Sifbronze or silver solder?

I had a Jacobs chuck which had the outer sleeve cracked from top to bottom . Hence it would not fully tighten. I was lucky enough to be given a replacement from another damaged chuck. So all is now fine.

As a matter of interest, In wondered if the split outer sleeve could be repaired. I don't want to braze into the gap, as this may well be enough increase in the sleeve diameter to render the sleeve useless. When you try to finally tighten the chuck, I could barely see the gap open.

The outer sleeve is castellated and the crack is in one corner of a castellation. I propose to clamp the sleeve tightly to eliminate the gap and to braze a fillet over the offending crack. My query is Sifbronze or silver solder for the fillet? I suspect a sifbronze fillet would be stronger, but either may well be a strong enough repair.

I am just curious to see if the job can be done as I have already replaced the cracked sleeve .

Regards,

Andrew.

If you are going to squeeze the sleeve tightly together how is silver solder going to flow into the gap? All you will do is melt silver solder over the top of the crack.

The heat may well destroy the fit of the sleeve, but I would use sifbronze. Better fillet but you will need the right flux.Noel.

Hello Baz

Quite correct, I do NOT want silver solder in the crack! I want to make a fillet over the crack in the corner of the castellation, where the crack is. If you reread my post I am bothered that putting a few thou on the diameter of the sleeve (by putting braze in the crack) will make the sleeve diameter too large and it won't be able to finally tighten. When trying to tighten the chuck with the split, you could barely see the crack opening , so only a very few thou increase in sleeve dimension renders the chuck useless.

So to be clear. I do NOT want braze in the crack!

Andrew.

Many years ago now, but I have used drills with such cracks "repaired" by putting a jubilee clip around them. It worked well.

Shrink a sleeve over it. Or even loctite.

Is the sleeve of a Jacobs chuck not somewhat heat-treated? Will bringing it up to brazing temperature have some effect on that?

The shrink fit sleeve is a good idea. Even something (that ends up) 1mm thick would develop enough squeeze to stop the crack opening up.

If the chuck has ribbed outer sleeve, turn the ribs off first and recreate them on the new sleeve. The finished item would look like an original that has had a couple of extra mince pies.

I would be wary of loctite only on the basis that a layer of it might be a lot 'springier' than steel to steel contact.

.

Probably only a little [if any] springier, methinks … bear in mind that it is relatively easy to shear [say] an M8 bolt that has been retained with 638

MichaelG.

The use of a jubilee clip or better still a sleeve sounds a much better idea. I am sure using Sifbronze on the sleeve (I do have Siff bronze flux) may well alter the hardness of the sleeve or distort it, but it really is an academic exercise and if I ruin the sleeve then nothing is lost!

A word about why the sleeve cracked. I needed to get the 1 MT taper out of the chuck and replace it with a 2MT taper. I followed Tubal Cain's instructions, these are to be found in his book on Drills and tapping. He recommends drilling and taping the inside of the chuck and using a bolt to force out the recalcitrant taper. He also goes on to explain how to dismantle a Jacobs chuck. As mine was a bit notchy in action I decided to take it apart with a view to cleaning and lubricating it. Following his words and music, I finished up with a cracked sleeve !!!

So if anyone else follows Tom Walshaw's advice, beware you could finish up with a cracked sleeve! He didn't mention this possibility!

Thanks everyone!

Andrew.

Would the worm drive part of the jubilee clip present a hazard when spinning around? One wrong move near the chuck before it has come to a complete halt would hurt. Even grasping it wrongly when stationary could be painful.

In addition, you would need to hide it when anyone came to your workshop, in shame at its ugliness.

Machine up a shrink fit sleeve would seem the best bet ? Noel.

I think what Andrew using a donor chuck is not just the best solution, but the only one worth even considering.

Andrew,

I once saw an overnight engineer's "repair" of a big multipoint socket used for tightening nuts on a silage harvester that had split open end to end. Being a farming job, it was being used on an extended bar with pipe added for leverage. An outer thin walled sleeve had been shrunk or forced on, I can't be sure which, and the job was back and running again in the field the following morning.

It was used in this condition for many years afterwards. On the strength of that I would go ahead.

Regards Brian

The jubilee clip I mentioned earlier was also in a farm workshop. It had been like that for years. I have often been amazed at the length of time farm bodges last.
Also I can remember from my youth swinging from a 12ft scaffold bar on a pair of stilsons before I could persuade a coupling on a 2" pipe to undo.