Meeting Date: 
Sun, 11/28/2010
Start and End Time: 
9:00 am - 6 pm
Personnel Present: 
Personnel Present: 
Personnel Present: 
Personnel Present: 
Personnel Present: 
Tasks This Meeting: 

Build a new hand

Work on trying the Mag sensor and limit switches with the protoype board

Reflections For This Meeting: 

CAD makes really cool pictures - hope they work in real life too!

This was a long and big meeting - and both Gavin and Alejandro wrote part of today's engineering log.

Today we have GOT to get the new hand design finalized, and the hand built. Plus, we're going to try to figure out the prototype board's digital stuff so we can use limit switches from there.


Karl and ALejandro designed the new body of the hand in CAD. Karl did most of the preliminary design and Al turned it into drawing.


Here is the hand in place the way we used it with the dispenser and batons. This is how we designed it, in place on the baton dispensor.

TTHe finished CAD drawing - for the hand, both the flat and the 3 D


We printed out the flat drawing in a 1:1 size and cut them out.


We used a glue stick to attach them onto the sheet of PETG plastic. We knew we had to use PETG because of the intricate bends, and it is the easier of the 4 plastic allowed to bend.


A A rough cut around the pattern - ready for the bandsaw and detail cutting.


Here we are cutting out the parts using the bandsaw.

We had to use a jigsaw for some of the inside cuts.

Everything cut out and marking with the sharpie for where the bends will be made.

Using the deburring tool to clean up any sharp edges.

We used a torch to heat the plastic and make the bends -in this photo shows the bend for the shaft that will spin the flippers. 

Heating and bending the hand took a lot of slow and careful heating and bending.

We mounted the 1x4 plate underneath the hand so that we could mount it to the spinner servo.

You can see we had to bend carefully so that we still had a smooth surface for the batons, but also got the Tetrix pieces in to where they needed to be.

We started to bend the inside bends to bring the top up.


The blue sharpie marks told us nicely what kind of bend and curve we needed to make in the plastic.

Heating and bending the side pieces up.

We built some springs so that when we push agains the wall - and are a little bit off- that it will straighten automatically. Here is the CAD drawing for the spring idea and the flat cut out. CAD sure makes this substantially simpler to do!

Cutting out the spring template using the bandsaw.

We had to make a jig to bend the spring down - this time we used the heat gun to get a more uniform heat over a larger area.

We then mounted the spring to a piece of channel...

... and put a couple of screws in as guides.

Using the heat gun, we locked the springs into place using the guides and a pair of pliers to carefully bend the plastic into the correct shape.

We used the torch and some pliers to wrap the end of the spring around the guide screws so that we had a place to mount it.

2 finished springs (we figured we would probably need a spare)


We mounted the spring onto the hand and now we are worried that they are too tight. The spring doesn't seem right.



Although the spring might be too tight, the rest of the hand concept looks like it will work correctly. The batons slide out nicely through the door opening.


Gavin is looking at the programming and documentation for the prototype board's digital sensors.


Gavin worked with Karl to try and figure out how to wire the experimenter's board with the protoype board, to test the Mag sensor and the digital sensors.


Gavin found the documentation on line for the prototype board.


We took the potentiometers that we had used before, and had to un-solder and clean up the solder to use them again. Here Gavin is using the solder sucker to accomplish this (it works great!).

Gavin started soldering the new prototype expansion board.


Hopefully you can see in the lower right corner of this photo is an LED on - and the magnet is approaching the Mag sensor (hall effect sensor) . Woo Hoo! We can sense the magnet with it on the prototype board. The little black dot on the experiment board is the entire Mag sensor!


After Gavin got everything to work on the experimenter board, he drew it out onto paper so that we can build the real circuit board.

Here is Gavin's drawing for the prototype board.


Here I am mounting the spring onto the hand.


I am using the CAD software to guide me on how to put everything together.