Can anyone identify this tool please

[Norfolk BoyParticipant @norfolkboy]

A tool of 150 thou or thereabouts would be held in this fully articulating head. well made and designed with a pip in the tube to stop rotation when tightening the knurled grip.

Does anyone know it's purpose?

 

Edited By Norfolk Boy on 26/08/2020 13:43:23

Edited By Norfolk Boy on 26/08/2020 13:44:05

[Norfolk BoyParticipant @norfolkboy]

Unknown tool item

[RainbowsParticipant @rainbows]

Place long needle in the grip, place tool in tool post. Aim the needle tip into a centre punch or centre drill mark in the workpiece and use that to centre it in your 4 jaw chuck by seeing how much the needle wobbles.

Not sure of the name but I do remember seeing someone use a tool like this that way.

[Keith LongParticipant @keithlong89920]

It looks like an aid to centring a bar in a 4 jaw chuck. A rod like a scriber would be held offset in the collet so that the short end could engage a centre pop in the end of the work and the other end left to "waggle" around in space. Then as the work is centred in the chuck so the the centre pop runs true the "waggle" at the free end reduces. The offset / unequal projections is to give you a magnified indication of the centre pop run out. Pre dates the ready availability of cheap dti's etc and could be made up by the machinist himself. would also be a good exercise for an apprentice to make up as part of building up a tool kit.

[NimbleParticipant @nimble]

Hi Norfolk Boy,

An article Titled "an Elegant Centering Tool " appeared in the January 2009 issue of MEW by John Slater and showed a similar item a Starret No. 65 Centre Finder. and also gave details on to make your own similar item using a plain spherical Bearing rod ete as part of the tool. It also gives reference to an article by Peter Spenlove-Spenlove's article in Model Engineer Vol191 Issue 4208 14th Nov 2003.I hope this helps.

Neil

[Rod RenshawParticipant @rodrenshaw28584]

I have always called it a "wobbler", more properly a centring tool as described above. I use mine quite a lot as you don't need the tailstock centre as other types do.

Rod

[Nigel Graham 2Participant @nigelgraham2]

The shape of the body suggests it was made for use on a particular lathe, and the lack of a name bears out Keith's suggestion, so this specimen could well have been made by an individual turner or apprentice. Or indeed by a fellow model-engineer long gone before!

Another common design for these, strips the needle mounting back to a circular gimbal.

Both forms are in L.H. Sparey's The Amateur's Lathe, p.70, ("The Centre-Finder&quot with a photograph of the type Norfolk Boy shows, and a drawing of a much simpler, nay minimalist, version of the ring-gimbal.

In one respect it is more versatile than a DTI. Its purpose is in centring by a centre-pop, so the outside of the work-piece can be any shape, such as a plate, irregular casting or rough cylinder. A DTI can only work as a centring tool on a cylinder with a good-quality surface.

[Norfolk BoyParticipant @norfolkboy]

Thanks to all for your various insight and acquired knowledge. I will keep it on the shelf until I find an opportunity to put it into play. I appreciate the effort someone went to to make it, so will endeavour to see how it works out in practice.

Regards Alan

[HopperParticipant @hopper]

It's certainly a fancy one with the height adjuster and collet to hold the pointer. You don't usually see that. Well worth restoring as a piece of engineering history — and using of course.

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