I'm Stuck

Or at least the no3 morse taper is.

I have just purchased a refurbished AMA25 mill and this weekend I got it set up on the stand and tried to remove the drill chuck. I slackened the draw bar and gave it a tap with a plastic hammer (PH), no joy. I hit it with the PH, nope, I whacked it really hard, uh uh. I tightened it against the retaining nut so that it was in compression and squirted in some gt85 in through the slot in the quill and left it overnight. Next day I made a cap out of ali to go on the top of the drawbar and hit it with a hammer, still no joy, so I got a bigger hammer, not a chance.

Am I missing something? Has anyone got any ideas before I break something?

Edited By Tim Chambers 1 on 16/12/2014 00:50:00

Milling sideways with no support under the base of the cutter and it should drop out... so only leave a teeny gap of a millimeter or two under the bottom of the cutter for when it drops

Morse tapers are useless unless they are supported by the bottom of the cutting tool

Edited By Ady1 on 16/12/2014 01:42:35

Hi Tim,

I have a similar milling machine and my drill chuck was also really difficult to get out. On my machine there is an ejection mechanism - when I slacken the drawbar it pushes against a nut. I had to use a lot of force to get it loose. If you have to use a hammer, is it possible to support the bottom of the spindle with a piece of aluminium or brass, between the spindle and table (wind the head down). This way your hammer blows should not affect the bearings. I do have a copper hammer I use to "persuade" stuck morse taper tooling.

Thor

Hi Tim,

I cringe every time I have to whack the drawbar. Not sure how much damage it does to the bearings. Would like to add a removal tool for releasing the cutting tool but have not worked out how to do it yet. I have a Sieg SX3 mill which has a slot in the side of the spindle for removing chucks that have a tang but not much use for tools with a draw bar.

What I do is support the mill spindle with a wooden block and hit the drawbar with an aluminium mallet.

Paul.

Edited By Paul Lousick on 16/12/2014 09:00:24

You may want to let the mill run for an hour to warm it all up, if the tooling was inserted into a warm spindle which then contracted slightly it won't come out as easily.

J

PS Paul is that a bit of boiler stay weld prep going on?

Edited By JasonB on 16/12/2014 09:15:28

Thanks for all the ideas, gives me something to try. I'm not really a fan of the "Brute force and higgerence" way of doing things,

Tim,

My comiserations

There have been several previous discussions of similar problems; and, I think, a couple of useful extractor devices described.

... Have a look through some of these threads.

MichaelG.

Edited By Michael Gilligan on 16/12/2014 09:22:30

Morse tapers on mill heads are horrid.The real trick is not to overtighten the draw bolt in the first place. The taper hardly needs any help at all, just a nip.

I remember listening to a really angry person giving Mr Warco a real piece of his mind at one of the mod eng shows in the 80/90s. I was having an earwig as I had the same machine at the time. I think Mr Warco helped him out of his dilemma in his really useful way.

So.

Undo the drawbar bolt, just 1/2 to a full turn, quill clamp on, metal hammer and give it a quick sharp bang. The drawbar should stop the tool dropping mote than a 1/8th. Because its in overtight, you might have to have a few goes at it.You feel guilty every time you hit your new machine, but you lean fast.

If you loosen the draw bar too much, you are likely to strip the draw bar threads. as I said, its a horrid way to do things, but in practice, once you have got used to it, it works

Paul,

An auto-eject drawbar is easy to make as I found.

Have a look at the last photo I posted in my thread Marlow A3 Milling Machine.

It shows the one I've just finished.

I will be adding another photo of it installed.

Geoff - Found more tools I forgot I had when searching the Shed yesterday.

Edited By OuBallie on 16/12/2014 09:41:41

We recently ran an article in MEW which , in short, described a bit of pipe which was large enough to surround the tooling and a slotted plate to fit over the top around the end of taper and support the spindle, essentially the same as Paul's suggestion but a bit more rigid.

With the spindle supported properly you can whack the drawbar hard and avoid any damage to the bearings.

Ady's suggestion is worth trying, mill a bit of aluminium - less likely to damage the cutter, and fit the drawbar but leave it loose enough that the tool can only drop a mm or so as extra insurance.

