Fanuc cnc 1/4-20 threading program???

Figurehead · Aug 13, 2020

Hello all, new to this forum. I am running a fanuc cnc and need to make 1/4-20 threads on a piece of 304 stainless. I will be using G92 for the threading. Does anyone have a complete program for this operation? The length of threads is 7/8” long and the OAL of the part is 10.0” with both ends being chamfered. Any thoughts or help would be greatly appreciated. Thank you.

Guest · Aug 13, 2020

Without knowing the type of machine and the programmable limits it would be impossible to write the whole code. I have two Fanucs close to the same generation, a program that would thread nicely on one would crash the other.

Figurehead · Aug 13, 2020

It’s a Fanuc series 21-T. As far as the limits, not sure, where would I find them? Thanks for your reply.

Dan from Oakland · Aug 13, 2020

Why G92? Use a canned cycle.

Guest · Aug 13, 2020

Dan from Oakland said:
Why G92? Use a canned cycle.

A lot of machines anything more than G32 or G92 was an option. I have a 21T and those are the only threading cycles.

Guest · Aug 13, 2020

Figurehead said:
It’s a Fanuc series 21-T. As far as the limits, not sure, where would I find them? Thanks for your reply.

What kind of machine? Fixed headstock? Sliding headstock, gang tooled, single barrel turret, double barrel turret?

As an example this is all the code to make a 4-40 thread including calling up the tool and it's exit. That is on a 21T, no way it will work on yours unless it is a Star-SE16

(THREAD)
M45
M3S550
G0X.32Z.150T505
G1X.25F.02
G1X.200F.005
G92X.103Z.365F.025
X.099
X.096
X.0935
X.091
X.089
X.0875
X.086
X.0845
X.083
X.0815
X.0815
G1X.3F.02

Figurehead · Aug 13, 2020

It’s a Star SH-12. I am more concerned on making the 1/4-20 threads than the OAL of the part. Is that still possible with this machine using G92 program? Thanks again.

Figurehead · Aug 13, 2020

Sliding headstock, gang tooled and single barrel turret.

Guest · Aug 13, 2020

Figurehead said:
It’s a Star SH-12. I am more concerned on making the 1/4-20 threads than the OAL of the part. Is that still possible with this machine using G92 program? Thanks again.

Even a bare bones SH12 should work with G92. Doesn't that machine only have a 5" Z stroke? Do you have a sub spindle? I have made 11" long parts on mine and it only has a 4" Z stroke and no sub. It is doable, but it isn't a job for a rookie.

Guest · Aug 13, 2020

Figurehead said:
Sliding headstock, gang tooled and single barrel turret.

The pics of SH-12 I see don't have any barrel turrets. Got a pic of yours?

Figurehead · Aug 13, 2020

Sorry about that. No barrel turret. I am trying to single point the threads. I am making threaded parts but can’t seem to get the right pitch for the 1/4-20.

Here is the program I am using:

M43
G0X.394Z0T303M3S500
G0X.256M24
G1X.181F.0015
G0X.394
G4U.0395
G92X.2000W.8750F.05
X.1980
X.1960
X.1940
X.1920.....X.1600
G0X.394

This is a program I am using from the manual. It was an example program, but I am alternating it to try and make the 1/4-20 threads...

Guest · Aug 13, 2020

Figurehead said:
Sorry about that. No barrel turret. I am trying to single point the threads. I am making threaded parts but can’t seem to get the right pitch for the 1/4-20.

Here is the program I am using:

M43
G0X.394Z0T303M3S500
G0X.256M24
G1X.181F.0015
G0X.394
G4U.0395
G92X.2000W.8750F.05
X.1980
X.1960
X.1940
X.1920.....X.1600
G0X.394

This is a program I am using from the manual. It was an example program, but I am alternating it to try and make the 1/4-20 threads...

Sorry I went away, I needed to go to town and get some supplies. Your program as posted is way too aggressive for even plastic, for 304 I would go 12-15 passes.

Guest · Aug 13, 2020

You have probably smoked your single point tool by now. On 304 doing a 1/4-20 I would start with 600 RPMS and passes that look like this.

X.2336
X.2268
X.2216
X.2172
X.2134
X.2099
X.2067
X.2037
X.2009
X.1982
X.1957
X.1932
X.1909
X.1887
X.1887

Nerdlinger · Aug 13, 2020

Check the length of the carbide land on your guide bushing. I’d be surprised if it’s long enough to do the entire 7/8” without multiple feeds....maybe with a left hand tool you could do it, though. I know in my Tsugami you can use G32 for “continuous thread cutting” to do little sections at a time and have them all match up in the end. Good luck!

Guest · Aug 14, 2020

Nerdlinger said:
Check the length of the carbide land on your guide bushing. I’d be surprised if it’s long enough to do the entire 7/8” without multiple feeds....maybe with a left hand tool you could do it, though. I know in my Tsugami you can use G32 for “continuous thread cutting” to do little sections at a time and have them all match up in the end. Good luck!

Good point I think the bushings I have range from .650 to .850 land length. For .875 I would just shim the tool out.

Figurehead · Aug 14, 2020

Ok. Will give it a try. Won’t be until Monday. Thanks everyone for your help and input.

Fancuku · Aug 14, 2020

T303 M8
G97 s400 M3
G0 X0.35 Z0.2
G92 X0.24 Z-0.75 F0.05
X0.23
X.221
X0.213
X0.206
X0.2
X0.195
X0.191
X0.1876
G0 Z0.5 M9
G28 U0 W0
M1

Delw · Aug 14, 2020

What size is your stock? if its 1/4 + .010 in you can make the thread as long as you want and not worry about the guide bushing., then when thread is all done then you finish the major to size in one pass. we do it all the time in sliding heads. basically your cutting your thread and all the machine work prior to cutting the major down. that way it slides nicely in the bushing.
if your stock is bigger than 1/4" then teachmeplease had a good example a few months ago on hwo to do it on sliding heads.
look for his citizen posts

Fanuc cnc 1/4-20 threading program???

Plastic

Guest

Guest

Plastic

Titanium

Guest

Guest

Guest

Guest

Plastic

Plastic

Guest

Guest

Guest

Guest

Plastic

Guest

Guest

Guest

Guest

Stainless

Guest

Guest

Plastic

Cast Iron

Stainless

Similar threads