Need help with simple thread mill program

[Captain Midnigh]

1001 G92 X0 Y0 Z0 (Set floating zeroes)
1002 S1200 M3 (Start Spindle)
1003 GO X-16 (Move to clear part)
1004 GO Z-20 (Z down to start of thread)
1005 G1 F4 x1.920 (Move in to start cut)
1006 801 L8 (Call sub to cut threads, loop 8 times)

9001 701
9002 G3 R15 I15 J0 X-15 Y0 Z1
9003 701

When run. I get one thread, and on the second thread, the Z does'nt move .
I can't get a continuios thread.

[Dave1]

Is your subprogram in incremental?
Dave

[Captain Midnigh]

Yes it is, but I've tried absolute also. I also tried calling each thread on it's own line. It moved on the first line, but not on the second. I tried calling each Z position in absolute, instead of going to that position, it added them,
like it was in incremental.

1001 G92 X0 Y0 Z0 (Set floating zeroes)
1002 S1200 M3 (Start Spindle)
1003 GO X-16 (Move to clear part)
1004 GO Z-20 (Z down to start of thread)
1005 G1 F4 x1.920 (Move in to start cut)
1006 G3 R15 I15 J0 X-15 Y0 Z1 (Cut first thread)
1007 G3 R15 I15 J0 X-15 Y0 Z1 (Cut a circle, no Z move)
1008 G3 R15 I15 J0 X-15 Y0 Z1 (Cut a circle, no Z move)
1009 G3 R15 I15 J0 X-15 Y0 Z1 (Cut a circle, no Z move)


Same program in absolute

1001 G92 X0 Y0 Z0 (Set floating zeroes)
1002 S1200 M3 (Start Spindle)
1003 GO X-16 (Move to clear part)
1004 GO Z-20 (Z down to start of thread)
1005 G1 F4 x1.920 (Move in to start cut)
1006 G3 R15 I15 J0 X-15 Y0 Z-19 (Cut first thread)
1007 G3 R15 I15 J0 X-15 Y0 Z-18 (Tried to go to -39)

[Dave1]

What version control are you using? Are you sure your z isn't moving .0001??? Are you programming in metric? Need more info.
Dave

[Captain Midnigh]

I got my threads cut with single line programing, but I still can't get a sub program to work. (If enough monkeys, push enough buttons, or somthing like that.)

[Ben Colby]

I'm assuming from previous posts, you're using a Centurion IV.
Are you using a thread mill or a single point threading tool?
Can we see the code that worked for you?

Regards,
Ben

[Captain Midnigh]

Hi,
I'm thread milling again. Can someone help me write a thread mill program? Pardner 4 Centurion 4 controler. Single point cutter, metric, 26mm left hand thread, 1mm pitch.

[Ben Colby]

I've never written this code in metric before but I think you are missing some code.
I believe you need a G71 in your main before your sub and/or in the sub. This enacts the
Metric Mode on the controller. The Z in the Helical statement is the pitch of the
thread.1mm (.03937 your pitch) multiplied by the number of sub routine loops (lets say 10 loops) would give you .394 or 10mm worth of thread in Z.

Cutter compensation cannot be used with Helical moves with the Centurion IV.

As far as the thread being left handed, I would guess threading from bottom to top or
running the spindle in reverse?

Good luck and keep us in the group posted of your results;

Ben

[Captain Midnigh]

Programed and run in metric mode. Cutter comp off. Clockwise spindle. Cut from botton up. Can not enter more than 1mm pitch in one pass, or it will cut the pitch larger than 1 mm.

[Ben Colby]

Are you cutting an internal or external thread? How long is the thread?
Can you post your code.

Ben

[Captain Midnigh]

External, 16 threads.

1001 G92 X0 Y0 Z0 (Set floating zeroes)
1002 S1200 M3 (Start Spindle)
1003 GO X-16 (Move to clear part)
1004 GO Z-20 (Z down to start of thread)
1005 G1 F4 x1.920 (Move in to start cut)
1006 G801 L16 (Call subrutine 16 loops)

9001 701
9002 G3 R15 I15 J0 X-15 Y0 Z1 (Makes one thread, then no Z movment)
9003 701

[Ben Colby]

I've never written a program without Tool Length Offsets (TLO) so I'm not sure how the
control would respond without them, particularly when jumping in and out of a sub.
Your code also does not define absolute G90 or incremental G91 program mode.
I always start in G90 and switch to G91 if I'm going to use incremental commands.
I also set my G92 in Mdi and don't include it in the program unless I I'm changing to a
different workpiece, but that's not causing you a problem. I set my G92 in mdi because
if you were to jog the machine between parts and not send it back to program zero, it
would create one where you jogged it. Back to the threading problem.

I would try the program using a TLO. Set the tool on the top of your workpiece and
enter the data into the tool register Z setting ( item #6 in your menu.)
Then enter it into your progam
1003 G90 (absolute mode)
1004 G101 G300 P.1 (Call TLO#1, set Rapid plane too .100 above top of workpiece)
1005 G99 (rapid TLO#1 to R plane)

At this point I would try G91 before jumping into the sub or as the first line in the sub.

Remember to switch to G92 in the main after the sub finishes.
You will also need to remove the TLO in the main after the tool is finished.
G92
G100 (remove TLO)
G0 Z0 or G98 to retract spindle to G92 setting.
M5
M2

I hope this helps, because I honestly don't see anything wrong with your subs helical
code. I'm also not sure about the G91 mode but it makes more sense too me than G92
for your helix. I'll try it on my machine if I get chance.
Please post results,

Ben