (hinge joint- type 1)
  7. Knuckles, Thumb base and Wrist (ball and socket joint - type 2)
  8. Elbow and Arms (hinge joint- type 2)
  9. Knee and Legs (hinge joint- type 3 )
  10. Magnetic Ball and O-Ring Joint: STEM behind it. (ball and socket joint for hip and shoulder joints- type 3)
  11. Magnetic Ball and O-Ring Joint: Force measurement
  12. Magnetic Ball and O-Ring Joint: Assembly
  13. Limb-wise assembly: Checklist
  14. Joint tightness measurement
  15. Past versions and upcoming features
  16. PUBLU in action: Posing Time
  17. Academic Relevance: Broader context of 'Story telling techniques' and 'Design process'

Now we will continue with the introduction talking about 1) STEM/ STEAM connect, 2) Merits of the design, 3) Tips to read the Instructable, and 4) Supplies. Or if you prefer you may directly jump to the fabrication process by going to 'Step 1- Head and Eyes'.

STEM / STEAM connect: Making this magnetic joint and most of the other joints requires application of knowledge of STEM- Science, Technology, Engineering and Math. Some of the joints require measurements of weight, thicknesses, using instruments like micrometer screw gauge, a home made pan balance, or measuring volumes in a measuring beaker used in the kitchen- so plenty of exposure to STEM. In fact this puppet design would fall under the wider umbrella of STEAM, which is a newly emerged way of looking at disciplines (A good read on STEAM is here- Concordia University Blog- STEAM ). The A stands for Art and Design. In the case of PUBLU, we can easily state that STEM has been used in the creation of an object of Art and Design. In a classroom setting of grade 9 and above (as sharp blades are involved in the cutting), the planning and construction of multiple puppets could be undertaken as a project that could run for a couple of weeks with students working in groups. In the latter half, a small story could be adapted to be made into a photo-comic version that would involve posing multiple characters, using props, backgrounds, lighting etc. This puppet fabrication and subsequent production of a photo-comic could also be part of an animation course in a College/ University setting as a complementary art to stop motion film making, due to the involvement of the aforementioned techniques along with photography, screen play, posing, costumes etc. It has been my dream since childhood to create a comic book by photographing posable puppets that would have their own unique faces, clothes and body types. I believe that photographing posed puppets with props and a background would be a simpler way to create the hundreds of frames of a comic book rather than drawing each frame. I have been a fan of Tintin comics and these are the inspiration for my wish of making a comic book. PUBLU was designed with an objective of creating a puppet that could hold its pose, allowing it to be photographed for the purpose of creating a comic book-like story book or a slide show. This format is called Photo-comic. Demo of PUBLU's posing abilities and its debut in a short slideshow format story -'PUBLU and Rubberdy' can be seen in the videos in this section and lot more photographs in the second last section- 'PUBLU in action: Posing Time!'.

PUBLU Puppet could possibly be used for stop motion animation as well, and I have made a small animation called - 'PUBLU's First Punch' added in, as a proof of concept, but I am not sure if it would 'stand up' to the high expectations of that technique ( PUBLU Puppet of course is able to stand upright on its own, without the help of the magnets underneath its feet ! ). A few advantages that set apart using puppets for creating frames of a comic is the ability it affords to the artist to tweak the pose or the lighting or camera parameters during the production stage, which is not that easy if one is drawing each frame. The other thing is it saves the artist from drawing repeating features in each frame.

Merits of the design in terms of choice of materials- The following synthetic materials- plastic, rubber, have certain physical properties that have proved very beneficial to the design- Polyurethane (PU), NBR - Nitrile butadiene rubber (used for O-rings), acrylic (beads), and PVC (PVC pipe), nylon (cable ties), PP- polypropylene (used for eyes, and finger hinge).

  • PU tubes and acrylic beads available in various colours and sizes - from 4 mm to 16 mm diameter;
  • PU and PVC- Can be cut with a shaving blade or hack saw respectively- hence good for making structural elements. "Be extra careful when cutting PU tubes with sharp blades !!! "
  • PU, PVC and NBR adhere well to epoxy resin (Araldite)- this is a quality that most plastics lack;
  • PU has right flexibility- can be used for making a) Snap fit ball and socket joints and b) Claw-Grip-Hinge-Joints.
  • PU is neither too flexible- can be used for making the limbs;
  • PU, PVC and acrylic are lightweight- suitable for making posable puppets parts- weight should be minimum;
  • PU, nylon and NBR are abrasion resistant- suitable for joint parts where repeated rubbing movement occurs.
  • PU has a smooth glossy attractive surface suitable for making puppet body.
  • NBR has the right kind of friction- neither too rough nor too smooth allowing it to be used as a socket receptacle in a magnetic Ball and socket joint.

And of course, the physical properties of metals like the NdFeB magnets, the brass washers (being non-magnetic), the Galvanised Iron (GI screws or strip) are critical to the proper working of the design.

Merits of the design in terms of the features and assembly procedure:

  • The procedure is not too complicated and one can make it at home using DIY methods.
  • The total cost of materials for one puppet came to not more than ₹ 300 INR or $ 4.30 USD (as on Jan 2020).
  • The limbs have a sufficiently large range of movement.
  • There are 40 points of articulation including movable eyes.
  • The fingers are articulated hence almost all hand poses can be created right there without the need to use replaceable hands to achieve different poses (Replaceable hands are found in some of the commercially available designs of posable puppets).
  • The fingers are not bony and thin. They are already the right proportion to the body dimensions, that they do not require an additional layer of rubber or latex, which is required in the case of metal wire armature puppets.
  • The joints are strong enough to hold the weight of the limbs that they are supporting, but not meant for handstand kind of extreme poses, or for holding up heavy objects.For such cases the objects or limbs could be suspended by strings temporarily.
  • The joints have a right amount of tightness which ensures that the user need not have to struggle to move the limbs.
  • The tools required for fabrication are all hand held, light, inexpensive and easy to get online or in hardware stores.
  • No 3-D printing required, but one could print a few parts if one wishes to- specially the limbs. 3-D printing not recommended for joints, as the 3-D printed plastic does not have the desired physical properties- specially elasticity.
  • To make other creatures, suitable types of joints could be chosen from the 7 types of joints to construct the creatures.
  • Modular nature of the joints- It is also possible to make 'bystander puppets' which need not have the full functionality as the main characters. These puppets can be made with joints that are easier to make. Basically a mix-and-match of joints is possible.

... And the demerits:

  • Making a batch of 4-5 puppets would require 2-3 days at least, compared to other faster DIY methods like aluminium wire armature.
  • In general, the essential materials would not be available in a single shop. I had to source the 8 or 9 critical materials from different shops and some online. For small orders, the shipping charge is sometimes more than the product price, or worse- they don't ship small quantities/ lengths.

Tips for reading the Instructable and during fabrication-

  • The dimensions are in mm if not mentioned. In some places dimensions are given in inch and feet: The usual symbols are used- 10" = 10 inch and 2' = 2 feet.
  • ID and OD stands for Inner and Outer Diameter of a tube respectively, and φ (phi) refers to the diameter.
  • The sequence of steps can be reordered depending on your convenience. I have documented the steps in this Instructable according to the body parts and not necessarily according to the fabrication sequence. Thus you will see some steps already done in the photos, even though the description may not mention it.
  • In the photos, I have highlighted the body part in consideration by the 'caption boxes', so do click the photos to make the captions visible.
  • For proper curing of Araldite joints, ensure that the room temperature is not too low (above 20 degrees C is fine, below 10 degree C can be problematic), else the cured epoxy resin will not be strong.
  • For cutting the PU tubes, either hold the tube so that a small end overhangs the edge of a table, or clamp it in a mini vise with some portion sticking out of the jaws, and then cut it using a shaving blade by cutting beyond the edge of the jaws of the vise. This is shown in a photograph in the section on making fingers.
  • I will continue to post updates about design improvements so that it is easier to use and easier to make the puppet, and of course have better functionality.
  • Questions, comments /suggestions are most welcome, in case something is not clear in the documentation.

