How to attach a quality drill chuck to a Morse Taper 2 arbor?

I intend to buy a quality drill chuck - a 1-13mm Rohm - for my Myford ML7, but the advert says the chuck has a "JT6 mount".

Can someone please explain (in simple terms!), how to (a) select and then (b) securely mount said chuck onto a 2MT arbor which I'll also buy. I have watched a few videos on youtube, but would be more confident asking knowledgeable fellow modellers.

Any advice gratefully received.

JT6 is the size of the tapered hole in the back of the drill chuck.

To fit it you need an arbor that has MT2 on one end and a male JT6 on the other.

If fit by just making sure tapers are clean , put together and then give it a quick tap with a soft hammer, may not be the right way but it has worked for me

Edited By JasonB on 01/06/2017 17:42:16

Have a look in ...

http://www.arceurotrade.co.uk/Catalogue/Chucks/Drill-Chuck-Arbors/MT2-Drill-Chuck-Arbors-with-Drawbar-Thread

​... usual disclaimer.

5th one down on the list should solve your query

George

Just buy a No2 MT to JT6 arbor and push the arbor into the JT6 socket in the chuck! ..Just make sure that the arbor and the socket are clean and push together (and a tap with a mallet might be appropriate!)

Norman

I have always cleaned both tapers, put chuck onto taper, hold the assembly morse taper down and strike the tang on the bench with a quick tap. Do not hit the chuck with anything, if the jaws are extended you will damage the chuck. To remove open the chuck fully, put a piece of steel through the chuck, hold over a bench and strike the steel with a mallet, taper falls off ( hopefully onto the bench).

I have always found winding the jaws right in, then using the drill press to push the chuck down onto a block of wood works fine.

Tapers are 'Quite Interesting'. Morse Tapers are cut at an angle that locks to resist turning but will release when pulled or pushed out. The Jacob Tapers are cut at an angle designed to jam in the matching socket more-or-less permanently. Getting a JT6 chuck off the arbour is more likely to be a problem than getting it to stick in the first place: Arc sell wedges for the purpose.

I don't understand why one taper angle jams solid while the other releases. Clever stuff.

Dave

.

It certainly was clever stuff, Dave

... Which makes it somewhat depressing that the modern 'Euro Standard' B16 taper has the same angle as MT2.

Making it largely a matter of chance which one releases first.

.. 'though of course the B16 is shorter, so

MichaelG.

I would have thought the MT should let go first as that will be the one being forced out of the socket by the drawbar, ejector wedge, tailstock screw, etc

I've got a B taper on the chuck I use most on the lathe, never had that slip but have had the MT turn in the tailstock barrel

I wonder if the fact the B taper has a smaller area than teh MT is why it starys together. assuming the same force applied to both tapers then the smaller area of the B taper will mean more force per metric/imperial measure of area. For example if 10lls pressure applied to put the parts together then if ratio of area was say 3:1 the B taper would go together with 30psi and MT 10psi.

Edited By JasonB on 01/06/2017 19:10:44

Jason,

It was the use of paired extraction wedges that worried me.

... Purely hypothetical as mine are all JT

MichaelG.

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P.S. ... I responded before I saw your edit, but you raise an interesting point.

Edited By Michael Gilligan on 01/06/2017 19:13:04

Not sure why the wedges should make the MT let go as they act against the back face of the chuck and the large end of the MT taper not the nose of the spindle?

Hello,

If you want a Rohm drill chuck on an MT2 taper. just buy a complete unit from Tracy Tools. They do a range of Rohm chucks on MT tapers and they are cheaper than most, especially if you have to buy the chuck and MT2 taper individually if you want to DIY!

Andrew.

When I bought chuck and tapers from Tracey they came as separate parts I had to join together

B16 is not just the same taper as MT2, it's actually meant to be the small end of MT2 and B18 is the large end - all the B-tapers are actually stub versions of Morse Tapers.

Neither taper should let go when used with a drill, they are all 'self holding tapers'. Google tells me that 7 degrees is the typical angle for steel on steel.

Expressed as ratios 1:5 or less will easily separate, 1:10 will will detach with difficulty, 1:20 is typical for toolholding (e.g. Morse & brown & sharpe tapers are about 1:20, Jarno  1:24).

Jacobs have angles from 1.41 to 2.3 degrees, many of them have a significantly more 'open' taper than Morse or B tapers (about 1.5 degrees) , so the B-taper is NOT a retrograde step.

Neil

Edited By Neil Wyatt on 01/06/2017 20:02:53

Another trick is to put the arbor in a plastic bag and pop it into the freezer for a few hours. Remove and tap the Chuck on gently. As the arbor warms up and expands you will get a very good lock. This worked for for my first drill chuck, which had the annoying habit of coming loose at the most inappropriate times.

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Neil,

Let's agree to differ on that one ^^^

I did not say anything about tapers "letting go" in use.

I did not suggest that the Jacobs taper would hold 'harder' than the Morse.

My only concern is that by using equal angles on both tapers, the behaviour when deliberately trying to separate chuck from arbor will be less predictable.

The JT fitting was designed to release before the Morse.

MichaelG.

Edited By Michael Gilligan on 01/06/2017 20:56:06

You can buy drill chucks with "integral shanks". I have a couple of Vertex units, one with R8 for the mill and one with MT for the lathe. They are available from Chronos and other suppliers. Good quality at a sensible price.

Thanks all for the information.

Morse tapers all ~1.5 degrees

Jacobs tapers 1.4 to 2.3 degrees.

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We will have to agree to disagree on that too!

Neil

Michael, did you see my comment above about using wedges?

When separating chuck from arbor the forces are between chuck and the B or JT taper, the Morse has nothing to do with it, Will post a pic a bit later to show how the wedges act in use.

It's all to do with the angle of dangle and the coefficient of friction between the materials. When drilling, Morse tapers rely on the axial forces to help prevent rotation. That's why they're not good for milling without a drawbar. The best way to break a drill chuck taper is to tap the chuck radially.

Andrew