Ok, I’ve been anxious not to stall on this project.  Momentum is key!  Over the weekend I got all three axis wired up, and I put the electronics in this neat enclosure.  Notice the monster heat sink, and the cooling fan.

Last night I finally finished rudimentary software tuning.  When I told the Z axis to move 1”, it did so.  Since X and Y are configured the same, I could hardly just stop there.  All three motors seemed pretty happy, so I decided to try cutting something really simple.

First, I need to mention that the ball screws and nuts that I installed have a relatively high backlash.  If I remember, it’s somewhere on the order of .005”.  That’s quite a bit.  When I cut out a 2” circle, the actual inside diameter was about 1.9”.  If you think about the number of direction changes involved with a single axis while cutting a circle, that’s probably about right.  Fortunately this can be calibrated and adjusted in software.  Later this week a dial indicator should arrive and I’ll use that to measure and adjust for backlash.

Update: No, it isn’t right.  I just took a shower after writing that and realized something really funny.  0.1” seemed like a suspiciously accurate error, so I double checked the gcode that I ran.  The script I used to generate my circle uses a roughing pass.  When I made the above video, I stopped the program after the roughing pass.  The roughing pass used a radius of .825.  Add on to that 1/2 of the cutter diameter of 1/4” and you get .95 radius.  Double that to get diameter and you get a 1.9” circle.  I’ll run the whole program tomorrow and see how it does.

In other news, I noticed that the X axis motor was not holding very well.  I could grab the coupler and turn it by hand.  Some investigation revealed that VREF was way too low on the board, but it’s also turned up all the way.  Z and A also seem to have the same problem.  I’ll check into it more tomorrow.  All in all, things look pretty good so far!