Chin Yu 4 jaw chuck

I came across this 10" Taiwanese Chin Yu chuck last week end, it is in excellent condition but I can't find much about the company. Does anyone know of them, were they thought to be ok?

It is a D1-4 mounting and was missing the three pegs so I ordered a set and was surprised to find that they didn't fit! The new pegs are threaded M10x1 the threads in the chuck are M10x1.5, is the coarse thread unusual? I will make some threaded sleeves to change to the fine thread when I get a few minutes.

M10 x 1.5 is definitely not standard. Although originally an American standard the D1 camlock is incorporated into the ISO standard 702-2. This specifies M10 x1 for the stud thread for D1-3.

Interesting, thanks Stuart. I have checked the pins against the ones that came with my D1-4 chucks on the GH1322 and its the same as those so M10x1 is used for D1-4 as well. I've looked at 702-2 and it confirms the pin diameter and length changes between three and four.

Threaded sleeves will reduce the strength somewhat. If you have a mill and rotary table, it would be safer to drill and tap another set of holes for the pins. Another option would be to get M10 x 1 helicoils and a tap and convert the existing holes without loosing any strength.

Threaded sleeves in the chuck body would be satisfactory.

To check how good the chuck is, clamp the jaws tight onto a bar of soft aluminium which has been turned and the witness marks made by the jaws will tell tales.

Edited By old mart on 05/10/2020 15:52:24

Edited By old mart on 05/10/2020 15:57:21

Thanks for your comments old mart, yes I did the bar test the other day and it was fine!

The plan is to fit M16 externally threaded sleeves into the opened up holes in the chuck. I made the sleeves today from EN16 as in the photo. If I get chance tomorrow I'll set the chuck up on the mill and clock the mounting face to as close as I can get to zero and then clock to each of the counterbores that the pins fit to and open the holes out to M16. Fortunately the holes are marginally over 16mm dia to allow the 15.9 dia pins to float so they don't fight the central tapered spigot location. I've ordered some Truloc 360, it has a longer working/setting time than the 638 I have, that should be ok to keep the sleeves in place.

Looks like you got a good one. I have drilled and tapped some 6mm holes in the faces of ours to hold balance weights to help when odd shapes are turned.

Yes, I was thinking back to when I was on the handles and most of the four jaw chucks had set of tappings equally spaced radially between the jaws. Four screws were screwed in tight at the diameter required, the heads were faced off to set the job against, usually used when finishing the second end of a gear wheel or similar to make it parallel. It has to be said most of the chucks were much bigger than 10" though!

I think I might just flip the chuck over and put some M10 holes in for that while I'm at it, they could be used for balance weights as well, bonus!

638 Loctite is primarily a sleeve and bearing fit, you are right not to use it when screwing in those sleeves, as it has a very short cure time. I had to find a product to secure the halves of a milling machine spindle which had a combination of threads and sleeve fit. I chose Loctite 620 which gave me plenty of time to screw the parts together and tighten them. 620 is also a sleeve and bearing fit, but as the joint is never going to be unscrewed, it will be fine.

That made me chuckle, I've used 638 and indeed you don't get many minutes before it sets!

Had an hour or two to drill and tap the holes in the back of the chuck this afternoon, I'm pleased to say it went well and on a trial assembly all looks good. Just waiting for the adhesive now, hopefully that will come tomorrow and I can get this little job finished.

Minutes,you say for 638, I would not use it on anything that would take more than ten seconds to fit together. And even less time if the parts are even a light push fit as I recon even a little localised friction warming the joint can cause tears.

Had the chance to mount the new chuck on the lathe, face runout negligible, tiny bit over 0.01mm on diameter at first set. Happy bunny!