rotary table size

After the great ideas about boring big holes with my mini-mill, I have decided to purchase a rotary table, as I hope this project will lead to
doing many more of the parts. Harbor Freight now lists a 3" and a 4" rotary table. I am sure the 6" is to big for my mini-mill, but would there be any disadvantages to using the 3"? I think I will order the 4" but wanted to hear the flames from fellow chipmakers.
Thanks, Rod
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I have an old tilting rotary table that has a chuck and through hole that allow me to mill the extractor relief cut on barrel breeches. One problem is that when tilted straight up, the chuck and table are so tall, that I can't get it under the quill of my little Rockwell knee mill..
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Buy the largest rotary table that your machine will accommodate. Mounting items on the table is always a problem, so the larger the surface, the better chance you'll have of having a place for hold down clamps. That rule applies even to larger machines. By the time you get up to 12" tables, they become a real problem to handle. At that point, you might consider buying the largest one that you are comfortable in handling. a 15" Bridgeport table is likely more than many can handle without equipment.
Harold
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My rotary table weighs ~100 pounds and the chuck is and 8" Buckchuck.. I take off the vice to move it about the shop.
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I bought a very nice horizontal/vertical table made by Phase II. Excellent buy -- but... It was closer to 6.75" than to 6", weighed a ton. And when used on either of my small mills (Burke #2 horizontal with a 4x20 table and Centec 2A horizontal/vertical with a 4 x16 table) there was hardly any room to maneuver .. Excellent table but not practical for the small mills. I sold it to a fellow RCM'r and instead bought the Phase II 4" H/V table with a tailstock. Fits nicely. Not quite all the features of the 6" table, but more than adequate vis-a-vis stiffness and accuracy for a home shopper like me. Get the 4". Some points to consider:
1. You want a horizontal/vertical table. The slightly higher price than for a horizontal-only table is well worth it.
2. Don't buy a rotary table unless you can get a tailstock with it. Having a tailstock opens up all kinds of machining possibilities that are nigh impossible without it.
3. Check out the spindle taper. An MT2 taper is fairly typical for small tables. If you can't find out what the spindle taper is, pass it up.
4. You will probably want to buy a small (e.g., 3") direct mount 3 jaw chuck and also a small direct mount 4 jaw chuck. Get the 4-jaw chuck first. You might pick these up a used machinery place if you're lucky.
5. Lay in a supply of T-nuts, clamps, etc. in the right sizes. A table without the ability to hold things down is useless.
6. Indexing attachments are nice to have, but not on these small tables. I've yet to see one that was worth the price and the bother for the typical one-off and two-off stuff I do. If you can divide 360 by the number of faces you have to make, there's no real problem (just care, time, and arithmetic) getting each successive cut to within less than 1 minute.
I assume you're not thinking in terms of any production stuff, where time and repeatability are important issues -- if you were, you wouldn't be using a mini-mill and looking for anything small than a 6" table.
Boris
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Cook's Used Machinery in southern NJ had a nice tilt rotary table when I was there last week. It looked like a Pratt and Whitney 36" model.
But that may be a bit larger than what you were looking for.
Errol Groff
On Wed, 03 Nov 2004 19:04:09 GMT, Rod Richeson

Errol Groff
Instructor, Machine Tool Department H.H. Ellis Regional Technical School Danielson, CT 06239
860 774 8511 x1811
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Couldn't he mount the mill on it? Opens up all kinds of possibilities.
Steve
Errol Groff wrote:

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On Wed, 03 Nov 2004 19:04:09 GMT, Rod Richeson

The biggest one you can handle and will work on your machine.........I have a 12" and its more than what I can handle without the aide of a lift or hoist..........It always seems even when trying to hold a small item on a large RT, you still do not have sufficient room to hold it. Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wife, I had no input whatsoever. Remove "nospam" from email addy.
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check out lathemasters prices and rotary tables. Its nice to be able to have a tail stock to work with a rt, as well as add plates to it........why buy a HF or other brand thats just a regular old RT. I have seen these tables this company sells and they are decent quality for the money......I am not affiliated with lathemaster at all.
http://www.lathemaster.com/RotaryTables.htm Visit my website: http://www.frugalmachinist.com Opinions expressed are those of my wife, I had no input whatsoever. Remove "nospam" from email addy.
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