Stuck Collet Chuck Arbor

[ukazak]

Hi Guys,
I am all new, to machining and to this site. I made a "grave" mistake, that "I know now" . Couple of years back I bought my mill (MFL 20) and just pluged in and start playing. All went fine other than couple of times stripped gears and changed.. everything was smooth and nice, up until I decided to change collet chuck...! it refused to come off... Yes, I tried to hit the drawbar as hard as my heart would alowe and oiled, WD40'd and evry trick I heard.. but, arbor is stuck.. No, it wont come off... I am doomed live with this stuck collet chuck arbor.
I didnt have any need to change for mandrane or any other reason to move it than.. or now really.. but it just bothers me, I should have removed the thing and get the rust and dust, all cleaned up when I receive the machine before I use I guess...
Well, what now? anybody has any ideas.. I can take the headstock down and apart it but, it would it be any use at all? what shall I do..? can anybody help me on this?

[Fergus OMore]

I've no idea of what sort chuck is jammed but sometimes two opposing steel taper wedges progressively tightenned will succeed when brute force and bloody ignorance( my usual technique) fail.

[andyf]

If you don't want to hammer any harder in case you damage the bearings or bend the column, and if wedges don't work, you could try removing the spindle, turning it upside down and slamming the end of the drawbar down on to your bench.

Andy

[Miner]

I'm 100% in agreement with Norman and Andy on this. You do NOT want to be hamming on that drawbar very much. There's not a precision bearing maker in the world that wants to see impact force transmitted thru the bearings.

I tried Googling your mill, But not much came up. So what type of mill is it? What taper is it? What type of collet chuck? It may require the head to be removed and then taken somewhere that has a press. Support the bottom of the spindle and then press the collet chuck out.

You could try tightening a rod into a collet, Tighten the other end into the mills vice and  Use that to help pull on the collet chuck while tapping on the loosened drawbar. It might work? I REALLY hope that's not a R-8 taper and the taper spun in the spindle shearing off the internal set screw though. If so, You might never get it apart.

Pete

[ukazak]

Oh! Ooops, I made mistake on the machine type. it is " Optimum BF 20 Vario and MT2 /10mm Draw rod"
Thank you all, Andy, Fergus and Pete,

Er32 type of collet chuck and arbor stuck. and If I hit the drawbar on the top, which I dont like at all  (once so hard that feeding arm on side had almost a quarter turn like I was to drilling...) and I know than it will not come off by brutal force as Fergus said.
I dont know if  spindle will come out from either openning while the chuck is still attached..(?)

[ukazak]

You could try tightening a rod into a collet, Tighten the other end into the mills vice and  Use that to help pull on the collet chuck while tapping on the loosened drawbar. It might work? I REALLY hope that's not a R-8 taper and the taper spun in the spindle shearing off the internal set screw though. If so, You might never get it apart.

Pete

You mean a smaller draw bar from under side screw to the chucks arbor and pull up while is in mills vice and small taps to the losened draw bar at the top?
Now that I havent tried before... I will soak is WD40 overnight and try that first thing in the morning..

Taking to ındustrial park and using press.. I am sure will demage something else inside or outside?
Thanks

[philf]

Is it possible to use the ER32 chuck nut to pull the chuck out?

To try you would probably need to machine a sleeve which would slide over the chuck and then a thick (say 6mm) split washer on top fitting between the sleeve and the end of the spindle.

The significant force generated wouldn't be seen by the bearings at all.

Cheers.

Phil.

[Fergus OMore]

Obviously, you have something mis-aligned- and twisted.

As a follow up, stuck tapers are the normal for car and lorry suspension rod ends and the accessory firms have extractors. In fact, I have several- left from those days.

Much of the removal of tapers is by feel- which is almost impossible to describe in words. It all depends on just how much space that is available. I have used a pair of cold chisels to take up the distance and then a pair of screwdrivers- opposed to way that chisels are placed.
Tightenning up has to to be evenly made.

Years ago, I extracted a flywheel/clutch on a 997cc Mini cooper which had fretted onto the crankshaft. There was a 1/2" drilled plate with three High Tensile bolts almost snapping and the extractor bolt was 1" stuff.  I lay on the engine whilst my father hit the extractor bolt with a 14lb sledge hammer.

You may have to be prepared to sacrifice the least important part and I suspect that the spindle is the most valuable part. Crack the bearings- if all else fails.

