I'm in the same boat. Just got a 2UVR and can't wait to strap my stepper motors to it.
I started analyzing where the slop in the quill lies and how much. The places I can find slop starting from the tool are:
1. Quill to the hand feed lever "pinion shaft"
2. "Pinion shaft" to "horizontal worm shaft" behind the Tree emblem
3. "Feed worm wheel" (the gear behind emblem) to "verticle worm shaft"
To measure #1 I put pressure on the hand feed lever to lock up the rest of the mechanism and with an indicator mounted under the quill, lifted up on the quill itself. Suprisingly I got only 0.003-0.004" movement.
I thought #2 was where the bulk of the slop was until I pulled the Tree emblem off and saw the gear and shaft sliding significantly in and out with the hand feed lever movement. With the gear and shaft retracted I put pressure on the gear with my hand while actuating the hand lever, looking for movement on the indicator. I saw only 0.002" movement before the gear and shaft would begin to push out against my hand.
#3 has so little if any slop and is geared down so much from the quill that I don't think I can even measure the effect on the tool.
Conclusions:
It appears to me if you could constrain the horizontal worm shaft with a bearing you would have only 0.005-0.006" backlash in the quill with a motor mounted to the shaft. If you can add a stiffer spring to the feed lever as mentioned above, strong enough to overcome negative Z forces from helical tools, you could take out the 0.002" and potentially only have the 0.003-0.004" in the quill rack. Adding some kind of external HEAVY spring to the quill itself could take out all the slop, but as previously stated you'd be interfering with the collet mechanism.
I'm only going to be using this for home projects and I'm not even going to bother changing out the lead screws for ball screws. I'm going to simply let my software adjust for backlash and call it good.
What do you guys think? Have I missed anything?
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