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Unstick ML7 chuck

How I did it

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peter blair12/10/2017 15:43:44
34 forum posts
25 photos

This is the second time I have managed to get my 3 jaw chuck stuck on my ML7. The first time I was really new to this lathe and I just locked the back gears and tapped the key with a hammer and was VERY lucky I didn't break any gears. I am a little wiser now and didn't want to risk that maneuver again. I read and re-read all the information I could find on the net and tried everything I could find. I tried release oil, heat, clamps, strap clamps, an impact wrench and just about everything else I could discover. In the end I made an aluminum gear lock.

1. I first loosened the belt tensioner most of the way and tied the belt front to back with some string. I did this just tight enough to allow me to push the tensioner back to sort of lock the shaft. I used the largest pull on the shaft to do this.img_4909.jpgNext i spent an hour with a 1/2" thick by about 3" wide piece of aluminum and cut mating teeth in it. I didn't do as good a job as a lot of you might have. I did make the mistake of first cutting a circle the diameter of the outside of my gear instead of the diameter of the inside of the teeth. This cause me to remake it.img_4913.jpgOnce I was happy with the fit, or at least mostly happy I proceeded to dress it into the large gear.img_4910.jpgWhile holding it with some force I put a crescent wrench on one of the jaws and tapped it with the palm of my hand.img_4912.jpgBecause of the good 'lock' of the shaft the chuck spun off the second time I hit it with my hand.img_4915.jpgAfter a very careful cleaning I now have a light coat of Never Seize on the threads and hopefully I will not have this issue again!

not done it yet12/10/2017 17:23:23
1959 forum posts
11 photos

You were still locking gears. Ne este par? Only consolation was you were meshing on several teeth, but with minimal useful width and the ally teeth would have sheared before the gear teeth. Remember those cut teeth would likely only be bearing on the single t

ooth that was actually meshing at the time! It does seem that the chuck was not really very tight, after all.

Do make sure the registering surfaces are meticulously clean, as well as the threads, and fit parts while at, or close to, the same temperature.

If I were doing that, I think I would soften a wide thermoplastic bar and make moulded teeth full width in a few minutes. Smacking the adjustable with a soft faced mallet is far better than cracking the chuck key drive casting in the chuck, mind (chuck jaws are stronger than the key operating parts).

Lambton12/10/2017 17:29:46
639 forum posts
2 photos


Put anti seize compound also on the chuck register and back face where it contacts the spindle. Also never spin the chuck onto the mandrel - just screw it up gently but firmly by hand.

Look at page 64 of MEW No. 255 where you will find a simple design for Myford mandrel lock spanner.


ega12/10/2017 17:57:57
784 forum posts
72 photos

Prevention is better than cure. If a lot of heavy, intermittent cutting is being undertaken it is a sensible precaution to check from time to time that the chuck has not become overtight (the same point applies to faceplate work where intermittent cuts are perhaps more likely).

Speedy Builder512/10/2017 18:22:06
1533 forum posts
103 photos

I think I would like to put a big bit of hex bar in the chuck and put your spanner onto this Hex bar instead of a single jaw of the chuck.

Howard Lewis12/10/2017 18:32:45
1300 forum posts

You were indeed lucky! Engaging back gear to lock the mandrel and then hitting the chuck is pretty surefire way to strip teeth off at least one gear!

I think that the standard advice is to tighten the belts, put a stout piece of wood across the chuck jaws (obviously fairly well open) and then to hit the end of the timber smartly with a mallet or hammer.

The theory is that the tight belts connect the mandrel to the inertia of the motor, and the suddenly applied load (which is supposed to be twice the value of a gradually applied load) should call for an accelertion which is so great that it breaks the bond between chuck and mandrel.

+1 for anti seize, but DO NOT then run in reverse. Starting up could well loosen the chuck!


peter blair12/10/2017 23:22:56
34 forum posts
25 photos

Thanks for all the comments. I would like to share a little as a result.

1. I did try the belt tension on and a length of wood in the jaws and when I hit it with a dead blow hammer the belt slipped a little and no results.

2. Thanks for the suggestion of holding a piece of hex stock instead of wrenching on a jaw.

3. Not tight? I guess you could say that but tight or not all methods I used failed

4. Yes indeed I was still using the teeth of the gear but not just one or two as I would have been with the back gear involved. I do believe this was much safer for the equipment as I believe that the aluminum would have failed way before the gears, as you suggest.

5. Great idea to heat some thermal plastic and make a matching gear that way.

6. I have carefully cleaned all mating parts and applied a thin coat of never seize. I reinstalled the chuck as suggested above.

7. Unfortunately I do not have a copy of MEW No. 255.

8. I do only small work and if the cuts have been intermittent they would have been very minor.

Niels Abildgaard13/10/2017 05:26:49
116 forum posts
11 photos

There is a key between bull gear and spindle I think and this is endangered by process shown.

For lathes where possible ,this way looks better

Edited By Niels Abildgaard on 13/10/2017 05:28:04

Martin Dowing13/10/2017 07:41:30
245 forum posts
4 photos

As an long term owner of ML 7 I may advise following:

#1 Lock backgear, insert key into socket and tap the key using reasonable strenght, but with *bare hand*, not a mallet or hammer. This works in 90+% of cases and would not strip teeth of your gears because your hand is going to hurt badly well before you get there, unless you are training of karate or something similar - then be reasonable. If doesnt work, proceed to #2.

