New mill user, a problem I can’t figure out.

[Robert Bowen-CattryParticipant @robertbowen-cattry70600]

Good morning all,

Several weeks after buying my WM16B I have finally made my first chips. The mill sat on my workshop floor for several weeks while I had a concrete slab poured and I installed a new shed in order to clear my workshop, build new benches and get the mill installed.

Everything seems to be working fine, I trammed the head and vice, and made some cuts. However, I have an issue that I can’t seem to find an answer to. The table is noticeably stiffer to move in the X axis in one direction. Moving the table to the left is harder than moving it to the right.

I’ve checked the gib several times and think I have it adjusted correctly, no slop and the table moves smoothly, just requires more effort in one direction. Is this normal and just needs breaking in, or have I done something wrong? The Y axis moves smoothly in both directions.

Any advice for a noobie would be most gratefully received.

[Tony Pratt 1Participant @tonypratt1]

I’m not familiar with your exact mill but my first thought is to check the X screw movement thrust bearings on either end of the table within the bracket next to the micrometer dials. Moving the table left or right will load the bearings individually, one may be faulty?

Tony

[Robert Bowen-CattryParticipant @robertbowen-cattry70600]

Thanks Tony, not something I had thought to check. Will take a look.

[Clive Brown 1Participant @clivebrown1]

My 16B is OK in this respect. Another possibility; the gibs are tapered. Have you tightened up the adjustment screws at both ends? If not, the gib may “float” endwise when the table is moved, making for a wedging action.

[JasonBModerator @jasonb]

I was just going to say the same as Clive.

This is the WM16 but I expect the 16B is similar, you need to have both screws bearing on the ends of the tapered gib so it can’t move as the table is moved.

[Robert Bowen-CattryParticipant @robertbowen-cattry70600]

Thanks guys. I’m pretty sure the gib is set correctly, I’ve had it out a couple of times but will check it again.

[Clive FosterParticipant @clivefoster55965]

Can confirm that a floating gib is definitely a potential cause.

Had the same problem over 20 years ago with the big, one off market test, square column bench mill with integrated VFD drive I bought from Chester. Single adjuster at one end of the taper gib strip with a slot way wider than the head of the setting screw.

Considerable side float in action gave exactly this tight one way loose the other problem.

Having adjusters at both ends is not necessarily a total palliative. If there is anything behind the gib preventing it from sitting properly flat both sides it will tend to tilt giving the same effect. The end adjusters stop end to end movement if correctly tensioned but do nothing for tilt. I’d run a beady eye over the top and top corner of the slot into which the gib sits. When doing a re-furb I always take pains to scrape out these corners.

A inescapable issue with affordable machines is that they cannot get the careful inspection and hand fitting needed to ensure such effects are never present on delivered machines. They rely on a decent standard of machining producing things right enough to work in a satisfactory manner. Which it generally does. But when stuff is, for any reason, not quite right but right enough to assemble OK you can end up with some really weird stuff to track down.

Clive

[ChrisLHParticipant @chrislh]

I agree with the Clives and Jason that the jib is the most likely cause. The jib doesn’t have to be tapered to present this effect. If the dimples in the jib are not spaced at exactly the same centres as the screws (very likely !) then the jib can assume a variety of positions depending on which screw is tightened first and then the proposed jamming action can take place as a result of the screw point riding up on the conical surface at the bottom of the dimple under endwise friction. I’ve experienced this on my Myford taper turning attachment and live with it because I use it rarely. G H Thomas writes about his fix for the problem in “The Model Engineers Workshop Manual” on page 181 etc., “Topslide Locks”.

[Harry WilkesParticipant @harrywilkes58467]

have you spoken to Warco ?

H

[Robert Bowen-CattryParticipant @robertbowen-cattry70600]

Many thanks for all your help guys, I think I am well on the way to resolving the issue.

I’m working from home today so popped out to the workshop in my lunch break. I removed the left hand wheel apparatus, and took the gib out again and reinstalled it, and immediately the table was moving with the same effort in both directions.

When I reinstalled the left hand wheel the problem re-occured. By backing out the nut that holds the wheel on I could get everything to move properly again, but it left a 3-4mm gap between the wheel and the fitting on the end of the table.

I took the right side off, cleaned and re-oiled the bearings and re-installed the wheel, but even with the retaining nut tightened all the way down I still had the gap at the other end. I then decided to add a washer on the right side between the nut and the wheel which seems to have closed up the gap at the other end to less than a millimetre, but still allows the tablel to move well in both directions. I wonder if there should have been a washer there from the factory but it was missed off?

I ran out of time at this point and had to go back to work, but I think with a bit more fettling I can close the gap up more, or maybe fill it with a nylon washer.

 

[hurnbyParticipant @hurnby]

Sounds like you’re on the right track.
I had a case where the clearance was too large and it was affecting the accuracy of the operation.

[old martParticipant @oldmart]

Try it with the gib very loose,then that might be confirmed or eliminated. I thought of the cheap method of making the leadscrew nut antibacklash, the cut being too close to one end and flexing in one direction.

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