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G32 after G76 for thread cleanup?

On Haas's I have done the same with no issue, but on Fanuc lathes like our old mori's it would not work for the reason's that Bill said. The z starting point will not line up. You can Follow what Sinha said , but it is just easier to use a g76 to follow a g76.
or even better me , if you can use a full profile lay down insert and eliminate the need for a wipe pass......
 
Hi All:
I was under the understanding that G76 can tailor the incremental infeed at an angle you pick from several options.
One of them is Zero (straight in) so far as I know.
I am only familiar with two line G76 so the last two numbers of the first line should do it: G76 P100000 in my world.
So if you ran the G76 thread that way theoretically you should be able to run a G32 or a G92 cleanup pass from the same start point unless I'm totally off base.
Wiser folk than I... am I correct or is my thinking totally cockeyed?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
Well, prolly so, and Sir William said that as well. (among others?)

But it is bad practice to run a 60* thread with 0 infeed angle.
Your chip will not flow well at all.


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Think Snow Eh!
Ox
 
Hi All:
I was under the understanding that G76 can tailor the incremental infeed at an angle you pick from several options.
One of them is Zero (straight in) so far as I know.
I am only familiar with two line G76 so the last two numbers of the first line should do it: G76 P100000 in my world.
So if you ran the G76 thread that way theoretically you should be able to run a G32 or a G92 cleanup pass from the same start point unless I'm totally off base.
Wiser folk than I... am I correct or is my thinking totally cockeyed?

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
Selecting a 0 infeed angle will allow for G32 or G92 to align with a G76.

IME, 0 infeed angle results in lower tool life and poorer thread quality than using an infeed angle. With 0 infeed angle you have equal chips off each insert edge "colliding" on the top of the tool. This makes for a messy chip that doesn't clear off the tool or part very well. It's my opinion that it also results in higher pressure on the tool tip and results in shorter insert life.
 
Hi again All:
Ox and Vancbiker wrote about how shitty a thread plunge infeed produces.
I mostly agree.

On brass and cast iron it seems to work just fine although I don't really see the point.
On square threads and some buttress threads you have no choice:
opening shot side view.jpg
On this part I had to run it in this orientation because the fingertip end of the thread has a bullet shaped root...so no angled infeed allowed because the vertical wall of the buttress thread got in the way in this orientation (but this goofy thing was cut with G32 passes anyway...a bazillion of them.)
The final part ran in 316L and it ran fine, but I ran it with oil.

Having said all that, there was another thread on PM recently (I can't remember which, otherwise I'd put in a link) where a number of participants swore straight in infeed is the only way they ever do it, and claimed no difference in the thread quality they produce.

If anyone recalls the thread I'm babbling about, please link it.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
Are you thinking of the thread that involved an Acme, or Buttress type thread?


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Think Snow Eh!
Ox
 
Hi Ox:
I don't know just which thread it was...I believe it started out with a G92 question from the OP and kind of went from there.
If I remember right, he posted that he didn't bother with angled infeeding and others chimed in from there.

It struck me as odd at the time...if I remember right, the OP was a G92 fan and just chose the same start point for each pass or something like that because it was easier for him to code that way.
I don't remember why he didn't seem to like G76.
In fact I don't remember much at all about the thread...the main takeaway for me was how many posters agreed that plunge infeeding was perfectly OK in their hands.

This conversation brought that thread back into my consciousness.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
That's why I think it was not a 60* V thread in that thread. (post?)
There was a reason that he wasn't feeding in on an angle, and some couldn't see past the fact that there is other threads out there than 60*V's, even if they hadn't ever made one.

At least that's the recent thread that I remember/saw.
I don't read all of them by any means.


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Think Snow Eh!
Ox
 
or even better me , if you can use a full profile lay down insert and eliminate the need for a wipe pass......
A full profile insert is nice but not enough often. In the case of the op’s situation he’s cleaning burrs from another operation.

In my often situation I need very nice burr free threads even on the lead in / lead out chamfers. The only way I’ve found to get this is with a spring pass on the od and threads. Another thing I just recently did was to put a wire brush in a live tool holder to knock of some final burrs on an od thread.
 
Could well be, Ox...at any rate it's not that important.
Going back to the OP's question...I always run a second G76 pass with my first cut depth the same as my final depth as sinha and others have posted.
It's always worked for me, and for the stuff I run, I lose a second or two by taking the extra air pass...no big deal.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com
 
A full profile insert is nice but not enough often. In the case of the op’s situation he’s cleaning burrs from another operation.

In my often situation I need very nice burr free threads even on the lead in / lead out chamfers. The only way I’ve found to get this is with a spring pass on the od and threads. Another thing I just recently did was to put a wire brush in a live tool holder to knock of some final burrs on an od thread.


I go back with the profile tool that made the feature to begin with if need to clear entry (?) and exit burrs.


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Think Snow Eh!
Ox
 
Thanks for the help everyone.

I ended up just putting in another G76 and it worked fine. I don't really mind the second spring pass, even though I don't think it's necessary, but it was the easiest way to achieve what I wanted.
 
I ran a few jobs where I had to go in and do a clean up pass because of a cross hole. And Bill is right. G76 infeeds at whatever angle you put in your initial G76 parameters so the Z start position isn't the same on the first pass as it is on the next or the last. And Kevin is right. You don't really want to use 0 on your infeed angle.

So what I did on my first 'set-up' piece is change the spring passes in G76 to something like G76 P050060 Q... R...

This gave me 5 passes to write down the final Z start position on the screen which I could then use in a G32 as a clean-up pass.
 
Be careful. In my experience, G76 and G92 (never tried G32) synchronize differently even when everything else is equal.
I would just use G76 for the rerun with the initial depth as the full depth.
 








 
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