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Design and technology

Level 2

Andrew Murton

Step 1: the Brief

Conceptual statement

Machines are needed to move things under control of either human or computer. They are generally needed to enable humans to either move heavy/difficult items or perform repetitive actions. Example include earth moving equipment that use hydraulics and assembly robots on production line that use motors. In certain environments where safety is an issue it is important for humans to be isolated from hazards when they are handled. For my client Mr Richardson. For him I am required to produce a prototype that allows a human to move a small container of hazardous material remotely between defined locations.

Specifications

· A defined container must be able to be moved within the defined envelope.

· The movement must be able to be controlled by the hand.

· The operator must be at least 500mm from the container at all times.

· All controls to be fitted in a single package

· A rotary base must be used as per provided drawings.

· Structural elements are to be made from the materials provided.

· Materials used must be processed within health guidelines.

Step 2: First Task Research

These are the hazardous containers the robot arm has to pick up they are 110mm long and 54mm diameter.

the side view of the distance that the arm needs to reach and the lay out the robot arm needs to move in the hashed area is the minimum amount it has to move. The distance from the pivot is 350 mm.

Step 3: Stakeholders

My main stake holder is Mr Richardson as I’m making a prototype robot arm for him.

Wider stake holders are: * Osh as I have to build this in a safe manner using machinery that is safe for me to use. * The tech department as they supply the materials I’m going to use and the tools. * The laser cutting company as I may use them to cut my parts. * Anyone else that helps me in ideas that lead to the development of my prototype.

Early stake holder interviews.

Mr Richardson Does the base of the arm have to be in the center of the pivot?

No it can be on the outer edge of the turn table.

Can the container be picked up with a rod through the tube? No as they are solid containers with end caps.

Can they be picked up with some sort of electro magnet? Yes as they have steel tube in them.

Step 4: Key Factors

:As this is my first project my knowledge of what techniques that can be implemented is minimal so in the design of this my options are minimal so this is another key factor I have to consider in my design.

:As this is a school project and I am constrained to time and materials available this is a key factor in my project.

:My design is also constrained to the machines available at this school.

:Another key factor is that my design has to be able for a human to easily be able to understand and operate my project.

Step 5: Main Research

picture 1

Hydraulic digger. This digger is designed to use hydraulics to dig dirt, rock and other material. It also has lots of other attachments that can be used for a myriad of tasks. My robot arm will use a similar arm design to this to gain full movement needed for the task.

picture 2

This is a robot arm that is similar to what I will be designing and prototyping. It has the basic arm design of the digger but has extra rods to keep the head 90 degrees from the ground to make it easier to pick up the objectives. The use of a vacuum griper works well in some cases but in my case it won’t work for my robot arm.

picture 3

I like how the use of springs to counteract the weight of the lamp. This can be incorporated in to my design as it will accommodate for the weight of my arm so my hydraulics only have to carry the weight of the objective making the movement of my arm a lot smoother and more precise because it does not have to carry its own weight and the objective.

picture 4

As there is many different Mechanisms for gripping the Container but many are too complicated Or too time consuming for me to design and Include into my design/ build or though The better they are designed the more Precise and stronger grip but I have to be Able to fit into my total build.

Step 6: More Stake Holder Interviews

Discussion

with Mr Richardson

· What other specifications would you like to have incorporated in my design and why?

1. All the controls brought together in a simple controller design that’s clean and easy to use.

2. Minimise all waste and reuse when possible.

Any products, materials or techniques would you like to be used in my design and prototyping?

1. Try and use products that are available and are cheaper.

· Any safety features do you want to have included in my design?

1. During testing have at least as possible of pinch points and other areas that that can be harmful to the operator.

· Any cultural aesthetics would you like to be included in the design of this product? For example it could include the shape in the design or choice of colours.

1. Have a clean design that looks more like a robot arm.

· What is the distance the robot arm needs to reach?

