9x19 G4000 CNC Conversion

[jhowelb]

Just thought I'd share a few photos of a very slow conversion project. Slow because I'm slow.
Due to the confined area in my shop I wanted the X axis motor on the back side of the lathe. Not wanting to reinvent the wheel I opted to retain the existing screw and just couple onto it as shown in the pics.

So far so good.....flame away!!

[Runner4404spd]

nice work, although i believe that chunk of cast iron you removed added some rigidity to the crosslide ways. nice looking setup though. good lcuk with your conversion.

[jhowelb]

The stratigy is to use the existing screw. To this end I made an adjusting nut with an extended set screw to attach the stepper to.

[Runner4404spd]

nice work. i am closely following this thread since i'm working on my own cnc conversion but i'm swapping to a ball screw for the z axis, and will be using an acme thread for the cross slide.

[jhowelb]

There was a "domestic emergency" that interrupted my last post. (A dog, a wasp and a veternarian)
What I wanted to get across was that this arrangement on the z axis is temporary to allow me to cut a ball screw down complete with thrust bearings and threads to preload against back lash.
Now to get this screw to turn required some finaglin'!
First I upgraded from HobbyCNC 200 oz/in to an eight wire 425 oz/in from Keling. Inc (http://kelinginc.net/KL23H286-20-08B.pdf) and then wired it to run uni-polar. I think about 300 oz/in running that way.
Still wasn't good enough so I took the lead screw out and reduced the diameter slightly then polished where it sits in the socket and is pinned at the gear box. Even with all this I had to persuade things by running the saddle back and forth while squirting the screw with WD40 to clean the grooves of the threads.
Working good, now, as is evidenced by the pictured piece of al scrap I turned down under computer (Mach 3) control.
Next, fine tune the motors, work out the backlash as much as can be done and rig a "pulse card" to the spindle for thread cutting.
BTW, the cut in the saddle shouldn't cost much in rigidity, the tunnel does not run parallel th the ways beneath it and "cast" don't flex much. I've seen machines built much like this from factory.
Anyway, here's pics. Enjoy!

[kreutz]

Good Job!!

[cut more]

jhowelb,
nice job!
I have the grizzly G4000 too, what are you using for stepper drives?
I was thinking of driving my x axis from the gear rack for the handwheel, any thoughts on if that would be a good or bad idea?
Thanks,
Cutmore

[jhowelb]

HCNC provides the driver and X axis motor (200 oz/in).
If you can live with the motor hanging out in front of the machine, ready to whack you as it whips by, if you can deal with the backlash in the existing pinion system or make one without backlash, you bet! It would work. The problems just seemed unsurmountable to me.
Backlash might be handled with a spring because the cutting forces are always toward the negative end of the axis, unless you use a rear tool post (as in cut off tool, maybe). Even that could be worked around.
In my fourty plus years experience I have come to believe that anything one can imagine can be done with varying degrees of acceptability.
For example, I once built a Gengery style lathe from cast scrap aluminum and cold roll steel. When fitted with a cnc system, it was very accurate and is still functioning today. In someone elses shop because I sold it in a moments weekness.
Good idea? If it works for you, it's a good one. If you don't try you'll never know. You can always change it later AND you will learn bunches in the effort to say nothing of the good wholesome entertainment you will gain in the effort.
Share your experience with others and GO FOR IT!!!

[jhowelb]

O.K.! A little input from anyone who's been down this road would be nice about now.
I have purchased a pulse board from CNC4PC ( http://www.cnc4pc.com/Index_Pulse_Card.htm ) and intend to use it to provide spindle timing for Mach 3. There needs to be a disk with a slot in it attached in such fashion as to allow mounting of the diode and sensor.
About now I'm having visions of a part being thrown from the chuck and riccocheting about the headstock to wipe out the disk and pick up assy. I don't see an "invitation" to a dammage safe mount.

Anyone........???

[kreutz]

Look under Reflective Tachometer in this place:
http://www.shumatech.com/dro-350/add-ons.htm

There are a lot of tips on how to mount it and adjustment procedure.

[RotarySMP]

I used a tab between the spindle preload nuts on my mini-Lathe, cutting an optical gate.

http://www.wrathall.com/Interests/CN...le_encoder.htm

Some of the mini lathes have the same set up inside the haed casting.

http://www.arceurotrade.co.uk/projec...es/C3_BC5.html

I am sure you could rig up something like this on your 9X.

[Adobe Machine]

rotarySMP , Mark. I'm curious.. is this like a Hall effect switch ? ( passing a ferrous piece near a magnet, it changes the resistance in the magnet, therefore 1) or is this a light sensitive switch ? Thanks for the info/.

Adobe (old as dirt)