Set up tool???

found this today whilst having a lockdown clear out, any ideas?. 10 inches long.

Edited By bernard towers on 19/05/2020 17:04:13

It may be an indicator to centre work?

Howard

If you have a small bar with a dimple in it that can mount in a lathe tool holder you can pin the short rod between a workpiece with a centre dimple and the bar. The long arm will describe a large circle if the workpiece is not centred allowing workpiece centring regardless of outline or having a suitable indicator.

Martin C

It's a cheap homemade centring tool. Usually there is a fixed bar with a dimple in in which the pointed end inside the ring rests. The sharp end outside the end rests in a dimple in the work. As long as the fixed bar maintains the short rod in contact with the work, then as the work rotates, the out of centre amount is magnified by the long length which describes a circle in free space. Adjustment of the work can then be made until the long end remains stationary at which point the work is centered.

Somewhere I have a book with a drawing for it, but can't lay my hands on it at the moment.

Peter G. Shaw

Check Good -Old -Sparey.! You will find that tool mentioned in his book, and it works !

Well you lot beat me too it!

Neil

Thanks a lot it’s obvious once explained, just couldn’t figure out how to use the pointed rod which was enclosed in the center. Amazing the information out there!

What do you suppose that ring with the 4 square bosses is made from? Commercial casting or kit? Or cut from some extruded section etc the maker found lying around?

It's a cool old piece of kit from back when dial indicators were a luxury item in the home shop. I mightbhave to make one.

Interesting technique. It occurs to me that one could achieve the same with a straight rod pushed through a rose joint, perhaps held in the toolpost or on a mag base.

Can you then rely on the centre dimple to check tailstock alignment?

Rose joint....

Lump of rubber. Long wire(knitting needle).. continuously adjustable ratio.....

Hi,

May have to make one of these. I assume having the two lengths the smaller end is used for roughing the centre of the work, then rotate 180 degrees, and you have a fine adjustment.

Would be interesting to see how accurate this could be by checking with a DTI. and seeing which method appears quicker to use?

Jon

The device can only be used with the small end toward the workpiece as it has to be held between the internal point and the centre mark. The long end amplifies the movement in the same way as a lever indicator (here) making it easier to see the error.

Brian G

I seem to recall a similar idea either on here or in HSM or MEW or some such where the centering rod was held at its pivot point by silicone adhesive. I think it was a bit of square tube with the maximum size hole drilled across it, the end of the tube filled with silicone and the wiggler pushed through the cross drilled hole. The square tube was of a size that it fitted in a tool holder.

Edited By ANDY CAWLEY on 21/05/2020 10:13:59

Ok I have totally misinterpreted the replies above, I was under the impression that a rod with a centre drilled into its rear and a point on the other end was held in the centre punch mark, and held with the tailstock, this tool then clamps to the rod and draws the circle in the air.

Thanks for the link to the website.