· The radius of the circle is 350mm

Step 7: Developed Brief

Conceptual statement

Machines are needed to move things under control of either human or computer. They are generally needed to enable humans to either move heavy/difficult items or perform repetitive actions. Example include earth moving equipment that use hydraulics and assembly robots on production line that use motors. In certain environments where safety is an issue it is important for humans to be isolated from hazards when they are handled. For my client Mr Richardson. For him I am required to produce a prototype that allows a human to move a small container of hazardous material remotely between defined locations.

Specifications

· A defined container must be able to be moved within the defined envelope. 350mm diameter.

· The movement must be able to be controlled by the hand.

· The operator must be at least 500mm from the container at all times.

· All controls to be fitted in a single package

· A rotary base must be used as per provided drawings.

· Structural elements are to be made from the materials provided.

· Materials used must be processed within health guidelines.

· Have all controls brought in to one place which is clean and easy to use

· Minimise all waste and reuse when possible

· Use products that are available and cheaper

· Have a clean design that looks more like a robot arm.

· During testing have at least as possible of pinch points and other areas that that can be harmful to the operator.

·

Step 8: Materials Research

Tensile strength

Acrylic has a relatively high tensile strength compared to other plastics.

MDF is at thin sheets has very little tensile strength

Steel has very high tensile strength for its size.

Aluminium has quite high tensile strength but not as much as steel.

toughness

Acrylic is quite impacted resistant but is still quite brittle

MDF is quite impact resistant but dents easily

Steel is very impact resistant and wont snap

Aluminium is quite tough and resists impacts.

Ductility

Acrylic is flexible somewhat but is quite brittle although it can be heated up and bent in to any shape.

When thick enough MDF is quite rigid but will snap on sharp corners

Steel is somewhat ductile but if bent to many times it will become brittle and snap.

Very ductile and malleable and can be bent to a certain extent but will start to crack.

Durability

acrylic is durable but not scratch resistant

MDF is reasonably hard but is still a lot softer than most wood, less dense.

Steel is very durable but will scratch.

Aluminium is the next step down in durability from ferrous metals.

weight

acrylic is not very heavy

MDF is very light but comes at a cost of strength

The only downside of steel is that it is very heavy

Aluminium is a lot lighter than most other metals

colour

Acrylic comes in many different colours

After sealing the MDF you can easily paint it any colour and get a good finish

The steel sheet that is available is coated with zinc and paint but can be repainted to suit your needs.

Aluminium in its self has a very nice finish.

Corrosion resistance

Acrylic is UV resistant and doesn’t corrode

MDF doesn’t rust but is susceptible to water and it will swell and delaminate but it can be treated with varnish to stop water getting to it.

Steel will rust/corrode but the sheets already come coated in zinc and paint to stop the air and moisture getting to the metal.

Aluminium does not rust or corrode because of its chemical property’s protect it because it forms a oxidized layer that is held on very hard to the surface.

·
Overall I found acrylic to be the best for my project because of the characteristics it has making it the best for the job. I will be using acrylic in my project because it is easier to manipulate, cut and form compared to metal but also much stronger and durable then MDF and also it doesn’t rust, corrode or decompose in sun light. The cost compared to aluminium is similar but acrylic is lighter than aluminium and easier to cut and form it in to shapes. Acrylic is available as it is provided but the school where not all types of aluminium is available. And steel is plain to heavy and hard to manufacture in to desired design.

Step 9: Further Research

picture 1

In further research I found that if I use 2 different size syringes to give more force applied to the arm compared to having all the strain put on a small syringe but the trade-off is the distance the small syringe has to travel more distance.

