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!

Sunday, July 22, 2007

Touchy Touchscreen

I finally got around to attempting to hook up the 15" touchscreen I purchased off eBay to the mill's PC.  I was initially quite impressed as Ubuntu 6.06 recognized it as a Micro Touch screen and loaded the appropriate USB driver right off the bat.  What I didn't realize is what a pain it was going to be to get X to recognize it as pointing device.

To make a long story short, I searched the net for any and all documentation regarding this and found very little.  Google just wasn't giving me the results I wanted.  I finally pieced together enough information to get it working, but I wish Google had sent me to this web site first.  That is exactly the procedure I ended up using.  Had I found that site earlier it would have saved me many hours and curse words!

Sunday, July 15, 2007

Enco Phase II+ Quick Change Tool Post for 9x20 Lathe

Rather than mess around with shims to get my lathe tooling centered to the chuck, and to enable me to use boring bars and parting tools, I purchased a Phase II+ quick change tool post from Enco.  After reading a significant amount of information on how to get this piece to fit on the 9x20 lathe, I was a little apprehensive.  However, after about two hours of shop time it is mounted and works great!

The first thing I learned is that making an adapter to get the new QCTP to work with the stock tool post stud is easier than I thought.  I simply took the stud that came with the new post, cut off all but about 0.75" of material below the threads on one end, then drilled and tapped it for M8x1.25.  That enabled me to screw that adapter onto the stock stud, slip the new tool post over it and use the included nut to sinch it down.  Much easier than I thought it would be!

The other thing I learned is that 1/2" tooling seems to work fine for me without modifying the compound slide.  I had read elsewhere that this modification was necessary, however I've got the tool centered and everything seems to work fine.  Perhaps I'm missing something, but if so, I'll likely discover it in the future and, at which point, I'll post my mistake here! :-)

Thursday, June 28, 2007

New Member of the Family: 9x20 Lathe

As luck would have it, a buddy of mine decided to part with his Harbor Freight 9x20 lathe for a price I was willing to pay.  I'm glad I have it and can't wait to make long stringy chips!

I must say though, that I think I should have bought a lathe first.  Realizing that Chinese machine tools are essentially elaborate kits (without instructions), it would have been nice to have the tools handy to make new rotating and/or power transmission parts myself.  If I had to do it all over again, there is no question in my mind that I would be better served by getting the lathe before the mill.  Although, I think the mill will likely be used more often, the lathe is more of a necessity or rather a more "basic" tool.

The mods to the lathe will be pretty tame to begin with.  First and foremost will be the 4-bolt compound slide mounting plate.  That seems to be a priority for many folks so, drawing on their experience, it will be mine too.  I may just buy one rather than make it myself to speed along the time-to-production for my new lathe.  A quick change tool post (Enco Phase II piston design) will be next for sure.

My first two projects will be: a custom espresso tamper for my recently acquired espresso pot, and new pulleys for my mill.  As I stated in a previous entry, I basically was making lathe parts on my mill by using the CNC's circular interpolation to cut pulleys.  This time around I'm going to buy some HTD5 timing pulleys and taper bushings (probably from from econobelt.com) and open up the ID of the pulleys on the lathe.  As I infrequently change speeds on my mill, I'm throwing out the step pulley concept in favor of a higher HP capacity drive system.  The variable speed DC motor can take care of variance within whatever range the pulleys put me at.