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Morse Taper Removal

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Alan Worland15/12/2011 21:58:54
247 forum posts
21 photos
Michael, That sounds a very controlled way of removing tools - I will consider this as I have the spindle of the lathe and the quill of my milling attachment to cater for.
(sorry I didn't see your message earlier but I have only just switched on - been in the workshop making a generator for my Stuart No4 to drive)
 
Alan
Jim Greethead16/12/2011 06:55:59
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131 forum posts
8 photos
I had a lovely time today swapping from Jacobs Chuck to Collet and back again using my new lashup and thinking "what a clever boy I am".
 
Right up until the collet came loose and the cutter gouged a piece out of the job I was working on.
 
Luckily, Murphy was Xmas shopping so it was not the last cut of a complex piece, and it didn't ruin the job.
 
So tools in the taper need to be more than hand tightened. Or it needs stronger hands than mine. Or I need to redesign the handwheel ... maybe something like those bathroom taps with the cross on the top to give a better purchase.
 
What do you reckon?
 
Jim
 
Ian S C16/12/2011 10:14:01
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7468 forum posts
230 photos
Most supprised that the collet came loose, things like that happened when I first started, I had an end mill in the Jacobs chuck, I knew nothing of collet chucks, or anthing else to do with milling. One of the first things I made was a tap wrench, its got a chunk out of it where the chuck fell out. I did learn quickly. Ian S C  ps, I still use the tap wrench, the bit out of the side reminds me to do the job propperly.

Edited By Ian S C on 16/12/2011 10:16:43

Jim Greethead16/12/2011 10:58:39
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131 forum posts
8 photos
Sorry, I should have said that the collet chuck came loose. It came out of the spindle because the drawbar had unscrewed.
 
It was a bit odd because it came out, the cutter gouged the job and then it bounced back and tightened up on the drawbar. So when I stopped the machine and checked, the drawbar was tight.
 
Thinking there was something mysterious going on, I started work again. When it happened the second time, I twigged. And tightened the drawbar with a spanner. That fixed it.
 
It is possible that the inertia of the handwheel causes it to loosen when the spindle accelerates. That happened when I used a steel handwheel. So I swapped it for an aluminium one having less inertia. It seemed to be ok but maybe several starts caused it to loosen.
 
Next step is to try a handwheel with less inertia but more hand holds - like the tap handle shape.
 
I am reluctant to give up altogether because it is just so much more convenient than the spanner and hammer method.
 
Jim
 
Peter G. Shaw16/12/2011 11:25:38
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1531 forum posts
44 photos
Jim,
 
On the Warco MiniMill and other Sieg X2 type milling machines, the complete head moves up and down the rack. What this means is that the actual spindle is rigidly located vertically (and horizontally) by the bearings inside the head hence any bashing on a drawbar transmits the shock onto the spindle, then via the bearings onto the head itself before reaching the rack which is part of the column.
 
Another way of looking at is to compare it to the lathe spindle. OK the lathe spindle is horizontal and doesn't move, but just the same, any bashing on a drawbar inserted from the rear of the lathe spindle must eventually end up being transmitted via the lathe headstock bearings.
 
Actually, I can't see how in your description the shock load does not go through the bearings as unless the rack is cut into the rotating spindle, then the bearings must be brought into play. I have a, ok cheap, vertical drill which has a rack cut into an outer sleeve which moves up and down inside the fixed head. Within this outer sleeve, there is the spindle, supported by two bearings, top & bottom. The spindle itself also slides up and down inside a square spline which is directly connected to the pulley drive system. The result is that if the rack is locked, any vertical shock loading on the spindle will pass from the spindle to the outer sleeve, and hence the rack via the bearings.
 
Regards,
 
Peter G. Shaw
David Littlewood16/12/2011 13:17:58
533 forum posts
I would question whether shock waves only travel in straight lines, as is assumed by some posters above. Personally, I avoid giving anything other than very light taps on tapers, usually to remove drilling chucks with no drawbar.
 
David
Gordon W16/12/2011 14:44:16
2011 forum posts
One must assume that the designers of machine tools allow for the extraction forces when specifying the bearings ? BTW one short, sharp crack with a hammer usually causes less trouble than many "gentle" taps.
S.D.L.16/12/2011 16:54:37
236 forum posts
37 photos
At technical college many (35) years ago it was always a good sharp tap with a lead hammer.
 
