Hey everyone. I have some big news about my current prosthetics project. I have gone and ordered the prosthetic hand from shapeways and it should be arriving in a weeks time. This has effectively been paid for by those who have bought from my shapeways shop, so thank you to all of you.
As you may be able to tell from the above renders I have finally learned how to use Blenders Cycles render engine!
Whilst the elastic elements don't yet neatly fit within the fingers this is due to the hand being quite small. As Hollie grows bigger they should disappear in later designs.
You may notice that the tendon torsioners are similar to James Holmes Siedle's design. This is because I re-engineered the idea for use in SLS nylon. I adjusted each block so they sat parallel with the back of the arm to maintain a sleek look. I also made two version of the rotary part of the tensioner.
I'll update the blog once I receive the hand. Hopefully it'll be ready for Hollie to start using.
Since I'm based in the UK it's always nice to see local stuff turn up. I also like seeing the digital descendants of my design from two years back.
I notice an interesting tensioner system by James Holmes Siedle. I'm reverse engineering it for Hollies hand since I wasn't happy with the screw version.
I was looking at my posts and realised I hadn't posted an update about hollies hand. This is about v3 of the hand which had some issues that would mean it wouldn't work. I've been doing some R&D on it and hope to have something coming together in the next few weeks. Unfortunately I have freelancing and consulting gigs to find that're distracting me.
I posted the design to thingiverse a while ago.
Here is a part of the version 4 hand, which involves fingers and hinges printed all as one piece.
For the last year I’ve been working at Hobs Reprographics as a 3D Printing technician. In this role I’ve mostly been taking peoples 3D files and converting them into a 3d printable format, as most programs can’t export suitable files on their own. I then printed them out in either a Projet 660 full colour printer or an ProX 800 SLA printer, and very occasionally a Cubex.
Anyway I learned a lot from Hobs, but as you may have noticed my blog posting had slowed down significantly. This echoed the slow development of what I was doing in meatspace. My main endeavour has been to make a prosthetic hand for Hollie. As I was only able to grab a few hours here or there, and was pretty tired even when I could, the progress was slow.
So I took the plunge again and have decided to set up as a freelance design and a 3D printing consulting expert. This should give me the flexibility to finish what I want to whilst providing an income.
So if you, or someone you know wants to design something for 3D printing then get in contact with me. Or if you’re with a company looking at getting into 3D printing but are not sure if you’d get the most out of it, or which of the hundreds of printers to buy, then again contact me.
I shall be setting up a dedicated website and twitter handle for the design and consulting job probably tomorrow. Pricing will also go on there. I’ll clean up this website and take advantage of some new shapeways apps. I’ll set up some permanent cross linking between my website, twitter facebook etc.
Some of you may now about Bioloids.
These are cute little humanoid robots designed for research and playing football, although there may be some other uses. Anyway I noticed that they lacked one thing… well ok two things…. in the form of hands. Yes you can put together some parts to make a gripper, but it’s a bit large and not as anthropomorphic as the rest of the bot. I decided to remedy this, and thanks to Trossen robotics putting the CAD parts online I got to playing around with it. It turned out to be surprisingly easy to design parts that would fit. Since I don’t have a Bioloid, or a spare servo I can’t really test this, but I might end up putting it on shapeways.
In other news I am still working on the full size prosthesis for Hollie, as well as the conventional robot hand. I’m just working on the kinks regarding the nylon printed springs. It’s proving to be very much a goldilocks thing, where no designs yet are just right.
One big issue is the hysteresis of the spring. It starts at position A, moved to position C, but doesn’t move back to A, but partway between them to B. Luckily movement between B and C is reliable and predictable. The problem is that if I print in position A I need to know that position B will be ok.
The following is an overview of how I went about about creating Hollies unique Robohand.
The first step involved Hollies father creating a series of alginate molds of both her left and right hands. Instructables gives a large number of tutorials on this process, with a number of them being focused on hands.
He then used these alginate molds to make plaster models of Hollies hands.
I then took these plaster models and used a technique called Photogammetry to turn these models into Computer models. The particular tools I used were 123d catch and Autodesk recap 360. These are both free Autodesk products that let you turn a number of photos into a 3D model.
I used a grey paint to bring out the contrast in the hand.
I also added coloured dots to the hand which gives myself and the software reference points to find in 3D space.
The final addition I made used a giant coloured QR code, which the model rests on. The QR code serves the purpose of helping the software know the surface is flat, as well as giving reference points to pick. The colour is also there to help me identify which precise square I’m using as an alignment mark. Trying to identify a black square out of many black squares is needlessly difficult.
The resulting model looks something like this:
Not very useful, so I used another free bit of software called Blender, to edit out the parts of the mesh I don’t need.
Blender gave me some useable models, but photogammetry isn’t perfect and so I used a somewhat less free piece of software called Zbrush to tidy things up further, as well as to re-position the fingers.
Quickly back to Blender to create a printable model,to scale things correctly and to mirror Hollies full hand. Then I printed out the first models on my Lulzbot printer. This gave me a direct comparison to the plaster cast hand to check.
I will describe how I combined the two models to create the fitting hand in Part 2
It’s too late now to go into details regarding the finger tests for Hollies hand. It’s going well though and I hope to incorporate what I’ve learned into the new design.
Below is a video from the test.
I will update about the methods behind the design process hopefully before the weekend.
So first of all I’m not dead! 8 months is a long time, so I have some ground to cover.
Firstly my working relationship with Easton broke down after became too unreliable, and seemingly unwilling to use the strengths that he could have bought to the project. Luckily I managed to get him to finish off the remaining Kickstarter arms. Speaking of the Kickstarter arms they are available either through my shop on Shapeways, or as a download from Thingiverse for those ambitious enough to print one for yourself.
Since I didn’t have a functioning business I had to get a job. Luckily it’s local and I’m working with 3D Printing. It’s given me some breathing room to learn new techniques, such as using iMaterialise Magics software.
In my spare time I’ve managed to make some small designs, which are available on Shapeways.
This involve converting pdb protein structure files into printable models.
Biology inspired art pieces are also available.
I am also updating the website and enhancing my social media profile.
But the big thing is that I haven’t stopped on the robot hand design, although progress has been slow. I’ve been focused on combining 3d scan data with the robohand mechanics. The first and protoype model is being made for a young girl called Hollie. I finished the first stage of the design this weekend and had her try out some elements of it.
I have yet to add the mechanics to the design. My original plan was touse pins and elastic like my kickstarter hand, but this proved time consuming. Instead I am going to take an idea from the Flexy Robohand model. Instead of the filaflex material though I want to engineer an elastic joint straight out of the Shapeways WSF material. I have some experience from experiments with this material and believe it to be possible. As far as I know this is also the first robohand varient made via Shapeways.
You may also have noticed that Hollies right forearm is shorter than her left forearm, requiring me to create a new mechanism to control the fingers.
The copying of her left hand was achieved through a multi-stage process involving making a silicone mold and plaster model of both her hands. I then used Autodesk 123d Catch to turn it into viable models. I then used Zbrush, Blender, Meshlab and Meshmixer to make the above design. I plan to use Autodesk Fusion 360 to make the mechanical parts of the arm.
I hope to have the prototype joints completed this week. To try them out next week, and incorporate them into the design. Hopefully by the end of next month I will have a functioning prosthesis to give her.