Thursday, March 10, 2011

Development board arrived

My PIC32 development board arrived today!

I also got a trial stepper motor controller with it.

The development board looks as good in my hands as it did in the sales literature.

My old PC power supply even had a power connector that fit with the board already installed.  It is a relict of a battery charger for an old Sony digital camera that I finally retired last year.

I am also wanting to adopt Rapman's use of milled linear guides and linear bearings.  If you look hard these are not all that expensive.  For bearings, I found this little unit...

To be well within budget.  Guide shafts are a little pricier.  In the US it appears that 12 mm shafting is the least expensive while still being stiff enough for a printer.  Most pricing seems to be running around $0.50/inch.  That's not cheap, but not impossible.

Being a Scots-Irish tightwad, however, I kept looking for a better deal and ran across this...

...which comes in at a bit under $0.07/inch.   I spoke with the vendor today and they are checking to make sure that it meets CNC requirements for a linear guide.  The general impression was that it did, but I want to be sure.

If that price does follow, it should be possible to replace the effective, but overcomplicated z-axis arrangement of Rapman which derives from the old Darwin design...

...which has 8 mm guide rod and a plastic bushing with a 12 mm guide rod and a proper linear bearing.  That extra rigidity might allow me to control the position of the print table with an single, proper lead screw attached to a cantilever beam which contacts the bottom of the print table in the center instead of three or four lead screws, or cheap studding {threaded rods}, more likely.

Certainly the leveraging the guide rods as vertical structural members should simplify the design a bit.

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