Most workshops I have seen a similar or a big copper mallet.
 
Was always told 1 big tap with a decent soft faced hammer was better that lots of little taps.
 
Steve Larner
Dusty16/12/2011 18:52:48
498 forum posts
9 photos
Gentlemen remember the old adage 'never force anything, always use the correct size hammer'
Jim Greethead16/12/2011 20:05:31
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131 forum posts
8 photos
Peter, of course you are right. I have just checked the drawings for my mill (why didn't I do that before making an idiot of myself) and the bearings do, indeed, take the shock load. Pardon me while I take my foot out of my mouth and bash my head against the wall
 
Gordon: That sounds sensible. They don't provide any alternative so perhaps they have allowed for it.
 
Steve: I did a course at the local Tech recently and this was still the method of removing chucks. One thing I did notice was that, as you say, it was usually a lead or copper mallet rather then the steel lump hammer I have been using. Are the soft hammers more gentle on the machine?
 
Dusty: Good advice. And following Gordon's admonition to use one big whack rather than a lot of little ones, I guess the correct size hammer is the biggest one at hand.
 
And lastly, thank you all for your contributions and for keeping me on the straight and narrow. I appreciate it all.
 
Jim
 
Nicholas Farr16/12/2011 20:56:03
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3988 forum posts
1799 photos
Hi Jim, the main reason for using soft faced hammers is for the hammer to be the sacrificial element in the operation, that is that whenever you use a hammer for hitting things deformation occurs somewhere. If you continually hit a rivet for example, it will deform into the required shape to do its job, whereas the hammer being much harder will not deform by any significant amount, and this is an ideal situation. When hitting the head of a drawbar on the other hand, you do not want the hexicon head to deform so that eventually you can't get your spanner on, therefor the soft face hammer deforms and becomes sacrificial. The resultant energy transmitted into the the job in hand will be about the same. (Hammer weights, swing force and area of hit taken into consideration)
 
With regards hitting the drawbar to remove chucks etc., I don't think you'll do much damage to the bearings in normal use, providing you are not using a sledge hammer to crack a monkey nut. As has been said one short sharp blow rather than lots of little ones.
 
Regards Nick.
Jim Greethead16/12/2011 21:31:04
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131 forum posts
8 photos
Thanks Nick, that explains it
Jim
 
GoCreate17/12/2011 03:20:22
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387 forum posts
119 photos
Here is a simple solution by a Sherline owner.
 
It's cnc machined but can easily be modified for other machines and convensional manufacture. Does require the spindle to have some extension available though so, in this respect, may not be a universal solution.
 
 
 
Nigel

Edited By tractionengine42 on 17/12/2011 03:21:26

BERTO17/12/2011 05:16:45
46 forum posts
Jim,
I suspect the reason your handwheel came loose is not just inertia but because you have two right hand threads working in unison and not pulling against each other as they were designed to do .
If you screw the threaded rod into the rear of the collet chuck until it bottoms out then loosen 1 1/2 turns, now screw your handwheel down untill it touches the top of the spindle making sure the drawbar does not turn then use a locknut and some loctite to lock the handwheel to the threaded rod .
This way hou have created a drawbar with a large handwheel that will work the same way as a normal drawbar and only using 1 thread to pull the chuck up into the spindle .
You can still use the slide hammer idea as it will sit on top of the handwheel as before all it means is when you turn the handwheel to loosen or tighten the drawbar the drawbar also turns and screws in or out of the chuck .
 
Nigel ,
That was one of the methods i was thinking about for my HM46 as it has a splines on the spindle and to use a backing out nut i would have to disassemble the machine so i can turn a thread on the end of the spindle .
I could make a splined collar easily enough .
The collar idea is now in the lead !
 
IAN
jomac17/12/2011 12:47:07
113 forum posts

Hi ,Peters right. shock loads to the bearing and gears/splines, is a NO NO, also not mentioned is the fact that in a small square columb mill the dovetails also take a hammering, which is why you can have problems in tramming the mill parallel. In some cheap Asian mills that have round columbs, the verticle round tubes can get bent at the bottom where it fit into the base, I know cause I had an adjustable devise that had verticle and horizontal round hollow tubes, the tubes were too thin and the casting were diecast, so both were bent and distorted. So how do I cope, well the draw bar has a Nylock nut and the draw bar has a square top, all I need to do is set the nut to the right depth??? and lock it down to this. And most importantly !!!!!!! I have a heavy piece of hardwood or a heavy but soft piece of metal, that I put under the quill, its only then that I belt the crap out of it, thus no problems with bearings or splines getting damaged. By the way hasnt this subject arisen before, and no one read it.

