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#31 Re: lathes

Posted: Fri Aug 30, 2019 9:42 pm
by Ant
Anyone know whether all 80mm tos chucks have the same jaws? I've lost one of the inside jaws for my md65. Still got the outside Jaws so it's still just about usable as is but not for smaller stuff.
I'm loathe to buy another chuck if I can replace the jaw set but I'm not sure if all 80mm tos chucks would have the same scroll.
There seem to be generic sets of Jaws available but nothing specifically for the original md65 chuck
Any ideas?
Cheers ant

#32 Re: lathes

Posted: Fri Aug 30, 2019 11:01 pm
by jack
Possible but unlikely.

I would get a new set on sale or return. There's no standard for the scroll.

#33 Re: lathes

Posted: Sat Aug 31, 2019 12:34 am
by Ant
Thought as much, I did manage find some that 'should' fit

https://rover.ebay.com/rover/0/0/0?mpre ... 1753185414

The second photo is a chart with the dimensions of the jaws on it and the 80mm dimensions conform to the remaining jaws I have. Measured them with digital calipers and they are almost exact, a tiny tiny bit smaller which accounts for 40 years of wear.
The seller also does some straight cut soft jaws which have the same dimensions which are about 15 quid cheaper, I might get some of them first, abit less to lose if they don't fit

https://rover.ebay.com/rover/0/0/0?mpre ... 1388483543

Here's hoping

#34 Re: lathes

Posted: Sat Aug 31, 2019 3:47 pm
by Paul Barker
Three jaw chuck are not usually perfectly centred so you have to mic and shim to centre them if you need to turn object round or you’ll get a step. If you can get a four jaw Chuck you can centre it perfectly with a micrometer on a stand to adjust the offset.

#35 Re: lathes

Posted: Wed Sep 04, 2019 10:26 pm
by Ant
Decided to order the straight cut jaws, if they fit OK I'll get the inside jaws
Also managed to get myself a proxxon mf70 milling machine for a good price.
Only little, but spot on for the jobs I have in mind for it. small parts for the unipivot arm I'm working on like headshell parts, arm rest bits, ect. Little but precise

#36 Re: lathes

Posted: Fri Sep 06, 2019 1:11 pm
by Ant
Got the soft jaws for the chuck which fit the scroll nicely, run in and out fine, nice and tight without any slack
Looks like the scroll could do with a clean out just to make sure there's no crap in there, had a quick look and it's a bit grotty
Could do with a drill rod just to check the runout, looks reasonable as is using a bit of stainless, and I can always do some fettling of the inside faces if it's out.

#37 Re: lathes

Posted: Sat Sep 14, 2019 5:16 pm
by Ant
Got round to checking the runout on the new chuck jaws with an ancient borrowed imperial dial guage (why on earth my father in law even has a dial guage I dont know, he's never used a lathe in his life....) and a drill rod, was quite a way out, about 13 thou.
so I bored the jaws by clamping a penny washer flat against the chuck face to tension them, then boring with a bar taking tiny cuts until all the jaw faces had no trace of the original surface, and I was hearing a good hit on all 3 jaws
Then took them out and filed off the little shelf left by where the washer was so that a bar can go all the way through
Rechecking it, I've got a reading of about 1.5 thou about 3/4" from the chuck raising to 3 thou about 12 inches away from the chuck
I don't think I can get it any better tbh, not with the brazed bars I have, maybe with a better bar with inserts instead.
But much better than it was, and not bad for a 40 odd year old 3 jaw scroll chuck

#38 Re: lathes

Posted: Sat Sep 14, 2019 7:44 pm
by IslandPink
Good effort !

I should point out, that in Germany a few years ago I saw a lecture from the owner of Moore Precision in the US. They make diamond-turning lathes for optics.
He had a slide with period photographs showing various landmarks in their machines. There was one from 1959, explaining that using the 'spherical carbon bearing', that was when they were first able to achieve a runout of 25 nanometers.

#39 Re: lathes

Posted: Sun Oct 16, 2022 8:40 pm
by dragonflywood
cressy wrote: Sun Sep 25, 2016 11:37 pm Finally managed to get hold of a small drill chuck that fits the tailstock on the lathe so i can now have a go at some other stuff like record weights and control knobs.

Its proved pretty much impossible to get a chuck for it, I think it will have to be a custom made backplate and a generic chuck.

Any idea where I can get a backplate made?
It's an odd size, the thread size is m30 x 1.5

Cheers ant
Hey Ant

I know its is an old post, but I have the same lathe and am really struggling to find a chuck for the tail stock - can you tell me what / where you found one?

Cheers

Luca

#40 Re: lathes

Posted: Mon Oct 17, 2022 9:27 pm
by jack
The tailstock is a #1 Morse Taper. You can get a suitable chuck complete with taper here:

https://store.lathes.co.uk/parts/hobbym ... tock-chuck

#41 Re: lathes

Posted: Mon Oct 17, 2022 9:40 pm
by Ant
If you mean the hdm 850 lathe rather than the hobbymat, i think it was an m10 threaded chinese drill chuck rather than a specific lathe tailstock chuck
Its the same as this one

https://www.ebay.co.uk/itm/314092502100 ... media=COPY