#2. There is an accessory for ML7, very useful for example for tapping, which is a handle which can be installed on journal from the back. It works by means of split pipe and a cone which expands pipe upon tightening screw. So install it on your lathe, disengage belts, etc. Mandrell must run freely. Now open jaws of youch chuck and on motor side stuff under one of these a wooden block, in such a way that jaw would hit this block and stop when mandrel is turned. Now, with an aid of your handle turn journal rapidly, so the jaw will hit wooden block. Try to gain some momentum. This nearly always helps, if not proceed to #3

#3 Leave wooden block like in #2 but drive jaw of chuck on it *under power, on slowest speed and on backgear (this speed is 35rpm). You must reverse direction of motor rotation. I have 3-phase motor, so it is easy, using 3 position switch, if you have 1 phase motor, which turns only one way, you may try to cross v-belt, one which drive countershaft (longer one would be needed around for this occassion). Didn't try trick with v-belt, it is just idea.

#3 never, ever failed.


Jon Gibbs13/10/2017 08:12:01
738 forum posts

Another possibility is to use a rubber (boa) strap wrench around the bull gear.

Steve Jordon has a good video here that might be useful...


Robin13/10/2017 08:41:16
259 forum posts

I managed to seize a chuck on to my ML10. Removal was kind of brutal, an act of extreme unction, terrible galling occurred. The spindle nose did not survive but the back gear I was hammering against did.

I replaced the spindle. The new one didn't quite go all the way in to the taper roller but I reckoned any future movement would be in the correct direction. It didn't have far to go so I reckoned it would quickly fix itself if it wanted to be problematic.

Martin Kyte13/10/2017 08:57:15
1301 forum posts
9 photos

Hi Peter

I concur with Martin Dowing in a general sense.

Arrange for one of the wound out chuck jaws to contact a thick bar end or chuck of hardwood standing on the cross slide or rear shear if you must. You can add a pad of aluminium under it if you wish if you are using metal. Take a firm grip on the drive belt and smartly turn the spindle backwards so the jaw contacts the top end of the bar. This should release the chuck.

When reinstalling do make sure the threads and register are clean on the spindle and the chuck to avoid future lock ups.

regards Martin

Phil Boyland13/10/2017 09:12:23
37 forum posts
13 photos

This method works a treat. Much safer and you could also make a paper washer from some gasket material to go between the chuck and spindle.

ega13/10/2017 10:19:39
784 forum posts
72 photos

peter blair:

I feel sure that if there is a member near to you they would be glad to show you or lend their copy of MEW; unfortunately, like so many other people asking for help, you have no public profile and I don't think you told us where you are.

The MEW article is based on an idea by L H Sparey and described in his essential book The Amateur's Lathe.

The principle of this method is the same as Steve Jordan's but, to me at least, seems quicker and less messy. Incidentally, I would not recommend standing the chuck on its register on removal as seen in the video as this is likely to cause any chips present to fall into the chuck thread.

That said, plus one for the Boa as a generally useful tool.

The stuck chuck is more likely to afflict those who leave their chuck in place for long periods and, for peace of mind, you might consider loosening your chuck after every work session.

peter blair13/10/2017 14:44:01
34 forum posts
25 photos

Thanks again everyone. Wow what a lot of good information.

1. Niels, I don't quite understand about the danger to the key as the bull gear was not connected during this process BUT the photo you sent is great and should be easy for me to make.

2. Martin. Tried #1 along with all my other efforts, Hurt my hand . . .#2. I have seen such an item and am planning to make something similar to allow me to operate the lathe with a handle but was not available at the time. #3. I have a reversing switch so this method could be tried but as I said I am nervous of using the back gear for this process and it looks as if there are several ways for me to try in the future without endangering this part. Incidentally, it was suggested that I shouldn't use a wrench on one of the jaws of my chuck but several people have suggested I use a block of some sort to stop the movement by hitting it against one of the jaws. Seems contradictory to me?

3. Jon. That was the first thing I tried but was unable to hold the shaft well enough

4. Robin, glad I didn't try that.

5. Thanks Martin. I did try something quite similar to this but couldn't seem to get enough momentum

6. Phil, lots of people have suggested this and I may not have had the correct strap wrench but it sure didn't work for me. I just couldn't get the wrench tight enough. Incidentally I did try several of the suggested methods combined.

7. ega., sorry about the lack of information, I have now remedied that.I am presently awaiting a copy of The Amature's Lathe from amazon. I typically do little lathe work as I am a dedicated wood turner and only am trying to learn the in's and out's of metal lathe work to assist in making tools etc for my addiction . . .

Jon Gibbs13/10/2017 15:02:49
738 forum posts
Posted by peter blair on 13/10/2017 14:44:01:

3. Jon. That was the first thing I tried but was unable to hold the shaft well enough.

Hi Peter,

Yes, I had that trouble too until I saw the dodge recommended by Steve Jordon. You need to put some leather, rubber or other conformant packing underneath the join between the two ends of the rubber strap. That makes all the difference.


peter blair13/10/2017 15:19:30
34 forum posts
25 photos

Thanks Jon.

ega13/10/2017 15:44:36
784 forum posts
72 photos

peter blair:

Thanks for your response.

I have sent a message to your inbox on this website.

peter blair13/10/2017 16:31:13
34 forum posts
25 photos

Once again, it is great to have all of you as a resource.

On a different topic, has anyone made an adjustable carriage stop for the ML7? If so would you care to point me in the right direction or share with me?


Edited By peter blair on 13/10/2017 16:31:56

ega13/10/2017 17:25:46
784 forum posts
72 photos
Posted by ega on 13/10/2017 10:19:39:

The MEW article is based on an idea by L H Sparey and described in his essential book The Amateur's Lathe.

Correcting myself, the LHS book is A Man and his Lathe.

Apologies to anyone who spent time looking in the wrong place!

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