Chuck for a Chinese 9x20 Lathe

[addjunkie]

If the aln screw head is beyond use, you might get it out with a torx bit hammered in, bit of heat first. Ifthe doesnt work, drill it down the middle. You could try a stud extractor. Or just start with small drill and keep increasing size till you can pick the threads out

 

[Windy Miller]

From that diagram, part no 102 is the same as I have on my lathe, but yours looks to be different. Mine is only about 10mm thick and has holes for a C spanner. Yours seems to be far bigger and has grub screws.

I wonder if the spindle nose has been damaged in the past, and your ‘102’ is a replacement, or maybe it’s simply an adaptor to fit a chuck with a different thread?

 

[mrsbruce]

I can remove the grub screw ok, but everything is solid after that. I had removed the spindle before to regrease the bearings, and in truth, everything looked original. It is my belief that the back plate has never been removed before, but then, why would the back plate hole edges be so worn. Unless it was ‘factory’ tight with that horrible sticky grease they use?

 

[mrsbruce]

Yes, here’s a photo from one of the manuals.

 

[mrsbruce]

Found one that looks a bit more like mine from another manual.

 

[Kram]

Can you remove chuck from its back plate, it may be easiest to make up an adaptor for that.

Does look like a lot of overhang already.

If the bearings are standard size like my 32007's then replacement flange mount spindles should be available.

 

[mrsbruce]

From that diagram, part no 102 is the same as I have on my lathe, but yours looks to be different. Mine is only about 10mm thick and has holes for a C spanner. Yours seems to be far bigger and has grub screws.

I wonder if the spindle nose has been damaged in the past, and your ‘102’ is a replacement, or maybe it’s simply an adaptor to fit a chuck with a different thread?

Definitely feasible. I will have to take the spindle out and investigate further.

Is there another grub screw beneath the first? Quite often a second grub screw can be fitted to ‘lock‘ the first in place.

H*lls bells, that is some overhang from the spindle front bearing! I would suspect there is something non-standard with that set up. I would not be surprised if that first collar (in front of the bearing) has been fitted over the original spindle.

Cannot see any other screw underneath, but as someone on another forum mentioned here said, a pin was discovered under the offending grub screw.

 

[mrsbruce]

Can you remove chuck from its back plate, it may be easiest to make up an adaptor for that.

Does look like a lot of overhang already.

If the bearings are standard size like my 32007's then replacement flange mount spindles should be available.

Yes, the chuck bolts on with 3 allen bolts, so easy to remove. I took it off to clean up the chuck, but it’s obviously been well used.

 

[Windy Miller]

… but as someone on another forum mentioned here said, a pin was discovered under the offending grub screw.

If indeed you DO have a hidden pin, it’s likely to be visible inside the spindle.

 

[mrsbruce]

I have one of those ‘bendy camera tight space’ things. I shall take a look i side it.

 

[mrsbruce]

Ok, I had a look with the camera, and concluded there was only the grub screw, which seems to fall nicely into a grub screw sized hole in the spindle. Then after hatching a cunning plan, finding bigger bars, and some grunting, the back plate was finally persuaded to part from the spindle.

I then removed the spindle and checked that out, and have added pictures. Hope they can reveal some more clues.

 

[addjunkie]

That brown stuff would cause the reluctance to move. A right good clean and itll be fine, but measure the thread for new chuck back plate…

 

[mrsbruce]

That brown stuff would cause the reluctance to move. A right good clean and itll be fine, but measure the thread for new chuck back plate…

Will do.

 

[Windy Miller]

Glad it’s off at last!

Get yourself a C spanner that fits the spindle, and a strap wrench to go round the chuck and it SHOULD come off easily once you’ve cleaned off the brown stuff from those threads.
If the strap wrench won’t cut it, I have a big (30mm?) nut & bolt welded together that I grip in the chuck, that I can turn with a spanner or socket whilst holding the spindle with the C spanner.

 

[mrsbruce]

Spent some time last night cleaning the spindle, chuck, and backplate. Looking less grotty now. Just trying to get the space through the spindle less rusty. I considered a citric acid bath, but one of the spindle bearings won’t come off without being damaged. The bearings are not absolutely perfect, but are too good to wreck or replace.
Maureen

 

[addjunkie]

Youll need heat to get that bearing off easily. But if your happy with it as a bearing, just clean the inside as best you can and box it up.

 

[Chippie]

Just to add, a bit late to the party……but looks like an M39 x 4 thread….
The lathe looks like the generic 9 x 20 Chinese lathes based on the Enco 918…
It is usual to buy blank backplates and cut the internal thread for the spindle then fit the chuck to the back plate after machining the chuck register on it..
I’ve bought backplates for my Chester 9 x 20 from Chester machine tools…