Show me your Rotary Table hold down fixtures

[projectnut]

My rotary table is a bit different than most. Rather than a single set of T slots that intersect at the center of the table mine has 2 sets in one direction and a single set at 90*. So far everything I've used it for can either be clamped to the table using standard milling machine clamps, or held in the 10" 4 jaw chuck.

Here's a picture of the table before it was cleaned up.

 

[DavidR8]

Here is a photo of the chuck adapter I use. MT to 1.5 x 8. Fitting on the left is used as a drawbar to seat the MT.

View attachment 357580

Cheers,

Adrian

Thanks for this photo Adrian, I was struggling to picture how to attach a chuck for a threaded spindle without taking it off the backplate.

 

[Janderso]

For larger work, I will center the RT on the mill spindle and zero my DRO. For there, I can offset my table to locate features on the work piece, using a pin or edge finder, depending on the accuracy required.

I guess what I'm missing is the part position relative to the spindle center=rotary table center.
I know I don't touch the table (other than the offset) once the RT is centered.
I am struggling with finding center of a part prior to the offset.
The part needs to be on center and the only way I know how to do that is the DRO and an edge finder.
I can't use the tools when I can't move the table.
I'm missing something simple here.

 

[Grendel]

Here we go, you can see the two little bars I added to the two threaded holes, but of course any shape would work

 

[mickri]

If you are using a 4 jaw chuck put the chuck on the lathe and center the part. Then move the chuck to the RT. Or with the 4 jaw chuck on the RT set up a DI and spin the RT to center the part just like you would on the lathe. If it is an odd shaped part that you have mounted on the RT pick whatever edge(s) you want to reference off of and move the part until it is centered on the RT. You will have to be creative in figuring out how to move the part.

I don't have a RT. I use the swivel base that came with my vice and made a backing plate that fits my chucks. It works for milling things at an angle and doing precise bolt circles.

 

[RJSakowski]

When I use the RT, I will zero the DRO on the central axis of the RT. I do so either by using an edge finder in the RT socket o mount a piece of material in the mounted chuck and cut a cylinder with an end mill by rotating the RT table and centering that cylinder with the edge finder. With the mill spindle now referenced to the RT, I can move my table for various offsets. If I wanted to align a workpiece with the x axis of the mill,I would set the RT at 0º and move to my desired position and use whatever method was acceptable to locate the feature.

The actual operations vary depending on what my starting workpiece is I need to accomplish. Usually, I will start with the RT as a first op setup so only a rough alignment of the workpiece is required. A square from the base of the RT will usually meet that requirement.

Alignment becomes more difficult if you are trying to position a pre-existing part. If you are trying to machine a circular feature, you would want the center of the arc to be at the center of the RT. I would center drill the center of the arc so I could use an edge finder or test indicator to center tha part. Then I would probably clamp the part and move the table to locate a secondary feature. I probably would bother with trying to set the RT angle but simply record the angle and use it for calculating an offset (it would be nice if it were possible to set the RT scale to zero).

 

[Flyinfool]

I am not sure how to explain this but I will try.

First I set the RT to exactly zero degrees and locked it in position.
then I got my RT setup on the mill with the T slots square to the table.
I then mounted a piece of scrap steel to the table and milled both sides square so that I know it is exactly square to everything else.
Now I flipped the RT upside down, clamped that bar into the mill vice, and drilled & reamed 2 holes for dowel pins.

I took a lot of time with each of these steps to make them as accurate as I possibly can.

Now whenever I put the RT on the mill and bump those 2 pins against the side of a T slot, I know that with the RT set for 0° the RT T-slots are parallel to the mill T slots.

When putting parts on the RT I can now square them to slots and know they are square.

I still need to set up a 3 and a 4 jaw chuck for the RT.

 

[Janderso]

I am not sure how to explain this but I will try.

I think you explained the process quite well. I can understand it.
Now I can see why some make the pallet square. Easier to align parts to the Y-X axis and easy clamping.
This is just a fiddly business.

Flipping the rotary table =80 lbs. will be tricky.

 

[davidpbest]

i'm not sure if this is totally responsive to your question, but here is what I have done to help things a bit. I also use the gizmo Joe Pie made (referenced in a video in a prior post in this thread) for doing some alignment, and I have made a fixture similar to what Flyinfool described with precision dowel pins for situations where I'm not using a chuck on the RT.

 

[Janderso]

Thank you David.
That sure makes things quick and easy.