Introduction: Skeleton Run
This Halloween themed project is an animated skeleton with a manual mechanism that simulates walking on the spot as the handle is turned.
The skeletons head contains red LED's that flash as the handle is turned, the flashing being controlled by the rate of rotation of the handle.
Manual turning of the handle acts as an on and off switch which allows the LED's to be maintained on as a night light or turned off when not required.
The skeleton also glows in the dark using Luminous filament once exposed to a bright light source.
Attachments
Supplies
3D Printer
Filament Luminous
Filament Black
Wire 1.22mm plastic coated steel wire
Wire 1.5 mm steel wire
Red LED 5mm - Qty 2
Resistor 330R - Qty 2
Transistor PNP ZTX751 or equivalent (Eg. MPS751 or KSA708YBU)
Hall sensor Sensor DRV5032
Magnet 3mm ball or alternatively 3mm x 1mm disc
Pin Header right angle - 5 pins
Pin Header straight - 2 pins
Stand off M3 x 5mm
M3 nut
Self tapping screw M2 x 6mm - Qty 2
Self tapping screw M2 x 8mm - Qty 2
Bolt M2.5 x 30mm - Qty 3
It may prove more cost effective to buy a range of values rather than individual values unless you already have them available. Some components may also have a MOL greater than the quantity specified in the component list.
No affiliation to any of the suppliers used in this project, feel free to use your preferred suppliers and substitute the elements were appropriate to your own preference or subject to supply.
Links valid at the time of publication.
2mm drill bit
2.5mm drill bit
Drill
Saw
Pliers
Soldering Iron
Solder
Sanding paper
Wire wrapping tool for 30 AWG wire
Plastic glue
Clear Tape
Know your tools and follow the recommended operational procedures and be sure to wear the appropriate PPE.
Step 1: Design
The design was created using BlocksCAD
This consisted of three main parts, the skeleton, driver and flasher..
The skeleton is made up of 15 parts, head, upper torso, lower torso 2 x (upper arm, lower arm and hand) and 2 x (upper leg, lower leg and foot), with the joints made using pivot hinges.
Loops to attach the wires are included on the hands and the lower leg.
The driver is made up of 14 parts 4 x (sides), top, centre separator, crank shaft, 4 x (rod bearing), 3 x (handle)
Additionally, 4 piston rods made from wire, 2 x M2 screws and 3 x M2.5 bolts.
The flasher is made up of two parts the enclosure and the disc.
Additionally, a ball magnet, screw and electronics are required.
The details of the flasher electronics are in another step.
Attachments
Step 2: Printing
Print details.
All elements are printed in PLA. (Skeleton in Luminous filament and Base in Black Filament)
Layer Height: 0.15 mm
Infill Density: 100%
Base Adhesion: Skirt with the exception of the Spindle which uses a Brim.
Brim is used on the spindle due to its small contact area with the bed which without can easily detach, ruining the print.
Step 3: Skeleton Assembly
The skeleton is designed to need no glue or screws for assembly and everything is a push fit.
Remove any blobs, strings or blemishes on the contact surfaces and ensure they are smooth by light sanding or filing.
The limbs on the skeleton are designed to be loose.
Ensure the loops for the wires are facing backwards and clear to allow the manipulating wires to move freely.
The upper and lower limbs for the legs are interchangeable between left and right with the exception of the feet which have a defined side.
The upper and lower limbs for the arm are interchangeable between left and right with the exception of the hands which have a defined side.
The upper and lower torso are designed to be a tight fit but does allow positioning.
Assemble the legs and push into the pelvis.
Assemble the arms and push into the shoulders then insert the caps to hold them inplace.
Press the upper and lower torso together.
Push the head onto the neck.
The size of the skeleton is 120 (L) x 50V(W) X 20 (H) mm
Step 4: Base Assembly
Crank
The crank has 4 rod bearings in two sizes and these are a push fit onto the crank.
The wider bearings fit on the outer part of the crank and the shorter bearings fit on the inner part of the crank.
They are designed to be push fit but will require a little pressure to fit in place.
Prior to fitting the bearings ensure the surfaces of the crank and bearings are free from abberations to prevent the bearings binding.
Press the appropriate bearing on to the crank being careful to hold the crank as close to the bearing as possible to reduce the likelyhood of snapping the crank. You may need to put the bearing on a flat surface and apply pressure with a flatblade screwdriver to the part of the crank in the centre of the bearing.
Repeat the process for the remaining bearings.
Support
Fit the central support by pushing it onto the central part of the crank a slight twist will be required allow it to slide into place.
The support rod is made of 1.5mm steel wire cut to a length of 62mm, file/sand 5mm from the end of the wire to remove and residue and wipe with a lint free cloth to which has been applied a little IPA or similar degreasing solvent.
Hold the wire in a non conductive clamp and tin the end just cleaned with solder. Allow to cool.
Secure both the M3 x 5mm standoff and the wire in non conductive clamps with the tinned end of the wire pushed into the standoff and solder the two together. Allow to fully cool before touching or moving.
Push the threaded end of the standoff into the hole in the grid and fit a nut to hold it in place.
Sides
Fit the sides with the holes to the crank one on either side these are interchangeable allowing either to be used as left or right.
Apply a little glue/cement on the top lip of the sides.
Sit the grid onto the top of the sides with the centre support pushed into the central slot in the grid the centre support is keyed to only fit one way with a cut out that sits under the nut.
