What are these tapers used for?

Yes!

Harold

Next question, Harold. Is there a reason for mandrels to be B&S tapers? How are they best utilized? My guess is OD work on short pieces, turned between centers, but that's just a guess since I don't yet know much about these.

Thanks again,

-Bruno

Aside from using them when I ran precision grinders, I've never had much need for them, so I don't have much experience with them. In this case, I'm of the opinion that they are a specific taper so they can be used successfully in holding a like taper. Mandrels I used were a specific size, with gentle taper, say a couple thou, end to end. That's a necessity if you expect the part that's mounted to go on square. Could be someone with more experience in that area can add something of substance.

Your assessment of how they're used is pretty close to how it's done. An arbor press is generally used to press the mandrel in the work piece if it's to be turned or otherwise machined.

Grinding usually demands that parts are installed stress free-----so they're usually just wrung on by hand. The pressures in grinding are well reduced as compared to machining, so that's adequate to drive the part.

Harold

Those mandrels may have been made by B&S, but they are emphatically not B&S tapers. Much too gentle for that. I've never seen a B&S #5 or #6 taper, but based on the common #7 & #9, a B&S #5 or 6 taper would be very small. #7 is somewhat smaller than MT2 and #9 somewhat bigger than MT3. However, without measuring, it is easy to confuse them with B&S tapers. The most likely reason that B&S sold a set of tapered mandrels is that B&S tapers are quite common on precision grinders. In fact, other than on my old Burke mill and others like it, about the only place you see B&S tooling these days is on precision grinders. Harold explains the use of such mandrels on his subsequent post.

I measured them and they actually do conform to the spec for B&S 5 and 6 tapers, and being extended further at the larger end.

They appeared with a small 6" lathe I bought a few years ago and have just been sitting in a drawer. I was trying to figure out if I'll ever have a need for them. Sounds doubtful.

Thanks Harold and Boris.

-Bruno

Unfortunately you have only part the setup. These mandrels were meant to be used with expansion bushings to hold cylindrically bored objects for further machining.

Scanned to the dropbox:

Thanks, Tom. Now that makes sense of these things!

-Bruno

Back in the days before photo reproduction---the artists could really draw explanatory drawings---sometimes better than a photograph because of the shading that could be done w/o use of exotic lighting effects.!!