Neil

Once you get it out, don't over-tighten the drawbar when you next fit a milling chuck or collet. I guess there should be a recommended torque somewhere to avoid overtightening? The problem with the "milling a bit of aluminium" approach is that it may also pull the chuck off its mounting taper! This could be a bit nerve-wracking.... But still you are no worse off once you have stopped shaking!

I saw an MT drawbar design in ME once made of high-tensile steel - exactly what you don't want! I have also seen it recommended to smear a little light oil on the taper to facilitate ejection.

I'm not sure about the warming argument, presumably the socket and taper would expand at the same rate so if at the same temperature there will be no difference?

Tim,

I don't know if there's suitable access on your mill quill - but can you get a morse taper ejector in?

e.g. https://www.cromwell.co.uk/KEN4829520K
or http://www.rdgtools.co.uk/acatalog/3MT-DRILL-DRIFT-1578436.html

Dave

.

John,

Consider this:

• Morse Taper is, by design, self-holding.
• The difference between a snug-fitting Morse Taper, and an impossibly-stuck one, is only a matter of microns on the diameter.
• A drawbar, pulled-up tight, will pre-stress the "fit" of the arbor in its socket.
• ... Warm the assembly and the inside diameter of the socket will grow [very slightly] more than the external diameter of the arbor.
• The pre-stress in the drawbar will therefore pull the arbor just a few microns deeper into the socket.
• ... When it then cools down, the arbor will be stuck tight.

That's my story, and I'm sticking to it.

MichaelG.

Michael

I agree with your explanation of an cooler arbour becoming stuck when inserted into a warmer spindle socket and the spindle subsequently cools.

But once stuck and subsequently running the machine to warm the spindle, the arbour will also warm and both expand equally, so the arbour will remain stuck. This is what I think John was referring to when he said he was not sure about the warming argument.

Nigel

Well I've been out and had a play this afternoon. I clamped the vise on and stuck a bit of old cast iron in it, found a slightly rusty 7/16" endmill out of my uncle's box of bits and set to with the drawbar in compression (pushing down on the arbor).

It cut a very nice slot, especially as I just threw it together to try it out. Only problem now is the chuck came off the arbor revealing a thick coating of loctite in the taper. The arbor is still stuck fast.

With my mill/drill (MT3), I would loosen off the drawbar about 1-2 turns and bash it with my plastic headed mallet as the normal means of release. That would stop the chuck falling out.

If I'd overdone it, I had a nice old spring loaded slide hammer of unknown parentage with a taper end that fitted in the extraction slot in the quill. However, I soon learned not to overtighten it in the first place so this wasn't something that happened frequently.

The other, more direct method is to remove the drawbar and drop a length of steel (brass?) bar into the hole from increasing heights until it releases, achieving a sort of slide hammer effect (piece of wood to catch the falling chuck etc). If anything gets damaged it's likely to be the MT adaptor rather than the machine itself. But one smart tap with the mallet was normally enough.

Murray

Bring the quill section which actually holds the taper down onto a piece of wood which is sitting on the table, release the drawbar a couple of turns and hit with a copper mallet or similar.

As you are supporting the quill in this way the bearings shouldn't be loaded.

Tony

Where do you think the bearings are?

By design and construction of mill, those things underneath the quill do nothing to take the load off the lower bearing if directly under quill. It needs to be on the protruding taper that revolves.

There are better arrangements but essentially nothing wrong with MT3, back drawbar off 1/4 to 1/2 a rev then short sharp dead blow following through guarantees. I leave a 4lb hammer held close to the head and 17mm spanner within reach just for this purpose. How do you think the pneumatic drawbars work without using above and no quill lock. Think this calls for a video tutorial, just got to have the knack.

Other person what happens when don't tighten things up, they work loose and or cutter drops, give it some.

If worried about bearings theyre cheap and a good excuse to replace the dire originals with decent branded quality ones.

Can you get an SD chisel drill above it?

If so set it to chisel only use a chuck attachment and hold a long bar in it. You may need to insert this first against the MT end. Turn on the drill and press it firmly against the taper having supported the quill as described previously. The vibration mat be enough to shake it free in a similar way to an impact driver.