Supplies:

Materials required are shown in photographs in this section -

The first photograph shows the critical and difficult to procure components, and the second photo shows easily available material. Of course this is not an exhaustive collection of materials. The other less critical components have been mentioned in the relevant sections. The last photo is of the tools and adhesives.

  • Polyurethane tubes of O.D x I.D : (4 x 2.5), (6 x 4), (8 x 6), (10 x 7), (12 x 8) or (12 x 9), (14 x 10), (16 x 12)- Got from a shop that stocks plastic tubes. Better to get small lengths of about a meter or two from a store than buy online as one has to purchase the entire coil in online purchase option.
  • Plastic beads (3, 4, 5, 6, 9,10, 14 mm ) - Got these from craft shops and also some online- Made in India Beads
  • Steel Balls (that attract to magnets): 8 mm and 11 mm dia: - These were difficult to procure online as small quantities are not easily available. I got mine from bike or car repair shops or specialty hardware shops.
  • Brass washers:-- 6 ID and 8 ID:- Got these from a hardware shop that stocks washers, fasteners etc. Not tried the online purchase route. Alternatively one can use epoxy putty by moulding it.
  • Strong NdFeB alloy magnets - Available online on Snapdeal, FlipKart (company names-'Techamazon', 'Art Ifact', 'Perfect magnets') , or Amazon or

    Goodwill

    or in specialty hardware shops.

  • O-rings : I purchased NBR O-rings from the company-ISG Elastomers (India). They accept small orders too. Here is their website - ISG O-rings or O-ring details, where you will find an O-Ring size chart in a downloadable pdf format.
  • Cable Ties
  • PVC clad electrical wire
  • PVC water pipe- 1/2"- It actually has an outer diameter of 16 mm and ID of 12.5 mm (1/2") -10 cm long section for a single puppet
  • PVC conduit pipe- 1" (OD) - 10 cm section - (used for electrical wiring casing, has a thinner wall diameter than the PVC water pipe ).
  • Strips of GI (galvanised iron): Sourced from scrap lying beside electrical cabling work area. Instead of this source, one could cut strips from an MS (mild steel) sheet of 1 mm thickness. Not done this myself, but guess it might be an alternative.
  • Steel pins
  • Earbuds
  • Nails
  • Long Screws
  • Short Screws and Nuts
  • Large nuts
  • Large paper clip / U-pin
  • PP Plastic sheet
  • Foam core

Tools/adhesives required-

  • Araldite
  • Epoxy Putty (M-seal)
  • Hack saw
  • File
  • Cutting plier
  • Mini vice- clamp- amazon
  • Scissor
  • Shaving blade
  • Tweezer
  • Scale
  • Micrometer screw gauge -not absolutely necessary, as it is required for measuring paper or other sheets thickness and if that thickness is approximately known, that is good enough.
  • Drill- hand or electrical powered
  • Access to a stove for heating metal parts

Teacher Notes

Teachers! Did you use this instructable in your classroom?
Add a Teacher Note to share how you incorporated it into your lesson.

Step 1: Head and Eyes

  • Materials required- PVC pipe, moderately stiff Plastic sheet, coloured paper
  • The head requires a PVC pipe piece of 25 mm OD, 32 mm length, and about 1 to 1.5 mm wall thickness.
  • For the eye sockets, make two holes of 6 mm dia, at approximate positions as shown in the photos with a drill by securing the tube in a mini vise.
  • For the eyes, mark two dots with a permanent marker on a white glossy strip of PP plastic of length x width of 45 x 13 mm, as shown in the photos. The PP sheet can be got from a craft shop or cut from a file cover.
  • The rectangular strip can be moved up-down or left-right to orient the gaze as demonstrated in the video titled "Posing PUBLU Puppet" that appears in the beginning of this Instructable.
  • For the eyelids you may use coloured paper sheet or coloured plastic sheet.
  • To achieve various expressions, the paper can be cut at an angle as shown in the photos. For example a neutral expression can be achieved by simply using a horizontal edge for the upper eyelid, whereas 'A'-shaped or 'V'-shaped cut will be suitable for showing pitiful or angry expressions respectively.
  • Alternatively one could make almond shaped holes in the coloured sheet and use different sized holes for different expressions. Whichever way one chooses, it will require replacement eyelid templates. These templates could be made by cutting holes with paper cutting knife or with laser cutting a strip of paper/plastic.
  • For the eyebrows there are many well known ways- You could either stick strips of dark sheets or pieces of cord. Also one could draw the eyebrows with a pencil, as a pencil mark on a PVC surface can be erased and redrawn.
  • I have drawn the lips with a pencil. One could also use epoxy putty to make replaceable lip shapes- both the methods are well known.
  • For the ears, one could use 3 mm foam core and sticking with Araldite and for the nose I have used a 4 x 2.5 mm PU tube that is cut at a steep angle.
  • The head could be capped with a cap/ hat or a wig or simply by drawing with a pen or by placing a hemispherical cap and making the hair with silicone RTV sealant (graphite powder can be added to the sealant before it sets, to impart it color).
  • The head couples with the neck via a vertical piece of PU tube as shown in the last photograph.

Step 2: Chest and Shoulder Blades: Crossed Slits Joint

Description

The two-axis translation joint consists of two perpendicular slits- one horizontal slit in the chest PVC tube, and a vertical slit in the 'shoulder-blade-like' part. A single screw and nut holds the two parts together. By loosening the screw a little, it is possible to translate the shoulder joint up- down and back and forth. This allows us to translate the shoulder ball for shrugging and drooping, or front and back movements as shown in photos #1 and 2

Material and tools

  1. PVC pipe of size 25 mm OD
  2. Small screws, nuts and washers
  3. GI strips
  4. Tooth picks
  5. Hack saw
  6. Araldite
  7. Nose plier for bending the GI strip
  8. paper cutter for cutting tooth picks
  9. Drill
  10. Pencil or marker
  11. Scale

Procedure

  1. The chest is to made by cutting slits and cut outs in a piece of PVC pipe with a hack-saw as shown in photo #3. The dimensions are shown in the renderings (photos #4, 5 and 6).
  2. The shoulder blades are pieces of the same sized PVC pipe, cut out as shown in photograph #7. The length of shoulder blade is 30 mm, width 15 mm. Length of slit is 12 mm, and width is 4-5 mm depending on screw dia.
  3. The shoulder blades are inserted inside the chest tube and attached to it by a single screw plus nut and washers on both ends, as shown in photo #8, 9 and 10.
  4. Photos #11 and 12 show the assembly with the shoulders and arms.
  5. For attaching the neck a horizontal bridge has been made with a GI strip as seen in photo #8 ,9 and 12. Over this bridge an 8 mm PU tube has been attached with Araldite. On top of this tube the neck joint has been affixed. At the back, this GI strip has been attached to the chest PVC piece. An alternate way is to take an 'sleeping-L' shaped GI strip and attach it directly to the PVC pipe rim that is seen in the rendering (photo #4).
  6. There is an update (added on 7th Mar 2020): I have attached a pair of toothpick pieces to the inner sides of the shoulder blades, so that the nut does not rotate when the screw is tightened or loosened from outside. Earlier I had to hold the nut with a rod to prevent it from rotating. The last five photos (# 12 - #17) show these nut guides being assembled by sticking these with Araldite. So now the washer that was on the nut side (inside) should not be placed. Only the washer that was on the screw head side is required.
  7. The trick of attaching the guides is to place the nut on the slit, with the screw going through it. Then place the toothpicks (of 2 cm length) on the sides of the nut and attach the toothpicks to the PVC pipe by just three drops of Araldite on the outer edge, as shown in photos # 14, 15.

