[Fudd]

What is the best way to program to cut multi-start threads on a lathe with a Fanuc OT controller on it?

Thanks,

Scott

[wms]

Fudd .. er Scott,

As far as I know, (and I could be wrong) you can't program multi start threads on a Fanuc OT control...

If you or anybody figures a way to do it..please let me know.

[duluthboat]

If the controller won't let you idex the start point, you will have to shift Z zero to give you the right start point or index the part.

Gary

[Zep]

thread would be done using a z value shift and two thread programs
similiar as to what follows
G00 X1.1 Z.1
G76 P010060 Q20
G76 X.9 Z-1.0 P060 Q250 F.25
G00 X1.1 Z.225
G76 P010060 Q20
G76 X.9 Z-1.0 P060 Q250 F.25

FEED OF .250 WITH A .125 SHIFT between canned cycles will start second thread 180 degrees from start of first thread

this will work if your 0T is set up for two line canned cycles.

program will probably vary depending on programming style but the concept is the same. two thread programs using a feed of 2x your required pitch
with a shift of 1 required pitch ie. this program would result in a 1 inch 8tpi two start thread. (minor dia. is not to spec. just an example)

[Fudd]

Thanks Guys. That worked like a charm.

Thanks,

Scott

[wms]

Thanks Zep and Gary too.

Old dog learns new trick. :wave:

[Zep]

not bad for a chip sweeper eh!

[khamul2000]

can any one tell me if i got this right. i have to make a new thread on a head for one of our deep hole drilling machines. The thread is 4 TPI 0 TPF 4 start and 1.75" long. when i normally program a thread cycle i use a G92 command. I believe what i need to do is instead of running at a feed rate of .25 for a normal 4 TPI thread. I increase the feed to 1.000 and run the thread cycle and then off set the my z by .25 three more times in which case would give 4 start points, 1 every 90 degrees, and 4 TPI?

EG:

Z1.25
G92 X2. Z-1.75 F1.
X1.9
X1.8
X1.7
X1.6
Z1.
G92 X2. Z-1.75 F1.
X1.9
X1.8
X1.7
X1.6
Z.75
G92 X2. Z-1.75 F1.
X1.9
X1.8
X1.7
X1.6
Z.5
G92 X2. Z-1.75 F1.
X1.9
X1.8
X1.7
X1.6

I believe that would work would it not?

[Jaytough]

i am in china and hve just been working on a machine useing G92 to set multi starts all you need is to add an L soG92 X2. Z-1.75 F1d L2 or 3 or 4 this is the divisons of the
we are making long pitch herringbone grooves 3000mm pitch and tis just devides it to what you want so if the lead of the thread is 100mm and 4 starts it would be F100 L4 as long as your encoder can handle the divisons it works well