Collet Identification

Some while ago I bourght a box of mixed collets off eBay. The ER 32 versions are no problem but there are a great many small collets from
3mm to 12mm capacity that are 'similar' to the ER type in-as-much-as they are multi-size but have a 15mm stright portion at front and back with a 30 included angle centre section.
I've put a photo and drawing (.PDF) up at www.special-time.co.uk/drawings so that anyone who might have an idea what equipment these were originally designed for (or even who manufactured them) can properly identify them.
JG
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The ID number that I think I can see on the side of one collet may well be a clue. A quick look at the catalogue on the Crawford collets web site didn't reveal much I'm afraid to say. Bob
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from "Emimec"

Thanks for the response Bob but the number on the side is simply the size range of that particular collet - in that case 12 - 11.
Before posting, I'd spent over an hour on Google and found nothing anywhere near the description.
I suspect that they are from some now defunct chuck or workholder and I'm hoping for someone who already has some and knows exactly what they are.
JG
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They look like the collets that some of the Osborn / Elliot milling chucks were fitted with........They worked like the Clarkson Autolocks, but you had a seperate threaded collar that screwed onto the shank of the cutter.
ttfn.....Alistair

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from "Alistair Ross"

Thanks for that pointer.
The fact that an 'Osbourne Elliot' was Editor of Newsweek for 6 years and died in 2008 along with the fact that George Osbourne has recently produced his first budget has meant that 'Google' thows up a great many inappropriate referencies. :))
As yet I've not been able to find an image of an Osbourne/Elliot Collet which I can compare to mine since it seems that the Clarkson Autolock became more popular on these machines.
The concept of a separate threaded collar certainly makes sense o it is worthwhile persuing that line of enquiry - when I have more time.
JG
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I'm wondering if there is confusion here with Bristol Erickson Acramill chucks ? http://www.gandmtools.co.uk/cat_leaf.php?idd55 Bob
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from "Emimec"

Scaleing the photo on that page tells me that the Collet front OD is ~27.5mm rather than the 15mm on mine. Another 'clincher' that this is not what I'm looking for is the fact that the Acramill collets are specific size not 'multi' bore.
JG (Still searching)
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Sorry, was pointing more at the type of collet referred to in another mail that mentioned the collet had a separate threaded collar. I use DA collets, ER collets, (both of which are of similar design to yours) and Clarkson collets, and very large Crawford collets. The only ones that are genuinely called Multibore are the collets I use on the EMI-MEC lathes. These go up to 2 inch, and have a spring clip to keep the segments together (In theory) . All the others, with the exception of Clarkson, are to an extent multibore, but by only a gnats. They still come in specific sizes, 10mm 12mm etc, and can only cope with very small deviations from the stated size. Unlike the true Multibore that has a range of about an eighth of an inch Bob
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from "Emimec"

Yes Bob, I'm very familiar with 'Multbore' Collets since I used to be commercial manager of the export department at Herert Small Tools in the 70s and sold very many of them to the rest of the world. That is why I put quotes around just multi.

I guess you've had one (or more) fall apart on you then :)

For relatively large values of 'gnats' - just like the ER range these have 1mm range.

Just like the ER range, these are specified by range rather than a single size ie. 12-11, 11-10 etc. except at the low end where the range is 0.5mm - 4-3.5 & 3.5-3

Agreed, 1mm is no where near the 1/8" or 3mm of true Multibore but what really separates these from the Acramill (and gives them the 'range' that they can hold), is that they have 16 slits rather than 8. (Except for the 0.5mm range)
JG
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