Jacobs JT2S taper

[VicParticipant @vic]

[VicParticipant @vic]

What’s the point of the JT2 S (short) taper? One of my chucks has it but I can’t find anyone that actually makes an arbor for it! Even Jacobs themselves don’t seem to make one. Yes I know a JT2 fits but it’s not very elegant and wastes space.

[Michael GilliganParticipant @michaelgilligan61133]

I think you may have answered your own question, Vic

The purpose of a short taper is to minimise the space occupied,

MichaelG.

[Clive FosterParticipant @clivefoster55965]

I'd always understood that the JT2 S was primarily intended as as male taper for drilling machines. Presumably exploiting the shorter body and shorter taper in the design of the machine to gave a greater distance between drill and table for the given overall size.

The slightly smaller diameter allows a 14 mm Ø spindle to be used whilst the full size version needs either 9/16" or 15 mm Ø.

Overall it seems an awful faff to save 1/8" in length. But sizing of Jacobs, like Morse, tapers is somewhat less than logical.

However according to Yukiwa Seiko, a Japanese maker of drill chucks and other tooling, **LINK** :-

JT2S is a short type of Jacobs taper No.2. The taper angle is the same as JT2, but the taper length is a little shorter than JT2. As the difference is just the taper length only, it is possible to mount a JT2S drill chuck on a JT2 arbor. Generally, JT2S taper is usually used in Japan while JT2 is popular in U.S.

So the preference may be largely geographical these days.

Clive

[VicParticipant @vic]

Thanks Clive. I won’t be going to Japan to get an Arbor!

It still begs the question, why do manufacturers make chucks you can’t get the correct arbor for.

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