Step 3: Limb Length Segment Proportions Used for PUBLU

Description of the two diagrams and photograph-

Depending on the limb lengths that you need for making your puppet character, the tubes should be cut accordingly. In this step I have shown the limb length segment proportions and lengths that I have used for this particular puppet. The limb segment length is to be interpreted as axis-to-axis length between joints.The following piece of writing of this section is a bit of diversion and can be skipped, in case you just want to get started with the fabrication. This is a chat about why I am using the limb segment length proportions that are used for PUBLU Puppet.

  • The first diagram gives the proportions in terms of integers (mostly), some numbers are half integral.
  • The integer proportions presented here have been derived from the data given in the book- Humanscale 1/2/3, Joan C. Bardagjy, Alvin R. Tilley, Niels Diffrient, Published by The MIT Press, 1974.
  • In this book the average limb segment lengths have been given in inches (measured for humans and averaged), not the integer and half integer proportions, that are given in this Instructable.
  • I noticed that the limb segment lengths for the 50th percentile (a short form of referring to the 47th to 53rd percentile group, in terms of height) could be expressed in terms of proportions that are integers.
  • For example the hand length is 7.5", forearm length is 10", and upper arm length is 11.1" (all are averages for that percentile group). This could be converted (quite closely) to the integral proportions- 6 : 8 : 9. The 3rd percentile group could also be expressed in terms of the same integers- ie.- 6 : 8 : 9
  • But for the 97th percentile group, I noticed that the same limb segment lengths were better described by the proportions- 7: 9: 10. These are also integers but different from the 50th and 3rd percentile groups.
  • Starting with the arm as basis, I noticed that the other limb segment lengths (legs etc) could also be considered to have integral proportions. Only some of the limb segments had to be half integral proportions. This half integral issue can easily be taken care of by multiplying all proportions by 2, giving all numbers as integers, but to keep the numbers small I have chosen this system.
  • The second diagram converts these proportions to limb segment lengths of the puppet in mm units. Taking one unit as 4.5 mm, the height of this puppet comes to 250 mm. These dimensions have been used as reference for the limb segment lengths of the puppet.
  • It was of course possible to directly scale down the dimensions given in the "Humanscale:1/2/3" book to arrive at the required limb segment lengths for the puppet, but I found it highly entertaining to play with the numbers to find out a mathematical pattern- hence the integral proportions study.
  • Playing with the numbers and proportions also got me interested into developmental biology ( another way of a STEM connection). I don't mind making a hypothesis (its a big word!) that these numbers could actually be involved in the biology of the length of limb segments (think of -humans vs bats vs giraffe vs cat and so on- each animal has different limb length proportions). I use the word 'hypothesis', as I have not come across such integer based system of limb lengths proportions. I have only heard about the Vitruvian man by Leonardo da Vinci (Thanks to The Da Vinci Code !) where a common proportion - the Golden Ratio supposedly keeps appearing.
  • This was simply a diversion from the puppet work and there is no necessity of using these particular proportions for making your own puppet. The proportions will depend on the characters that you plan to make.
  • The third photograph shows that it is useful to keep the puppet on top of this scale drawing for marking the limb segment lengths during fabrication. It is also clear from this photo that the tube length that are used are obviously going to be shorter than the limb length that are drawn

Step 4: Ankle, Waist and Neck: the V-Cut-PU-Tube Joint

Description: This joint relies on the elastic property of the PU tube. The basic idea is to insert a bead into a V- shaped slot cut in the side of a PU tube. The size of the bead should be such that it fits moderately tightly into the cavity formed by the V-shaped slot opening, thus the bead diameter should definitely be slightly more than the inner diameter (ID) of the PU tube. Cut a V shaped notch in the PU tube with a razor blade with dimensions as given in the list below. Insert and join a pin/ nail/ screw in the hole of a bead by either heating the pin/ nail/ screw or by sticking with Araldite. For heating the pin/ nail/ screw, grip this with a nose pliers and heat it on a gas flame (not a candle flame as the soot will create a non stick layer). For small beads (for neck, wrist) it is better to stick with Araldite, rather than heating and joining, as the small bead gets distorted by heat. To prevent tearing (though this does not happen that easily) at the corners of the V-cut made in the PU tube, a spot of Araldite could be applied. Though I made one 'V-Cut-PU joint' for the wrist of the right hand, seen in photo #6, I prefer using the 'Bead-in-PU-Rings joint' described in a later section.

Material and tools-

  1. PU tubes of dimensions given in the specs below
  2. Plastic beads of various sizes as given below
  3. Nail/ screw/ pin/ Paper clip (U-pin)
  4. Shaving blade - Be very careful while cutting PU tubes with blade. Clamp the tube in a mini vise while cutting it. Do not try to cut PU tubes with a hack saw- it does not cut cleanly, as PU tube is a tough material

Dimensions -

  1. Ankle:- PU tube- 12 OD x 8 ID x 14 mm length; Plastic bead dia- 9 mm; Nail length- 1" x 2 mm dia shaft; width of V cut- 10 mm, depth of V cut- 8 mm. In case you use PU tube of dimensions 12 OD x 9 ID, then I recommend using a 10 mm dia plastic bead with it.
  2. Waist:- PU tube 16 OD x 12 ID x 25 length; Plastic bead dia- 14 mm; screw length- 18 mm or 3/4" x 3 mm dia shaft; width of V cut- 13 mm, depth of V cut- 11 mm
  3. Neck:- PU tube- 6 OD x 4 ID x 9 length; Plastic bead dia- 5 mm; steel pin length- 15 mm x 1 mm dia shaft; width of V cut- 5 mm, depth of V cut- 3 mm. There are two such joints to be made for the neck These two joints will be at the two ends of the 15 mm pin shaft. One joint will be just above the shoulder level, while the second joint will be at the back of the head/ skull, as shown in photo #5.
  4. Wrist:- Everything same as neck except the PU tube length is 10 mm and the V cut is not in the center of the PU tube. The V-cut center is 4 mm from the thumb side as seen in the last photograph.

Step 5: Foot

Material required - for both feet

  1. PU tubes: (OD x ID)- 12 x 8, 8 x 6, 6 x 4, 4 x 2.5
  2. Magnets: 3 x 3 - 4 no.s, 3 x 1.5 (or 4 x 1.5) - 2 no.s.
  3. Cable ties: 2 mm width- 2 no.s

Tools:

  1. Blade - (Cut the PU tubes with blade, not with hack saw)
  2. Araldite
  3. Epoxy putty
  4. Cutting plier / nose plier for cutting Cable tie
  5. Scale

Procedure:

  1. The foot structure is almost entirely made of PU tubes. Refer to the first diagram for the sizes of the various tubes that need to be cut and kept ready.
  2. Near the ankle, two magnets of 3 mm dia. x 3 mm height are stuck to the end of the 8 mm and 6 mm tubes, with their polarities as shown in the first diagram. In the front, a single magnet of 3mm dia x 1.5 mm thickness is stuck to the toes, serves to magnetically attach the toes to an iron/ steel floor in a pose that requires standing on toes, or raising the ankle.
  3. A 12 mm OD tube is cut in half along its axis and forms the back of the ankle, thus concealing the magnets. A diagonal cut should be made to this tube at the top to fit the contour of the ankle joint tube, as shown in the side view of the foot.
  4. The ankle joint is described in the previous section called 'Ankle, Waist and Neck: the V-Cut-PU-Tube Joint'. Once the ankle joint is made, it is to be simply stuck on top of this 'raft' of tubes that makes up the foot.
  5. The toes joint is a Hinge joint made using Cable Tie. This joint is the same as described in the 'Arm and Elbow: the Cable-Tie Joint' step.There are four fingers that are attached to the 6 mm OD tube that acts as a hinge. The toes move together as a unit as seen in last photo.

