Saturday, 9 January 2016

A compound slide for the Unimat SL.

Taper turning on an SL is done by swivelling the headstock, a bit of a nuisance as the headstock needs resetting afterwards. Most other lathes are fitted with a compound slide (also known as a top slide), which sits on the saddle and can swivel to any angle. I noted a few aftermarket ones being sold on eBay that are designed for the SL, and managed to win one;


Its quite nicely made, although the milled slots for the turning tool are a bit rough and the tool clamping holes are tapped out of true. Neither of those faults will affect the performance of the tool, but its a shame more care wasn't taken. However, a gib strip is fitted (to my suprise), and everything moves nice and smoothly. Total travel is about 32mm, more than adequate for my needs, and the resettable handwheel is marked in .05mm increments. One revolution moves the toolpost 1mm. Here it is fitted to my machine;


One neat touch is that the 'T' nut is fitted with grubscrews so that it can be locked in place into the saddle slot, so that the entire slide can be loosened and swivelled around without it moving along the slot;


The base plate looks to be an alloy casting and has degrees cast on. The tool slots are too small to take my usual 6mm square turning tools so I've had to grind up a new tool from 3/16" tool steel.
A quick test;


A better use would of course be turning tapered chimneys.

Paul.
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3 comments:

  1. Mark9 January 2016 at 18:05

    I must admit over the last few days or so, while figuring out my Unimat 3, I'd been trying to figure out how you'd turned chimneys without one, but hadn't yet gone back through the blog to find out. I'd completely forgotten that the headstock on the SL can rotate. I can imagine that resetting the headstock could be a right pain if you were switching back and forwards frequently.

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    Replies
    1. Paul B.9 January 2016 at 18:59

      I don't mind setting and resetting the headstock to be honest, its just a part of using an SL, but I like to have options, particulary ones that could speed things up.
      The compound slide has been sitting in a box since June(!), but its only today that I've finally ground up a tool for it. It will come in very usefull very soon...

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    2. Anonymous10 March 2024 at 21:31

      Aligning the headstock, after turning a taper, or using the milling option is simple. Get a 10 inch piece of 1/4 HSS round bar stock and sharpen a point on one end. Chuck it into the headstock and line the point up with the point on the dead centre in the tailstock. Move the tailstock as far away as possible and tighten it down. Then extend the 1/4 rod until the pointed ends are almost touching. Line them up and tighten the headstock

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