Okuma ID thread turning critique

[mkd]

G97S578M03M41
G0X.2653Z.3078
G71X.5013Z-.6B29D.0063H.036M32M75F.0357

doing a 1/2-28 ID thread with a little micro100 solid tool.

sucker is taking over 30 passes. With only .015" depth of thread this seems ridiculous although it is working well on the machine.

 going to be switching to 17-4 stainless @35Rc next week. How many passes should it take in the experience of some turning experts here?

thanks in advance

[wdg5555]

.01 depth of cut is a very safe starting point for 1/2 threads. Which i believe would be a "D.02" since okuma lathes use diameter instead of radius. It also looks like in your program that your starting the first cut at x.2653. This Should be the minor diameter of the thread. Check when your threader is actually cutting in X. I'm guessing there is a lot of air passes.

[mkd]

ok, changed start point to X.430 from original X.265. Didn't make a bit of difference on ridiculous number of passes or the fact that the first pass took a chip.

part chattered for the first 15 passed followed by no noise (broke the tip off).

Going to shorten the stock stick out by an inch which is significant for Ø1.0" stock in hope of eliminating chatter.

seems like all those passes are just work hardening the material. I'll try D.02 on my next threading tool, and see....

[mkd]

boy that D sure is powerful. settled on D.012 for about nine passes.

..and no more chatter

 

[mkd]

Tool life with an uncoated C2 carbide threading tool isn't very good at all.

anyways, check out ebay for what i'm making

[mkd]

I've been using M32 which according to the manual will infeed along the angle of the thread, thus all of the wear will be on the leading edge of the tool. anybody notice better wear by switching to M33 which supposedly does a zig zag infeed on successive passes?

[crazy^millman]

4 minutes ago, mkd said:

I've been using M32 which according to the manual will infeed along the angle of the thread, thus all of the wear will be on the leading edge of the tool. anybody notice better wear by switching to M33 which supposedly does a zig zag infeed on successive passes?

I always used that process to get even wear on my threading inserts.

[mkd]

OH man! blew the tip off on first part .......again!

 I was real careful to setup the face angle of the bar to be ever so slightly negative rake to ensure i'm not rubbing with the back.... and still blammo.

More negative front rake angle?

anybody got a favorite tool for .500 threads? would an insert be better?

TIA

[mkd]

Anyone ever roll-tap 17-4 @ 35 Rc?

[Mike@Lustre]

do you have live tooling on the lathe ?? have you considered thread milling ??

[mkd]

Yes, live tool, Y/B axis actually.

 In retrospect the problem was probably the goofy boring bar setup I was using leaving some irregularities in the bore. Multiple problems actually. . This what i get for trying to "force" a machine into production while programming a mill/turn. FACEPALM.

 any ways gotta put my pet project aside and run some real parts.