Author Topic: Plain Lathes  (Read 606 times)

Offline Roger B

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Plain Lathes
« on: January 19, 2019, 08:11:43 AM »
The plain (non screwcutting) versions of the Schaublin lathes as well as number of other watchmakers lathes do not have leadscrew or rack to move the carriage. It is slid into position by hand and then locked there. The longitudinal cut is made using the compound slide. The compound slide can also be set at an angle for taper turning. How is the compound slide set parallel to the lathe axis for turning parallel work? Would you use a test bar and a DTI or is there a 'clever trick?

There are several examples here:

http://www.lathes.co.uk/schaublin/page10.html

The picture below is taken from this website.
Best regards

Roger

Offline Florian Eberhard

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Re: Plain Lathes
« Reply #1 on: January 19, 2019, 08:51:58 AM »
Hey Roger

These Schaublin Crossslides have a retractable stop for setting the compound exactly parallel to the rotational axis.
So you could say there is a trick for setting them.

If you look at the last picture of the lathes.co.uk page, you will notice this small knurled knob right to the handle of the cross-axis. This is a retractable pin (which can be adjused by rotating it - there is an excentric on the tip of it).

The compound slide has god a dovel pin which protrudes into the t-slot of its clamping screws. So if you want to set the compound parallel to the lathe axis, you just release the index pin (the picutre shows the released position) and rotate the compound until it stops at the index pin.

I can show you how that works in "real" , I have got a schaublin cross-slide with that feature.

Now for other lathes, you could make yourself a setting tool which clamps on top of the compound slide and then move the cross slide in until your tool touches a test bar. A bit like the tramming tool for the milling machine. (but its sufficient to use two set screws instead of the two dial indicators)

Florian
« Last Edit: January 19, 2019, 09:20:54 AM by Florian Eberhard »

Online sco

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Re: Plain Lathes
« Reply #2 on: January 19, 2019, 09:18:44 PM »
I put a mag base on the slide holding a lever dti with the point running along one of the bed ways and adjust until there's no change in the reading from one end of the slide to the other.

Simon.
Ars longa, vita brevis.

Offline Roger B

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Re: Plain Lathes
« Reply #3 on: January 22, 2019, 10:24:07 AM »
Thank you both  :ThumbsUp:  :wine1:  Those methods are certaintly better than having to use a test bar, especially if you have a workpiece in the machine.
Best regards

Roger