Lathe: Crunchy noises in lower gears

[Lee Jones 6Participant @leejones6]

What do you suppose is going on in the lower ranges here?

 

 

Also really noticeable near the end of the video.

 

 

https://photos.app.goo.gl/AsV6gVudmENqeTGZ7

 

As usual. Any help would be gratefully received.

Edited By Lee Jones 6 on 07/12/2021 16:38:50

[Lee Jones 6Participant @leejones6]

[JasonBModerator @jasonb]

Did the headstock get refilled with oil when it was stripped and recently repainted? Bed and cross slide look like there is not much oil on them

I'd also take the chuck off and disengage the gear train to the gear box to eliminate some of the moving parts and then you can see if the noise is from the headstock gears in which case whip off the top cover and have a look at all the gears as you rotate the lathe by hand also check the selectors are not throwing too far or not all the way.

[SillyOldDufferModerator @sillyoldduffer]

Wot Jason said: I suspect the selectors.

Did I see you grip a running chuck with a cloth? Please don't do that – common cause of nasty accidents. Think dislocated joints, de-gloving, and broken bones, worse if your face is pulled into the lathe as well.

Dave

[Lee Jones 6Participant @leejones6]

That's not me in the video.

I'm from the South and have much prettier hands.

Edited By Lee Jones 6 on 07/12/2021 17:32:45

[OldironParticipant @oldiron]

Posted by SillyOldDuffer on 07/12/2021 17:20:39:

Wot Jason said: I suspect the selectors.

Did I see you grip a running chuck with a cloth? Please don't do that – common cause of nasty accidents. Think dislocated joints, de-gloving, and broken bones, worse if your face is pulled into the lathe as well.

Dave

I agree 100%. Nearly fell off of my chair when I saw the rag.

regards

[Howard LewisParticipant @howardlewis46836]

Obviously has loyalty card at the local A & E!

If the gears are noisy, his 127T is very rusty which won't reduce the noise level.

If the gears are noisy, it could be that the backlash on the changewheels is too little, or non existent.

Always worth setting with a sheet of paper in the mesh to give about 0.003" (0.075 mm )

Some thick lubricant on them helps as well.

Howard

[Lee Jones 6Participant @leejones6]

Yes, certainly looks like it. I'll pass on all of your concerns when he arrives on Saturday.

Thanks for all the suggestions – I'll put them all to good use when it's in my possession.

[Michael BriggsParticipant @michaelbriggs82422]

I took delivery of my M250 earlier this year. It had some damage to the headstock gears which made some ratios noisier than others, probably caused by changing the gear selection under power or before the spindle had stopped. Also the gearchange was a bit notchy for some ratios.

I changed the gearbox oil, that made the gearbox a bit quieter and improved gear selection. I always change gear with the spindle stationary (as you should). Over time that has greatly improved the smoothness of the selection.

As Jason has suggested, remove the top cover and have a look inside the gearbox.

Michael

[Lee Jones 6Participant @leejones6]

Lathe arrived today. It's in pretty good condition. All axis moving smoothly, etc.

I did mention the rag. Not sure the advice was accepted or not, but I passed it on in any case.

First thing I did when it arrived was change the gears in the screw cutting gear box (I would feel that they were not properly seated) and slacken off the change gears a little. And guess what, no more noise. Thanks for all your responses chaps.

One further question regarding setting the change gears …

Howard, you mentioned using a piece of paper. How does that work exactly?

[JasonBModerator @jasonb]

If you cut a few strips of photo copy paper into strips about the same width as the gears you can put that between them as you tighten them and the banjo, just run them back and forth a couple of times by hand.

This gives a small gap so they don't rub but not so much that you get noise and wear.

Some lathes also have different thickness washers to space the gears sideways so they don't touch and ring.

Edited By JasonB on 11/12/2021 20:09:21

[Ian PParticipant @ianp]

I run my M250 off a VFD and most of the time leave the headstock gear selector in the 550RPM position which is as near a straight through drive as it can be. At very slow motor revs (about 5Hz) there is a chattering noise from the gears until there is some load on the spindle when it quietens down. (same as the infamous cloth effect). If your lathe has a single phase motor, (which are not a smooth as three phase ones), then that might explain some of the noise you hear.

Ian P

[Howard LewisParticipant @howardlewis46836]

Lee,

Jason's picture shows exactly how to do it.

Ideally, you are looking for some paper that is 0.003" thick, to give just a minute amount of backlash. This will prevent any root / crest interference between the gears.

Some good thick lubricant will complete the work.

Having no backlash is likely to cause nise and wear to the gears and the studs which carry bthem.

With proper backlash and lubrication the action will be so much better.

Howard

[Lee Jones 6Participant @leejones6]

Makes sense to me. Thanks for the explanations.

I'll set that up at the same time as installing the DRO which I should be ordering tomorrow.

Hopefully it arrives this side of the festivities.

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