Warco mini lathe handwheel fettling?

[Chris VeitchParticipant @chrisveitch14689]

 

I wasn't sure whether to post this in Beginner's Questions as I've just bought the lathe and I'm just moving up form a Unimat so I am a beginner in model engineering terms, but since it doesn't really seem to be a beginner's issue it's going in here. Can someone please let me know if it's considered bad form…?

My new Warco Mini Lathe has all the rough edges common to the breed, but the compound slide (not even sure if it's the right term) hand wheel is particularly rough. It has around 0.6mm backlash as delivered and is secured with the two fairly rough lock nuts shown in the photo below.

I have the David Fenner mini lathe book and I've read the ARC guide on stripping and refining it, but neither seem to show such an arrangement. Does anyone have any tips or references on refining this arrangement? Curiously, the very similar cross slide hand wheel has very little play in it and is well assembled.

In addition to that, the hand wheel isn't drilled at 90 degrees but that could be redrilled and bushed. I'd also be interested to know if there is a possibility of converting these fixed dials to indexed?

Edited By Chris Veitch on 15/12/2013 10:18:48

Edited By John Stevenson on 15/12/2013 10:37:09

[Chris VeitchParticipant @chrisveitch14689]

[Ady1Participant @ady1]

If you want to save yourself a LOAD of "backlash issues" then fit a cross slide DRO as your first project

10 quid for a vernier and it's one of the most useful mods you will ever make

modern Digital aids

It was 1-2 years before I did mine and I wish I'd done it on day 1

Try and get exactly the same vernier, different models have different functions

BTW you only really need the compound slide for tapers, putting a toolpost on the cross slide makes things much stiffer

Edited By Ady1 on 15/12/2013 12:19:05

[BazyleParticipant @bazyle]

2 nuts is actually a step up from some quite reputable lathes which just expect the handwheel grub screw to do the job.
The backlash can come from the adjustment of those two nuts but also the fit of the screw thread to its nut (which usually has no option for compensation on a topslide) and the way that nut is held to the body which might just be loose.
It is normal to have to do some adjustment here as they are put together against the clock.

[Martin WParticipant @martinw]

Post not applicable to this lathe so removed.

Martin

Edited By Martin W on 15/12/2013 14:31:16

[Chris VeitchParticipant @chrisveitch14689]

Thanks for the ideas so far, guys. I can see I'm for an Interesting Journey with this machine – although I still think they're great value for less that £500. An hour or so's fiddling this afternoon has the backlash down to a reasonable 0.07mm although the compound slide screw action is still very uneven.

I suspect this might be to do with the way I've remounted the "bracket" (as it's know in the Warco parts list – it's the component which forms the end bearing for the compound slide screw) onto the end of the slide – it's attached by a couple of M3 cap nuts to a fairly small area on the end of the slide, so I'm dubious about its squareness. I guess there's some clever trick to tightening the screws holding this correctly – which I haven't got, and it seems to be throwing up some eccentricity in the screw which wasn't there before.

[Gordon WParticipant @gordonw]

Does not seem like to much backlash to me. The two thin locknuts can be tricky to set just right. May be worth taking the gib strip out and cleaning up if needed. I only use the topslide for tapers, most of the time it's locked solid, nearly as good as a cross slide toolpost, helps with parting off also.

[Chris VeitchParticipant @chrisveitch14689]

No, I can definitely live with 0.07mm and probably a bit more. My current concern is the binding on the compound slide screw but a bit of further investigation reveals that this is due to the index wheel (correct term? – the stainless collar on which the index divisions are marked) binding against the bracket. It's secured with an M3 grub screw which isn't midway along the collar, and the collar itself isn't a good fit on the plain machined section of the screw.

Consequently everything runs OK when the collar is loose, but when the grub is tightened it exerts and uneven pressure on a loose fit and pulls over and binds at that point, giving a very uneven action. My workaround for the moment it so leave the collar loose and carefully set the locknuts, which gives a bit more backlash but the motion is now smooth. Unfortunately the Warco doesn't give the option to lock in this axis, other than over-tightening the gib screws.

A long term option would be to bush the collar and maybe secure with a pin rather than a screw, but it looks like fairly tough stainless and there's plenty more to do yet…

[BazyleParticipant @bazyle]

Do the nuts bear on a sleeve and the index collar run on that or is the index like a big washer in the set up? So will the set up will go together without the index? If so you can just skim a bit off it in your own lathe. Otherwise anyway you need to make a sleeve and bore out the index to fit over it. If you are feeling clever you can build in a ball thrust bearing while you are at it.

Don't be afraid to take the slide apart and drill & tap an extra hole to use for a lock. While you are there if the gib has dimples for each screw research how to do it better – there is stuff on the net about that poor practice.

[Chris VeitchParticipant @chrisveitch14689]

Posted by Bazyle on 15/12/2013 15:52:15:

Do the nuts bear on a sleeve and the index collar run on that or is the index like a big washer in the set up? So will the set up will go together without the index? If so you can just skim a bit off it in your own lathe. Otherwise anyway you need to make a sleeve and bore out the index to fit over it. If you are feeling clever you can build in a ball thrust bearing while you are at it.

Don't be afraid to take the slide apart and drill & tap an extra hole to use for a lock. While you are there if the gib has dimples for each screw research how to do it better – there is stuff on the net about that poor practice.

No, there's no sleeve – the index is like a big washer. Therefore it's possible to think things are going OK when tightening the index and then to foul it all up by slightly over-tightening the nuts, which obviously have a much greater force than the little grub on the index can hold if you overdo it. I take your point about sleeving it and it's definitely a job for the future, although I'm not too confident about boring the stainless collar accurately. My only previous experience of cutting stainless is with a plasma cutter, and that definitely wasn't in the spare bedroom…

I'd agree that a lock is a useful addition – once I get things working satisfactorily it will be one of my first mods. And yes, the gib strip has already been out and it has dimples – I'll investigate.

[frank brownParticipant @frankbrown22225]

can you insert a thin (and narrow) shim between the shaft and the collar , aligned with the rubbing edge. I think that tightening the grub screw will lever the collar the other way if the shim does not run from the back to the front (knob end)?

Frank

[Chris VeitchParticipant @chrisveitch14689]

Posted by frank brown on 30/12/2013 22:36:37:

can you insert a thin (and narrow) shim between the shaft and the collar , aligned with the rubbing edge. I think that tightening the grub screw will lever the collar the other way if the shim does not run from the back to the front (knob end)?

Frank

I don't know, Frank – but I'll give it a try.

Edited By Chris Veitch on 31/12/2013 10:23:48

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