morse taper sticking

"Somehow i don't think morse taper is ideal at all for this particular task."

Ronan,

Your are quite correct the 2 Morse taper is not ideal for this application in general however the better options of R8 or International taper systems are too big to be used on small milling machines - so we are stuck with 2 or 3 Morse.

Eric

Hi Ronan

From what you say If the taper was (walking out) when milling I would venture to suggest that the taper on your collet chuck may well be slightly large at the small end. It has already been intimated that you should check the tapers one against the other by blueing. Do not use excesive amounts of blue on the socket (you should barely see the blue) as it could lead to a false reading. Clean both internal and outside tapers thorouly before blueing with something like meths. The other cause could be excesive side load on your milling cutter. i.e. blunt cutter, to large a cut, or to fast a feed.

Dusty,

From what Ronan has said there is nothing wrong with the taper on his collet chuck.

It is well known that an unrestrained Morse taper tang, even when properly fitted into a socket, will work loose due to the repeated change in side load imposed on it by the milling operation. This is why milling machines have a drawbar to retain tapered attachments.

The important point is to only tighten the drawbar to the minimum amount to retain the tang.

Over tightening a drawbar achieves nothing other than to make it very difficult to remove the tang without a lot of brute force as Ronan experienced.

By the same mechanism a milling cutter will work its way out of an ordinary drill chuck no matter how hard it is done up. This is why we have ER, Clarkson or Osborn milling chucks.

Eric

Problem of using a pair of wedges (If not used in the hole of the quill) is that they can remove the chuck from the morse taper tang, leaving the tang still stuck in the quill.

Perhaps this offers a release mechanism - loosen drawbar and use on a bit of scrap until it undoes itself.

I thought that but he did say it was a collet chuck

Speedy Builders said:

"Problem of using a pair of wedges (If not used in the hole of the quill) is that they can remove the chuck from the morse taper tang, leaving the tang still stuck in the quill."

This could happen with a drill chuck, however a properly manufactured milling chuck should be good.

Peter.

I also thought the sticking might have been caused by me not removing the chuck from the machine often enough, but i never let any corrosion appear on any of my machines, so doubt its the problem, sticktion ? What also worries me is if i buy a set of morse taper collets (the type that hold the tool directly in the quill) they might also stick. I was going to use these as they give a bit more room in the z -axis.

I have an X3 and have only one item that is hard to get out and thats a reduction sleeve for M3 to M2 for one tool. All the M3 collets work fine and come loose as soon as I lightly tap the drawbar. The Caveat here is to buy good quality collets and not cheap sets. Cheap poor quality will either not hold the cutter or the cutter slip with the load applied. The difference in quality between sellers is very marked.The gain in working height is worth the cost !

If you need a reduction sleeve then buy one with a threaded collar to allow withdrawal. It makes life much easier.

Clive

Collets should be less likely to stick as most of the length is is the flexible bit.
The type of head you have is not as big as a regular turret mill so you could think about a big G clamp with a forked anvil end that reaches into the bottom of the mandrel not the housing and then you could apply any amount of pressure not touching the bearings.

.

Ronan,

The sticking is a "Design Feature" of the Morse Taper ... it is, by design, a self-locking taper.

As others have mentioned; it was originally intended for drilling, where the only loads are axial and torsion. ... In this situation the taper should "lock" and will need ejecting in some way.

The problem with using MT on a mill is the side-loads; which tend to "walk" the taper-fit apart.

Fundamentally; Using MT on a milling spindle is bad design, and therefore we resort to excessive drawbar tightening; which then results in the other problem.

A proper taper for a mill is self-releasing, and always needs to be held in firm contact with a drawbar.

Your problems are simply down to the design compromise that was chosen for your mill.

It appears that your MT is an excellent fit ... so; Use the lightest drawbar tension that still prevents the taper "walking apart", and have a look at impact-free methods of extraction.

MichaelG.

Lambton and Michael G

Whilst I agree with what you have both said regarding morse tapers the point I was making was, that if the taper were to be slightly large at the small end ( even a few tenths)this would tend to cause the problems experienced. I mean both walking out and sticking. I will deal with the sticking first, if the taper is slightly large at the small end you will get a line contact in the socket this can be tightened to a far greater degree that if the same load is spread over the whole of the taper shank. in consequence you will need far more force to release it.

Walking out is exacerbated by the small end being large causing the front end (the larger of the two ends) being able to rattle around in its socket, yes I know that it is a bit extreme but is possible.

I am afraid I am of the school that says never accept anything that is not proven, I have not seen anything on this post that says the tapers have been checked one against the other! unless that is done you cannot discount anything.

My own milling machine has a 3 morse quill and yes I have experienced the problems that have been described. I do have the advantage of over 50yrs experience in engineering when overcoming these problems.

Dusty,

You are of course correct ...

My comments were based on the presumption that both tapers were actually Morse

i.e. I was highlighting the underlying design problem, that MT is not "fit for purpose" in this application.

If either or both of the tapers are wrong then the situation will be just as you describe

... [ but in that case they are not actually "Morse Tapers" ]

MichaelG.