I want to make a simple indexing head for my lathe (as per multi-start threading, for example, just with more divisions by far).
I'm told the hobby shop on campus has an indexing mill head, but I haven't seen it yet. I want to double-check: is it likely that it will be capable of drilling divisions of 80, 84, 100, 112, 144, 192, and 360? If not, are there places that can do this, and hopefully not more expensive than $100? I need all of those holes drilled (1072 in all), 1/8" diameter, 1/4" deep through the side of a cylinder with that wall thickness.
84, 112, 192 don't work with my dividing head. Maybe they can do differential dividing. But you can do the dividing by the scales and get lost when you don't print out the numbers needed. Anyhow, it will be a pain.
For multi-start threading, you don't need indexing at all.
You might consider subbing this one out to a cnc shop. It would probably cost less than you could make in the time it would take you to manually index all those holes.
As a point of reference, it took me better than a full work day to manually index 360 divisions on a protractor head that I was told to make. Got a blister from cranking, too.
I figure it would take a competent operator about ten minutes to program it and probably well under 10 seconds a hole to run it.
Any CNC on campus? That would be the ideal situation, if you could get it done for free or cheap.
I would not expect any difficulties in the numbers you are using, just the mind numbing hours it'll take to drill them all.
As all of your divisions are an even number, it is highly likely you will be able to get these using the dividing head, making the
*BIG* assumption that the required indexing plates [generally three] are available.
Use of dividing/indexing heads is not extensively covered in the newer machining courses. (p196-222) Moltrecht, K.H., "Machine shop Practice - Vol II" Industrial Press:NYNY ISBN 0-8311-1132-1 has a good section.
Multiple start threads are even less documented. You will need to get some of the older publications. Milne, Lours J., p130-132 Machine Shop Methods" Lindsay Reprint ISBN 0-917914-223-7 has some information as does Smith, Robert H. p5-31/5-33 "Advanced Machine Work" Lindsay reprint ISBN 0-917914-23-6. Both pubs show line drawings of special face plates.
You will need not only the dividing head but also some way to hold what I assume is a piece of large diameter tubing or pipe. Most likely this will be an arbor with a MT or BS taper to match the dividing head, a tail stock of some type to support the other end of the arbor, and 2 "cats' heads" to center/retain the tube on the arbor. This will be a major project in itself, and set-up will be time consuming. Be sure you don't drill into the "cats' head" screws and that there is adequate space for the [internal] clamps at each end of the arbor. If necessary, you may have drill the pipe and then machine off the extra material.
An alternative is to fabricate a plate to mount to the dividing head, to which in turn you can mount the tubing.
The required space should also be verified. If 1/8 inch diameter holes with 1/8 between holes is assumed, this is 360*(1/8 + 1/8) or 90 lineal inches. Whether the holes are drilled radially or axially, this is a diameter of slightly over 28_1/2 inches.
This requires considerable head-room and large risers for the dividing head, and is at, if not beyond, the limits of the typical Bridgeport mill.
This is an ideal job for a 4 axis cnc machine with rotary table. From your email address, you should be able to get a government job or two done in the cnc labs.
What are you planning on machining?
Good luck on your projects, whatevery they may be.
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