Saturday, October 22, 2011

New Socket Milled & Hand Support Update

A day off of work does wonders for making progress on personal projects.  Yesterday, I was able get the silicone hand support filled with sand and the latest version of the ball base socket milled.  Fair progress.

In consulting with my wife regarding the hand support, we came to the decision that using oil instead of water would be best for the long term keep of the sand in the enclosed space of the hand support.  We explored several different kinds of oils and we settled on a type that has a very long shelf life.  I was drawing on her expertise as a soap maker, where oils of many kinds are used.  We have many kinds in stock.  So, the hand support is filled with sand and oil now.  There is some air trapped inside which needs to be removed.  I figure using a hyperdermic needle to suck the air out would be best, however, I don't have any needles handy at the moment, so that will be on the shopping list.  The hand support feels like an oversized beanbag chair for your hand, extending all the way down to the wrist.  It is very comfortable.  Once the air is removed, it will firm up a bit.

The latest version of the ball socket was a long time in the making.  I've had several setbacks that kept it from getting done.  Most of the issues have been related to my CNC router.  This successful version comes after five other failed attempts to create it.  The failures all had a machining error of some sort or another.  It all boils down to the fact that this is a tiny little CNC router with weak stepper motors and I'm asking it to do more than it was designed to do.  After a 3.5 hour marithon session last night, I eventually got it done by running the machine at about 40% of the job speed.  It made for a late night (I didn't get done until about 1:30 AM), but at least it is done.  The piece was milled out of a polycarbonate block measuring 1.75" square and 0.75" tall using a 0.125" ball end-mill.  The stepdown was backed way off to 0.01" per pass, so it took about 75 passes to mill down.  This was a single-sided milling effort this time.  None of my double-sided attempts were successful.  I'll just have to manually locate and drill the eight holes on the underside with a template and drill press, so not so hard and probably the right way to do it anyway.

Ball Base Socket (0.75" tall):

Ball Base Cap.  It covers the circuit board that hugs the bottom of the Ball Base Socket (shown above).  The hole in the bottom is for the eight wires that need to connect back to the microprocessor unit:

All components:

 All Components, combined 

 Hand support shown next to the combined trackball assembly:

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