flatness of faceplate ?

[gerry maddenParticipant @gerrymadden53711]

[gerry maddenParticipant @gerrymadden53711]

Ive just bought a cast iron faceplate. I bolted it on the the spindle and checked the runout in several places. This was fine. But as I wasnt intending to use it I started to remove it. Suddenly I noticed that it didnt seem to be totally flat. On more careful inspection I have now found that the last 20mm or so of its radius is cambered off (in the headstock direction) by about 1mm. Is this normal ?

[JasonBModerator @jasonb]

Always best to skim a new faceplate when its on the lathe.

 

J

[gerry maddenParticipant @gerrymadden53711]

But to make this faceplate nominally flat all the way across its 160mm diameter I will have to skim 1mm from two thirds of face. Thats not so much a ‘skim’ as a significant machining operation !

 

Im not sure if this cambering is deliberate/normal or accidental.

[JasonBModerator @jasonb]

Accidental.

 

What lathe is it for and if a new one I would be asking for an exchange as it is a bit excessive

[mgjParticipant @mgj]

Don’t forget that it will never be truly flat because if the lathe is set correctly, it should turn very slightly concave.

 

And as Jason said, it would be someone being a touch unwise if they just put a faceplate (or a chuck backplate) onto a lathe and expected it to be true.

 

Still 1 mm is a bit more than one might have expected, but it won’t matter so long as the outer edges remain thick enough to remain rigid in use. So that might be a machining allowance?

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Hi Gerry ,

 

The actual answer to your question is that your faceplate is defective and should be returned to supplier . New faceplates bought for old lathes are often out of true to the extent of a couple of thou but 40 thou is grossly excessive .

 

Just for interest :

 

The quality of faceplates and the means of mounting vary with different manufacturers . Most mainstream manufacturers take reasonable care but just occassionally in industry you come across something special . Both Hardinge and Schaublin make their equipment to such exacting standards that you could can buy faceplates and a range of other accessories which are guaranteed to fit perfectly – and experience shows that they always do .

 

The proper shape for a faceplate is just dead flat and running true to lathe axis . Its rare now but sometimes the faceplates on lathes such as Dean Smith and Grace were actually scraped and a certificate of accuracy given .

 

MW

Edited By MICHAEL WILLIAMS on 21/01/2012 11:46:49

[gerry maddenParticipant @gerrymadden53711]

Gentlemen, what is it they say, the taste of poor quality lasts a long time after the pleasure of a low price fades ! I have a decent lathe but decided the makers own faceplate was faaaaar too expensive. So I bought a surprisingly cheap one – almost too cheap to even bother sending back. So I live and learn, again !

 

Thank you all for your comments which have been quite both helpful and enlightening. I suppose its not often I will need to use the whole 160mm face so in the mean time I can just skim a little each time to get a flat and true ‘working’ area.

 

And I see also now that its not particularly thick (about 10mm) compared to others so it may have a quite limited life and be simply unsuitable for bigger tasks. But at least now, thanks to you, I know the characteristics I need to look for and appreciate what Im paying for when I buy my next one.

 

Gerry

[Tony Pratt 1Participant @tonypratt1]

Gerry, there is another similar pearl of wisdom “the quality remains long after the cost is forgotten” This was penned a long time ago by a Mr Rolls or a Mr Royce I can’t remember which and still remains as true today. We have all been tempted by cheap, cheap, cheap and paid more in the end.

Tony

[NJHParticipant @njh]

Hey Gerry

 

So you’ve got a cheap faceplate and it needs 1mm removed. It is probably still the most cost effective solution to skim off that 1mm ( unless you can persuade the vendor to supply a more accurate replacement.) As has been said, nearly all faceplates will need truing up from time to time and, in truth, how often are you likely to use your faceplate?

 

Regards

 

Norman

[David Clark 13Participant @davidclark13]

Hi Gerry

The first thing I would do is see how much material stands proud of the mandrel nose.

I f you have to skim the faceplate true, you don’t want the mandrel nose protruding beyond the faceplate.

regards David

 

[blowlampParticipant @blowlamp]

Don’t throw it away, Gerry.

 

Maybe consider fastening a sacrificial plate to it once you’ve got rid (probably in years to come) of the 1mm camber.

Even some thick aluminium plate would be OK and could be skimmed when needed.

 

The beauty of this is you can drill/tap it at will for those awkward jobs and replace when you need to.

 

 

Martin.

[jason udallParticipant @jasonudall57142]

futher to the sacrificial face plate…have heard of using old brake discs …obviously mounted on other faceplate.

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