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G84 rigid tapping on 1997 daewoo puma 200 with meldas 500 controller

C

cgrim3

Cast Iron
Joined
Dec 4, 2020
Location
Baltimore
Hi all,

We have never rigid tapped before on our cnc lathe but a job has come up where we need to rigid tap. The controller is meldas 500 on a daewoo puma 200 from 1997. I am form tapping a 3/8-24 thread. I have the following code:

N900 T0909 G54;
G00 X0. Z.2;
G84 S500 M3 Z-1.2 F.0416667 R.1 P0., R1
G00 G40 T0900 X10. Z6.
M1

I have the RPM info in the G84 line. I originally had it above the G84 line but the controller spit out a P181 No S-CMD (Tap) error. This is saying that the RPM info should be in the G84 line instead of above it.

Before trying to rigid tap, I did put ",R1" in the G84 line to call up parameter 29 which is auto sync tap.

When I start the program, the tool rapids to .2" in front of the part like it is supposed to. Then, the spindle tries to turn but it doesn't. The spindle does not turn and the tool doesn't move. I assume this is because in rigid tapping, the Z movement of the tool is linked to the rotation of the spindle, so since the spindle isn't moving, the tool won't move either. However, the control does not throw an alarm. What should I do to fix this?

Note: I can get the unsynchronized tapping to work fine (by taking out the R1) but the rigid tapping doesn't seem to work.

Any help would be appreciated.

Thanks,

Chris
 
Last edited:
OK.
Rigid tapping must always be done from a stopped spindle.
So -

M05;
T0303;
X0 Z.25;
G97S250M29;
G84 Z-.75 F.0416;
G80 Z2.;
etc

The M29 synchro tap is cancelled when the G80 is instated.
 
Hi Doug,

Thank you for the reply. Having the spindle stopped beforehand doesn't seem to be the problem. We have been testing out the rigid tapping in MDI so the spindle is stopped before calling up G84. I did try running the code you posted and the machine still won't do it. The reason why I did not use the M29 is because other forums said that, for mitsubishi meldas 500, to turn the parameter on, you have to put an ",R1" in the G84 line and it will run rigid tapping, but I am not sure how true this is. However, nothing has seemed to work. I have gotten nonsynchronous tapping to work though.

I am not sure how similar rigid tapping with meldas 500 is to fanuc but I am just doing what other members in other forums said to do. If anybody else has experience rigid tapping in meldas 500 on lathe, please feel free to chime in.

Thanks,

Chris
 
I'm not at all familiar with the Meldas control, but to have two R words on the same line doesn't seem right on any control.
 
Did you try giving it the feed with E instead of F?

What about adding a G99 to your G84 line?
 
Yeah I did turn on parameter 29 and it did work without the ",R1". For some reason I am not sure why, it won't work with the ",R1" if parameter 29 is turned off. But yeah, the machine runs fine when not using ",R1" but having parameter 29 on. Is there a way to tell if it is actually working and if the machine is actually rigid tapping because it just looks exactly the same as if I was nonsynchronous tapping.

And both the "E" and the "F" work fine. Since it is 24 tpi, it would be "E24" or "F.041667"

I haven't tried the g99. Let me try it in a couple minutes and I will let you know. Again, thanks for helping me out.

Chris
 
cgrim3 said:
.....I have the following code:

N900 T0909 G54;
G00 X0. Z.2;
G84 S500 M3 Z-1.2 F.0416667 R.1 P0., R1
G00 G40 T0900 X10. Z6.
M1

......
Click to expand...

My Meldas 50 equipped mill does not like an M3 on a rigid tap line. Since G84 is right hand tapping and G74 is left hand tapping the machine does not need to have M3 or M4 in the command line.

There may be parameter settings and maybe ladder logic could play into this to some extent.
 
We have the same machine with the same controller. Had the same problem and after much research, it turned out that the machine was not equipped with rigid tapping.
Make sure you have the option for Rigid tapping.
 
Vancbiker, I did try it without the m3 and the controller threw an error. G74 is a face groove cycle. You can left hand tap with it?

e723, how did you find out your machine did not have rigid tap? I'm going to call Ellison Technologies tomorrow to get more information. We bought the machine used a long time ago and am not sure if it has rigid tap or not. e723, does your machine still have parameter 29 which is synch tap even though your machine does not have rigid tap?

