Cylinder restoration- brazing?

Sleeve it. It's much easier.

There used to be someone here who ran a specialty service business, sleeving brake cylinders. Maybe he's still around.

Is there enough wall thickness to bore it out for a sleeve? any little dimple in the repaired section will be a leak...not to say it can't be done that way, just seems an extra path to failure.

bill

Sleeving appears to be the way it's done.

-- Live in the sunshine, swim the sea, drink the wild air... -- Ralph Waldo Emerson

Use a brass or bronze sleeve. Common restoration process for old cars. Or find a replacement, if it's a common part.

Stan

My brazing would take a lot of cleaning up.

If you can get a bearing ball that is big enough, you might try ball sizing to get a smooth polished id on a sleeve.

Dan

Ordinary brake-cylinder hones (which are cheap) will do it, too. I'm not sure you want a polished bore. It would depend on the piston material.

=A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 =A0 Dan

Probably a better choice for just one repair. I had thought once about starting a business of restoring brake cylinders using stainless tubing and using ball sizing to quickly get the id to size and also to change the fit from a sliding fit to a press fit.

Dan

That's an interesting thought, but I'm not up on the practicalities of piston-and-bore mechanics. It appears to me that every general type of application, from IC engines to hydraulic cylinders, has its own dynamics. I was covering honing in a big way around 10 years ago, when Sunnen precipitated a big change in the field by using solid, diamond-impregnated hones to cut away larger volumes of metal and to correct straightness, roundness, and dimensions at the same time. It's quite a feat and it introduces some tricky issues of piston-fit, because of the way that diamond hones tear the metal surface.

Stainless as a bearing surface is another tricky issue. You get great corrosion resistance with the higher grades in the 300 Series, but they make terrible bearings, with a strong tendency to gall. It looks like brass and bronze are the most practical materials for that job.

Interesting you mention that as a mate that works at Ricardo mentioned when we were down the pub recently about honing technologies and how the current processes can improve the roundness of the bores from around 10 microns as bored to 5 microns after honing. Then there was mention of fast helical honing?, maybe I misheard, and laser honing which is not in production use as far as he knows yet but is potentially up and coming.

I don't know about laser honing. I'm a few years out of touch.

Yes, the newer honing technology doesn't allow the hone to follow the existing walls of the hole. With diamond abrasive and a hard, unyielding hone body, it makes its own hole shape. And it can cut quite a bit of material. In smaller holes, they can do a lot better than 5 microns (0.0002"). One micron is more like it.

As for helical honing, Sunnen makes production hones that are helical in shape, and they're fast. They clear swarf like a twist drill. That may be what he was talking about.

I was assuming, perhaps wrongly, that this was a bore for brakes and the material touching the stainless would be the rubber cups, not another metal. Or if there was metal to metal contact, there would be almost no pressure.

Dan

Frankly, I no longer remember what it was for.

Stainless works fine as a bearing surface against many materials. Austenitic (300 Series) stainless is not good against steel. I'd have to dig up some old books to see how it does against other metals.

Hardened stainless -- 400 Series or precipitation hardening -- is another matter. It has little tendency to gall and it runs well against other hard steels.

just send it to White Post Restorations - they do this for a living

We used to make SS stell pumps and used Waukesha 88 as a rotor this was fit in a honed hole with a few tenths clearence and worked perfect. This matertal can only be purchase from the Waukesha Foundry if I remeber correctly.

db

lol, I should use spell check

db

Aha. A "nickel-based alloy with anti-galling properties." That would explain why it makes a decent bearing surface.

Regular austenitic stainless galls easily.

It's an interesting material. Apparently the bismuth prevents galling. You may find this short piece from _Design News_ interesting:

Thats what we were using it for 25 years ago. We manufactured vertical form-fill and seal machines and used this material because it was easy to remove after use for sanitation. Of course it was the only material that would work with that tight of clearance.

Regards db