Gaining control

picture 2

The use of syringes to manipulate my robot arm has its benefits and its drawbacks: first they provide plenty of pushing power, they are available at school and are cheap the down sides are that the don’t have very much movement and the retracting force is minimal as it relies on a vacuum. The reason I chose to use these over the superior option of using linear actuators is they are available at school and don’t need separate controllers just have another syringe attached that the operator can push and pull against to get sufficient control of the robot arm.

picture 3

an other option is to use linear actuators as you can get them down to very small sizes. They also have quite a lot of force both out and in but still have more travel than syringes and they are easier to mount so these would be the best option for my design but the reason I chose not to use them is because they are expensive and are not available at school so I would have to buy them myself and buy electronics to control them.

picture 4

Servos are another option as the act as the pivot and the way of moving the arm so it would be a quite a compact way of controlling The robot arm with precise control but the reason I chose to not use these is because, one they are not available at school so I Would have to go out and buy them and to get ones with sufficient Power they are really expensive and require remote control which Also if not personally had it would be another expense I would have to pay over $100 and would take time to be shipped to new Zealand so I chose not to go with this option which Mr Richardson also agreed with.

Step 10: Initial Concepts and Modelling

picture 1,2,3

This concept I chose to try and use a counter leaver style

design which gives good leverage but since I chose acrylic it would put too much stress on the joint and may snap it and all so I would have problems with having the syringe not being able to bring the arm back up so I did not use this in my final design. As from card modelling and testing on the board that has all the dimensions required it would be able to reach far enough but Mr Richardson and I were worried that either the syringe would not be able to bring it back up or the acrylic would snap.

From
card model testing this concept I found that the general dimensions allowed for almost sufficient minimal distance required but to use syringes to control it would not work for example the syringe on the second pivot would have to do all its work on the pull back for one it’s not designed to have a very good vacuum and also for the operator to pull the syringe back they cannot multitask and use the other controls as well. From discussion with Mr Richardson we tried attaching the syringe underneath but having certain brackets to hold them it would not reach far enough so we decided not to develop this idea as it had other problems like retraction on the main arm syringe.

Step 11: Concepts

gripper 1

My first concept is the idea I have chosen to use in my robot arm as it is simple to build because it only has one moving claw. And implement in to my robot arm as I can use available materials such as acrylic and syringes to power it. From discussion with Mr Richardson he liked this one the best because it looked the beast and was the simplest out of all of them to build and it could be made from available materials. Also if I cut the claw to the same diameter as the container it would naturally stay together so you don’t have to constantly apply pressure to keep the grip on the container.

gripper 2

This concept is similar to concept one but instead of having one moving claw it has two which makes it easier to pick up the container and can still be made out of available materials but from playing with another robot arm that has this idea implemented when using syringes when closing the claw the syringes would move to one side or to the other making the claw malfunction which I did not my robot arm to have the same problem so I chose not to use this concept.
gripper 3

For concept three I have used the idea of having a worm gear/ screw clamp which would give a very strong hold on the container but since I am constrained to time and resources to implement this idea I my robot arm as I have to get around having a motor powerful enough to clap tightly and not have the whole thing bind up so I chose not to use this idea

gripper 4

For concept four the use of an electromagnet is practical as it has no mechanical moving parts but one down flaw is that the metal tube in the container makes the container naturally roll close to the ground due to gravity so the electro magnet is not able to get close enough to reliably pick the container up and move it around. So I have chosen not to implement this idea.

gantry robot arm

The idea of using a gantry style robot arm has one great of that the weight of the arm and the container don’t actual have to be lifted and only the container is being passively moved around but the main flaws in this concept was that even though it would put less stress on the syringes they would not move far enough and for me to use belt drives and gears it would take longer to make as it is more complicated and they are not available resources supplied by the school.

chosen concept picture 3

This is my chosen concept to use in my build because it gives a lot of movement for a small movement of the syringe. For my gripper I chose to have one claw fixed and one moving and have the whole set up hanging and using gravity to keep it perpendicular to the ground at all stages of the arms movement. For the main arms acrylic is the most suitable as it is easy to manipulate and is light but is still strong enough when all held together. For the pivots aluminium channel is best because it is stronger than acrylic and is already in the shape needed for my design and is lighter than steel. This concept meets my specifications because it looks like a robot arm, it can use available materials including syringes and it can reach far enough to the minimum required distance of 350mm.

