Acceptable chuck runout?

[PaulF]

Hi all.

Just a question that seems all to obvious to me, having bought an Axminster super precision chuck for my Denford wood lathe and using it for a while, I was not happy with the finish on the wood after sanding, it showed up a semi circle ring on both outside and inside surfaces!!

With this in mind I checked the runout on the spindle nose and register and found that to be within .001", but then checked the chuck and found that to be .005". I then spoke to the manufacturers and they said that is within their tolerences.

Am I asking too much or is that the norm for a £200 chuck with extra jaws etc.
Done a lot of reading and some amatuers make their own backplates etc and get results of +/- .001" but others say shop bought is .005".

I have tried all the usual things to correct runout, or am I being too fickle for work on a wood lathe???

I seem to find that a lot of people like to keep within .002", What do you think?
The second backplate that I purchased had a rounout of between .010" and .004" depending on which way the plate was bolted to the chuck!!! (iam still in talks with them).

Thanks in advance.

[Steve]

Have you thought about reducing the register on the backplate and then just running a clock on the chuck and manualy setting it true?

[PaulF]

Hi Steve.

Yes I have thought of that, but with different spindle sizes at each end of the lathe it would mean clocking each time i change the backplate for inboard or outboard turning!!

I could always buy another chuck at £170 and get them both correct, but as always it money that dictates what you do.

With the so called high precision cnc manufacture of these backplates I would have thought it would be easy to make these things match, but I guess im wrong?, or could MONEY AND TIME be involved here??

Anyway thanks for the reply, guess I will have to try and make my own backplates now I have the metal lathe and see how that compares.
Regards
Paul

[Pete.]

My 1st lathe had been crashed heavily and the backplate had a slight buckle in it (small lathe, thin backplate. I simply reduced the register on the backplate then turned a new one to a good fit. Only reduced the thickness by about 2mm where the bolts pass through and trued it up a treat.