While this properly belongs in rec.crafts.metalworking, I am cross-posting to alt.machines.cnc as that is one of the most knowledgeable groups on the web as their contributors have an extensive traditional machining backgrounds in addition to cnc.
Info needed
Background:
I am hosting more than teaching a community college class in basic manual machining to a small group of very dedicated and enthusiastic students. This class is stressing traditional machining techniques emphasizing ingenuity rather than attachments. While I do have one student that is taking the class from a hobby or home shop standpoint, the others are looking to change careers (gun-smithing) or are involved in maintenance, generally involving obsolescent equipment for which parts are no longer available or available only with unacceptably long lead times.
In an end of semester discussion about what topics were of interest for the spring session, production of one-off gears came up. I have made a few simple spur gears using a dividing head and an involute gear cutter on a Van Dorne horizontal milling machine with both the cutter and gear blank on arbors.
The class has available two V-10 Emco lathes, one of which has the vertical milling attachment.
Lather by Tubal Cain and Gears and Gear Cutting by I. Law (Work Shop Practice series) [see
However we do lack a way to index the gear blank.
Money is very tight and we need to stay under the Administration's (financial) radar.
It appears the least expensive alternative (other than a one-time ebay buy) is the Cen-Tec 6 inch rotary table with indexing from Harbor Freight [see
(1) If anyone has one of these units, what are the hole patterns on the index plate.
(2) What has your experience been with this unit?
(3) Can you do compound indexing with this unit? I came across this in an old edition of the Machinery's handbook. In addition to turning the crank/worm so many holes, you also turn the index disk so many holes on another ring of holes in either the same or the opposite direction. This gives the same effect as differential screw threads. Effectively you multiply the number of holes in each of the two patterns you are using.
(4) Has anyone done gear cutting with one of these units using a flycutter? For the class project we will be cutting additional Emco V10 change gears (M1 module) from 1/2 inch thick 6061 T6 aluminum plate. Thanks for any hints, advice, etc. anyone may care to contribute.