4" rotary table

[Budz100]

I am a toolmaker during the day and I have a shop set up at home. I know I just can't get enough of cutting metal I guess. I am used to using rotary tables but this has me a little confused. I already own a six inch, I think phase 2, rotary table. It is 4 degrees per revolution or 90:1, which makes sense to me. I always wanted a 4" horizontal/vertical because the 6" seemed a little heavy for my benchmaster mill. So I found one at a flea market, and it looks to be new. What I don't understand are the graduations. It is 9 degrees per revolution or 40:1. OK still sounds right, a little coarse, but useable. But now this is wierd, the graduations on the handwheel show 4 degrees per revolution. I could kind of understand 4 1/2 degrees, I suppose. Nothing looks altered in any way, it just seems wrong. I have looked this over, counted the turns, figured I was nuts, checked it again and I get the same thing. I would really like to be wrong and have someone show me what I am missing. This rotary table looks similar to the one grizzly sells with indexing plates, they say that one is 72:1 though. Has anyone seen this before, or have any ideas? Thanks

[oldtiffie]

Just actually physically count the number of hand-wheel turns per 1 turn of the table. That will settle the worm/wheel ratio.

Deal with the dial after that.

[winchman]

I'm pretty sure we have a Palmgren 862 with a 40:1 ratio at the school. I'll check to see what the dial graduations are today.

[winchman]

That's what it is, and the dial on the handle is marked for 9 degrees just as you would expect.

[Budz100]

Thanks for checking yours. It still has me confused, it's like having a mill move .200/rev and the dials say .075. It just doesn't make sense to me.

[JCHannum]

Welcome to the site. Always good to have an experienced toolmaker join up.

Could you post a photo? With a flea market purchase, is is just possible that it has been "repaired" at some point with a misfit handwheel.

[Budz100]

I'll see if I can get a pic tonite. I am about as positive as I can be that it wasn't repaired. All of the finishes match and it still had the original cosmoline on it.

[philbur]

I once owned a Taiwanese RF40 mill/drill bought new. The dial on the quill fine feed was marked as 3mm per rev. After several wrong critical depth cuts I discovered that the down feed was actually 2.5mm per rev.

Phil

[oldtiffie]

2.5mm x 0.04" ~ 0.10"

My RF-45 mill quill fine down feed is calibrated as 3.0mm and its pretty right.

[Budz100]

Here are some pics.

http://i1262.photobucket.com/albums/ii608/budz100/Picture300.jpg

http://i1262.photobucket.com/albums/ii608/budz100/Picture299.jpg

http://i1262.photobucket.com/albums/ii608/budz100/Picture301.jpg

[TGTool]

Ooh, Cadillac gauge in the second picture. I've got one that unfortunately sat outdoors on a pallet sometime during its life. Still scratching my head whether and how it could be restored sufficiently to be reliable. It turns smoothly but the step rings are rusty and they have to be really right. Maybe it's a moot point in the end. A 24" Cadillac gauge on a 12 x 18 surface plate would probably look about as useable as a V8 on a motor scooter.

[Budz100]

Yeah I like that cadillac gage. It's an 18" I got off ebay. I think I paid $30 for it and $35 for shipping. Gotta watch for them deals.

[winchman]

From the last picture it does look like the dial goes from 0 to 50 four times. That would work with a 90:1 ratio.

For a 40:1 you need it to go from 0 to 50 nine times.

I'm guessing that the RT was available with two different ratios, and somehow the wrong dial got installed on this one. Seeing how the vernier marks line up with the dial might confirm this.

There have been several threads here about marking dials, so it might be worthwhile to make a sleeve with new markings to install over what's there.

[JCHannum]

The handwheel collar reads 0-60, which is even more puzzling if it is 40 turns.

[Budz100]

Yes, the handwheel collar is definately 0-60 four times. I think I figured it out yesterday to be 2 minutes 15 seconds an increment. I can't see that as being a nice even number. It is 40:1, no mistake. Thanks guys.