The reason I chose to use this concept is because it is able to reach almost all the specifications for example…..

· It is able to reach the required distance and still able to come back right in

· it can be made out of the available resources as it can be made out of acrylic and syringes to control it

· it has a clean design and looks like a robot arm

· It will fit in well with my claw.

· After desiccation with Mr Richardson we decided to go with this idea and have the claw freely hanging so as he moves the arm out it will stay perpendicular to the ground.

Step 12: Syringe Mounting

For mounting the syringes was the next task so looking at others and trying

my own ideas I found that the best option was to use pre made channel because after trying is myself when bending the aluminium it snapped and after talking to Mr Richardson he showed told me that to bend it fully I would have to bend it partially and heat it up and let it cool before bending it again which takes up time and would not be as accurate as the pre made material which is also available at school.

Step 13: Tools Techniques

Band saw

Techniques.

Don’t rush and don’t take sharp corners you may break it. The alternative is to cut it by hand with a hacksaw but is slow and hard to keep it accurate. Another option is to get every this lazar cut which is the best option but since this is a proto type I would only laser cut the final product which I don’t have time to do. As I have tried this I found the ban saw gave the best quality of cut and in the least amount of time Health and safety. To keep it as safe as possible maintain the machine according to instructions and do not remove guards.

Drill press
Techniques

With acrylic and drilling go slow and don’t sharpen the drill bit it will just grab and shatter your work. Another option is to use a hand drill but you can’t keep it perpendicular to the ground so I chose to use a drill press Health and safety Wear safety glasses and clamp down work. Make sure the drill is on the right speed setting.

File
Techniques

Don’t draw back towards you to keep the surface at 90 degrees. If the file is clogged use a wire brush to clean it. Another option is to use a belt sander but you can’t get in to the tight corners so at the end when I go back and clean up the edges I will use both of these in construction. I have also practiced this technique on acrylic as it may not work on other materials and I found draw filing takes material off faster and still keeps a straight edge. Health and safety. Check to see if the file has a secure handle so to keep the metal from accidentally stabbing you.

Hack saw
Techniques

Stand with a stable stance and hold it with one hand on each end and being careful when starting go slow and don’t pull backwards to hard. I could also use a jigsaw but they can be too violent and crack your work. Health and safety Check the blade is sharp and in the right direction.

Step 14: Extra Key Factors.

· One factor is not just time but shearing the tools as we are in a school environment.

· One other key factor is the availability of my stake holder.

· another is maths ability as it is possible to mathematically work out all the sizes need but am not capable of the calibre of maths so in a small amount of parts I have to use guess and check.

· Time scale as I am working on this at school and only some at home it restricts me to how complicated I make this project.

· Cost as the school doesn’t provide any more money then what they use for materials I cannot go out and buy specific materials without using my own money.

· Having everyone make the same base designed by Mr Richardson it saves me time and makes the build process easier as its predetermined and I only have to build off it.

Step 15: Fixings Research

I chose to use

threaded rods and bolts as the rods I can cut to the as act length I need and be able to adjust it from each sided and for the bolts I use them when I am only able to attach from each side for example when mounting the syringes and have them pivot. I chose to use these because after discussion with my main stakeholder Mr Richardson we decided these were the best option over using shaft and bearings with c clips they would be better but would take more time and the materials are not readily available to me without having to go out and find them.

Step 16: Build Phase

This is my first pivot that attaches to my turn table. picture 1

I decide to use pre made channel for my pivots as it saves time and saves me bending aluminium which requires heating to allow to father bending it, so I chose this direction. As a benefit it gives a pre-set dimension I can go back to and having 3 of these in my arm they keep everything parallel. For this part aluminium is the most suitable as it is still easy to manipulate in to desired shape as it is already in a channel shape but is not as flexible as acrylic so it is suitable for the use in the base pivot.