Step 6: Fingers and Thumb: the Claw Joint

Description: This is a miniature hinge joint in the middle of each finger. The name claw joint is because of the shape of the tiny C-shaped rings and the way these grip the earbud tubes elastically. The way to imagine the structure of this claw is to think of two fingers (or claws) in the front and one opposing thumb, that together can grip a tube, with the thumb being placed between the two opposite fingers or claws. The tube in this case is a 3 mm piece of an earbud stem.

Materials required-

  1. 4 x 2.5 PU tube
  2. Earbuds-Preferably same colour as the PU tube- blue in this case.
  3. Steel pins
  4. 1 sq.mm electrical PVC wire- preferable same color as the PU tube (The OD with insulation is about 3 mm).
  5. 3 and 4 mm dia plastic beads

Tools/adhesives-

  1. Shaving blade
  2. Cutting plier
  3. Araldite
  4. Epoxy Putty
  5. Rag
  6. Nail polish remover (required in case the beads have a pearl coating on them, else not necessary)

The steps are for both hands- left and right. The Claw joint that forms the hinge joint at the centre of each finger is to be made by the following steps-

  1. First day- Take 8 plastic beads of 3 mm dia and two beads of 4 mm dia, and dip them in nail polish remover or any other mild organic solvent, and wipe them off with a rag to remove the pearl-shine coating. This is shown in a photo in the next section. If the beads are uncoated, then this step can be skipped.
  2. Cut steel pins and electrical wire insulation of lengths as shown in the photo #2. The lengths shown are for one hand. Cut twice the number shown in the photo.
  3. For base of thumb- cut a 4 x 2.5 PU tube- 7 mm (2 no.s). Cut one end at 45 degree angle as shown in photo #2.
  4. Cut the 4 x 2.5 PU tube into thin rings each 1 mm thick using a shaving blade, as shown in the photographs #3 and #4. Cut 25 such rings.Out of the 25 rings, take five rings and split them into 2 pieces each, giving 10 numbers of semi-circular pieces, as shown in photo #5.
  5. Take the remaining 20 rings and make a cut with a shaving blade so that the O shape becomes C shape whose ends touch each other. This is the claw.
  6. Slip two C-shaped rings and one semicircular ring onto a 1 cm piece of earbud stem as shown in photo #8. In the photo the length of the earbud stem is 3 mm but use the 1 cm stem as a dummy tube that will not be part of the assembly. It is only being used for placing the rings together thus allowing the rings to be stuck to the insulating part of a wire.
  7. Take another piece of an earbud stem and make a V-shaped shallow cut in its side, close to one end as shown in photo # 6. The centre of the V should be 1 mm away from the end of the stem. It should be small enough that if a pin is inserted in this, it should go in tightly.
  8. Cut off and discard the sharp end of a pin and insert the blunt pin in the shallow V-shaped notch that was made in the earbud stem as shown in Photo #7. Cut a 3 mm length piece off from this earbud stem.This piece will include the V-shaped cut too.
  9. Now follow the sequence of assembly as given in photo #9. In this sequence there are three stages of assembly- In the first stage araldite is applied to various parts. Apply Araldite on the area shown in photo #10 while sticking the parts. Photo #11 and #12 are for additional reference.
  10. In the second stage, Epoxy putty (M-Seal) is used as a building and joining material.
  11. In the third stage the two parts of the finger are snap fit together via the claw joint. The claw joint can be opened up by prying open the C-shaped claw.
  12. The finger joint is ready as shown in Photo #13, and the fingers seen incorporated into the palm are seen in photo #14.

Step 7: Knuckles, Thumb Base and Wrist: the Bead-and-PU-Rings Joint

Description: This joint relies on the elastic property of PU tube. The basic construction for the knuckles joint is as follows and the other two joints have the same working principle. A trough is formed by cutting a PU tube along its length. In the groove of this trough multiple (or just two) PU rings are placed close together and stuck to the trough. The separation between the rings is such that if a bead is inserted in the space between the two rings, it will fit in a snap fit manner. The trough bends slightly so that the rings splay out and allow the bead to fit into this gap. In terms of movement freedom, this joint mimics our knuckle joints very well. It allows back and forth movement of the fingers like a hinge joint and it also allows some sideways movement of the fingers, thus the fingers can splay (spread out) as shown in photo # 7.

Material required:

  1. 8 x 6 mm PU tube
  2. 6 x 4 mm PU tube
  3. 4 x 2.5 PU tube
  4. 3 mm plastic beads- 8 no.s- for the fingers
  5. 4 mm plastic beads - 2 no.s for the base of thumb joint
  6. 6 mm plastic beads - 2 no.s for the wrist joint.

Tools/ Adhesives:

  1. Blade
  2. Araldite
  3. String
  4. Nail polish remover
  5. Paper binder clips- 2 no.s
  6. PVC tube of 25 mm ( 1 inch outer dia) as a base support (Any cylindrical object with similar diameter will do)
  7. Two identical weights in small plastic bags.

Procedure:

  1. Cut a piece of 6 x 4 mm PU tube to a length of about 25 mm. Cut this PU tube along its length to form two trough shaped halves as shown in the first photograph.
  2. Pierce a hole in each end by inserting a heated pin. Through these holes, pass a string as shown in the first and second photo.
  3. Tie this trough shaped PU tube over a PVC tube as shown in first and second photo. This will force the PU tube to form an arc shape.
  4. Cut the 4 x 2.5 PU tube into 10 rings of 2 mm thickness- 5 for each hand. These will form the base of the fingers.
  5. Remove the pearl-shine coating of 10 plastic beads (3mm - 8 no.s , 4 mm - 2 no.s) by using nail polish remover as mentioned in the previous section. Shown here in the third photo.
  6. Pass two threads (call them A and B) though the holes of the ring and bead alternately as shown in fourth photo.
  7. Tie multiple knots each on the right end of string A and left end of string B so that the string cannot come out if pulled from the other end. This is shown in fourth photo.
  8. Put equal weights in the two small plastic bags, and loop the Paper binder clips over the plastic bag handles. Clip on these Paper binder clip to the other ends of string A and B, as shown in fifth photo.
  9. Apply very carefully a few drops of epoxy adhesive to almost half of the cylindrical surface of the PU rings.
  10. Place this small 'necklace' of PU rings and plastic beads over the trough as shown in fifth photo. The weights suspended to the strings will cause the beads and the PU rings to press against each other.
  11. When set, the epoxy adhesive will stick the PU rings to the trough. Remove the plastic beads by inserting a pin into the hole of the beads and prying them out from the joint. This completes the knuckle joint, as shown in the sixth photo.
  12. Now the fingers can be attached to the knuckle bases simply by press fitting into the spaces between two rings as shown in the seventh photo.
  13. Repeat similar procedure for the base of the thumb joint. The difference is that in this case the bead will be 4 mm dia, and the rings/ tubes of the 4 x 2.5 PU tube will be of length 2 mm and 4 mm. You will get an assembly as shown in eighth photo.
  14. Attach this assembly to the rest of the palm by Araldite in the space meant for it as shown in 9th photo.
  15. The wrist joint has a same structure. Only the size of bead and rings is different. In this case the bead is of 6 mm dia, the rings are made of the 6 x 4 mm PU tube of lengths 5 and 2 mm and the trough is made of the 8 x 6 mm PU tube.
  16. The last photo (11th photo) shows an alternate way to join the rings with the trough. Instead of bending the trough, the rings are stuck to the trough at a spacing such that it is slightly smaller than if the beads were placed between the rings.

