7/23/14 RIT Arm Editing and Printing Pins

I spent today in Inventor with the Derek Arm.  Improvements were made in all the pieces except the fingers and knuckles.  First, I fixed up the trouble with the thumb tube in the palm by making the curve less extreme.  All it took was some quick dragging of control points.  Now the string should be able to tread through with less resistance.  Hopefully this helps with the lag in the closing of the thumb.  Next, I made the tensioners square.  After that, I edited the gauntlet to accept the new shape.  Here are some screenshots.

I put some holes through the gauntlet to reduce the amount of material used as well.  It should hold up just as well as it did with all the excess material.  

I decided to do the same for the forearm cuff, however, I'm not sure how it will turn out.  

I'm hoping to do a bit more editing with the arm tomorrow.  Then, I plan on printing it to show what Alex and I have done to improve it.  However, I don't think putting a few holes in it would make it worth printing another arm.  

I'll have to do more work on improving the overall functionality of the arm.  While I think it works fine now, we should do some brainstorming to see if there's anyway to make it better.  For example, the shape of the palm works, but it doesn't seem right to me.  I think we should come up with a better shape for it. We should also consider ways we can use the palm to get better grip out of the hand.  Maybe we can use the space inside the palm or pipe to apply the variable grip mechanisms.  Maybe the palm itself can slightly to better grip the object.  Maybe adding another thumb on the other side would help grip.  

I would like to make the first pair and second pair of fingers closing time be slightly staggered, splayed, and closer together as well.  In order to do this and make it effective, I think the arm needs variable grip. I'll come up with some sketches for that tomorrow hopefully.

While Sam was working in Inventor I spent my day in Rhino trying to sort out our modular tensioner problems. After searching around the web for awhile I decided to try a snap pin design similar to the pins used in the Cyborg Beast fingers. I already had one of these pins drawn up from when I was working with the Cyborg Beast earlier so all it took was some clever extruding and scaling.

My new pin design (shown in green)

Printing pins vertically like I have drawn above can sometimes be problematic but hopefully with some supports the print will turn out okay. Further testing on this will be conducted tomorrow.

Well that's all for today!

Alex + Sam