lathe operation question

lathe operation question time.

I have a very small lathe (sherline, 17" bed)

I need to turn some "longer" items in it between centers. What are some suggested methods to actually locate the center of the rods and then support them correctly to center drill the ends?

The far end can be supported with a steady rest, but if it's not perfectly centered, even trying to center drill it will result in more of a donut shaped groove than a hole.

geometrically locating the center of the stock and centerpunching it, then lining it up with a livecenter and trying to setup the steady rest doesn't work in the item isn't perfectly round, and lots of plastics aren't. If the were, then just replacing the live center with a center drill would work as the next step.

So what are the normal procedures for this?

Reply to
Cydrome Leader
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First, set your steady rest rollers near the chuck, off of a short piece of the same size raw stock, and then move over it to the right side and lock it down.

Another way is to attach an indicator onto the right end of the part and then indicate your live center with it, adjusting the steady rest rollers as needed till you are centered reasonably close.

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So if I understand, the real problem is that the piece is not round to start which makes locating a center hole and using a steady rest difficult. In that case I would not drill the center hole on the lathe. I would use an hermaphrodite caliper and scribe the position of the center on the end as well as possible (for example if the rod is oval find the width along both axes, and make the scribe for each direction with different caliper settings). Then punch and drill on a drill press or by hand.

As for supporting the long piece, you might need to use a traveling rest. Start cutting at either end where it is well supported, then once you have some length of round surface, you install the travelling rest on that portion and it will continue to support the round surface that the tool has just cut as the tool progresses. Obviously you have to readjust things if you have steps in your cut.

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The hermaphrodite caliper method can center a section of rough tree branch to whatever accuracy you have the patience for. A cheap pencil compass works well too. The center is where the compass draws the largest possible continuous circle without going off the edge.

PM's suggestion works well if the stock is round, but not for an almond or egg section plastic extrusion (or water pipe).


Reply to
Jim Wilkins

Using some scrap material, you could make a small cap that fits over the end of the rod. Center drill the cap and use your cap as a centering guide.

Reply to
Denis G.

I would never try to center PUNCH it. I would simply have the end near the chuck jaws for a good center and use a center drill to slowly at first drill a center hole. If needed, peck drill the center.

Mart> lathe operation question time.

Reply to
Martin Eastburn


But this only works if the part diameter is smaller then the spindle through-hole.

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"PrecisionmachinisT" wrote in news:RYadnWdfGo20hZfNnZ2dnUVZ

And that through-hole isn't very large on the OP's Sherline, only about 7/16" IIRC.

Reply to
Doug Miller

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