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+--- Thread: Using a chuck table (/thread-2442.html)
Using a chuck table - Sunset Machine - 01-04-2015
I use this setup primarily for gear blanks in order to get the faces parallel and to bring the blank to proper thickness.
The first step is to face one side, then drill & bore to size. Then we install the chuck table: lightly snug it in the jaws and use the drawbolt to snug it tight. Then we loosen the jaws and mount the gear blank.
The blank is lightly snugged by the jaws and a bolt to tightly snug it to the chuck table, the jaws tightened and the bolt removed. You'll have the blank held by the tips of the jaws; don't overtighten, you'll spring or break something. Light cuts only!
With both sides faced, it was ready for mounting on an arbor to do the OD. Once that was done, it went back in the chuck table for the recess in one of the faces. Finally, back on the arbor to finish the features on the OD of this bevel gear blank.
The last shot is of the blank mounted on yet another arbor on the mill. I'd been at this for 4 hours when the dinner bell rang. Hopefully I'll get this finished today and see how it meshes with its twin... It's the parallel tooth form; once down the middle and then two offsets for a total of three passes.
But that's another story...
RE: Using a chuck table - PixMan - 01-04-2015
I have to think about all the steps for a while. I'm not clear on why to use a method like that because I'd probably just chuck a big chunk of material in my 3-jaw, machine as many surfaces completely as possible, cutoff and flip around. Hold it in bored soft jaws to finish other surfaces, and throw it on the surface grinder if I needed anything more accurately parallel. Or, just hold the cut off, half finished piece in my 4-jaw chuck and indicate the back side true to get parallel and concentric.
I've got a lot to learn (or re-learn) about gear making. I don't know anything about "parallel tooth form". I thought you got the cutter as the form you needed and made a single pass.
One question for you about your lathe work:
I notice in the bottom photo of the gear blank mounted on the arbor that you have a quick change tool post. In the first shot of the part set up in the lathe with the boring bar, it's in a rocker post with a ton of shims under it. Why wouldn't you use the QCTP and either a No.7 boring bar holder with a reducing sleeve, or a regular No.1 or No.2 holder with clamp screws on the flats of the bar?
RE: Using a chuck table - Sunset Machine - 01-04-2015
Soft jaws would probably be better, but I don't like removing the jaws. This table is quick - you have but one bolt to deal with and no need to dial anything in. The drawback is the size - anything smaller than the chuck table won't work. It's also hard on the jaws.
Parallel depth tooth form. The teeth are radial, they fan out in a vee shape. Store bought gears have tapered teeth for full contact. Twice as strong but they need to be planed on a gear shaper. These can be milled.
To tell them apart at a glance: the tops of the teeth are straight for tapered teeth. That's not a typo- parallel teeth have wedge shaped tops. It's counter-intuitive. To cut tapered teeth on a mill requires filing & fitting. Parallel teeth are ready to go without filing. I'm sensing a repair in the wind and wanted to see how much trouble I can get in.
As to the lathe work, I have two of them. One is left with the jaws set for OD work. I just never bought a QC toolpost for it, but I do have a couple holders and in a pinch I borrow the QC from the other machine (different center heights). But with just two operations going it wasn't worth the effort.
RE: Using a chuck table - PixMan - 01-04-2015
Ah, two different lathes then. That explains a lot.
That said, you show using the "table" on the lathe which has the top jaws. When I use my soft jaws it's on my similar 3-jaw chuck and I just remove the 2 screws per jaw and swap them out. Yeah, it takes a bit of work but always worth the effort. Probably about the same time as mounting your chuck table (first time I'd heard the term) and quite a bit more versatile.
On the tooth shape, I figured that's what you meant. I've seen the teeth done on gear shapers (and high end Magerele gear grinders.) Fascinating and fantastically expensive machinery for making gears.
RE: Using a chuck table - Sunset Machine - 01-04-2015
Instead of 6 bolts, I'm working just 1. And back again, that's 2 to your 12. This has been working so well for me that I've never bothered making soft jaws. Just wanted to share a technique.