Drill chuck taper

I have a mystery 16mm drill chuck almost certainly of chaiwanese origin that I can't find a taper arbor to fit it.
I don't have the equipment to measure the taper apart from to say that
the socket is about 17.7mm at the large end.
A JT6 taper is too small by a small amount and the next Jacobs taper up, JT3, won't even start to go in.
I've looked at the B16 taper and that is far too small.
I've spoken to Arc Euro and Chronos about it and they have been unable to offer a solution.
Has anyone any suggestions please. I'm beginning to think I'm going to have to make one.
TIA
Bob
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wrote:

Could be MT2A, which appears to be a bastard/stub form of MT2. seems to get used in chiwanese drills, but I've never seen a specification for it...
Mark Rand RTFM
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Mark Rand wrote:

Mark,
I'm trying to fit into the female socket in the chuck. Are you suggesting that the chuck has the dimension of the first inch or so of the large end of MT2?
Bob
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Bob Minchin Wrote:

Hi Bob, If Jacobs taper 6 is only slightly too small could not you shorten one, so it would fit further on. Do you have a copy of Tubal Cain's Ned Ludd
--
ned ludd
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ned ludd wrote:

Ned,
I see your point but it is likely that the MT2 part becomes too short then and the chuck will bottom on the end of the spindle.
Regards
Bob
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Many years ago, in my neck of the woods, there were a fair number of these around. The taper was not accurately made in both chuck and arbour.
Steve R.
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Bob
Sounds as though it might be B18
Large dia 17.78mm Small diameter 16.2mm Length 32 mm
Don't know where you could buy one though.
Mike
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Anyone know where the specs of the B series tapers are listed ? seen the odd one mixed up with the JT's but never a full list.
John S.
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John S wrote:

John,
I've just found this site http://www.gpsystem.com/rohm/product1/pic09.htm
hth
Bob
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A couple of years ago I was interested in the :B" series of chuck tapers, purely for interest, I didn't need it for any practical purpose but I hate to know of a standard without knowing the details. I Goggled like mad but got no results. Some time later I was browsing the Jacob site again just for interest and came across the following PDF.
http://www.jacobschuck.com/pdf/Technical-Information.pdf
Regards Brian
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mikecb1 wrote:

Interesting Mike. I could only fit vendors for b12 and b16. The chuck does have B18 written on it but as i could not find a reference to this as a chuck taper size, I ignored this thinking to be a model number. I think you might have cracked the problem!. I had a MT2 blank arbor delivered today from arceurotrade so I'll have to brush up on my taper setting/turning skills. Thanks Bob
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A Google search for B18 Taper gives http://www.gpsystem.com/rohm/product1/pic09.htm as the first hit, (Google is your friend) Regards Brian
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Brian Lambert wrote:

Thanks to everyone who responded to my chuck taper query. The chuck does indeed have a B18 taper. I found an arbor ready made on Ebay for 4 which arrived today and it fits perfectly. The taper is shallower than the more normal JT6 and being the same angle as MT2 it looks quite different and has equal diameter at the joint between the two tapers (B18 and MT2).
Bob
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