[Miner]

Actually Phils got a real good idea that just might work. A good company with a press would certainly know how to use it to not do any damage. But what I meant about using the rod in the collet chuck and tightened in the mills vise was as you've mention pull up on the spindle while tapping on the drawbar. Just don't try to apply too much force with any of this. One way or another that Morse taper should come out. But I'd think Phils idea has the best chance of working.

Pete

[David Jupp]

One option is to strip down the mill spindle, apply some force in the correct direction via one of the idea above, additionally warm the spindle (but don't go mad).  If done fairly quickly the spindle will expand just a little before the heat penetrate to the chuck arbor.  This might just tip things in your favour.

[ukazak]

Is it possible to use the ER32 chuck nut to pull the chuck out?

To try you would probably need to machine a sleeve which would slide over the chuck and then a thick (say 6mm) split washer on top fitting between the sleeve and the end of the spindle.

The significant force generated wouldn't be seen by the bearings at all.

Cheers.

Phil.

Thank you for all of you guys, as I was lookin around in the net, and found out that, this is no easy thinking to tacle and still unsolved problem yet, I am not the only one got the stuck arbor  the problem. so far Phil's idea  of a sleeve and collet nut and combination of some warming might put the end of this globaly suffered dilema. There was even one suggestion that, thake out the drawbar completely and lean the chuck against the side of mill's vice and give slow power  turn a while..
The chucks diameter is 33 and height to spindle rim is 72mm. I think it will work but, I hope I got enough power to tighten the nut. Is there any danger of stripping the threts of the chuck or the nut to cause jamming?

[Fergus OMore]

I think that I have got it right but there is a 60+ page manual on the net. OK, it will not be a quick solution to strip the headstock down to get at the spindle with attached remaining bits but it all looks possible.

Before this, I would insert a proper close fitting rod down and give it a hard belt or three. What you are doing is you are belting the tapped end of the taper shank with a threaded draw bolt-- and that does not do much. Again, forget the WD-40. All that you are doing is removing the grease from the bearings- which if you go on like that, you will run( Brinell)  them-- and have to take the lot to bits anyway to replace them.

Sorry but that is my view- from a distance!

[mklotz]

Why does everyone think WD40 is a lubricant?  It's a bug spray that can be used to remove stubborn labels.  Nothing more.

Pour a dram of warm Kroil down the spindle, wait eight hours, then tap gently with a solid rod.

[Jonny]

The significant force generated wouldn't be seen by the bearings at all.

I beg to differ, whats holding the spindle in? Lower bearing

Three ways, Petes way but push up on drill feed handle whilst giving the drawbar loosened 1 rev a short hard crack. Its a knack not severe brute force but more speed and momentum following through.
The more you do it, the easier it becomes. To give you some idea how easy on MT3 i have changed over 60 times in the last day and half, 1lb hammer permanently left to the side hand held on stale just behind the head, no leverage.

[philf]

The significant force generated wouldn't be seen by the bearings at all.

I beg to differ, whats holding the spindle in? Lower bearing

Three ways, Petes way but push up on drill feed handle whilst giving the drawbar loosened 1 rev a short hard crack. Its a knack not severe brute force but more speed and momentum following through.
The more you do it, the easier it becomes. To give you some idea how easy on MT3 i have changed over 60 times in the last day and half, 1lb hammer permanently left to the side hand held on stale just behind the head, no leverage.

Sorry Jonny - I beg to differ with you.

I am talking about pulling down on the chuck by pushing the collet nut against the nose of the spindle itself - not the spindle housing!

Also - the chances of stripping any threads are very slim. I tighten up my ER32 collets with a lot of torque applied with 2 big spanners - and my ER32 threads aren't hardened.

Phil.

[philf]

Jonny,

See the attached drawing which perhaps explains my proposed method better than words.

Cheers.

Phil.

[PekkaNF]

How about putting it into tension like above illustration shows and spraying inside of the collet chuck with cold spray. On that sort of situation combination of static pull and thermo shock has opened up stuff. Another thing that has helped me a lot is to open drawbar just a little before giving it whack to it. I think that there must be pretty many thread to transmit the blow. Same thing on steering joint tappers on auto.

Once I was despairing with my fly rod, it simply refused to open and four piece rod is not very handy to transport when one ferrule in middle won't open. Not ideal situation in Oaxaca when had to go home next day. Tried everything and finally hosed it down with a cold water. It came unstuck - practically with no force.

