WM250-VF jam up help required

[Brian RutherfordParticipant @brianrutherford79058]

Facing a 6×5 plate this morning from the centre outwards using the powered cross feed and i noticed it had stopped cutting. The leadscrew has stopped turning and the lever to engage has jammed. The cut i was takings was only 2 or 3 thou. No bumps or bangs. Ive fiddled with the knobs but can't free it.

Any pointers on where to start stripping it ?

Tia

Brian

[Brian RutherfordParticipant @brianrutherford79058]

[Mick B1Participant @mickb1]

You've most likely run out of slide movement and forced the crosslide up against the handwheel casing. I've done that, in both directions.

If the main leadscrew's stopped, the shearpin (1/8" brass) inside the headstock end of the spring-steel coiled cover is probably broken, but not before it tightened the crosslide leadscrew against the handwheel casing as above. When it happened to me I just muscled it loose again and retightened the crosslide leadscrew nut in the middle of the top surface. Then replace the shearpin and you should be able to carry on with no significant damage.

[Mick B1Participant @mickb1]

If it feels too risky to force the feed lever out of engagement, you might need to loosen or remove the block where the engagement quadrant (really a partial gear) rotates. In one case I think I had to loosen off the guideplate with the zigzag slot in it that controls engagement lever movement.

If all else fails, phone Warco. They may not know exactly what to do in a particular case, but their advice has been helpful to me in the various troubles I've got myself into.

Edited By Mick B1 on 08/11/2017 13:41:26

[Brian RutherfordParticipant @brianrutherford79058]

Didn't run out of travel still got 65mm to go. What I did do was cut the motor as the grub screws on the toolpost caught the guard . Switched it back on without disengaging the feed. Oops.

[Mick B1Participant @mickb1]

Posted by Brian Rutherford on 08/11/2017 13:48:31:

Didn't run out of travel still got 65mm to go. What I did do was cut the motor as the grub screws on the toolpost caught the guard . Switched it back on without disengaging the feed. Oops.

Can't visualise how that would jam the crosslide. If mine still had its guard, I think the toolpost screws – if we're talking about the same screws – would just have pushed it up and out of the way, maybe cutting the motor, but with no obvious consequences on restarting.

Are you sorted now?

[Brian RutherfordParticipant @brianrutherford79058]

My mistake Mick b1. I did run out of travel. And jammed the slide as you said.

[Brian RutherfordParticipant @brianrutherford79058]

Lead screw will now turn but I think the shear pin has gone. I have taken the block off that the traverse lever fits into. The worm gear was stuck but moves in and out now. Just can't turn the cross slide handle although it moves a little bit.

[Mick B1Participant @mickb1]

Tried slackening off the two capscrews securing the crosslide leadscrew/handwheel bearing housing?

Could the crosslide leadscrew shearpin have fallen partway out so as only to let the handwheel rotate a few degrees? I had that happen too, but it ended up falling into the apron gearbox and jamming pinions in that!

Edited By Mick B1 on 08/11/2017 16:10:05

[Brian RutherfordParticipant @brianrutherford79058]

Will have a look later. It seems when I turn the Lead screw manually the handwheel turns dificult wvithout a C spanner for the nut . Can't get it out of gear though. I will put the block back tonight after tea and see how it goes

[Brian RutherfordParticipant @brianrutherford79058]

Will have a look later. It seems when I turn the Lead screw manually the handwheel turns dificult wvithout a C spanner for the nut . Can't get it out of gear though. I will put the block back tonight after tea and see how it goes

[60019Participant @60019]

If it's any consolation, you're not the first and I am sure you will not be the last.

This thread may help **LINK**

[SillyOldDufferModerator @sillyoldduffer]

Assuming the shear pins are OK, try spinning the chuck backwards by hand . (Not under power.) With luck the mechanism will back off enough to release the lever.

Dave

[Mick B1Participant @mickb1]

Posted by 60019 on 08/11/2017 17:22:50:

If it's any consolation, you're not the first and I am sure you will not be the last.

This thread may help **LINK**

You also learn to check as a matter of course that the whole cut's within the range of movement, and that you don't wander off and get drawn into something else while it's running. You also learn to recognise the change in motor note as the feed runs into obstruction.

Neverthless it's happened to me two or three times. The worst one was longitudinal feed with a locked saddle – that bent the drive pinion against the bed rack, making a very tight spot about every third turn of the saddle handwheel. But you can actually bend the pinion straight again with a standard crowbar!

But for all that, the lathe is still as accurate as ever and does good work nearly every day.

[Brian RutherfordParticipant @brianrutherford79058]

Need to knock the shear pin out of the Lead screw. Is just a hammer and punch. Seems pretty tight to me

[Howard LewisParticipant @howardlewis46836]

If you have a positive drive into the Apron, for longitudinal travel, but none to the Cross Slide, it looks as if you have sheared something within the Apron.

