Grinding down chuck jaws?

[TobyB]

Spent a fabulous 3 days with Richard Raffin (what a nice man) at Phil Irons new place (both terrific teachers) ... (this isn't a gloat, honest!) ... learn't a lot, VERY hospitable, but we talked and used chucks, and I could see their idea that VicMarc jaw tops are profiled completely flat without bevels, rounds, etc that provides a powerful and effective hold on tiny, narrow spigots or grooves that I couldn't achieve on the Supernova-Patriot chucks/jaws I have.

Can't afford to sell up my chucks/jaws and replace with VicMarc at the best of times, let alone at the current AU$ exchange.

Wondered if I could skim-down/re-profile the SN-P jaws to get rid of the bevel to make them more like VM? I have a Pro-Edge ... but would I wreck/burn/unbalance the jaws I have? Is this a job for a local engineering workshop? If so, what am I looking/asking for ... and at what sort of price?

 

[jasonB]

Find someone with a surface grinder so that they can take an exact amount off all the jaws, trying to do it by hand won't be accurate.

J

 

[myturn]

I've just returned from the same course (but different days) and it was invaluable, well worth every penny.

I intend to do the same with my chuck jaws and to start with I'm going to try using the wood lathe with the chuck (Patriot) mounted as usual and a flat diamond sharpening plate held on a faceplate in the tailstock.

If that doesn't work then I'll try on my engineering lathe with the Patriot mounted on the Myford headstock and the diamond sharpening plate attached to a vertical slide on the topslide.

If that doesn't work I'll reverse the operation and attach the chuck to the vertical slide and the diamond plate to the headstock.

If that doesn't work I'll get someone with a surface grinder to do it!

 

[myturn]

Well I first tried with the diamond sharpening plate on the ML7 topslide and the Patriot held in the ML7 chuck but the Patriot jaws just wore away the surface of the plate so that didn't work.

So I did what I should have done to start with and used a facing cutter, then cleaned up the edges by hand with some emery cloth.

It worked a treat, I did two sets of jaws and have some more to do but I'm happy that the method works.

I tested the modified jaws on the wood lathe and in in their "perfect-circle" position they will now grip a much shallower recess than before and with more contact area the jaws can be tightened less.

This should work for any chuck jaws that have that undesirable chamfer on the edges.

 

[TobyB]

Hi Mick

This sounds excellent ... doing it yourself, and maybe getting the jaws lined up "in use" rather than free off the chuck sounds good too.

But ... I only have one lathe (a WivaMac, with reasonable grunt if that's important?) ... but I have no experience of engineering metal lathes whatsoever ... and I'm not sure quite what a "facing cutter" is ... googling gives me the idea that it's something like a square-end scraper for wood. I can imagine lining up a diamond plate on a face-plate if I could work out a 2MT mounting for it ... but it sounds like that's not the way to go ..

Is this something I might be able to do myself with the odd extra tool/gadget, or will it be an expensive disaster better managed by taking the chuck(s) and the jaws to someone with a surface grinder who will do it properly for the first time, without the expensive costs of replacing wrecked kit?

Advice gratefully received ...

 

[TobyB]

P.S. : Glad I'm not the only one who got a huge amount out of the course ... it was the teaching of quite subtle technical tips and skills that are difficult to explain in a book or a DVD but can be practiced or demonstrated for real, in combination with the discussions of planning, shaping and the aesthetics of making an "OK" or "acceptable" piece, a good one, or ideally a superb one that I enjoyed. I like his books and his work. Meeting him in the flesh and seeing how he works reinforced this. An artist and a craftsman! I'd be reasonably content (alright, REALLY HAPPY) as being one or the other, to be both? !!!

Not claiming any brilliance, but I learned that a lot of very minor changes in the angles you grind and hold your tools are enormously significant ... very small changes produce "scraper" sawdust or long long long "gouge cutting" peelings ... practice!

Phil's hospitality and additional input terrific too. Well worth the trip ... and good food, Billy's company, "what a nice place", plums of the trees in the garden ...

Good few days ...

 

[myturn]

Hi Toby,

Like you, one of the most valuable things I learnt was the shapes to grind my tools to get the best out of them. Richard does it all by eye and hand, no jigs, and I am experimenting with my Tru-Grind jig to replicate as closely as possible the profiles he put on my gouges. When he sharpens a tool it might not look pretty but it sure does the job!

What I found amazing was when I was standing at the lathe struggling to shape something and he'd come over and put one hand on the end of the handle and guide it round perfectly, I guess that's 40+ years of exprience for you.

As regards the chuck jaws, if you know anyone with an engineering lathe they would be able to do it for you, it's just a matter of running the cutter across the face of the jaws a few times.

I wouldn't try on the wood lathe, it needs an accurate and controllable cross-slide to hold the cutter properly, and a carbide cutter. Surface grinding would be the alternative but a facing cut on an engineering lathe is prefectly adequate for this purpose.

cheers

Mick