Warco WM290 Cross slide acme block

[petro1headParticipant @petro1head]

Mine needs replacing as getting a lot of back lash. I have adjusted it but I suspect its too far worn.

So i either find a direct replacement or is there anything else I can do in the form of improvement ue anti backlash etc

[petro1headParticipant @petro1head]

[JasonBModerator @jasonb]

I watched this one a while ago but may be easier to buy a spare from Warco

[old martParticipant @oldmart]

Does your lathe have metric dials? If so the leadscrews are likely to be trapezoidal rather than ACME. You may be able to buy nuts that can be made to fit the lathe if they are metric, although the easiest option is getting an original nut, although the design may leave a lot to be desired.

[petro1headParticipant @petro1head]

Yes metric dials however not sure re thread, will take a photo

Edited By petro1head on 11/01/2023 20:30:49

[old martParticipant @oldmart]

What do the dials go up to per turn?

[petro1headParticipant @petro1head]

3.7mm

[JasonBModerator @jasonb]

That's unlikely to be a metric pitch and even if trapizoidal form it is not a standard one.

Pitch will be half that so 1.85mm which is not even a metric dial stuck on an imperial 10tpi screw.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by petro1head on 12/01/2023 02:07:03:

3.7mm

.

… The mind boggles !!

No wonder people find the need for DRO

**LINK** https://warcoblog.com/page/2/

MichaelG.

[DC31kParticipant @dc31k]

Posted by Michael Gilligan on 12/01/2023 07:38:03:

Posted by petro1head on 12/01/2023 02:07:03:

3.7mm

.

… The mind boggles !!

Possibly a misunderstanding of the question.

Maybe a wild coincidence, but on the lathe's spec. page (https://www.warco.co.uk/metal-lathes/302934-wm-290-lathe.html), it gives the _screwcutting_ pitches as 0.2 to 3.5mm, which when summed do make 3.7mm. Maybe the forum has been infiltrated by the AI bot…

[petro1headParticipant @petro1head]

Fortunately I have a DRO

This got me thinking so I check with the DRO and a Dial Gauge and one full turn give me 2mm

[Michael GilliganParticipant @michaelgilligan61133]

That’s a much better number

MichaelG.

[petro1headParticipant @petro1head]

Just goes to show how crap and disbalievable, the dial is.

I only want to take the backlash out as i anoying 

Edited By petro1head on 12/01/2023 08:03:16

Edited By petro1head on 12/01/2023 08:03:54

Edited By JasonB on 12/01/2023 08:26:10

[petro1headParticipant @petro1head]

This forum seems to not like Opera browser on a tablet sorry for the long post

[JasonBModerator @jasonb]

Have you got a picture of the dial? I would expect the highest number to be 3.6 and then when you get back to 0 that is 4.0 not 3.7

Small divisions are 0.04mm, medium divisions are therefore 0.20mm and with large alternate divisions being numbered the next from 3.6mm will cover 0.4mm

[petro1headParticipant @petro1head]

No need, you are correct and I miss read it. Doooh, thanks

[JasonBModerator @jasonb]

That's good to know, can't have knockers thinking all the imported lathes have crap unusual handwheel dials

Edited By JasonB on 12/01/2023 10:00:24

[petro1headParticipant @petro1head]

Indeed, official apology sent to Warco

[petro1headParticipant @petro1head]

Regarding the lead screw block replacement, you can't buy it on its own and have to buy it with a new leads screw, this makes it quite expensive, so will probable just shut up and put up with it

[petro1headParticipant @petro1head]

Unless someone knows an alternative or knows what thread the leads crew is?

[JasonBModerator @jasonb]

Not the easiest to measure the difference between ACME and TR as it's only one degree, hopefully they did the metric pitch screws with a different cutter to the imperial.

Don't forget it is a left hand thread which will be harder to find and probably more costly than righthand

I think it would be TR10x2 LH if actually cut to the 30deg, taps are available but at a high price though you might be able to find them cheaper or even rough screwcut it and then make a tap

[petro1headParticipant @petro1head]

I have seen people make their own using delrin

[SillyOldDufferModerator @sillyoldduffer]

Posted by petro1head on 12/01/2023 08:02:02:

…

I only want to take the backlash out …

Is that what wore out the block?

I expect the WM290 is the same as my WM280, where the block and it's adjustment is a simple arrangement.

The block is made of soft brass, a bearing metal that wears in preference to the screw. Anti-backlash is pretty crude – a slot is cut through most of the block close to one end, and a pair of screws allow the thin end to be bent to take up slack. Problem is that the thread wears quickly when the slot is tight, and frequent adjustment wears it super-fast.

As backlash doesn't matter much on a lathe because cuts always go in one direction, I only adjust mine when it gets bad enough that going generously backwards by dial to correct it becomes more than mildly annoying. This reduces wear massively. I think this is how it's meant to be used. Backlash is annoying rather than important on a lathe, so the adjustment only reduces it. Thus the block is compromise for simplicity and cost, not intended to do a perfect job.

Wear is a problem on all anti-backlash mechanisms, and reducing it requires a much more elaborate mechanism than a slotted block. The extra cost and complexity of a backlash free return may not be worth having, especially if the lathe has a DRO. The slot does a reasonable job simply, but keeping it done up tight causes rapid wear.

I decided it's not worth fixing. I've adjusted backlash twice on my WM280 in 7 years, and the first time wasn't really necessary! I manage well enough without DRO.

Dave

 

 

 

Edited By SillyOldDuffer on 12/01/2023 10:26:54

[HopperParticipant @hopper]

Posted by petro1head on 11/01/2023 16:09:33:

Mine needs replacing as getting a lot of back lash. I have adjusted it but I suspect its too far worn.

Exactly how much backlash are you getting?

Are you sure the backlash is because of the nut, and not because of the adjustment of the thrust bearing and handle on the end of the screw?

[not done it yetParticipant @notdoneityet]

Posted by Hopper on 12/01/2023 10:51:20:

Posted by petro1head on 11/01/2023 16:09:33:

Mine needs replacing as getting a lot of back lash. I have adjusted it but I suspect its too far worn.

Exactly how much backlash are you getting?

Are you sure the backlash is because of the nut, and not because of the adjustment of the thrust bearing and handle on the end of the screw?

And/Or possibly a worn feed screw as well?

[Author]

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