PekkaNF

[ukazak]

I tried today, 
Turned a close fitting sleeve and washer. it turned a few lines of thread, than came to a point that looked like trying to unscrewing a welded bolt.. wouldnt turn more. maybe I have to try to apply more power to it with a friends help.
one thing is for sure, one can easily depend his life on it. I did not put the chuck in there, it came on with the machine. it may have set a couple of years before it was sold to me, and I used couple of years and not removed once. So, it may be frozen until the death apart. There are no bending or twisting evidence on it, for it is spinning really  like you wouldnt know it was spinning, if if you didnt hear the machine running. if there was a twist it would wobble a bit..
may be they had placed the chuck right after test run (while machine and spşndle hot) snd there was a piece or two dust in it.. than sit there for couple of years and get rusted..
Tomorrow I will try again with doubled force to give turn or two more... if not, I may be to take down the head and get the spindle out to take it to a press shop.. hpefully, we get it out without bending the spindle or demage it someway..

[ukazak]

who ever discovered this "Morse Cone" thing, did realy a good job, I must say. Could never thought theoraticaly is possible that thing works..! no bolting, no screws, no glue, no welding..  but, it holds. It is amazing..!

[philf]

Ukazak,

I forgot to mention to grease the threads, washer and sleeve to convert more of your turning effort into trying to extract the taper.

I think someone has mentioned trying to rapidly cool the internal taper. I have some freezing spray for fault finding in electronics but you can also get freezing sprays for plumbing. I think you'd have to put as much tension as possible with the nut and then quickly cool the chuck.

I've found the opposite works on a stuck crank on a bike - tighten up the extractor as much as you dare (the threads are quite fine and only into aluminium) and then pour a kettle of boiling water over the crank. It may be difficult to get enough heat into the spindle quickly enough without damaging anything and cooling the chuck may possibly work better.



Good Luck.

Phil.

[b4dyc]

Firstly, a hello to all 

I have a similar looking mill to you (it has a M12 drawbar though)
The way I have to remove my collet is to undo the draw bar while stopping the spindle rotating in the quill it then presses the collet out. It does this because of the way its designed with a cap that fits on the end of the quill underneath the black plastic cap at the top. Its a way to remove them without hammering the draw bar.
 Always takes a good bit of undoing and often hear the little clink as it frees itself.
This is my millhttp://www.amadeal.co.uk/acatalog/MT3_Spindle.html#a29

Not saying yours is the same but hope it helps you out!

Andy

[Jonny]

Thanks Phil for the sketch, that will do the job no stress on bearings, with you now.
Its only ER stuff though, most of us will not use.

Andy I have heard and seen similar arrangents but limits its usefullness. ie dont want drawbar in with a drill or the need to swap drawbar over to different thread.
Easy to make, just a U shaped bracket close fit to top of hex drawbar. Perhaps a swing out jobby aiding easy removal and was thinking this way fro pneumatic jobby.

Cant beat the hammer

[Fergus OMore]

c'ant beat the hammer

What is missing in the discussion is the 'bloody ignorance' bit.

The difference between the areas of the ends of 8mm and 10mm draw bars is 50 sq.mm whereas the larger is half as much again at 78sq.mm.

Pi R squared- nothing more

If, as I suggested, the maximum diameter is used the area and the force which can be safely used is considerably increased.

I don't know what that available area is- but it is worth sitting with a pocket calculator and working the thing out.
It's a lot cheaper and quicker to do than to ruin both the spindle and the chuck body.  The cost of  a bit of round is a fraction of the potential damage. What has to be worked out is the bend in what are two thin draw rods when a thicker one is far more suitable.

Engineering is not merely the ability to chew a bit of metal to a different size-- and photograph it- and get applause. It needs a modicum of school arithmetic.

[lordedmond]

the word tapping is causing the problem  get the tension on as above then ( I use a two pound copper face hammer) and give it a swift belt no tip tapping it will need a high quick impact . when not if you get it out make sure you clean the male and female parts completely and always fiit dry with only just a nip up on the draw bar not much more that 1/4 turn from the slack taken up

Stuart

[Fergus OMore]

The deed is done but  the problem is age old. It dates back to the time of Nelson when the British Admiralty insisted on huge heads on bolts because the British sailors used too much muscle- and twisted the heads off.

We've now got to undo a problem which should never have arisen. All that a draw bar has to do is to just stop a mating pair of tapers from slipping under load.