Mating surfaces

Hi All

I'd be grateful for some advice.

As a novice at lathe work I thought that I might have a go at milling in the lathe so in my usual cheapskate fashion I decided to see if I could make a vertical milling slide by marrying an old lathe cross slide to an angle plate.

I've got to the trial assembly stage and I've found that when I tighten down the angle plate to the cross slide the cross slide gib needs readjusting - it becomes slacker. After a little bit of fiddling I conclude that either the cross slide or the angle plate isn't flat and tightening them down is opening the dovetail in the cross slide.

I suspect the angle plate (it was only £3) but I can't reliably detect a problem with a straight edge. If anything it is slightly concave (though less than 0.001") and I would have expected a bulge to open the dovetail in the cross slide.

I've put a couple of pictures to show the general arrangement here

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I'd be grateful for any suggestions - especially ones that don't involve spending lots of money.

Russell (aka Cheapskate)

Reply to
Russell
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Russell

I guess the easiest and cheapest solution is to tighten the cross-slide gib strips a bit after you've bolted the vertical slide down.

The alternative would be to have the angle plate and the cross-slide surfaces re-ground which might be a tad more expensive.

Mark

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Reply to
Mark_Howard

If you have access to a surface plate and some marking blue you can find out which it is by gentle rubbing.

Greg

Reply to
Greg

Micrometer blue even ;-)

Reply to
Wayne Weedon

Yes even that 8-), well it's late and I've been playing D&D for the last few hours so I'm in another world...

Greg

Reply to
Greg

And if it is not flat you can scrape it.

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Reply to
Charles Lamont

Have you checked for small raised burrs on the mating surfaces of plate or cross-slide? One in the middle might act like a fulcrum...

You could try fitting a large washer on each bolt between the plate and cross-slide, limiting contact to small areas. Or do away with the bolts, and hold the angle plate down with clamps & clamp bolts in the T-slots instead. Reposition to reduce distortion.

hth Guy

Reply to
Guy Griffin

I'm sorry but I'm going to have to agree with you... Marking Blue is a correct name for the product. Micrometer Blue is Stuart's trade name for their version. The one not to use would be Layout blue :-)

In this particular case. Blueing up the cross-slide and spotting and scraping the angle plate may well be enough, after checking for any dings or bruises on the cross-slide. It might not matter if both are completely flat so long as they fit each other in the intended location.

Stop Press. Brilliant (booze induced) idea.

Use three T bolts to clamp the angle plate (two at the headstock end and one at the tailstock end) and put a washer between the angle plate and the cross slide on each T bolt. The result will be slightly less rigid, but not enough to make much odds and it should prevent distortion stiffening the cross-slide.

Mark Rand RTFM

Reply to
Mark Rand

OK Thanks for all of those.

I'd wondered about just adjusting it as needed but I'm not happy about knowingly distorting the cross slide.

I'd wondered about using shims or washers - but I hadn't thought of using only three. I'd also wondered about checking for flatness but as far as I knew this morning I didn't know anyone who had a surface plate - but I know different now. He even put it in his pick up to bring roung this evening - then came in the car.

I think the budget can probably stretch to some marking blue.

I think that in this case the best solution is probably the most labour intensive. I've never tried scraping before so look forward to some more questions - are there any good links out there?

Thanks again

Russell

Reply to
Russell

This is pendant season innit!!

Depends very much who taught you I guess! I've always used Micrometer blue and I have not managed to use up a tin in 20+ years! But my late boss and mentor would insist only the faintest smear be used.

Marking blue on the other hand was sommat i'd not used since schooldays ;-)

Wayne....

Reply to
Wayne Weedon

Surely you mean pedant...

Peter

Reply to
Peter Neill

There you go! Was sat here waiting for that one

Reply to
Wayne Weedon

Surely if it was pendant you were hanging arround not sitting.

AWEM

Reply to
Andrew Mawson

It appears from reading on the net and in books that "marking blue" is used for both types.

This is most confusing ;-)

"Layout blue" is unambiguous, but I don't think there's an accepted and unambiguous name for the "stuff" used for printing from a reference surface to a workpiece.

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BugBear

Reply to
bugbear

More:

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pp 96,97

BugBear

Reply to
bugbear

Please, if you are linking to an 18 Mb file, give us some warning!

Reply to
Peter Fairbrother

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