This is my two parts of the main arm. picture 2

In this photo I was filing them down to the same size and testing what finish I can get on them as using a ban saw to cut the was the best option but does leave marks. Too keep them parallel when drilling and sanding I would put a spare drill bit in the hole drilled prior to the one I was drilling at the time to keep them lined up. For all pieces I am leaving the covering on to last as it protects it from scratches. Also when drilling I clamped them down and used none sharpened drills to minimize the chance of cracking the acrylic and I used a separate drill bit to align the two pieces together then drilled them both at once to make sure they are exactly the same. For its suitability for the main arms acrylic is easy to cut and sand to a nice finish and when held together it is strong enough and does not flex were steel or aluminium are over kill in strength but are too heavy.

For my gripper..... picture 3

I went with the idea of having one half fixed and the other half moving to keep the movement as simple as possible. To cut it out I cut multiple slots in the concave part and then went back and cut the pieces out because the ban saw blade is too wide for that radius as it is made for bigger materials but I chose to use it because it is faster and more accurate than cutting by hand.

Health and safety When cutting the acrylic I made sure the ban saw back stop was as low as possible. I used safety goggles to protect my eyes from any airborne pieces that could damage them. I also wore earmuffs to protect my ears from too loud sound produced by the saw. I also asked Mr Richardson the safest way to use the ban saw which in clouded keeping my hands as far away as possible.

picture 4

This is the first assembly of my three parts of my arm. The main arm, the forearm and the wrist which uses gravity to keep it perpendicular to the ground as the arm moves out.

picture 5-6

During testing I found the claw to work very well in fact with no pressure from the syringe it held the tube just fine and having cut the claws to the same diameter as the tube when gripping the tube fits perfectly and tightly.

Health and safety

When drilling the acrylic I used safety goggles and removed any loose clothing. Also I filed and sharp edges off so no one gets cut.

picture 7

In this photo it shows the whole gripper assembled and how
the whole set up hangs perpendicular the ground so were ever it is on the board it still can grip the tube because it uses its weight to hang down. While testing I found that my claw was wobbly because if I tightened the bolts any more it would flex the acrylic so I talked to Mr Richardson about it and we came up with the idea of having tubes slid over the rods that are cut to the right length so I had something to tighten the bolts against to. For the claw acrylic is the most suitable as it needs to be easily cut in to tight curves to be able to pick up the container. It is also strong enough. From initial functional testing the gripper, because of the physical design stays closed on the container even with ne pressure on the syringe which is one of the reasons we chose to use this idea over the others which helps in the controlling of this robot arm.

Step 17: Functional Testings While in Build Phase.

picture 1

During functional testing I found that my elbow joint did not move far enough so after discussion with Mr Richardson and trial and error by moving the syringe pivot up and down I moved the hole for the syringe pivot closer the pivot point to give more movement which it now moves the right distance but still retains enough leverage to lift the arm but now I could not bring the arm back far enough because it was stopped by the syringe so I asked Mr Richardson if I could move my whole base back slightly so it would come back far enough and still reach out far enough and he said yes and shown in this photo it still reaches the minimum limit it has to reach and pick up the container.

picture 2

As seen in this photo I chose to bring the pivot on the base
right to the edge to give the most distance for movement of the syringes and the least they have to move the more I can move the joints away from the pivot to give more leverage for the syringes to push on and results in a smoother more accurate movement of the arm in total when picking up the object.