Step 8: Elbow and Arm: the Cable-Tie Joint

Description:This joint is a simple hinge joint with the cable tie tied around a short PU tube, and the cropped tail of the cable-tie is inserted and fixed into the forearm PU tube as shown in Photo #2. The short length of the PU tube that acts as the hinge is attached to the upper arm with Araldite. So if the upper arm and the short tube are considered as the static part, then the cable tie and the forearm are the rotating part.

  1. Cut the PU tubes with a shaving blade according to the cutting diagrams -Photo #1. In this photo the cutting diagram is for the right arm. For the left arm, it will be a mirror image, with the same dimensions shown.
  2. On a PU tube of 10 mm OD and 12 mm length, tie a cable tie (moderately tight). This is the short hinge tube. On the tail of this cable-tie, slip in the head of another cable tie. Cut the excess length of the tails of both cable ties as shown in part (a) of photo #2.
  3. Stick a small blob of epoxy putty as shown in part (b) of photo #2. Before it dries completely, check if the 10 OD tube (this the forearm) goes over the blob. Remove the tube and allow the putty to cure (harden).
  4. Apply epoxy resin to the epoxy putty part and to the inside of the 10 OD PU tube (the forearm tube). Insert the putty part into the 10 OD tube with the orientation as shown in part (a) of photo #2.
  5. Stick the 10 OD tube to the table surface with Blu-Tack. Similarly stick the 12 OD tube (upper arm) with Blu-tack to the table so that it touches the exposed part of elbow as shown in the assembly diagram- last stage of photo #1. The Blu-Tack holds the tubes in place while adhesive sets.
  6. Apply araldite to the places in contact as shown in the assembly diagram- last stage of photo #1. Let the Araldite set.
  7. The final step in this procedure is to attach the shoulder ball and the bead that is part of the wrist joint. This assembly is shown in photo #4.
  8. The Elbow joint with upper arm and forearm is ready.
  9. The assembled arms are seen in photo #5. The two arms have been oriented differently with respect to each other, to show the back view and side view.
  10. This type of hinge joint is also used in the toes of the feet. The diameter of the hinge tube is 6 mm there. Refer to the 'Foot' step. Using a blue cable tie would blend it with the other blue tubes.

Step 9: Leg and Knee: Bead-and-O-Rings Joint

Description: The Bead and O-Ring joint is made by sandwiching the plastic bead between two O-Rings as shown in the exploded view in the first photo. The O-Rings are pre-stressed during assembly, hence when the Epoxy resin (Araldite) sets, the bead gets clamped tightly by the O-Rings.

Material required:

  1. PU tubes: (OD x ID)- 16 x 12 -2 pieces of 58 mm each, for thighs,
  2. PU tubes: (OD x ID)- 12 x 8- 2 pieces of 40 mm length each, for the shin.
  3. PVC pipe: (OD x ID)- 16 x 13- Two pieces of 16 mm length each.
  4. Plastic bead: 10 mm - 2 no.s
  5. O-Ring (ID x Thick):- 6 x 2.6 (ISG Part # 1-108 ) - 4 no.s
  6. Brass / GI washers / steel washers- (OD x ID)- 12 x 5 mm - 4 no.s
  7. GI strips: 4 x 1 cross section, 22 mm length- 2 no.s

Tools required

  1. Hack saw
  2. Mini vise
  3. File- for smoothing uneven edges left due to hack saw cutting.
  4. Araldite
  5. Weights - water bottles or grocery packs of known mass work fine

Procedure:

  1. Take about half foot length of a PVC pipe. Make a V-shaped slit in it as shown in photo#2, by clamping the piece in a mini clamp and using hack saw to cut. The center of the V-cut should be 8 mm from one end. Cut off 16 mm length of this piece as shown in part (b) of the second photo. Alternately a straight slit that goes almost half the circumference and of width 5 mm can also be cut as shown in the rendering (photo #1), by following the procedure given for making slits in the chest PVC part (Step 3 of this Instructable).
  2. Stack the five components (2 brass washers, 2 O-Rings, and a bead) - one on top of other in the order shown in photo #1 on a table. Measure the height of this stack. It will be about 13 to 15 mm approx.
  3. This stack is to be fixed inside the PVC pipe piece, so mark where the stack will be placed starting from one end, if kept symmetrically. Lets say the mark is = t mm from one end.
  4. Keep the brass washer on a spacer of about t mm and on top of the washer place the O-Ring, as shown in the diagram in photo #3(a). Apply Araldite between the the O-ring and brass washer. Also apply Araldite to the outer rim of the washer so that when the PVC pipe piece is placed to encompass it, these will stick together. Refer Photo #3(a). Let the Aradite set.
  5. Simultaneosly stick the other O-ring to the brass washer with araldite and let it set.
  6. On the next day (when Araldite has set) place the bead over the O-ring that is stuck inside the PVC pipe. Place the other O-Ring that is stuck to a brass washer, as shown in Photo #3(b).
  7. Apply Araldite near the outer rim of the topmost washer so that it will stick to the PVC pipe piece. Place a sheet of thin flexible plastic on top of this washer, so that when a cylindrical piece (the green piece placed on the washer in photo #3(b) ) is placed on it as a spacer, it will not stick to the PVC pipe. The actual cylindrical piece made of epoxy putty is also seen in photo #2 -part (d).
  8. Take two such assemblies (of the left and right leg) and place them on two vertices of an equilateral triangle of side 10 to 30 cm drawn on a table or sheet of paper placed on a table. On the third vertex place a dummy cylindrical piece that has the same height as the other two.
  9. Place a dining plate or any rigid, flat, circular object symmetrically on top of this tripod structure.
  10. Place a weight of about 1.5 kg (or more upto to 2.5 kg) on this plate, so that each pillar of the tripod would be bearing a load of 0.5 kg. The exact weight is not important, but to get the right amount of friction between the O-Rings and plastic bead, I have used a load of 1.5 kg. This will compress (pre-stress) the O-Rings as shown in photo #3(c) . This load can be more or less depending on how much friction is required. Let the Araldite set.
  11. After the Araldite has set, remove the load and the spacers, and insert a heated GI iron strip along the direction of the hole of the plastic bead as shown in photo #3(d). For heating the GI strip, grip this with a nose plier and heat it on a gas flame (not a candle flame as the soot will create a non stick layer). The knee joint is ready to be assembled to the thigh and shin.
  12. Refer to photo#5 for making cuts in the 16 mm OD, 58 mm length PU tubes that will form the thigh. These cuts are for sticking the knee joint and the hip ball. The hip ball is a steel ball stuck to a magnet (referred as secondary magnet in the step where the magnetic ball and O-Ring joint is described), seen in photo #6. The magnet is stuck to a strip of GI (galvanised Iron) that is bent making an angle of about 120 to 135 degree, and the GI strip is in turn stuck to the PU tube as seen in photo #6 and #7.
  13. For the shin a 12 mm OD PU tube of 40 mm length has been used. Make a cut in the shin tube for sticking the GI strip that comes out of the knee joint. Refer to photo #4.
  14. A view from the back is shown in photo #8, where the cuts in the thigh tube are clearly seen. In this photo the nut that is the pelvic region is seen and we can see that it is at an angle to the vertical.
  15. Photo # 9 shows the range of movement of the knee joint, it is almost 180 degrees.

