Dismantling Burnerd 3 jaw chuck

[ettingtonliam]

Having had reason to remove my elderly 4" Burnerd 3 jaw from its backplate, I thought this would be a good opportunity to clean and lubricate the internal mechanism. I am faced with an outer circle of 3 slot headed screws, and an inner circle of 3 small allen cap screws.
How do I procede from here?

[uuu]

It's worth watching a video. Here's one: YouTube

In his example, he has three screws holding on the backplate - after that, the outer three are long screws that retain the three pinions, which drop out of their holes once the screws are free. Then the inner screws allow the back inner to come out (this can be reluctant), followed by the scroll.

Wilf

[ettingtonliam]

Thank you. That tells me exactly what I needed to know, although I don't admire his techniques with the hammer when dismantling (didn't look like a copper hammer to me), and I prefer not to have my fingers in close proximity to a revolving wire brush!

[ettingtonliam]

I have to report that it came apart beautifully, just a little rapping around the edges with a rawhide hammer was enough to bring things apart. It was very clean inside, but quite dry, no signs of hardened grease at least. When I put it back together again, after I've washed it in white spirit, I'm thinking of using spray on motorcycle chain grease, for its no-fling properties.

[uuu]

I think Burnerd are fans of molybdenem disulphide grease. If I remember right.

Wilf

[jon38r80]

Trouble with grease is all the bits of metal from machining just sticks to it , I've read that light oil or graphite is supposed to be better from that point of view so the little metal bits dont gum up the works.

[ettingtonliam]

Much to my surprise, when I opened it up, there was no metal debris in that central cavity at all!

[jon38r80]

No grease and no debris

[ettingtonliam]

Well, rightly or wrongly I've taken Wilfs advice and re-assembled it using Molybdenum Disulphide grease. It operates very smoothly now. Now I know how to take it apart, it isn't a big deal if I do it again in a couple of years.

[steamer5]

Hi Richard,
These guys recommend grease….. www.worldwidechuck.com/chuck_grease.htm. There’s of course but grease never the less.

I looked at getting my Emco 3 Jaw serviced by them, they tried to get the specs from Emco, no go, so I gave up…shipping to the States & back to NZ wasn’t going to be cheep, then the fix on top. Ended up getting a new Chuck from the UK…at least it was only one shipping feee.

Cheers Kerrin

[simplyloco]

Nov 18, 2021 9:56:44 GMT steamer5 said:

Hi Richard,
These guys recommend grease….. www.worldwidechuck.com/chuck_grease.htm. There’s of course but grease never the less.

I looked at getting my Emco 3 Jaw serviced by them, they tried to get the specs from Emco, no go, so I gave up…shipping to the States & back to NZ wasn’t going to be cheep, then the fix on top. Ended up getting a new Chuck from the UK…at least it was only one shipping feee.

Cheers Kerrin

I was advised by my old school military instructors never to put lubricant anywhere near a lathe chuck. I have kept to this maxim for nearly 60 years, and my chucks run true and they don't jam up!
Just keep them clean folks...

[ettingtonliam]

Well, I wouldn't put any on the scroll or the jaws, just keep them clean, or possibly a powdering of dry graphite from time to time, but the inner cavity showed no signs of fluid or particle ingress, so I used some lithium/molybdenum disulphide that I had in there. If moly is alleged to cause staining, it won't matter in there will it?

The OM (Pratt Burnerd) provided a little spring loaded ball oiler on the face of the body, going through into the cavity, so they obviously intended some lubrication in there. What lubricant they used on assembly in the factory, I have no idea. This chuck is so old it was probably rendered down mammoth fat.

[uuu]

Here's a copy of the Pratt Burnerd catalogue:

Burnerd by Wilf, on Flickr

I also have a "Bison" chick, with one of those sprung-ball oilers. It's instructions advise to use grease of "penetration number 250" on disassembly, then "viscosity 10-3m-2sec 10St. via the grease nipple".

Wilf

[ettingtonliam]

Nov 18, 2021 17:26:05 GMT uuu said:

I also have a "Bison" chick, with one of those sprung-ball oilers. It's instructions advise to use grease of "penetration number 250" on disassembly, then "viscosity 10-3m-2sec 10St. via the grease nipple".

Wilf

Thanks Wilf
What those grease specifications mean, I have no idea! Interesting that they fit a spring ball oiler and then tell you to apply grease through the grease nipple!

Anyway, its done now, Lithium/Molybdenum Disulphide grease.

[JonL]

Aside from the swarf issue, I wonder whether a lubricated chuck has greater or lesser grip that one than has been kept free of lubrication? Assuming on both that the contact area between jaws and workpiece remains dry.

[ettingtonliam]

Well, the Pratt Burnerd catalogue Wilf shows above claims dramatically improved chuck jaw forces if you use their special grease, presumably because they believe that it reduces internal friction.