Also I found having to undo and tighten lock nuts every so often is very time consuming but Mr Richardson gave me the idea of using normal nuts for the build and then replace them later.

picture 3

Here my arm is fully extended proving it can reach the max limit to match the specifications set by my stakeholder Mr Richardson.

picture 4

With my main syringe upon testing it moved far enough but
was not able to retract the arm as it was to heavy so I discussed the Idea with Mr Richardson of using a spring to help the retraction of the arm but the only problem was that to find a spring with the right tension would be hard then I remembered I had some bungee cord from when I went bungee jumping which has hundreds of small strands that I could keep adding strands till I get the right tension and after testing it works well. And now I have it tensioned to a point where it will auto retract even when fully extended and with the container which helps a lot with the controlling of its movements as you don’t have to put much effort in to retracting the syringe which in testing Mr Richardson found very helpful.

picture 5

In some more testing I asked Mr Richardson to place the
object any wear on the board and what I found was I could turn it one way but bring it back the vacuum in the syringe wasn’t strong enough to bring it back so I talked to Mr Richardson about getting some lead to balance it out but he reminded me that lead is poisonous so I had to come up with some other weigh which he gave me the idea of using a scrap piece of steel and screw it to the turn table.

Step 18: Bringing All the Controls Together

For bring all the syringes together in to one control panel I had the idea of just getting a piece of wood and drilling 4 holes in it and attaching the syringes to it and from discussion with Mr Richardson he said this was the best option as we have spare wood in the materials class so I went and found a piece about the right size and measured it out to fit 4 syringes and after cleaning it up Mr Richardson thinks it looks good. I have also placed them so the two main arm controls for one hand and the gripper and rotational syringe for the other hand to make it easier to control it. Also Mr Richardson wanted me to name each control to make it easier for him to learn the controls.

Step 19: Final Evaluation of Specifications

· A defined container must be able to be moved within the defined envelope. picture 1

In this photo it shows my robot arm working in the constraints of the defined minimum area it has to move which it does with ease.

· The movement must be able to be controlled by your hands. picture 2

In this photo my robot arm meets the specification of being able to be controlled by your hands because it has all the syringes attached together.

The operator must be at least 500mm from the container at all times. picture 3

In this photo I have a ruler showing that the control board is at least 500mm away from the user at all times because I made sure when cutting the pipe I gave and extra 500mm to each piece

All controls to be fitted in a single package picture 4

To bring all the syringes in to one package I drilled 4 holes in a piece of wood and screwed in the syringes in so they are all held tightly together in a single package. Which are aligned for easiest control and are named so is easier for Mr Richardson to learn the controls.

A rotary base must be used as per provided drawings. picture 5

My base was built exactly to the provided drawings and then I worked around it to build my robot arm. By measuring and remeasuring a was able to get my base as close as possible to the provided drawings.

· Structural elements are to be made from the materials provided. picture 6

As shown in this picture my structural parts of my robot arm my frame is made from acrylic that is provided by the school and also the aluminium. This is one of the reasons I chose to use these materials because they are already provided and I don’t have to go and find them.

· Minimize all waste and reuse when possible

To minimize waste and reuse when possible I started off by using old syringes and only replacing the ones that needed it I also used scrap acrylic and aluminium to make my brackets Before and during I have chosen materials that are cheap and available at this school for example have used acrylic which the school provides and scrap aluminium for the syringe holder at the base.

· Have a clean design that looks more like a robot arm. picture 7

As from discussion through the whole project I have seeked feedback from my stake holder to gain the best idea of what he wants but for this specification I was not able to reach as in the start I did not ask him to be more specific so when designing this robot arm it meet all the functional specifications but how it was designed it was very difficult to cover all the workings to make it look to how I now know he actually wanted like this photo but he did like how it was still as clean as possible and was simple in design Were it need 1 less controls because it had the claw just Hanging due to gravity so what I would do again I would Find out exactly what my stake holder wants.

During testing have at least as possible of pinch points and other areas that that can be harmful to the operator.