Step 10: Magnetic Steel Ball and O-Ring Joint :- the STEM Behind It (Step 1/3)

In this step I have shown how the magnetic steel ball and O-Ring (MBOR for short) joint has been assembled and explained the STEM behind the working and assembly of this joint in a two part presentation as YouTube videos. Some of the slides from the presentation have been put as photos.

The topics covered/ discussed in these two presentations are-

  1. Parts of the Magnetic ball and O-Ring joint (MBOR joint)
  2. The forces involved in the proper working of the joint
  3. Magnitude of magnetic attractive force (due to magnet) and repulsive normal reaction force (due to O-Ring) on the Steel ball plotted together: Equilibrium condition.
  4. How to assemble the joint : The challenge of affixing the magnet at a position precision of 50 microns.
  5. Pictorial representation: Pictures superposed on graphs
  6. Different ways of assembling MBOR joint: Correct and Incorrect ways
  7. Why to attach iron objects to the free ends of primary and secondary magnets ?

In the presentation I have not attempted to differentiate which part is Science, which part is Technology, Engineering or Math. It is a seamless description / explanation, in the true spirit of the interdisciplinary nature of STEM. This joint has good strength (resisting moment or torque) as well as a large range of movement. The range of movement is almost 2π steradian (unit of solid angle), which basically means that the lever arm tip can cover or reach all points on a hemispherical area of a sphere of radius equal to the lever arm length. I consider this joint as a high point among the 7 types of joints, and I take pride that I figured out the assembly and design on my own.

There is a somewhat similar magnetic joint that has been patented by Parviz Daftari and Lawrence Rosen- (Patent by Daftari and Rosen) and which I did see after I made my design. With all due respect to the work presented in the patent, there is no description of how the joint is to be assembled in the patent, even though it has the same components- strong magnets, steel ball and O-rings. In this Instructable I provide a DIY procedure of assembling the magnetic ball and O-Ring joint (or equivalently- magnet, ball and O-Ring joint). And as you will see in the videos given here, the assembly is not straight forward. The next two sections (steps) have the instructions for execution part.

Thus these three steps are basically-

  1. (Step 1 of 3) - Understand the rationale (suggested to watch at least part 1 of the presentation on 'STEM of MBOR joint').
  2. (Step 2 of 3) - Measure the magnetic force.
  3. (Step 3 of 3) - Assemble the parts.

Step 11: Magnetic Steel Ball and O-Ring Joint :- Measurement of Magnetic Force (Step 2 of 3)

Measurement of magnetic force between magnet and steel ball with respect to their separation.

This measurement of the force vs separation is a one time measurement for a particular combination of magnet sizes, magnet strengths (magnet strength is given by grade like N-52, N-42 etc) and steel ball size. But once you have done this measurement for a particular combination, the readings and results can be reused for the same combination. For example in our case we will have to do the force measurements for two combinations- one for the shoulder joint and the other for the hip joint, since we are using different diameter magnets but same sized steel balls.

Things required:

  1. Two strong magnets called primary and secondary magnets.
  2. Steel ball of appropriate size (steel ball size and magnet size are given in the next step- 3 of 3)
  3. M.S nut
  4. Cord
  5. A plastic pouch that can hold about 1 L water, or if you prefer- Various Gram Weights generally available in a school or college lab (multiples of 10 gm going up to little more than 1/2 kg).
  6. Micrometer screw gauge.
  7. Measuring cylinder or measuring cup with volume markings.
  8. Paper or rigid plastic sheet pieces.
  9. Araldite.
  10. Any steel framework - for instance a M.S rack, overhanging piece of rectangular cross section M.S section etc.
  11. A large vessel like a saucepan or a tub.

Procedure:

  1. Please refer to the first diagram for the terminology used.
  2. For the force measurement setup, refer to the second diagram.
  3. Stick the steel ball to the secondary magnet by Araldite.
  4. Magnetically stick the secondary magnet to a steel plate, for instance the bottom surface of a mild steel rack as shown in photo #3.
  5. Sandwich a few pieces of paper or card sheet between the steel ball and the primary magnet. These sheets determine the separation between the two. You may use a micrometer screw gauge to measure the combined thickness of the sheets. Note down this separation.This should be about a few 100 microns. Any thickness from 200 to 500 microns is good.
  6. Magnetically stick an MS nut at the free end of the primary magnet. Loop a cord through the hole of the nut for attaching weights, as shown in the second and third photo.
  7. Secure a pouch at the other end of the cord as shown in photo #4.
  8. Gradually pour water from a measuring cylinder/ cup into the pouch using a funnel (photo #5 and #6) till a point when the magnetic joint between the primary magnet and the steel ball will give way, and the primary magnet will fall.
  9. Make sure there is a vessel kept just below the pouch to capture the falling magnet, nut and pouch containing water. Ensure that no water gets spilled from the pouch when it lands in the vessel, by selecting a suitable small mouth pouch and by placing the vessel just below the pouch.
  10. Note down how much water was poured. This should be recorded corresponding to the separation reading that was done in a previous step.
  11. Restore the setup, but with one sheet of paper/plastic removed from between the primary magnet and steel ball. Measure the new total thickness and note it down. Data could be tabulated as shown in photo #7.
  12. Repeat the steps from 8 to 11 to get various readings of force vs separation. Finally include a reading with no sheets placed between the primary magnet and steel ball, corresponding to zero separation.
  13. Plot the force vs. separation graph which will look as shown in part (b) of second diagram.
  14. From the plot, determine the attractive force between the magnet and ball corresponding to a separation of about 50 to 60 micron.
  15. This value of the force will be required in the next step (step 3/3). Call this force or weight 'R'.
  16. For the shoulder joint the 'R' that I have obtained from the measurement is 470 gm weight, and for the hip joint I obtained an 'R' of 500 gm weight. The measurement data I got and the sizes of the primary and secondary magnets and the steel ball are given in photo # 7 and also in next section titled 'Step 3/3: Joining the parts'. In photo #7 the data is marked red. It is possible that you may get either the same 'R' or different, depending on the grade of the magnet you use.

At the end of this procedure you may realise that since we only need one reading of the magnetic force corresponding to a single separation of about 50 - 60 micron, so you may ask why do we need to measure for other separations. The answer is that the slope of this graph is also important. For stable equilibrium condition, this slope of the magnetic strength graph (its magnitude) should be less than the slope of the O-Ring compression graph.

Even though in the second photograph I have shown the compression graph of an O-Ring along with the magnetic force graph, the measurement of this data is not very critical, as long as you are using regular O-Rings and not a squishy rubbery material (whose spring constant will be much less than a regular O-Ring). The reason for bypassing this compression measurement is that we are using the pre-stress force as a proxy for the amount of compression of the O-Ring. The O-Ring compression measurement and the resulting graph would be required if we do not want to apply the pre-stress force on the O-Ring and alternatively just want to place a thicker spacer between the steel ball and primary magnet (you may watch the video where the STEM is explained). But I suppose, applying a pre-stress force is simpler than measuring the compression characteristics of the O-Ring, hence I have used the above procedure.

Step 12: The Magnetic Steel Ball and O-Ring Joint- Joining the Parts (Step 3 of 3)

Fixing the magnet to the Brass washer while pre-stressing the O-Ring.