It would make sense to me that any machine that could do a g76 threading cycle should be able to rigid tap but I am not an expert in these things.

Thanks,

Chris
 
cgrim3 said:
Vancbiker, I did try it without the m3 and the controller threw an error. G74 is a face groove cycle. You can left hand tap with it?....
Click to expand...

My machine is a mill, but threw out the M3 idea as something for you to try. Yes, my mill will rigid tap right hand or left hand up to 6k RPM.
 
So without using ",R1" I just turned on parameter 29 and put E24 for the feed rate (since it is a 3/8-24 thread). The machine fed at correct feedrate until the end, but once the spindle reversed, the feedrate dropped to zero and the spindle just kept turning. It seems F works better than E, but I emailed ellison technologies the serial number of my machine and asked them if it did in fact have rigid tapping.

It is awfully finicky. It doesn't like it when you use ",R1" and E. It only works when you use F for feedrate and turn on parameter 29. When I try to use ",R1" the tool rapids in to where it is supposed to but the spindle locks up and can't be turned.

Thanks,

Chris
 
From what I remember, it made no difference with par. 29. We had no luck and after going thru the manual, rigid tapping was not purchased originally. We dont do any high production work, so for the last two decades its all been single point. We single point 4-40 all the way to1" and larger internal threads. No biggie at all.
 
cgrim3 said:
Hi all,

We have never rigid tapped before on our cnc lathe but a job has come up where we need to rigid tap. The controller is meldas 500 on a daewoo puma 200 from 1997. I am form tapping a 3/8-24 thread. I have the following code:

N900 T0909 G54;
G00 X0. Z.2;
G84 S500 M3 Z-1.2 F.0416667 R.1 P0., R1
G00 G40 T0900 X10. Z6.
M1

I have the RPM info in the G84 line. I originally had it above the G84 line but the controller spit out a P181 No S-CMD (Tap) error. This is saying that the RPM info should be in the G84 line instead of above it.

Before trying to rigid tap, I did put ",R1" in the G84 line to call up parameter 29 which is auto sync tap.

When I start the program, the tool rapids to .2" in front of the part like it is supposed to. Then, the spindle tries to turn but it doesn't. The spindle does not turn and the tool doesn't move. I assume this is because in rigid tapping, the Z movement of the tool is linked to the rotation of the spindle, so since the spindle isn't moving, the tool won't move either. However, the control does not throw an alarm. What should I do to fix this?

Note: I can get the unsynchronized tapping to work fine (by taking out the R1) but the rigid tapping doesn't seem to work.

Any help would be appreciated.

Thanks,

Chris
Click to expand...
G97 S 500(INCH_ 24 _TPI)
T1010(TAP)
M08
G00 X0.0 Z1.
G00 Z .1
G84 Z-1.200 R .1 F.0416667 S500 D1 ,R1 (RIGID_TAP)
G80
G00 Z1.
G00 X6.000 Z5.500 M09
(SUB_USING_SOFTJAWS_1.590_INCH)
G10 L2 P3 Z-.4450 (G56_OFFSET)
G97 S2=500 (SUB_SPEED)
M09
G28 U0. M119 (PART_IS_2.500 LONG)
G97 S300(SUB_1.000_ENGAGE)
M03
M114 S 300 (SUB_ON)
G114.1 H1 D-2 (SYNC)
G00 B-27.625
G98 F150. (PART_IS_2.500_LONG)
G01 B-28.725(PICKOFF_POINT)
M118 (SUB_CLAMP)
M69 (MAIN_UNCLAMP)
G30 B0. (SUB_HOME)
G113 (CANCEL_SYNC)
M05 (MAIN_OFF)
M115 (SUB_OFF)
N2000 (SUB_SPINDLE_START_HERE)
G44 (TEST)
G56 (SUB_WORK)
G99 F.010
G50 S3500 (MAX_ SPEED_SUB)
G00 X2.200 Z-4.
G97 S2=500(INCH_ 24 _TPI)
T1030(TAP)
M115
M08
G00 Z-1. X0.0
G00 Z-.100
G84 Z1.200 R-0.100 F.04167 S500 D2 ,R1 (RIGID_TAP)
G80
G00 Z-1.
 
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