Holding work on a rotary table

[franco]

DanRwork,

If your rotary table is a 6" H/V Vertex or similar, make a 2MT with a threaded parallel extension on the large end with a diameter to suit your clamp. Drill the small end for a draw bolt - I use 8 mm, but 5/16 would be OK. Make a stepped washer with a hole to suit the drawbolt and the step diameter to locate it central in the bottom of the table socket.

The threaded extension can then be used to clamp the work to the table with no damage to the table or socket.

franco.

[DanRwork]

I have a small rotary table and want to cut a ring clamp to put on the non-rotating part of my quill.

Thanks to the many posters, I am able to center the rotary table, but am stymied on holding the work. The table is only a six inch table, and the work is started from a slice of 4 1/2 diameter aluminum round bar.

I have an inner diameter of 2.82" and an outer diameter of 3.94". There isn't a lot of space to grab. I put some 3/8 - 16 bolts with washers into the four T-slot nuts, but I can't use clamps and stand them off with step blocks since the balancing block would have to be off the rotary table, and that would prevent rotating the table.

It would also appear that I am going to need to hold this in two parts. Anything holding from the center (and I could put a bolt through the center but have a #2? Morse taper and very little space on the backside of the table to put a nut) would be worthless the minute I completed the inner circle cut. Anything held from the outside would be toast when I did the outside circle.

Can anybody suggest a solution here? I am sure there must be something logical, but I lack experience to find it.

If I only had a bigger rotary table....



[This message has been edited by DanRwork (edited 03-03-2006).]

[tattoomike68]

A chuck mounted on the table is always handy, the time spent to build a mount will pay off.

I have a chuckable face plate that I use in the lathe, it is a 1" plate circle with 100+ holes drilled and taped in it, and item like that could be mounted to the table to give you more room. A sub plate fixture is what I guess you would call it.

[goatherd]

I would suggest getting a nice piece of aluminium plate 3/4 inch minimum and about 12 X 12 inch square. Drill it and bolt it to your rotab and drill and tap for your stud set being carefull not to go into your table face. find you aproximate center and rotory mill a small hole to indicate your center from. resist the temptation to drill a lot of holes to start as they may get in the way of later setups. Sometimes you can drill and ream slipfit for pins for locating parts.Think this out in advance as you do not want your handles interfereing with the plate.

[doug931]

Sounds like your proposed ring is about an inch thick. Drill doles in it to match up wih the table slot. Counterink if necessary. Doug

[torker]

Dan, I made a fixture similar to the one Mike speaks of. It is a 1 1/2" thick round plate with three steps turned in it.
It has a MT2 center dropping out the bottom to make it easy to install.
It's held to the table with four small clamps and narrow T-nuts.
The steps are common sizes...3", 2/12", and 2".
I also made three different height caps that bolt on the top of this to hold things down on the fixture.
I'm assuming you don't have a lathe?
Russ

[Forrest Addy]

Sometimes you have to mske stuff in order to get other stuff made.

Make a 1/2" thick clamp ring big enough to cover the table with a bore that will clear the ID of your work. Drill bolt holes to clear the work and will catch the T slots.

With any luck 30 years from now you will have another job you can use this clamp ring.

By the way, what are you holding with this aluminum ring? Remember it's aluminum and if the quill you install it on warms up, the aluminum ring will thermally expand at double the rate of the steel or cast iron quill and may loosen.

[This message has been edited by Forrest Addy (edited 03-03-2006).]

[Evan]

Sounds like a job for a lathe. Cut the inside ID, finish the outside and part it off.

[HWooldridge]

I seem to recall Guy Lautard had a kink in one of his books about using a plate holding fixture for a similar problem. Get a piece of plate a little larger than your rotab then drill and tap holes all over it using 1" spacing. This bolts to the rotab and finger clamps are used to hold the piece to the plate. A series of four clamps which do not overlap the inside diameter will allow the inner machining. After you are satisfied with the first operation, remove two clamps and apply them from the inside so as not to disturb the setup. Add the other two clamps if there is room or just use two. You could also make a "+" piece to anchor it but make sure the part is initially centered on a threaded hole. The outside machining can now be completed.

[DanRwork]

I spent a bit of the day making a plate to extend the table, but I only had about an 8"x8" x 1" piece of aluminum to do it with. I started this after I read tattoomike68's response.

I mounted it in a Kurt vise extended for all it was worth, and centered it using an edge finder and the centerline button on the Acu-Rite 200M on the Hardinge Bridgeport.

I put in three rings of a 4 hole pattern drilling through holes at .402 (for 3/8 - 16 socket head cap screws and counterboring them to 5/8" diameter 1/2 inch down. This should allow me to mount it to the rotary table.

I could drill slots as 4 radials and use T-bolts (or whatever you call them... the bolts that have the T-flanges already attached) kind of like a lathe faceplate, or I could try to cut some T-slots into it with the slots bisecting the mounting bolt hole sets. I guess I could drill and tap a number of holes for mounting, but would probably feel obligated to go find Keenserts or equivalent to put in them for strenth...

Russ, actually I do have a 13x40 lathe, but the whole of the story is that the collar around the quill has to have a flat spot on the back and either have an integral arm that extends about an inch and a half out, or be drilled and tapped to accept an extension that would go out about an inch and a half. I am trying to make a collar to go on the quill of a 3-in-1 to mount the z-axis of an Acu-Rite 100-S. My success with side cutting on the lathe has been limited, because every time I try it, I am cutting cleanly with the tip, but smearing the cut with the side of the tool below it (I haven't found anything with enough side taper for small circles)... maybe it has to be a cutter with an insert?

Forrest, I was planning on trying to cut the clamp out of 1/4 inch T 6061 aluminum to try to keep the loss of vertical movement to a minimum. I have about 6.75" available on a 4" z-axis scale and reading head, but only 5 1/4 inches on the quill. I suppose a little machine has no business trying to cut with over 3" of the quill extended, since it just isn't rigid enough... but there are always those times when you are trying to squeeze out that extra little bit... your clamp ring makes a lot of sense. After cutting the internal diameter, I could then catch the inner T-slots with a clamping bar. Is there any way to clamp through the center of a Morse taper hole? I might be able to fit a thin threaded plate in the opening below, but I presume that the rotary table makers don't intend for that to be happening????