Set up and tools required-

  1. Two hollow cylindrical, rigid tubes of ID about 10 mm. This can be- Cap of a sketch pen or a PU tube of ID 10 mm or a home made tube made of epoxy putty (M-seal etc.)
  2. Brass washer size (OD x ID x thickness):- For shoulders- 12 x 5 x 1 - 4 no.s, For hip joint- 12 x 6 x 1 - 4 no.s
  3. O Ring size (ID x thickness):- For shoulder- 5 x 1.8 (ISG Part # 1-009)- 2 no.s. For hip joint- 6 x 1.8 (ISG Part # 1-010)- 2 no.s
  4. Steel ball size for shoulder and hip - 8 mm- Total 4 no.s. (Refer to the last point of the procedure)
  5. Primary magnets size (Dia x length):- For Shoulder- 5 x 5 - 2 no.s, For Hip- 6 x 3- 2 no.s.
  6. Secondary magnets size (Dia x length):- For Shoulder- 5 x 3 - 2 no.s, For Hip- 6 x 3- 2 no.s.
  7. Paper or rigid plastic sheets of total thickness 50 micron
  8. Micrometer screw gauge for measuring paper thickness.
  9. Araldite
  10. Known weights- eg. Water filled bottle

Procedure for making the shoulder or hip joint. Only the sizes of magnets, brass washer and O-rings will be different. (Do refer to the video in step 1 of 3 of the MBOR joint):

  1. Stick the following in a vertical stack with Araldite- One O-ring on top of two brass washers. Make two such sets- for two shoulders or two hip joints.Refer to the size of washers and O-Rings above. Let Araldite set.
  2. Place two hollow cylindrical tubes on a table. The tube is shown as a pink coloured tube in figure 1 and 2.
  3. On each of these tubes place the brass washers that have the O-rings stuck to them.
  4. Draw an equilateral triangle on the table with pencil/ chalk with sides of 15 to 20 cm. The edge length of the triangle depends on the size of a dining plate that you might have at home. The triangle should fit well within the boundary of the circular plate.
  5. Place these two tubes (on which the brass washer assembly has been placed) on two vertices of the equilateral triangle.
  6. Take two steel balls of 8 mm Dia and magnetically stick (no adhesive) two primary magnets, one each to the steel balls (this is described in the video as well). Place a sheet of paper of 60 micron thickness between each of the pairs of magnet and steel ball. The paper sheet will compress to a thickness of about 50 micron due the attractive force between the two. Newspaper paper is about 60 micron.
  7. Place the two pairs of magnet and steel ball on the O-ring as shown in the section view of part (b) of 2nd figure.
  8. Lift the brass washer along with the steel ball and magnet.
  9. Apply Araldite to the bottom surface of the brass washer close to the hole and to the sides of the primary magnets, so that after the Araldite sets it will join the primary magnet to the brass washer.
  10. Replace the brass washers over the respective hollow cylindrical tubes. Ensure the Araldite does not touch the plastic tubes.Hence the tube ID should be sufficiently large.
  11. On the third vertex of the triangle place any object that has a height approximately equal to the height of the assembly consisting of tube, brass washer, O-ring, magnet and steel ball, mentioned in the above point.
  12. On these three 'towers', place the flat dinner plate symmetrically. On the center of the dinner plate place a bottle of weight such that its weight plus the weight of dinner plate should equal 3 times the weight 'R' that was found in the previous step (step 2/3). For eg. if R is 400 gm weight, and if the dinner plate weighs 200 gm, then the bottle and plate together should weigh 400 x 3 = 1200 gm. Hence the bottle with its contents should have a weight of 1200- 200 = 1000 gm = 1 kg.
  13. When the weights are as described above, we have ensured that the force on the steel ball will be 1200/ 3 = 400 gm, by symmetry.
  14. Let this arrangement stay in an undisturbed place for a day, so that the Araldite will join the brass washer and primary magnet. Refer to the third photo.
  15. On the sidelines, stick another two steel balls of 8 mm dia, one each to secondary magnet. Ensure that the polarity is as shown in Photo#1 of step 2 of 3.
  16. Coat the steel balls with a thin layer of Araldite. This helps improve the friction of the balls with the O-ring and also prevents rusting of the steel balls.
  17. Once the Araldite sets, the assembly will be ready.
  18. Remove the steel balls that were placed over the O-rings. These are not part of the assembly.
  19. Place the steel balls that had been stuck to the secondary magnets, over the O-ring.
  20. This completes the making of the magnetic steel ball and O-Ring joint. The puppet body can be stuck to the primary magnet and the arm portion can be stuck to the secondary magnet.
  21. At the end I would like to say that if you are willing to experiment, then try using the following alternative for a a stronger hip joint- (a)11 mm steel ball, (b) 8 mm dia x 4 mm length primary and secondary magnets, (c) corresponding 8 mm ID brass washers that would accommodate the magnets, (d) Larger diameter O-rings - 7.6 mm ID and 1.8 mm thickness (ISG part# 1-011 ), (e) and finally a different sized nut as the pelvic bone or use two GI strips of 4 mm width, and placed side by side to make a total width of the strip 8 mm, that have been bent into the shape of an equilateral triangle. All this will be an experiment, but by making it this way, hopefully the hip joint will be stronger and not too heavy as well, so that the puppet would be able to hold its leg horizontally, which right now is not the case. I will try and make this new design hip joint soon and update it here.

Step 13: Limb-wise Assembly: Check List

In this step I have added photos and checklists of the materials required for making the following four parts of the puppet body-

  1. Head and Chest
  2. Arms and Hands
  3. Legs and Feet
  4. Magnetic Ball and O-Ring(MBOR) joints- Shoulder and Hip joint

*In the MBOR joint photograph, a 11 mm steel ball, 8 mm dia. magnets, larger brass washers and O-Rings are also included, but these will be used for the next version, and can be ignored for this version.

This checklist will hopefully be useful during planning and fabrication of PUBLU puppet. For better organisation I put these set of materials in 4 zip pouches so that I would be able to work on the individual parts separately.

Step 14: Joint Tightness Measurement

The strength of the various large joints was characterised by how tight these were in resisting an applied moment or torque. The moment is measured in units of gm cm instead of N m (which is the SI unit) only for convenience. For measuring the maximum moment, a weight was suspended on the lever arm of the joint at some distance from the axis and the point where the lever arm just gives way to the applied load was noted (Refer to the Photograph). Moment = force x lever arm. As a thumb rule- larger the ball, proportionally more is the resisting moment (or torque) it can exert, for the same frictional force. These are the typical values of the maximum resisting moment for the various joints.

  1. Magnetic Ball and O-Ring joint (MBOR):- 140 gm cm (for hip joint), and 60 gm cm (for shoulder)
  2. Knee joint (O-Ring and Bead joint):- 300 gm cm
  3. Ankle joint (V cut PU tube)- 220 gm cm
  4. Waist joint (V-cut PU tube)- 550 gm cm
  5. Wrist joint (V-cut PU tube)- 70 gm cm . This is shown in the first photo. The nuts have a total mass of 20 gm and their collective center is 3.5 cm from the bead's center. Hence 3.5 cm is the lever arm.

