How to remove operating screws from 4J?

T

tmenyc

H-M Supporter - Gold Member
H-M Supporter Gold Member
Joined
Oct 18, 2018
Messages
465
I'm cleaning out my 6" 4-jaw chuck; it came with my lathe and I've never used it before. Got the whole thing disassembled and cleaned up, but now see that I really need to get the operating screws out and clean them and around them as well, also to get grease in there. Are the parts on either side of each screw's center area wedges? How are they removed? I've watched every video I can find but either they don't show this step or those chucks don't have them.

4j.jpeg
Many thanks,
Tim
 
Removing the backing plate should give you access to the retention keys for the screws.
 
RJ, thanks...but I don't see what I'm missing! Here's the underside, backing plate removed, already cleaned. I don't see anything else that can be removed. Do the four circles, which are flush and without access from the topside, come out somehow? There is no brand or model identification on the chuck.
4j back.jpeg
Tim
 
I had never had my backing plate off. The four plugs have two fingers which seat along the sides of the keyway in the screw. Use a small drift from the front of the chuck to alternately tap the fingers, driving the plug back. Once they are clear of the screw, the screw will slide out. The plug can then be driven completely out. The plug on mine is a light interference fit.
 
Thanks, I'll give it a try this afternoon.
Tim
 
When you reinstall the plugs, try to align them as best you can and seat them so they are just shy of touching the screw threads. Insert the screw in its proper position ad tap the plugs in. If you fully seat the plug so that the bottom of the slot hits the screw recess and then tap it a few times, it should correct any slight misalignment. At that point, it will probably be difficult to turn the screw. Tap the fingers alternately a few times to back the plug out slightly and the screw should turn freely again.
 
I decided, life being short, that this was the point to not fix what's not broken. But I definitely do now understand how they're in there. Thanks!
 
I’d just use some brake cleaner and call it good once it runs clear from the slot.

John
 
tmenyc said:
I'm cleaning out my 6" 4-jaw chuck; it came with my lathe and I've never used it before. Got the whole thing disassembled and cleaned up, but now see that I really need to get the operating screws out and clean them and around them as well, also to get grease in there. Are the parts on either side of each screw's center area wedges? How are they removed? I've watched every video I can find but either they don't show this step or those chucks don't have them.
Click to expand...
Generally speaking, you don't want grease anywhere in a chuck because chips stick to it like glue. The screws don't need much lube, so a drop of machine oil is usually more than enough.
 
You must log in or register to reply here.
Back
Top