This was difficult in the way that to achieve complete safety would be is to cover everything up but since I had minimal time and experience I was only able to minimise the pinch points by in design by not having all the weight sitting on one syringe by having a bungee retract the whole arm so If Mr Richardson was working on the arm and the controls were let go on accident the whole arm would not just fall straight down crushing has hand with is its weight or in a pinch point which I have made that it will just push your fingers out the way but since it is not perfect having the arm get lifted up by the bungee there is no chance of these pinch points happening and instead of having someone get hurt the whole arm just gets retracted.

· Materials used must be processed within health guidelines

Looking back to the build presses I have included what I have actively done to keep me and other stake holders safe buy when using an specific tool for example using a hacksaw I fist checked its blade for direction sharpness and tension and then I used correct technique as taught by my year 11 teacher Mr Thwaite’s which is to have correct stance holding it with both hands and pushing forward lifting up and then bringing it back to start another stroke taking my time and not just going ham and risking breaking the blade and hurting myself and others. Another examples is when drilling I would clamp the material down and using safety glasses to stop flying particulates harming my eyes. Also with drilling and using a ban saw I took my time and going at the pace of the machine to ensure that I stay safe as possible.

In Late stake holder testing and discussion I have added NY locks and washers were needed and have cleaned up edges and removed covering. Also I have sealed the MDF base and turn table to stop water damage. He is also happy with its safety as he is far enough away and possible pinch points are minimal and are not that bad.

Step 20: ​Functional Results

Functionally from Mr Richardson’s and my testing it works really well it moves to all the requirements smoothly and is able to easily pick up the weighted container and move it to all corners of the specified area and also due to the bungee I have tuned it to when the controls are let go it brings the whole arm and container back up and back which Mr R Richardson thinks is a very good trait to have which helps with controlling the arm. Also placing the controls together and having them in pairs that are appropriate to each other like I have the two main arm controls and the turning and gripper together all for ease of use for the operator which Mr Richardson wanted and found worked for him he believes with some practice he will be able to confidently move objects around the area with ease.

Step 21: Pictures of the Robot Arm in Its Wider Social Environment

Step 22: My Final Thoughts

My knowledge that I have gained over doing this project is that if I was going to do this again I would firstly find out exactly what my stake holder wants even find real life examples that best fit their needs. Another thing I would do differently since now my skill is increased is that in the build I found that acrylic is not the best for the desired use as I found it was flexible and having threaded shaft through thin acrylic made for lose pivots so even it didn’t affect my robot arm that much but with extra weight or sideways stress I fear it would Se com to this flaw and either break or just jam up and stop. Here I show how much you can easily bend it by hand.

What I would do to fix this would if I didn’t redesign the whole thing to cover everything up: I would not use acrylic, I would use bushes for the pivots and make my own shafts and also having the bungee on one side it naturally would slightly twist to one side so to fix that I would have springs from both sides and doing this would make it not just stronger and more precise it would put less stress on the controls thus less stress on the operator. To achieve this I would need to have better time management which I need as I am doing this next year doing the level 3 standard. Also my planning was not the best as I needed to go back and add things but I could only do them as I learnt new things which I would be more proactive at finding everything out if I did this again.

<p>Greetings aemurton,</p><p>Good design, simple, functional, and easily repairable. In addition to the actual design for the arm, your write up shows a great analysis of the other factors that affect projects in the real world. The ability to acquire those intangibles and analyse them is a skill that will be of value for every activity you undertake. Whether it's an engineering project like this one, or you decide to go into management, or politics. or virtually any field, the ability to identify and analyse ALL the factors that affect a projects outcome is every bit as valuable as any engineering activity. Congratulation on identifying and integrating those factors into your overall plan. </p>
<p>next time please answer with a more constructive comments . good/bad</p>
<p>one step closer to being Tony Stark</p>
<p>Realy cool project :-D</p>
<p>did it for a school project had to have lots of writing if you just follow the photos you should get a good idea about it.</p>
Too long man! I didnt read half the stuff :P

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