cutting simple parts on lathe

Cydrome Leader fired this volley in news:kiq0ns $8vj$ snipped-for-privacy@reader2.panix.com:

From this, can we assume that the spindle bore in the Sherline is too small to pass the 1/2" material through?

If the bore is large enough, you'd be better off setting up a feed stop you can swing out of the way when machining, and only have as much overhang from the chuck as necessary to turn and part the work. Then loosen the chuck, feed more out to the stop, and re-tighten.

If you didn't want to build a feed stop, you could still make a small gauge that would allow you to measure the stickout from the chuck -- or you could just eyeball it, if that's what you're doing now.

LLoyd

Lloyd

the spindle bore is too small. It's something like 3/8".

Is there a sensible way to make a carriage stop for a sherline? It's pretty easy to overshoot a cut and you can't undo that. Since mine is fed by hand, I guess I'd feel the carriage slamming into metal block or something clamped on the ways, but it just doesn't seem like it would be all that accurate.

Assuming the rod would fit though the spindle, I'd probably use the toolpost as a depth stop of sorts. For right now, I'm just working towards the chuck. I've been touching the cutting tool to the end of the rod with a piece of aluminum foil as a feeler, resetting the DRO to 0 and working from there. Since the the side that gets faced off has to be cut again and again by eye until it's smooth, that then becomes 0 again and I face the

0.200" diameter part off at exactly 0.375". Changing the reference point for measurements seem wrong to me, but I can't think of a better way to do this.

Is the rest of the process I'm using sensible though?

Instead of doing a lot of cuts with a long rod, I'd start by making about-the-right-length cylinders (maybe just with a hacksaw), and holding them in a collet or (even better) soft jaws in a 3-jaw chuck. Finish one end square, so that when you reverse it in the soft jaws, the soft jaws can act as the stop for a second operation that makes the 3/8" nub and cuts to length.

The result would be a batch of parts, going from a rod, to rough cylinders, to one-end-flat cylinders, to one-end-flat/one-end-stepped finished length parts.

I've not found any. Nobody seems interested in teaching any skills that involve using your hands these days. It's pretty sad.

about-the-right-length

I though about chopping the parts up first, but there's no way to grab them. The 0.500" side of things will be less than 1/8" deep- not enough to securely clamp in the chuck and turn the other end down with. If I leave the rough end of the rod longer, I end up with about 50% scrap cut offs.

If I had or got a 1/2" collet, what would be the maximum "overhang" ratio for clamped to unclamped material?

How would you cut the stepped part, by hand if you had to?

Cydrome Leader fired this volley in news:kiqamj $bhj$ snipped-for-privacy@reader2.panix.com:

It works; it's not the best.

If you can afford to waste a little stock, you'll get better work by parting it up into lengths you can manage in the chuck, and working with little overhang.

If you can't pass it through the headstock, then cut it into lengths long enough to make two pieces (plus the amount to part them and finish off the 'cap' part).

Chuck, turn on end to the .2" dimension. Then flip it around and cut the other end to .2". Finally, part, finish one, re-chuck the other and finish it.

Even though it's more steps, you'll get better finishes with less chatter.

LLoyd

Cydrome Leader fired this volley in news:kiqet6$fpd$ snipped-for-privacy@reader2.panix.com:

See my post about cutting them into "two-part lengths".

Lloyd

about-the-right-length

Less than one would think; holding a tack by the head while cutting to make the pointy part... would work. Soft jaws in 3-jaw chuck is best. Hard collets, not so grabby (but you can get soft collets to custom-bore for this kind of task).

A live center in the tailstock can keep the work bottomed in a chuck while you do the cut in conventional fashion. Many chucks (and collets) can be fitted with a stop so the work bottoms at a repeatable depth.

I've actually done this kind of work with a file, chucking half inch rod in a drill press. Not recommended, but it DID work.

whit3rd fired this volley in news: snipped-for-privacy@googlegroups.com:

It's just not necessary! Turn two parts on one piece. You'll have the .2"o.d. 'stub' to chuck on while turning the second stub.

Like the sign says, "THIMK!"

Lloyd

An alternative is turning parts on both ends of the full-length stock, so you have to reset the steady rest half as often. jsw

Use a follower rest and you won't have to reset it at all.

Super.

I'll try this. The first parts didn't work anyways for other reasons, so it's time for try 2.