The second photo shows how the masses of small objects were measured. It is a well known pan balance technique. The coins are used as reference masses and the unknown mass is found using principle of moments-

m1 x d1 = m2 x d2

Step 15: Past Versions and Upcoming Features

Evolution of design of past versions -

  1. Around 2004: The first poseable puppet (1st and 2nd photos) was made using ball pen refills for limb segments held together with string running through the holes and yellow clay was for holding the poses. The problem with the clay was, for changing a pose the clay had to be reshaped. The weight of the puppet was also on the higher side, which resulted in the arms to droop if they were posed horizontally. Hence the puppet had to be short (about 10 -15 cm).
  2. 2011: In the second version (3rd, 4th and 5th photos) the joints were made using PU tubes, but all the joints were made of single or double hinge joints. Double hinge joints were used for shoulder and hip joints. There was very little friction between the joints, hence the limbs needed to be suspended by strings secured at a small ceiling like surface above.
  3. 2012: In the third version (6th and 7th photos) the magnetic ball and socket joint was used. This joint was almost a technological revolution ! The puppet could now be posed without the support of strings.
  4. Around 2015: In the fourth version (8th and 9th photos) Cable-tie based hinge joint was introduced for elbow joint. In this version the fingers were also made multi segmented. Small beads cut half way and an elastic cord looped around a pin that went through the hole of the bead held together the adjoining segment forming a tiny hinge joint. This design is similar to the mechanism used in wooden manikins. Though the joint works well, making this joint was very tricky.
  5. 2018: The fifth version (10th and 11th photo) the major changes are the the face and the magnetic ball and socket joint. In this joint larger magnets and steel balls were used for obtaining larger strength of the hip joint. For the hair, silicone RTV sealant was used and graphite powder of a pencil lead was used for giving it color.
  6. 2018-19: The current version of the posable puppet named PUBLU puppet has 7 distinct joints. Notable new joints are the tiny finger joints, shrugging shoulders, strong knee joint, 'V-cut PU tube ball and socket joint'. The head has eyes that can change the gaze direction.

(Even though a timeline has been given, that does not mean I was continuously working on the design. I used to work on the design and prototypes on and off when time permitted)

Upcoming features-

  1. Distinct face for each puppet made using epoxy resin or other suitable materials.
  2. Clothes for each character.
  3. 11 mm steel balls and 8 mm diameter magnets for a stronger hip joint.
  4. Capturing images in 3-D using two angles or two cameras and viewing in 3-D using various devices available today.
  5. And of course, I welcome the Instructables community members to ask questions, post comments and give suggestions about PUBLU puppet's fabrication. Do post your creations, in case you make a puppet. I would love to see your version of the puppet/s !

Other posable puppets in the world:

While I was designing and making prototypes of various versions, I was intermittently checking out the designs of posable puppets that were existing or being unveiled throughout the world. Some are commercially available, others are DIY designs. So here are some designs that I came across in Google searches or otherwise (in shops, books etc.)-

  1. The classic wooden manikin used for art - amazon
  2. Ball and socket metal armatures- kineticarmatures or amazon or animationtoolkit
  3. Ball and socket carbon fibre armature- George armature
  4. Aluminium wire armatures- anibild
  5. Modular wire plug in system- stopmotec
  6. Plastic/ polymer - stickybones or modibot or Stikfas
  7. Patent of a magnetic ball and socket joint (has some similarities with PUBLU's Magnetic Ball and O-Ring joint)- patent

Step 16: PUBLU in Action: Posing Time !

You will notice that PUBLU Puppet can comfortably hold a pose without any support like strings or magnets in the feet. The arms can be easily posed in a horizontal orientation.

Most of the poses have been set up on an ordinary non-magnetic surface. Only for some of the walking/ dancing poses, an Iron flat pan has been used for the magnets of the feet to stick on to. A flat cookie tin could also be used as a base.

Some photos are close-up views of the hand and fingers to demonstrate the wide variety of poses and the resulting expressions possible. The YouTube video posted in the beginning of this Instructable (link provided here as well) gives an idea of how easily the poses can be transitioned from one to another. The story - 'PUBLU and Rubberdy' is essentially a slide show with music and sounds added in. In the video the facial expressions have been manipulated by drawing the mouth and eyebrows with pencil (the mark can be erased with a rubber eraser and a new expresssion can be redrawn). The eyes and eyelids have also been manipulated to get the required expressions.

Step 17: Academic Relevance: Broader Context of Story Telling Techniques and Design Process

In terms of academic relevance, I have already talked about STEM in the introduction section, and you might have seen in the fabrication steps how this puppet building is a good STEM exercise. In this section I have penned down my thoughts about how this designing and making process fits into a broader context and lessons learnt.

Broader context of story telling techniques: If a spectrum were to be made of the different story telling techniques in terms of the complexity involved in their production, the Photo-comic technique would lie somewhere between a comic book and a movie with actual people, or a stop motion animation movie. According to me, this is how I would rate the different story-telling techniques (this is not an exhaustive list and the sequence is debatable ) in order of increasing complexity of production, considering the same running duration, and assuming the story is ready. This sequence does not in any way imply that writing a novel or verbally telling a story is easy. The techniques that appear at the beginning of the list are just less costly in terms of material and costs, and not necessarily less demanding in terms of intellectual effort by the creator/ narrator. Here is the list-

  1. Live person to person story telling without props.
  2. Novel
  3. Audio book/ radio plays
  4. Comic book
  5. Photo-Comic
  6. Live puppet show with puppets and props
  7. Human actors staging a play
  8. Movie with human actors and props
  9. 2-D computer animation
  10. Movie with human actors and special effects
  11. 3-D computer Animation
  12. 2-D hand drawn animation frames.
  13. Stop-Motion Animation

As we move down the list, we add in more sensory inputs. This sequence, in my opinion, is in decreasing order of scope for imagination available to the reader/ viewer/ audience! For instance, reading a novel or comic lends itself to wider interpretation and scope for imagination by the reader in terms of imagining voices of characters, guessing the mood of the scene without background music etc., compared to watching a movie that has so many sensory inputs- moving visuals, dialogue, background music and sounds.

Design Process:
While designing all the joints of this puppet, I would like to mention the strategy that worked for me. I realized some years back, that I was juggling between 4 kinds of activities intermittently- 1) directed thinking and imagination, 2) sketching and note-making, 3) trial and error (prototyping) and 4) letting ideas to incubate/ allowing the brain to work on the problem at the subconscious level- basically do something else :) ! One more attitude that worked well - Though I generated a handful of ideas, I was not hesitant to reject my own ideas and look for better ideas. These kind of techniques are mentioned in Design practice books; experiencing it on your own is different than simply knowing the methods.

STEM Contest

Runner Up in the
STEM Contest

Be the First to Share

    Recommendations

    • Indoor Plants Challenge

      Indoor Plants Challenge
    • Trash to Treasure Contest

      Trash to Treasure Contest
    • Sculpting Challenge

      Sculpting Challenge

    9 Discussions

    0
    s0200311
    s0200311

    17 days ago

    Fascinating. I love it!

    0
    guavamarket
    guavamarket

    Reply 16 days ago

    Thank you ! Very happy to know you like the work :)

    1
    botinabox
    botinabox

    5 weeks ago

    Outstanding job! Love the puppets, their tiny little arms, legs, hands, feet, and faces, and well as the intricate details of the physics, materials, and design processes and that went into making them. :)

    2
    guavamarket
    guavamarket

    Reply 5 weeks ago

    Thank you for the wonderful feedback! I sure enjoyed the design process and the outcome :) !

    2
    wpdiamond
    wpdiamond

    Question 2 months ago

    I think this is a great project and the results are incredible. I'm a teacher and was wondering about how much all of the materials cost to make one of them? I apologize in advance if you included this in your thorough write up and I overlooked it.

    0
    guavamarket
    guavamarket

    Answer 2 months ago

    Thank you for the compliment! I am happy to respond....The cost of material required for one puppet came to not more than ₹ 300 INR or about $ 4.50 USD.

    0
    wpdiamond
    wpdiamond

    Reply 8 weeks ago

    Thank you for your response! I think I'm going to give it a try!

    2
    jessyratfink
    jessyratfink

    2 months ago

    I love this project!! What fantastic documentation, too :D

    0
    guavamarket
    guavamarket

    Reply 2 months ago

    Thank you for the great feedback !