Need help to ID drill chuck taper

[TinkerJohn]

As usual, I seem to get some oddball stuff and once again I’m stumped! :-\

A few years ago I got an Asian drill chuck with a MT3 taper mount. The darn thing was very accurate and I need to change it to a MT2 taper mount.

The problem is I can’t figure out the taper for the chuck. I’ve tried a JT3, JT33 and JT6 and none of them worked. The best I can measure the chuck taper is .692 on the big end and .643 on the small end with a taper length of 1 inch and that does not match to any taper I know of. Do the Chinese use a taper totally different?

I’ve used several other Chinese chucks and they’ve had the regular JT. Anyone got any ideas what this beast takes? I doubt if you’ll be able to tell much but perhaps the pictures will help someone ID the chuck.

Thanks in advance for the help.

TinkerJohn
www.TinkerJohn.com

 

[Bogstandard]

John,

This chart might help you on your way, second one down

http://littlemachineshop.com/Reference/Tapers.php

Looking at your dimensions, with almost a 0.050" split over 1" looks like it might be JT6. But as you say you have already tried that - ????????????????

I know it sounds silly, but the taper used is usually marked on the side of the chuck. Maybe that is the Chinese bit, anyone read Mandarin?


Bogs

 

[TinkerJohn]

I thought twice before posting on such an old topic, but this may save someone some time since it took me a few months to find the answer. Persistence pays (maybe?).

The oddball chuck taper is a B18 and is found on drill chucks that come with some Chinese lathes. In fact, the chuck I’m working with came with the Grizzly G4003 (12X36)

BTW: Fairly common does not necessarily mean cheep, in fact the MT2 X B18 arbors I located cost *far more* than the chuck was worth.

---TinkerJohn---

 

[Mainer]

Can you get a stub Morse #2 arbor and turn the weird taper on it yourself?

 

[IanN]

Hi,

B18 taper is a DIN standard based on MT2 - see the pdf here:

http://www.jacobschuck.com/pdf/Technical-Information.pdf

(the above link was recently posted on another group)

Ian.