Saturday, November 3, 2007

Return of the X1

After some downtime, the mill has returned with added glory!  A touchscreen LCD on a swing arm and new controls cabinet make the mill completely self contained.  Also, I've added home switches for automated homing and interfaced the PWM component of EMC 2.1.7 to the spindle's speed controller.

The touchscreen was truly an indulgence.  I wanted an LCD so that I could mount it on an arm hanging off the enclosure, but found a cheap touchscreen on eBay and said "why not!"  The seller did not list it with very much detail, so it was a bit of a risky buy - not being sure if it would interface with Linux - but it has a standard Micro Touch USB controller in it, so I was able to make it work.

The new controls cabinet was the primary achievement though.  It allowed me to consolidate all the electronics into a common housing, and by tying the metal cabinet to ground, isolate the electronics from noise generated by the steppers, spindle motor and especially the coolant pump.  That cheap Harbor Freight pump really generates some EMI.

In the numbered image above:
  1. Incoming AC power switched by a master switch on the front of the enclosure
  2. Mini-ITX motherboard running Ubuntu 6.06 and EMC 2
  3. 5V DC power supply for logic circuits not run by the PC
  4. Breadboard for opto-isolated circuits and other interface logic (home switches, coolant pump and spindle PWM interfaces)
  5. Stepper controllers
  6. Solid state relay for coolant pump
  7. Spindle speed controller, driven by PWM signal output from EMC
  8. 720W ~48V unregulated power supply for steppers

Note the breadboard I'm using for some interface circuitry.  I've had a few comments on it from various folks asking why I would use something designed for temporary use in a seemingly permanent application.  The main reason is that nothing I do ever seems to remain permanent!  I'm always tweaking, upgrading and modifying my designs in one fashion or another.  In fact, I spend more time building the machine than using it many times.  After all, it's not the destination, it's the journey - at least for me!  So, rather than make a printed circuit board, use a perfboard, or wire wrap it the slam-dunk method was a breadboard.  Additionally, if I blow out an opto-coupler for some reason, it will be easy to replace.

With the added space the cabinet provided, and since everything is now in a common housing, it was easy to add some needed features to the mill.  Primarily home switches, and put the spindle and coolant pump under computer control.  The home switches allow me, for example, to set the offset of the vise from the home position and then I'm quickly able to locate it between power cycles.  The spindle and coolant pump automation make the mill completely hands off.  I can start a job and walk away and when done, the computer powers down the coolant pump and spindle.  Eventually this will also allow me to attempt rigid taping, etc.

Also, check out the video below of the spindle automation.  Basically, the mill moves into position, starts the spindle, enlarges a hole in a Radio Shack project box, retracts, then turns off the spindle.  I think it was about 6 lines of G-code, but it gets the point across.

As always, please feel free to contact me with any questions or comments on my setup!