Author Topic: JT Tapers  (Read 4114 times)

Offline JD

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JT Tapers
« on: May 14, 2013, 07:05:32 AM »
Gentlemen,I have a bench drill press with a 13mm chuck which is knackered the taper is JT 2 1/2 odd size?
trying to find a new keyless chuck is mission impossible  :bang: any ideas please.
John
If you cant fix it hit it with a bigger hammer

Offline DMIOM

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Re: JT Tapers
« Reply #1 on: May 14, 2013, 08:02:49 AM »
John,
just a couple of thoughts:
1/ Try calling Rotagrip or Gloucester?
2/ Is it a one-piece spindle/arbor (JT ground on the end of the spindle), or is it the more conventional spindle with MT + MT arbor. If the latter, is there any way you can get the arbor out (slot for wedge?) - that way you could get a new arbor and chuck with a more conventional JT

Dave

Offline JD

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Re: JT Tapers
« Reply #2 on: May 14, 2013, 08:45:37 AM »
Dave thanks for the quick response, the taper is part of the down feed spindle.
I will try your suggestions.
John
If you cant fix it hit it with a bigger hammer

Offline JD

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Re: JT Tapers
« Reply #3 on: May 14, 2013, 09:25:49 AM »
Dave
Have contacted your suggestions with no luck all I get is silence and "err never heard of that one before" also contacted RDG and Jack gave me this link http://www.practicalmachinist.com/vb/antique-machinery-history/old-drill-press-jt2-5-chuck-241535/
another one for the old grey matter to work on  :clap:.
Thanks again John
If you cant fix it hit it with a bigger hammer

Offline vtsteam

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Re: JT Tapers
« Reply #4 on: May 14, 2013, 07:26:39 PM »
What about making an adapter on the lathe? Bore JT2.5 and then turn to whatever common JT taper you want. At worst you will spoil a bit of steel, rather than a drill chuck if trying to rebore.

Maybe you can find a drill adapter that is already correct for a common chuck at the business end, though incorrect at the hollow end, but with enough meat there to bore it to JT2.5. Then you just need to do one operation.
I love it when a Plan B comes together!
Steve
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Offline John Stevenson

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Re: JT Tapers
« Reply #5 on: May 14, 2013, 07:47:40 PM »
Buy a JT6 chuck, blue it up and offer it to the spindle, run the machine and carefully polish the blue off and try again.
The differences between JT 2 1/2 and JT 6 are very small.
John Stevenson

Offline Lew_Merrick_PE

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Re: JT Tapers
« Reply #6 on: May 15, 2013, 11:48:06 AM »
Buy a JT6 chuck, blue it up and offer it to the spindle, run the machine and carefully polish the blue off and try again.  The differences between JT 2 1/2 and JT 6 are very small.
To clarify, I believe that John means Prussian blue rather than layout blue.

Offline JD

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Re: JT Tapers
« Reply #7 on: May 19, 2013, 04:52:14 PM »
vtstream
thanks for that, the drill is a bench top model and has limited space as it is between chuck and vice, so to turn up another adaptor would reduce this distance even more, thanks for the advice anyway.

John
I know I will have to buy a JT6 chuck and as you say there is very little difference between the two tapers but the thought of trying to hold the new chuck and polish out the difference while hanging onto the chuck at slow spindle speed (the thought of the chuck locking onto the taper and not letting go quick enough OUCH) thanks anyway.

I have a local grinding shop and have contacted them, for the price of a couple of beers he will re grind the  JT21/2 to a JT6, apparently he comes across this quite a lot.
Thanks once again gentlemen for your help. John 
If you cant fix it hit it with a bigger hammer