Drawing a blank on these…………………..

[Rik ShawParticipant @rikshaw]

[Rik ShawParticipant @rikshaw]

I have a number of these – all new. They are marked "Clarkson – Blank". There are small coned centres at both ends and I have sizes 3/8" and 1/2" diameter. I have googled but find no reference to them. Does anyone know what they were produced for as I have drawn a blank. All I can think of is that they could be ground as form tools or D bits.

Rik

[RainbowsParticipant @rainbows]

If they have a centre hole at each end that would make it easier to mount them on a grinder to make the final tool. Form tool making sounds about right.

Also if you didn't know those threaded shanks fit into Clarkson Autlock collets.

[Tim StevensParticipant @timstevens64731]

Potential counterbores?

Tim

[Johnboy25Participant @johnboy25]

I agree with Tim – they look like they can be ground into special size counterbores. I remember I found an odd size years ago – I had the tool room grind the pilot to a useful size. I've still got it in the arsenal.

John

[Rik ShawParticipant @rikshaw]

The counterbore idea is interesting and yes, it would work. However, in a production grinding environment it is/was common practice to leave a small centred "nipple" exactly like this for between centres grinding. It makes it easier to slice it of with an elastic cutting wheel after the necessary centre grinding has been completed.

Rik

[Neil WyattModerator @neilwyatt]

Surely they don't have a specific purpose – if they did, what would be the point? They are for you to grind into whatever special shape you need – a tapered endmill, a stepped cutter, a bullnose or concave shape….

Neil

[Andy AshParticipant @andyash24902]

It occurs to me that these could be used to check run-out at a realistic distance from a milling chuck.

Obviously you could just do that with a bit of ground stock, but these have the advantage that they have ground threads, and would be correctly mounted in a Clarkson autolock collet chuck.

Obviously you could clock a cutter near the chuck, but you would not be able to clock it at the tip where it matters. With a blank, those problems vanish.

[Michael GilliganParticipant @michaelgilligan61133]

Posted by Neil Wyatt on 11/06/2016 09:22:37:

Surely they don't have a specific purpose – if they did, what would be the point? They are for you to grind into whatever special shape you need …

.

Quite so, Neil

… Comparable to 'blank collets' [except for being the opposite gender]

MichaelG.

[Author]

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