Taking Chinese 3 Jaw Metal Lathe chuck apart for cleaning

Taking the Chinese 3 Jaw Metal Lathe chuck apart for cleaning. Really happy I did this. The chuck hadn't been as smooth as it had been and there was a lot of crap inside it. Back to its usual smoothness and a pleasure to use again. Never done it before and it proved fairly easy. If yours isn't smooth, don't hesitate to take it apart and clean it.

Edited By Blue Heeler on 29/05/2019 06:29:53

Edited By Blue Heeler on 29/05/2019 06:30:02

Brilliant Thank you

I'm surprised to see it's empty of any lubricant. The British and American chucks I have had apart all had a high-tack moly grease packed into the crownwheel and pinions cavity to lube the gear teeth.

(Tip don't pack it with standard black moly grease unless you want to end up covered in black spots! I (now) use clear synthetic wheelbearing grease. Proper chuck grease is stupid expensive.)

Also, some light machine oil on the scroll helps cut wear on the scroll and jaws without sticking swarf to it. Some high quality motorcycle chain lube teflon sprays also work well here if they dry out without being sticky.

Thank you

Thanks Hopper

The 8" three jaw on my `1326 BH Taiwanese lathe has not got as much grease in it as it had at first, it was packed solid, the chuck is very similar to Blue Heeler's one.

Ian S C

I have taken my Chinese chuck apart many times and never found any grease inside ,even from day one.

It,s no big deal and it does help to remove the little bits of swarf which find their way in there..

Just make a note of which jaw goes where, too easy to mix them up.

On mine there are jaw no. markings inside the slots and on each jaw, and zero markings on body and backplate. It should be easy to avoid misassembly. Mine has an oil point in the front face, so my assumption is to use the SAE 20 recommended for general lubrication, and not so much of it that it gets flung about .

1+1 for the worth of deep cleaning your chucks.

I found no lubricant of any sort inside the 3 jaw chuck supplied with my GH600. so I used some wheel bearing grease ( I have had the tin for at least 40 yrs ! ) also added a little 3 in 1 oil to the scroll , thin so the swarf wont stick to it too badly . Chuck is now smooth in operation and smells nice >

Brain C

I did whip it back off today and lightly grease inside.

I regularly strip and clean my 3 jaw chuck as part of a standard maintenance regime I have for my workshop equipment. 1st time there was no lubricant in it at all. I lightly grease the gears and apply thin oil to the scroll. Too much lubricant encourages swarf to accumulate where its not wanted and makes cleaning a much harder job.

Ordinarily you shouldn't have to pull the crown gear and pinions out very often. Maybe every year or three? If the cavity is packed with grease, not much swarf will make it in past the periphery of the scroll plate without getting caught there in the grease.

Pulling the jaws out regularly and cleaning the actual scroll by rotating it while sticking a suitable rag down into the spiral groove to clean swarf out is a good preventative measure. As is cleaning the jaws and the slots they run in and re-oiling.

This extract from Cliff Bower's Book of the Lathe (1955) is probably more applicable to flood coolant users:

PREVENTING WEAR

One of the main causes of deterioration in chuck truth is wear of the scroll bearing, and usually very little has been done by chuck manufacturers to minimize this. Wear in the scroll bearing arises from the ingress of swarf and other abrasive particles between the rotating surfaces, and these are often washed into the bearing by the action of cutting lubricants. One way to minimize the ingress of harmful material from outside the chuck is to pack the inside of the body with thick grease. This can be packed in by removing the back plate and the back cover plate from the chuck body. A better way is to force the grease into the body under fairly high pressure from a grease gun, and a means of doing so is to drill and tap a hole in the body for the insertion of a high-pressure-grease nipple. So that this will not be hazardous to the machine operator by projecting outside the body and catching in sleeves and other parts of his clothing, a recess should be machined so that the nipple is completely sunk below the body surface. The grease hole can be closed by a screw plug suitably shaped, to restore the smooth exterior of the body.

When grease is forced into the body under high pressure from a gun, it penetrates the clearance space in the scroll bearing. Since the pressure within the body will be fairly high, the passage of harmful material into the bearing will be blocked. Alter a time, the grease in the bearing will be washed away, and it can be renewed by applying more grease by means of the high-pressure nipple. The grease flowing through the scroll bearing will force out any harmful material which has penetrated into the bearing. The grease should have a fairly high viscosity; if it is too thin it will tend to be flung out of the pinion holes by centrifugal force, particularly if its temperature should rise for any reason.

The idea of using lubricant to scavenge foreign matter from a mechanism is also used for cycle hubs.

An old toothbrush pushed (rammed ) into a jaw slot, while the scroll is rotated makes an easy job of clearing the swarf.

Also handy for cleaning the slots, and the back of the jaws before refitting.

Howard

Amazing how useful toothbrushes are for the workshop!

Just got to remember to use hers & not yours 😁.

I use either chain lube for motor bikes or tac2 spray to lube my chucks and back gears of my lathe because it is designed to not fling off . - i used to use a 3 jaw mostly but mostly use four jaw now except for machining hex stock which is fairly rarely .

I bought a can of tac2 a couple of years ago, absolutely terrific stuff.