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WhizzbangK.C
02-12-2004, 06:20 AM
Does anyone have any plans or know of any for a thin (short) rotary table? One of the things I need to be able to do with my machine will require a rotary table of about 10" diameter. I see quite a few of them on ebay and other places on the web, but it seems that most in this size range are made to also serve as dividing heads mounted vertically on the table. While I can see the benefit of having one accessory do two things, in this case I need all the headspace above the rotary table that I can get, so the shorter the better. From what I can see it looks like the 10" tables are all taller than the 20" and above that are made to just mount flat. I have no problem with trying to make one, even designing my own is not out of the question, but I'd sure like to see some examples to get some ideas as to the best way to keep it thin but still rigid and true.
One idea that has occurred to me is to make the base and table in one unit and chain drive it from a reduction unit also mounted to the table. Proper choice of sprockets and gear reduction shouldn't be much of a problem, and I could avoid having to fabricate a worm drive and integrating it into the same base as the table. (I don't have the neccessary experience or skill to pull that off just yet http://bbs.homeshopmachinist.net//frown.gif .) It also seems to me that it would be easier to keep it short this way. I know I'd have to shroud the chain to keep chips out, but that shouldn't be a deal breaker either.

John Stevenson
02-12-2004, 08:35 AM
Dear Mr Whizzbang.
Not a lot of use to you as a kit but a firm in the UK called Model Enginering Services used to do a kit for a rotaty table that was designed for low profile.
I believe they have stopped doing these in light of the cheap imports but when they first came out there were no cheap imports.
perhaps a description may help.
Two major parts, base and table, the rotary movement was done with a standard gear wheel and a length of worm that meshed with this. The wheel screw to the underside of the table and because of the helix angle of the worm that pointed down at the same angle.
Disadvantage was it had to overhang the table for clearance on the handwheel but the advantage was it made the handwheel lower than the table top.
The underside of the table was machined at about 30 degrees and the base was done the same. This was the top bearing and was cast iron on cast iron, a good bearing medium and because of the large surface area it was well supported, the bottom bearing was a top hatted bronze bush that engaged in a spigot on the bottom of the table.
Adjustment of the table was by shims under a thrust that ran on the top of the top hatted bush.
Adjustment of the worm was by an eccentric bush that the worm ran in.
These were very good for their day and very useful being low profile.
Here's a quick and dirty sketch to show what I mean.
http://homepage.ntlworld.com/stevenson.engineers/lsteve/files/rotary.jpg

John S.



[This message has been edited by John Stevenson (edited 02-12-2004).]

Thrud
02-13-2004, 04:40 AM
Bison makes the shortest, least expensive H/V table that fits your parameters - it ain't cheap, but it is a damn fine table. KBC sells them as do other distributors.