Manipulators
Drill a 1.5mm hole in the centre of the lower torso between the legs and sit the skeleton onto the wire, no glue was applied allowing the body to move slightly due to variations in limbs and wire length which otherwise could result in stopping the movement. If glue is required because it is too loose use a flexible variety.
Install the 1.2 mm manipulator wires into the holes in the rod bearings and out through the slots in the grid.
The manipulator wires are different lengths for the arms and the legs with the same bend angle of 56 degrees.
Arm wire length = ~93.5 mm (2.5 (rod insertion) + 34 (56 deg bend) + 45 (90 deg bend) + [6 + 6 hook bends]) minimum
Leg wire length = ~68.5 mm (2.5 (rod insertion) + 34 (56 deg bend) + 20 (90 deg bend) + [6 + 6 hook bends]) minimum
Always better to err on the side of caution and start with a slightly longer length of wire as minor adjustments may be required in length and angles due to variations in joint variability.
Apply a little glue/cement into the 2mm holes in the rod bearing and insert the wire end.
At the 90 degree bend towards the end of the wire insert into the loop in the limb and apply a 90 degree bend to prevent it slipping out.
Crank Handle
Fit the front and back sides which are interchangable with each other allowing either to be front or back.
Apply a little glue/cement on the top and vertical lip of the sides.
The revolving crank handle is made up of three pieces; handle, spindle and crank.
Align one end of the spindle with the 2mm hole in the crank and insert am 8mm screw through the crank into the spindle.
Slide the handle onto the spindle and through the hole in the top of the handle fit an M2 x 8mm screw tighten enough to allow a little play between the handle and the spindle to allow free rotation.
Fit the rotating crank handle onto the long spindle protuding from the base and secure with an M2 x 6mm screw through the hole around the perimeter.
Testing
Rotate the crank handle clockwise to animate the skeleton to perform walking.
At this point adjustments may be required should the animation stall.
If the wire is too long the limb will stall going forward before the crank reaches or passes dead top centre.
If the wire is too short the limb will stall going forward after the crank reaches or passes dead top centre.
This issue could also occur at dead bottom centre separately or jointly at both top and bottom.
Quick adjustments can be made before or after the 56 degree bend by rebending prior to this or a little more involved by rebending at the hook to shorten or lengthen the wire at these points.
The base when assembled measures 62(L) x 44(W) x 40(H) mm
Step 5: LED Flasher
The circuit consisting of the sensor, 3 x resistors, 2 x LED's and a transistor are build on a small piece of stripboard and are housed in a purpose build 3D printed enclosure which is attached to one end of the box.
The stripboard layout is orientated such that the position of the hall sensor is located within the path of the magnet as it rotates on the disc.
Once the circuit is build test it to ensure it works prior to assembly in the enclosure ensuring it aligns with the disc.
Step 6: Flashing Eyes
The circuit with enclosure is an add on used to enable the flashing mode only.
The flashing eyes are controlled by the rotation of the handle which moves a ball magnet passed a hall effect sensor the output of which is connected to a PNP transistor via a base resistor. The PNP transistor has its emitter connected to the supply and its collector connected to 2 red LED's and resistors.
In the absence of a magnetic field the sensor output is high reverse biasing the base and turning the transistor off.
When a magnetic field of either polarity is detected the output of the sensor is low turning the transistor on, this effectively connects the LED's to the supply (less the transistor Vce), turning them on.
Thus rotating the handle results in the LED's flashing off and on. The rate of the flash is controlled by the rate of rotation of the handle, faster rotation, faster flashing and slower rotation, slower flashing.
Disc
Into the disc is attached the ball magnet into the ready made hole with glue, the disc is then fixed to the crank axle with an M2 x 6mm screw. Do not press the disc too far on the axle as it will rub against the supporting wall.
The assembled circuit slides between the channels with the hall sensor protruding over the orbital past of the ball magnet.
LED's
The 5mm red LED's are connect with 30 AWG white wrapping wire (~180 mm pre length).
Insert the LED's into the eye sockets of the skeletons head from the back, apply glue to hold in place if necessary.
Run the wire around the back of the head and down the neck and spine down to the back of the support rod, apply glue as required to hold it in place. At the edge of the grid behind the support rod drill a 2mm hole and feed the wire through.
Align the enclosure with the end of the base (apply tape to hold it in place) and using the holes in the enclosure as a guide drill through the base with a 2.5mm drill bit.
Remove the enclosure and feed the wire from the LED's along the lip and through the top right hand hole apply a little glue to hold it in place. Connect the wires to the resistors and 0V and ensure they are pushed to the side, so as not to foul the mechanism.
Fix the enclosure to the base with 3 x M2.5 x 30mm bolts (leave the hole coincident with the wire blank), so as not to damage the wire.
Power
Power is provided via 5V USB socket which is attached to the enclosure with two M2 x 8mm bolts and directly wired to the circuit.
However, the circuit can also be powered by batteries 2 x 1.5V, do not exceeed 5.5V as this will damage the circuit.
The base when assembled with the flasher enclosure measures 84(L) x 44(W) x 40(H) mm
Step 7: Operation
Apply power via the USB input or alternatively 3V (~2.5V min.) with batteries.
If the LED's illuminate then rotate the handle and they should turn off and with continued rotation turn on.
If the LED's are off then rotate the handle and they should turn on and with continued rotation turn off.
Step 8: Finally
If you got this far thanks for taking the time to check out this project.
Participated in the
Halloween Contest
