PM25 fine down feed, what am I missing?

Removed the washer/spacer from the head stock. One of the screws was loose. There was some swarf in between the washer and the machined cast iron. Cleaned it all up and reassembled. It's a little better. @higgite You are right, it has to be really tight to work. If all else fails, I could just chuck the washer in my lathe and take off 0.005 - 0.010" on the thickness. For now, I'm calling it good.
 
OP here. Continuation of thread. Sometimes I find the fine feed changes during an operation. Doesn't happen every time, but I find occasionally the quill DRO indicates a change of 0.0005" deeper than initial setting. Once or twice (in the past 6 months) I've seen it drop 0.001". What could be the cause of this?
 
WobblyHand said:
OP here. Continuation of thread. Sometimes I find the fine feed changes during an operation. Doesn't happen every time, but I find occasionally the quill DRO indicates a change of 0.0005" deeper than initial setting. Once or twice (in the past 6 months) I've seen it drop 0.001". What could be the cause of this?
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I had posted a long answer thinking that we were discussing a lathe. Nevermind.

Now that I have tuned in to what we’re talking about, I experience this same thing: I use the fine feed with quill DRO to set the DOC where I want, lock the quill, and then it changes a little during the cut. I figure that there must be play (lash?) in the quill.
 
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The PM25 documentation is a little confusing in the manual. Sometimes it says to lock the quill and other times not. I'm not surprised that the position might change as a result of locking. But I think the manual says to not lock the quill when taking the cut. That the worm should hold it in place as long as one hasn't backed it off.

I'm just looking for consistent results at the moment, so my post is to ask if there's a technique that can be used on this type machine that generates more consistent results (less droop?). If this is the limitation of the PM25, that's good to know as well. Is there a way to take up the "lash" consistently?
 
I have a different mill - PM30-MV - but I'm having a similar problem. To get the fine feed engaged on mine, the knob has to be SUPER tight. put a wrench on it tight. I can do it by hand, but I have to grip that knob so tightly it hurts my hand. (maybe I'm just getting old)

And there is a spot where it down feed sometimes 'jumps' or 'pops' or something. Feels like the spring is slightly binding then releases or slips. I need to take the whole thing apart to inspect it. There was another thread where the mechanism had been assembled incorrectly, and there was a large burr where a set screw had be installed wrong. Some cleaning and file work solved the issue.
 
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Wouldn't be surprised if there are issues inside the mechanism. It would seem that at assembly some of the cleaning was "optional". Me, I clean stuff before I put it together. A lot of these factories don't do these niceties, most likely due to cost pressures. Fortunately I don't have to SUPER tighten the knob (I think). Perhaps I will tighten the knob more and see if the nature of the problem changes. If so, maybe I'll make a larger diameter knob so I can tighten it easier.

I haven't noticed any binding on the fine feed, but I will look out for it. Thanks for the tip.

As for getting old, it happens everyday... Getting older is better than the alternative!
 
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