Grizzly G0704 Cnc Conversion

Or can CNC programs take the slack into account and compensate to get the accuracy you want?

Under a few conditions backlash compensation works, but not many. Cutting a circle for instance, it won't work. It will work for doing a hole pattern, but in general it will not work when continuous cutting. The only real way to get accuracy is to have zero backlash.
 
The ballscrew upgrade is really expensive. I want to see how it does with the leadscrews first.
 
The ballscrew upgrade is really expensive. I want to see how it does with the leadscrews first.

Look at what Linear Motion has to offer on eBay. Their pricing for ball screws and nuts is very reasonable. I spent about $125 for three pre-machined ball screws with nuts, and three each fixed and floating bearing blocks about a year ago when I converted a PM-932. The contact person is Chai and his customer service is very good.

Tom S.
 
Look at what Linear Motion has to offer on eBay. Their pricing for ball screws and nuts is very reasonable. I spent about $125 for three pre-machined ball screws with nuts, and three each fixed and floating bearing blocks about a year ago when I converted a PM-932. The contact person is Chai and his customer service is very good.

Tom S.
+1 on linear motion and Chai. I got 4 ballscrews and nuts along with a spindle motor and linear bearings. Good guy, and if you buy direct he will give you an additional 10% over eBay prices.
 
+1 on linear motion and Chai. I got 4 ballscrews and nuts along with a spindle motor and linear bearings. Good guy, and if you buy direct he will give you an additional 10% over eBay prices.
Thanks for the heads up about the discount. I'll have to look into it soon.
 
You can give him the specs for the coupling interface you are using as well as the bearing blocks and they will turn the ends for you. I just sent a hand drawn sketch. His email is linearmotionbearings2008@aliyun.com

I have no connection with them, just a happy customer.
 
I got the X and Y done and everything wired on Monday since it was a holiday.
I just got my Z axis done. I used the 3d printed direct drive nema 23 mount. I used linuxcnc and the jog keys on the keyboard (arrows) to make those aluminum standoffs for the Z motor. That's the first thing i've ever milled...yay!
Now I need to spend some time getting linuxcnc configured. I got a USB pendant too that I need to get setup.
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I have made some more progress on this. Last week I ordered the ballscrews.
I tried tracing text with a 1/8" endmill and the results are pretty ugly:
LsBeBWvh.jpg
You can see the backlash in the results. When drawing the O and D the start and end of the letter don't line up. This was before I realized that the bearing wasn't seated all the way so I had a ton of backlash. After I cut this I measured and it was .04" (LOL).. I tightened it up correctly and got it down to .003"
So then I setup the backlash compensation and tried an engrave operation instead and it was much better other than my board not being straight.
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Over the weekend I made the motor mount standoffs and the X axis mount (manually using the jog controls on the keyboard):
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Tonight I plan to replace the 3d printed X mount with this new one.

The Z axis mount is different for the ballscrews than the leadscrew version so I'll have to wait for those parts to arrive before I can replace it. I'm not sure about Y yet. It is more complicated since it has the spacer with the holes for the bearings.

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