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SMALL LATHES:
GRIZZLY G0602 10x22

CNC WITH STOCK SCREWS

I intend to CNC the Grizzly G0602 in 3 stages:

1: Quick, temporary and cheap using the stock screws.

2: Permanent mounting using Acme screws. Almost everything changes, and the X stepper will become a 381, but most of the Step One parts transfer upward.

3: Drop-in ball screws upgrade, which will fit the same mounts as the Acme uses.

I will do this conversion in three steps because:

1. Some of you may want to do a cheap stock screw conversion. I consider this temporary, but it could probably do quite a bit of work for awhile. It's also a good way to let the CNC take care of turning and threading the screws that follow.

2. Acme: This is a less expensive route than ball screws, and some may want to go this way.

3. Ball screws: Of course this is the most desirable path, albeit a little more expensive.

I've designed the parts to be maximally transferable upward from each step.

Home switches and threading indexer will be Hall effect sensors. I don't use limit switches for steppers.

1) STOCK SCREWS
This least expensive and temporary option will give capability to CNC turn the screws for step two.
A. Most of Option One components, including mechanical drive parts, will transfer to Options 2 and 3.
B. Motor mounts are simplified for rapid installation and quick functionality. Some parts will not transfer.
C. Spindle index and Home switches transfer upward.
D. Motor cables transfer upward with slight modification.
E. Flood cooling transfers in toto.

Electronics:
G540, Modified Keling 270 motor for X, Keling 381 motor for Z, Keling 48V PSU, Hall Effect indexing sensor and Home switches.
Estimated total electronics cost: $450

Here are the electronics for Stage One, stock screw conversion:
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From top left:X Stepper, Z Stepper, 48V PSU
G540
X home switch, Threading indexer, Z home switch, Spindle motor control relay.

The 48V spindle relay will control the 20A motor contactor on and off by Mach3. The Hall effect switches and sensor will run on a 25V Voltage divider circuit from the PSU, and plug directly into the G540 inputs with no other circuitry necessary.

That's everything but the Flood Cooling pump relay. That relay has already been mounted into an electrical box. No, the box isn't rusty, that's just a flash effect:
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CNC Steps 2 and 3 will use exactly the same electronics--Except the X motor will change to a 381oz. instead of a 270 oz.

I will use THIS $99 off-lease recertified computer:
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http://www.tigerdirect.com/applicati...486&CatId=1888

It will live in the HMC stand and run Mach3. UPS shipping = $16. Estimated delivery date 6/7/10. 2.8 GHZ is plenty of speed, 512 MB is lots of memory, 40GB HD, CDROM, new keyboard/optical mouse and no frills. 12 month warranty. Windows XP will be installed onto it.

Stage One will use the stock G0602 axis bearings:

I WAS going to replace the X bearing, but the 25mm size is weird and hard to find. The stock thrust bearing seems OK, and adding a washer under the shaft nut tightens it up and eliminates a lot of backlash. It will have to serve:
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Here's the 17 TPI X axis screw, in its 1 inch deep x 1 1/8 inch wide cavity:
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And its cast iron nut:
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The Z shaft-end bearing is just a brass bushing. Some extra lube and it's good to go. Longevity is a question mark though.
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Driving this rough half nut with stock 12 TPI Z screw might involve horrendous backlash. Mach3 Backlash Compensation may be put to an extreme test. We'll see. I may take it apart and attempt to smooth up the threads:
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I intend to CNC this lathe in 3 steps:

1) STOCK SCREWS
    This least expensive and temporary option will give capability to CNC turn the screws for step two.
        A. Most of Option One components, including mechanical drive parts, will transfer to Options 2 and 3.
        B. Motor mounts are simplified for rapid installation and quick functionality. Some parts will not transfer.
        C. Spindle index and Home switches transfer upward.
        D. Motor cables transfer upward with slight modification.
        E. Flood cooling transfers in toto.

Electronics:
G540, Modified Keling 270 motor for X, Keling 381 motor for Z, Keling 48V PSU, Hall Effect indexing sensor and Home switches.
Estimated electronics cost: $450





















2) ACME SCREWS:
    This option is much less expensive than ball screws and can do some useful work for awhile.
        A. Permanent Motor mounts are more complicated and use more material, but are also more solid and workmanlike.
        B. Everything in this option transfers to Option Three except the Acme screws & nuts.
        C. This option gives capability to CNC machine the ball screws for Option Three.
        D. Z screw protector is added.
        E. More powerful step motor added to X, because there is now room for it, and gearing is lower with Acme/Ball screws.

Electronics:
G540, Keling 381 motor for X, Keling 381 motor for Z, Keling 48V PSU, Hall Effect indexing sensor and Home switches.
Estimated electronics cost: $460

3) BALL SCREWS:
    Simply adds ball screws and nuts to Option 2.
        A. Ball screw nuts mount to same mounts as Acme nuts used previously.

Electronics:
G540, Keling 381 motor for X, Keling 381 motor for Z, Keling 48V PSU, Hall Effect indexing sensor and Home switches.
Estimated electronics cost: $460
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