Thread: General lathe condition questions

Originally Posted by jmebgo

so I would appreciate any answers that can be given!

Well you've only asked one question. Yes some backlash is inevitable. No it's not a problem. Welcome aboard.

G'day Joe
That slight movement of the dial without moving the screw (backlash) is present on most lathes (some have ways of minimising it). Really it depends on how much backlash is there as to whether it is good or bad. It occurs because the nut has to have some clearance on the screw or it would not turn (this is the cross slide screw the other site was talking about). This exacerbated by wear in the screw and nut.
If you can, see if the movement is a constant amount at both ends of the screw and in the middle. If there is more in the middle, it is probably wear (as the screw will probably be used more around the middle).
How much is too much? Depends on you and how much you are prepared to tolerate. I once had a lathe with over 40 thou (1mm) of backlash. It was usable but irritated me. To properly repair it you would need to make up or buy a new screw and nut - not a project for someone new to lathes, but not horribly difficult either. Once I'd done that, I got it down to around 8 thou. Not perfect but better and much more usable.

Michael

Hi Joe

Those little Qualos junior lathes seem to turn up on EBAY regularly , I must have seen at least six of them . Have you looked at the lathes uk web site ?

Which version are you are looking at to buy ?

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Mike

Hi Joe and welcome,
My small lathe has about 20 thou play and is easy to live with. My big LeBlond has a huge amount of wear in the screw, so much that you can clearly see the difference in the thread from either end to the worn middle. It is nearly 100 years old though so we can forgive that. A new one will be made once the machine is up and running.
The link you provided has lots of good points, But what it comes down to is what you want to do and how much they are asking for the machine. If you want something to learn on, a cheap, not so pristine lathe is not such a bad thing. If you crash a new machine it could be heartbreaking....but if you crash a $300 machine that is already somewhat worn the chances are you won't make it much worse than it already is.
Hope that helps, maybe a pic or link to the machine in question would be good too.

Thank you all for the welcome and replies. Sorry but I haven't got pictures, nor an asking price as yet, but it was just one I saw at a garage sale.

I'm pretty sure it isn't a Junior as it had the flat belt drive rather than the V-belt. I've looked at the website before, I'd say from memory it looked more like the top left hand corner lathe. I don't think it was the long bed version.

If I do go back to take a proper look, I'll take your advice Michael and check the backlash over the range of the motion.

Thanks once again,
Joe

Hi Joe
I have a Qualis Junior and the problem I"m having is the fibre/bakelite change gears are breaking teeth off, I cannot see any reason for this so I am putting it down to old age.
If the lathe your looking at has fibre gears i'd keep looking.

Hi Whitey,

I don't think it has the fibre/bakelite gears but I'll make sure.

Thanks for the heads up.

Joe

A lot of lathes have a slot in the nut for both compound and cross slides and an adjusting screw which brings the threads closer together, therebye minimising backlash. But as already stated, all have some backlash, how much depends on the method employed to minimize it. All that said, screws for cross and compound slides are reasonably easy to make as are the nuts.