chinese lathe tailstock is 3/16″ too high

[Don Smith 1Participant @donsmith1]

[Don Smith 1Participant @donsmith1]

I ordered a new tailstock assembly from Littlemachineshop.com and its just as high. This is some no name lathe off of E bay. I've had it a year and just now started to set it up. This is wildly out of spec. The original tailstock has a removable baseplate and the new one does not. Also, the new one has the wrong morse taper for my tailstock chuck and live center. So i"ll be returning it. I see nothing for this but to mill off the baseplate TOP. Millilng the bottom that much would nearly remove the V notch that matches the tail stock to the near side way of them lathe. thanks.

[Don Smith 1Participant @donsmith1]

any way to fix it without milling the baseplate of the tailstock? How to measure the height to know how much to mill off of the baseplate?

Edited By JasonB on 10/08/2021 06:50:44

Edited By JasonB on 10/08/2021 06:51:16

[Chris CrewParticipant @chriscrew66644]

Looks like you are throwing starting to throw good money after bad. Personally, I would think about cutting my losses and start trying to acquire a decent lathe from a reputable source or at least a private vendor who would allow an inspection the machine before the actual purchase.

[David George 1Participant @davidgeorge1]

Where are you based perhaps someone local can suggest a fix. Perhaps you can put a picture or two on here then we could help.

David

[Anonymous]

There's an almost identical thread on 'practicalmachinist' with the predictable blunt responses. That, and mention of 'littlemachineshop', implies that the OP is based in the US?

Andrew

[Tony Pratt 1Participant @tonypratt1]

'practical machinist' is meant to be a forum for so called professional machinists so the OP will get no help there, I would suggest speaking to Little machine shop as a starting point.

Tony

[JasonBModerator @jasonb]

Well you could go back to the supplier and ask them.

Failing that as you are unlikely to be able to track them down then google around for what looks to be the exact lathe under a different brand and see if they can supply a tailstock preferably having checked the height with them first.

If you end up cutting the existing one down a height gauge on the cross slide and some careful measuring should get you to within a thou then if you have a mill take off the excess.

This is why we say buying direct from an unknown source is a gamble some you win but this time you lost. It may cost a little more using a reputable supplier but you have a fall back.

Though there was one reply on Practical machinist that would solve the problem for the OP as he only want's it for a one off job.

Edited By JasonB on 10/08/2021 10:36:14

[Les Jones 1Participant @lesjones1]

If the headstock is removable from the bed would it be possible to make a packing piece to raise the headstock by 3/16" ?

Les.

[Mike PooleParticipant @mikepoole82104]

Posted by Les Jones 1 on 10/08/2021 10:41:03:

If the headstock is removable from the bed would it be possible to make a packing piece to raise the headstock by 3/16" ?

Les.

The same thought crossed my mind, a spacer made from ground flat stock might be easier than machining the tailstock base. The small gain in centre height may be useful but the tool post may need a similar spacer if the tools are not adjustable to the new height. The gears for screw cutting may be affected but probably can be still adjusted. If you have fixed or travelling steadies the these may need a spacer to perfectly centre them although they may well be satisfactory with just the normal adjusters. Some care will be necessary to ensure the headstock is refitted accurately.

Mike

[JasonBModerator @jasonb]

Problem may be that most of these type of lathe have the head sitting on the Vee bed at the back so you would need to carefully calculate the packing thickness to match the 3/16" at the front where the head sits on the flat way.

[old martParticipant @oldmart]

There will be a joint between the base and the top half, this is where the 3/16" would be best removed from. This would be easy if a mill was available. The alternative might be to mount the base on a faceplate, square up the surface and turn off the surplace.

The tailstock of the museum Smart & Brown has shims between the halves to get the height and direction of the quill on the centre line. Actually it is set 0.001" high on purpose. I ought to set it up and mill it to take a decent thickness shim, but I'm too lazy.

On the other side of the pond, The Home Shop Machinist forum is well worth joining.

[Neil WyattModerator @neilwyatt]

Posted by old mart on 10/08/2021 15:36:11:

There will be a joint between the base and the top half, this is where the 3/16" would be best removed from. This would be easy if a mill was available. The alternative might be to mount the base on a faceplate, square up the surface and turn off the surplace.

The tailstock of the museum Smart & Brown has shims between the halves to get the height and direction of the quill on the centre line. Actually it is set 0.001" high on purpose. I ought to set it up and mill it to take a decent thickness shim, but I'm too lazy.

On the other side of the pond, The Home Shop Machinist forum is well worth joining.

This.

I fitted a QR tailstock to my mini lathe, as I recall JS gave it to me as it was a leftover from converting one for specialist CNC that didn't require it. The advantage chiefly being it was easier to adjust than my homemade QR.

Coming from a different batch (maybe 15+ years younger?) it was slightly high – better than being low! As I recall, I took a bit too much off the baseplate but as the difference in height was in the upper part, I was able to be a bit more careful and thin down my original baseplate to leave me with a hybrid tailstock.

There are some arguments for getting the tailstock about 0-.001"/0.02mm high. What is important is making sure it is level so it doesn't rise/droop when extending it.

Neil

[Anonymous]

Posted by Neil Wyatt on 12/08/2021 10:40:29:

What is important is making sure it is level so it doesn't rise/droop when extending it.

The accuracy limits for my lathe gives tolerances for the parallelism of the tailstock barrel (with barrel extended and locked) compared to carriage movement that are biased upwards and forwards. Although the tolerances are small, 0.015mm and 0.02mm per 100mm in horizontal and vertical respectively. So if the tailstock barrel isn't perfectly parallel to the carriage movement it should be pointing slightly up and/or to the front.

Andrew

[Don Smith 1Participant @donsmith1]

thanks, guys. I had to get a height gauge to discover how much to mill off of the tail-stock joint. i'll be getting the parts to the machine shop sometime today, thurs the 12th of aug. Thanks again

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