Weight and finishing of the hand

A project log for TNS 1i

The idea is to create an accesible prosthetic hand that is commercially available in Colombia and doesn't use the classic string system.

Giovanni LealGiovanni Leal 09/16/2016 at 21:350 Comments

At the moment our 3D printer is in the shop under some maintenance, so things have been a lite bit slow. However this gave us time to perfect the CAD's, verify the premises of the build and even try some finishing touches.

So about the finishing of the hand, remember that has to be really nice and boost someone's self estime, so we can't just give her or him whats off the printer. We saw on Tested the following video and thought that it would be great to implement it on our prints.

So the closest thing that we found to that product was the following. It's called french resin.

At the beginning it was promising so we tried it out and let it dry but after two days the pieces became lumpy and cloudy.

Everybody has told us that we could use acetone vapor for the smoothing of the prints but remember that it is a very dangerous process that only applies to ABS and we are pretty much set to CF PLA. In the mean time we are sanding by hand or with a Dremel and applying a matte lacquer afterwards. Has been wonderful.

About the weight. For the person to benefit from the prosthetic has to be able to use it everyday, so one of the factors is that has to be light.... like really light. One of the benchmarks of the market weights 650 grams and it is made from real carbon fiber!!!

We have the advantage that the board, batteries and sensors will rest at the forearm and wont make that much torque. Because you know 500 grams at the hand is a lot.... lever.... torque... Arquimedes... you get it.

Soooo how much does it all the hand weights?

That much.... So we are really really happy about that... And believe us it's all there.

The other components weight that much neither.

So we are in the right track to bring something that will really make a diference to someone and that feels really good.