VN Looking For Dimension Of Vn "c" And Hardinge "5v" Collets

Hi All:

I've looked through several collet drawings on the web and in print but have not found what I am looking for. I'm interested in the radius of curvature on the nose of the collet. In other words I want to know the curvature of the surface that the cutting bit protrudes from. The VN collets I have look like they have a spherical front surface, but my Hardinge collets have a somewhat flatter and more conical front surface.

Normally, we only care about the taper and dimensions on the back side of the collet, but I am trying to measure and accurately draw a diagram of the collet retaining cap for the High Speed Quill Head. (See the photos in that thread for a picture of the threaded cap.)

The surface on the inside of the cap that touches the collet and pushes it back into the taper is machined with a slightly concave spherical surface to match the front face of the collet. It's a pretty difficult thing to try measuring accurately enough to get a decent idea of the radius of curvature. I'll be taking it in the work to see if our very accurate depth gauge can get to that machined surface and give me a profile.

But if I knew the radius on the front of my collets at least I would know approximately what that surface looked like. If anyone can point me to a drawing that would be great.

Thanks... Jeff

Jeff Sauer said:

Hi All:

I've looked through several collet drawings on the web and in print but have not found what I am looking for. I'm interested in the radius of curvature on the nose of the collet. In other words I want to know the curvature of the surface that the cutting bit protrudes from. The VN collets I have look like they have a spherical front surface, but my Hardinge collets have a somewhat flatter and more conical front surface.

Normally, we only care about the taper and dimensions on the back side of the collet, but I am trying to measure and accurately draw a diagram of the collet retaining cap for the High Speed Quill Head. (See the photos in that thread for a picture of the threaded cap.)

The surface on the inside of the cap that touches the collet and pushes it back into the taper is machined with a slightly concave spherical surface to match the front face of the collet. It's a pretty difficult thing to try measuring accurately enough to get a decent idea of the radius of curvature. I'll be taking it in the work to see if our very accurate depth gauge can get to that machined surface and give me a profile.

But if I knew the radius on the front of my collets at least I would know approximately what that surface looked like. If anyone can point me to a drawing that would be great.

Thanks... Jeff

Click to expand...

Jeff,

The Van Norman collet/toolholder drawing C-385-C shows an angle of 5 degrees, and 3/64 inch.

I am going to need one of these for my machine.

Ron

Drawing C-385-C shows a 5 degree cone at the nose of the collet. This looks exactly like some of the Hardinge 5V collets I have. But I also have a good number of genuine Van Norman collets that are distinctly spherical at the nose with the dimension marked "3/64" measuring nearly a full 16th of an inch, so clearly they are not made according to this drawing. I tried taking some photos, but it turns out to be a pretty difficult thing to photograph the differences. I'll try again under the microscope at work and re-post here...

Jeff

I'm looking forward to this discussion developing, as I one of my projects this winter is to tool up my 1939 Gisholt Ram Turret lathe to make several horizontal 5V arbors and harden them accordingly in my lil toolmakers oven.

Daryl
MN

Saw this thread,
Don't know if the attached blueprint will help-- but thought I would post it just in case-
Good luck,
Bob V

Slightly off topic here. On the horizontal arbors, I had some thoughts on these. I am currently making some face mill arbors out of 4140, and I thought about harding them, but they will warp. I am looking at P20 tool steel as a possible replacement. Might be a better option.

Jason

Like so many things I've not heard of P20.
Why P20 over O1?
https://www.hudsontoolsteel.com/catalog?shape=round&cut=nonstock

Daryl
MN

All the knifemaking may finally pay off, I can offer some advice/reasoning on steel selection.

O-1 can certainly be made tough enough to do the job, but the key benefit it's going to bring is abrasion resistance because of the Wo alloyed into it, which probably isn't a huge concern for a face mill arbor. Add to this the fact that as a hypereutectoid (ultra-high carbon) steel that is alloyed with aggressive carbide formers and you need pretty good process and controls in your heat treatment in order to not create lamellar "sheets" of carbides in the steel which can be a PITA when it comes to finish machining.

4140 is a bit more forgiving in heat treatment and can certainly be made tough enough to do the job. I'm not sure of how much dimensional shift will occur with the heat treatment though, I'd have to look it up. That said, it will be much easier on you and your tools for finish machining after heat treatment. You can do a reasonable heat treatment on it without too much precision in equipment, but if you can control your temperatures well, it benefits from proper soak/preheat times. I have a great heat treat recipe for it somewhere, I can try to dig it up if anybody is interested.

If you don't want to fool with the heat treatment, go with 4140HT. It's already heat treated, but soft enough to cut with HSS tooling.

deker,
Thanks for the post!
1. Which alloy is Wo?
2. I've got a cute oven 4x4x9 inches I'm hoping that will work. Haven't yet used it. Currently being rewired by a moonlighting oven guru. I'm hoping that will provide adequate control. My only prior heat treat experience has been with oxy-acetalyene (OA) and oil. I've also played with OA and Cherry Red. Opinions? I wasn't satisfied.
3. I was given about 8feet of 4140 with diameter to accommodate 5v collets. Looking forward to a recipe!!
4. I'll do some price comparison on 4140HT.
5. I'm hoping to offer some affordable 5v collets here come spring. Got to get a few other projects done first.

One chip at a time....

Daryl
MN

Uglydog said:

deker,
Thanks for the post!

Click to expand...

No problem! I'm happy to have something to contribute.

1. Which alloy is Wo?

Click to expand...

Wo is Tungsten. It used to be called Wolfram, so the original symbol of Wo stuck around. Kind of like Lead is Pb (Plumbum).

2. I've got a cute oven 4x4x9 inches I'm hoping that will work. Haven't yet used it. Currently being rewired by a moonlighting oven guru. I'm hoping that will provide adequate control. My only prior heat treat experience has been with oxy-acetalyene (OA) and oil. I've also played with OA and Cherry Red. Opinions? I wasn't satisfied.

Click to expand...

If it will reach temps of 1800-1900F and has enough of a control to set a temperature and hold it you'll be fine. If you need to do long soaks above ~1450F you may want to look into getting some Anti-Scale from Brownell's. You preheat the piece to about 500-600F, sprinkle it on and it melts onto the piece to provide a barrier to oxygen that will prevent scaling and surface decarburization.

3. I was given about 8feet of 4140 with diameter to accommodate 5v collets. Looking forward to a recipe!!
4. I'll do some price comparison on 4140HT.

Click to expand...

I'll have to dig around and see if I can find the HT schedule I used for a hammer head I made a few years back. It's tough as nails (ok, tougher actually). I'd recommend for something like 5v collets that you machine all of the external dimensions and maybe drill a pilot hole for the bore, then HT, then finish the boring and slitting (for larger sizes that would have thin walls anyway) if you can. This will reduce the possibility of warpage of thin cross sections during heat treatment. You may also want to cut the threads after heat treat to avoid leaving sharp edges that could create stress risers and cause cracking. I haven't worked a lot with 4140, so I'm not certain how much of an issue it would be, but in high carbon steels, I've been taught to always leave a small radius rather than a sharp corner before quenching.

5. I'm hoping to offer some affordable 5v collets here come spring. Got to get a few other projects done first.

Click to expand...

I'm hoping to see them for sale!

-d