Merry Xmas and Happy new year.

John Holloway

I

Deril17/12/2011 19:49:16
5 forum posts
1 photos

There is an alternative to blows at the drawbar.
Generally some form of extraction may be arranged at the work end of the taper.
For a collet holder with a closing nut a simple piece of tube round the holder between the nut and the quill will allow easy extraction by tightening the nut after the collet has been removed and the tube fitted.
For tools such as drill chucks and boring heads on morse tapers there is often enough unused length of taper outside the housing that a very short length of screw thread- from a salvaged water fitting- may be super glued on just clear of the housing.
A thin nut from the same salvage again allows easy extraction
 
Jim Greethead17/12/2011 22:03:02
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131 forum posts
8 photos
You blokes are proposing some really ingenious ideas and I am enjoying the discussion. Maybe the topic has arisen before John, but it is not easy to find it on the Forum.
 
Ian: I am not sure I understand what you are saying here because the handwheel is locked to the drawbar with locknuts on each side. I will, however, check that it is not bottoming in the collet chuck. Thanks for the suggestion.
 
Nigel: I keep thinking about that extraction tool. With a collar on the spindle, the world is the molusc of your choice; it opens a range of possibilities. If the extraction tool was modified so it could turn the drawbar, you could do away with the extraction bolt, unscrew the spindle until the extraction tool contacted the bottom of the collar and keep turning to press the drawbar out. It would require a lever on the extraction tool but then the tool could be used to tighten the drawbar as well.
 
Does anyone know how those automatic drawbar insertion and release mechanisms work? They sound like those air hammers used to tighten wheel nuts.
 
Jim
 
Jim Greethead17/12/2011 22:28:11
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131 forum posts
8 photos
 
The plot thickens
 
Jim
Jon18/12/2011 02:04:08
1001 forum posts
49 photos
Just get yourself an air powered butterfly ratchet and socket 3/8 will do.
 
You are quite right Jim every mill around the quill passes through the bearings like it or not.
Had similar happen time and time again i do tighten the drawbar up as much as i can. Some times with boring head have found its dropped and for it to do that must have loosened off. Bear in mind it was grollied up tight! Not wimpy hand tight asking for trouble.
For those that infer stressing V's etc by hammering the head i would suggest you have a close look at the forces involved when actually doing something, think you will be surprised how minimal knocking the drawbar loose is comparitively.
What i have found is a short sharp tap with 1/2Lb hammer does the trick 9 times out of 10 left in coolant tray. 17mm spanners left permanently in the T slot trough collection, new collet, drill chuck or tool replaced within 30 to 45 secs and do such things 12 times daily.
 
First thing i did on a new mill was make a spindle lock going in to the protruding splines.
 
Very easy to make up draw bars i have to replace twice a year on every day machine plus old one with three different threads. Locktite no chance not even silver solder or brazing will hold, V out and weld.
Its also common practice in engineering to use a whacking instrument be it spanner or hammer.
BERTO18/12/2011 06:47:38
46 forum posts
Just had a look at my mill and the collar idea went out the window as the spline dissapears down inside the head when at full spindle depth and to keep it above would mean the loss of 60% of the travel.
While i was playing and fiddling around changeing tools i noticed a screw in cover for the bottom bearing on the spindle and as it was loose i took it off.
I had a look up in there with a torch and found that the bearing was a taper type similar to what's used on hub bearings on a car and to my relief covered in moly grease !
I began to think of how a wheel bearing would suffer axial and radial shock loading because of potholes and corrogations in the road and maybe the designers had used this type bearing in a Mill as it can take some punishment or at least more than a ball type bearing .
Thoughts ?
 
Jim,
On the video it looked like the rod and hand wheel were not locked together and if they were inerteia and leverage or lack of it are your culprits .
What about making a new hammer that has one face of copper, brass or lead and the other end of the head a socket to undo the drawbar and the handle is used like a " tee" bar - 2 tools in one !
 
Ian
 
 
 
 


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