Warco WM250 back issues

[Mick B1Participant @mickb1]

Posted by Redsetter on 04/05/2018 06:42:23:

I think it is worth pointing out that the Warco 250/280 etc, are based on a German Wabeco design,

…

There seem to be significant design differences from Wabeco's current offerings. WM250V appears to offer a more useful range of thread pitches (Wabecos I looked at don't go coarser than 10 TPI ), 3 feeds per changegear config rather than Wabeco's 2 fixed feeds, and I didn't readily find powered crossfeed on Wabecos.

[mechman48Participant @mechman48]

Posted by John Hall 7 on 03/05/2018 14:55:13:

Would flanged nuts be better…no fiddling with washers?

​I have used flanged nuts for about 4 years now, much better, make sure that you get the non serrated type, & check their weight otherwise you could get some signs of imbalance, only slight, but a couple of grams lighter or heavier on one nut could give rise to vibration at certain speeds, highly unlikely but still possible. I doubt that these chucks are dynamically balanced on assembly. I found this out with the SHCS fixings on the back plate, I had signs of imbalance in the upper range & couldn't figure out where so on the off chance I removed the chuck removed & weighed the SHCS… one was heavier by a couple of grams. I did a tiny touch up on the belt sander & all 3 matched up to 10 grams iirc, it improved the imbalance some what, although not completely but still better.

​I know purists will comment on reasons for imbalance, ce la vie, but it's worth checking, & on these Chinese machines any little titivating that help goes a long way considering the mass production & questionable QC process.

George.

[John Hall 7Participant @johnhall7]

Thanks for the tip…

[Howard LewisParticipant @howardlewis46836]

With regard to the difficulty of holding the nuts in the very limited space between the backplate and the Headstock on a variety of lathes,

Some time ago, there was a short article in MEW, by M2Z, on a simple device for holding the nuts whilst allowing open end spanner access to the nut. It is only a bit of thin steel, but does the job! Make one.

Howard

[J BENNETT 1Participant @jbennett1]

Reading this old thread, I was very interested in the remarks about the fit of the 3 jaw chuck on the spindle. I have a very early WM 250 (2005) and the chuck is a very easy fit on the spindle flange, almost bordering on loose. Its started me thinking about whether I need to machine a new back plate for the chuck, if I can get one. Any views??

John

[Ron LadenParticipant @ronladen17547]

Posted by J BENNETT 1 on 28/12/2018 13:55:13:

Reading this old thread, I was very interested in the remarks about the fit of the 3 jaw chuck on the spindle. I have a very early WM 250 (2005) and the chuck is a very easy fit on the spindle flange, almost bordering on loose. Its started me thinking about whether I need to machine a new back plate for the chuck, if I can get one. Any views??

John

John, I dont know how loose you chuck to spindle flange is but I saw a video some time back where someone found that his mini lathe had a few thou of clearance between his chuck and spindle flange. He used it to his advantage though, when he clocked the chuck there was some run out. He slackened the fixing nuts until they just had a tad of grip and using a rubber mallet he worked around the chuck whilst checking it with the DTI. Once he had it has good as he could get it he tightened the nuts and lost the run out, well all but a thou if I remember. Of course if he removed the chuck he had to set it up each time he put it back but said it only took him 5 minutes to do.

Just a thought but you may want to do a permanent fix.

Edited By Ron Laden on 28/12/2018 14:46:28

[SillyOldDufferModerator @sillyoldduffer]

Posted by J BENNETT 1 on 28/12/2018 13:55:13:

Reading this old thread, I was very interested in the remarks about the fit of the 3 jaw chuck on the spindle. I have a very early WM 250 (2005) and the chuck is a very easy fit on the spindle flange, almost bordering on loose. Its started me thinking about whether I need to machine a new back plate for the chuck, if I can get one. Any views??

John

My view – if it ain't bust don't fix it!

Not difficult to get sucked into 'improving' lathes unnecessarily if you start by criticising the machine rather than the results it produces. In particular Far Eastern lathes care sod all for cosmetic details and are liable to look rough even at their best. But although details may offend the eye, I feel they are only worth fixing if they effect the lathe's performance.

It may be worth replacing the backplate if you can show it's causing poor results. Depends on what you're doing of course, but much of what's done in a 3-jaw chuck doesn't require the backplate and chuck to be wonderful – rather the opposite. Lathes cut relative to the spinning axis, not relative to the chuck, which means that short parts made in one go will be accurate even if the chuck is off-centre.

High accuracy in a chuck is valuable on longer turning jobs and – most importantly – whenever work has to be moved to apply other operations. Although an expensive 3-jaw chuck saves reset time because it is more repeatable, many amateurs switch to a 4 jaw for that kind of work. A well adjusted 4-jaw will out-perform even the best 3-jaw, the downside being the time taken to set them up.

It might be an an advantage to have a chuck with a loose register. Off-axis errors can sometimes be corrected by gently nipping the fixing bolts before tapping the backplate to centre a test rod as measured by a DTI. Only when the test rod is aligned are the bolts fully tightened. Again, the disadvantage is time.

If your backplate does need fixing, you might be able to replace it off-the-shelf, otherwise they're not difficult to make from a blank. Here's some castings on ebay.

Dave

[J BENNETT 1Participant @jbennett1]

Thanks Ron. I have seen that article.

Having looked on the Warco site for availability I realise now that the back plate comes with the recess for spindle already bored, so pot luck whether it would be any better than the one already fitted to the chuck. Should have rembered that, brain still addled from Christmas. Still last of the visitors went today.

I will check the run-out, something I haven't done for a while, and see if I can improve it using the article you referred to and the gentle application of the engineer's friend!

[JasonBModerator @jasonb]

You can bore your own from a casting or slice of bar. My 3-jaw backplate is a press fit on the spigot so will always go back on with no variation, does need jacking off to remove and pulling on working around the 3 studs a bit at a time. Chuck is also good so I get less than 0.001" TIR

[John Hall 7Participant @johnhall7]

I think it is made with a sloppy fit on purpose…this gives enough all round play to enable accurate cantering…there are a few vids on YouTube showing how to do it…simple but effective…If it’s not possible using this method…removing the chuck and turning it 60 degrees and refitting etc to see which position gives the best reading…..if that doesn’t result in a good reading..sometimes removing the jaws and trying them in a different sequence may help…

[Niels AbildgaardParticipant @nielsabildgaard33719]

I have an old model,recently made WM250 and like it more and more.It improved itself imensely cutting 4mm away from backside of flange as first operation .I had nothing but an Ifanger HSS boring head as tool and spindle was a litte hard.Carbide had left a better surface,but it is not very important

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