I too faced the same problem using my Sherline mill. What Rob suggested of feeding downwards and moving up again is by far the best method for small mills…I have been doing that since. The mill finish is great also bear in mind all axis x and y must be locked. The moving axis must be snug for feed movement only.

Good luck!
Steve wan -Singapore

This won’t help snatching during drilling with the DP handle, as the required force may overcome the head weight resulting in the pinion passing to the underside of the rack teeth, but with a speed handle on the fine feed this may be OK?

A very well written and interesting article. Thank you for taking the time to assist others, like me, who are considering a Mini-Mill.

Another solution, that springs to mind, is to add another rack gear or slit the existing one and mount alongside and tension one against the other. This is a classic way of removing backlash. You could add a belleville washer too to make it smoother.

Please note that this suggestion is offered without me having ANY knowledge of the available local space or mounting of the rack. The local features may make this kind of idea easy…or, indeed, impossible! :)

Often anti-backlash gears have two pinions side by side with a spring torquing them together so that’s, yet, another possibility.

I’d be interested to know if there is sufficient space and features which would make the twin rack suggestion possible. The answer might influence my Mini-Mill purchase decision.

Finally, I’ve talked to UK suppliers of many many Mini-Mills and they say that they hear of few problems of ‘head dropping’ so maybe some folk just get used to a set operating procedure as a work around.

Cheers

Frank

BUT…
Before I was able to install the air spring, my technique was to provide the same effect myself, using the 3-spoke drill press (DP) downfeed handle. Let’s assume you’ll need more than one pass to get to depth. Here’s the drill…
1) Bring the head down close to where you’re going to make the first pass (say, 1/4″ high), lock the Z-gib, and engage the “fine feed.”
2) Apply UPWARD force with the DP handle while unlocking the Z-gib.
3) Maintain that upward force while turning the fine-feed knob clockwise to bring the head down to cutting depth.
4) Maintain that upward force while locking the Z-gib. (Any axis that doesn’t need to move should be locked while making a cut.)
5) Let go of the DP handle (whew!) and make the cut.
6) Z-gib is still locked. Re-apply the upward force with the DP handle and take up any slack that may have developed in the fine-feed gear train using the knob.
7) Maintain the upward force and unlock the Z-gib.
8) Go to step 3.

It’s tedious, but it works.

Paul in Pittsfield

http://www.littlemachineshop.com/products/product_view.php?ProductID=2258&category=879658189