If the Apron is like that on the Warco BH600 and its clones, the drive is taken from the worm into a gear which has a multi tooth dog clutch on each side. This slides to and fro, to drive gears for either the longitudinal traverse, or the Cross Slide.

It is possible that this is pinned to the shaft, and that the pin has sheared (When I jammed up my BL12 – 24 and bent the pinion shaft, I was lucky in that the damage was confined to the longitudinal traverse pinion and shaft, so did not investigate this area). The article in MEW 254 includes a small view of the Apron from above, ready for reinstallation.

If you would like file of this, of about 4Mb, PM me.

I had already replaced the steel rollpin in the drive to the feedshaft with a 5mm brass pin, but the jam up did not shear it, so it now has a 2.5mm drilling down the centre, to weaken it. You may wish to do the same, in the hope that, next time, it will fail and prevent greater damage.

Howard

.

Edited By Howard Lewis on 08/11/2017 18:39:19

[Brian RutherfordParticipant @brianrutherford79058]

Thanks to all for your replies. Special thanks to Mick b1 for his advice and the link.

Too tired to do much tonight so will leave it till morning as I don't want to make it worse. First job will be to remove the shear pin in the Lead screw, so far it's resisted all attempts with a hammer and punch so probably best to try to remove the Lead screw from the housing.

Will keep you posted

Thanks

Brian

[Mick B1Participant @mickb1]

IIRC when I did this I removed the tail-end leadscrew bracket and unscrewed the vertical capscrews securing the apron to the saddle. Then you should be able to pull the leadscrew out of the sleeve at the headstock end and remove apron and leadscrew as a subassembly. Keep it vertical so as not to spill all the oil.

[Howard LewisParticipant @howardlewis46836]

It is possible that the shear pin has sheared and then jammed again, after some rotation of the driving shaft.

Is it possible to start drilling it? This might conform/deny this theory, (drill part way and try to look down hole. Should be no steel shaft visible at bottom of hole.

If there is, try rotating the shaft 180 degrees and drill out the brass ,from the other side. With a bit of luck you can then remove the shaft from the drive, allowing you drive /drill out the remnant from the drive.

Howard

[Stuart RiddellParticipant @stuartriddell45006]

This may be a daft question, from a complete novice, but can the lathe still be operated without the shear pin in place. I am just looking at a WM250V and am assuming it has one of these or do all modern lathes have it

[Mick B1Participant @mickb1]

Posted by Stuart Riddell on 09/11/2017 07:47:45:

This may be a daft question, from a complete novice, but can the lathe still be operated without the shear pin in place. I am just looking at a WM250V and am assuming it has one of these or do all modern lathes have it

Yes it can, but the leadscrew won't be turned by the headstock geartrain, so there'll be no power feed for turning, facing or screwcutting.

WM250V has one for the main leadscrew just in front of the headstock 'bulkhead', and one for the crosslide leadscrew just behind the bearing housing. Almost any properly-designed lathe will have these, modern or not.

[not done it yetParticipant @notdoneityet]

Stuart,

The lathe can be operated manually (no theading or power feed) but in this case, with the apron jammed, that would be unwise without sorting out the reason for the jamming. Unfortunately, some might mean fitting a non-shearing item in place of the shear pin. In that case the lathe would cheerfully go on operating until a jam occurs, but this time much more damage to the gear train would likely be the result. There may be a bent shaft in Brian's apron which is preventing much movement in either direction of turning.

[Mick B1Participant @mickb1]

Posted by not done it yet on 09/11/2017 08:22:50:

Stuart,

The lathe can be operated manually (no theading or power feed) but in this case, with the apron jammed, that would be unwise without sorting out the reason for the jamming. Unfortunately, some might mean fitting a non-shearing item in place of the shear pin. In that case the lathe would cheerfully go on operating until a jam occurs, but this time much more damage to the gear train would likely be the result. There may be a bent shaft in Brian's apron which is preventing much movement in either direction of turning.

In the WM250V, I think it's more likely that one of the leadscrew nuts would get damaged than the headstock gears.

Since Brian was facing – not turning – when the jam occurred, it would be the crosslide leadscrew assembly that was under load, and I *don't think* that's strong enough to distort the apron pinions or shafts. If the shearpin didn't do its job, I'd guess the crosslide leadscrew nut is the more likely casualty.

Still speculation, though really.

[Stuart RiddellParticipant @stuartriddell45006]

Sounds like it would be handy to keep a couple of these as spares in the toolbox but good to know it can still be used without them the good old fashioned way

[Brian RutherfordParticipant @brianrutherford79058]

Took the centre bolt off the cross slide which dropped the nut which allowed me to unwind the cross slide leadscrew and withdraw it. Pretty good bend in it at the start of the thread nearest the front. Will put it in the lathe between centres to see if I can straighten it. Pity I can't use the cross slide to do it

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