What's new
What's new

LH Rigid Tapping on Mitsubishi Meldas 500 Puma Lathe

runninwideopen

Aluminum
Joined
Oct 31, 2014
Hi all,

I've gone from scratching my head to pulling my hair out. I can't figure out how to get LH rigid tapping to work on this machine. I've tried the following things I've found on other threads.

M4 spindle rotation before my G84 - Starts off correct, spindle does not reverse at the bottom of the hole.
G74 - Program stops. No error. Nothing happens.
G84.1 - Bad G Code
G184 - Bad G Code
G88 - rapids in, then rapids to next position without threading out of the hole.

The book doesn't seem to mention reverse or LH tapping at all. If anyone has any other suggestions or another helpful thread that I haven't found yet, I'd appreciate it.
 

Camputer

Aluminum
Joined
Feb 5, 2020
We do a lot of left handed tapping here. I'm not sure if your machine is the same but our Doosan's fanuc control has a specific M code for this.

Here's a sample

G97
M29S200P11
M176
G84X0Z-1.100R0.F0.04167
G80
M177
G0Z0.11
M5P11

The M176 signals reverse spindle, so it becomes a LH tap cycle.
M177 sets it back.
 

DouglasJRizzo

Titanium
Joined
Jun 7, 2011
Location
Ramsey, NJ.
Hi all,

I've gone from scratching my head to pulling my hair out. I can't figure out how to get LH rigid tapping to work on this machine. I've tried the following things I've found on other threads.

M4 spindle rotation before my G84 - Starts off correct, spindle does not reverse at the bottom of the hole.
G74 - Program stops. No error. Nothing happens.
G84.1 - Bad G Code
G184 - Bad G Code
G88 - rapids in, then rapids to next position without threading out of the hole.

The book doesn't seem to mention reverse or LH tapping at all. If anyone has any other suggestions or another helpful thread that I haven't found yet, I'd appreciate it.

M176 is motor polarity reverse. M177 is Motor polarity forward. On 2011 and newer Doosan's you would put the M176 on a line by itself BEFORE the M29, then, AFTER you cancel with a G80, you have an M177 on a line by itself.

On the Mits it "might" be different, check your M code list for "Motor Polarity."
 

runninwideopen

Aluminum
Joined
Oct 31, 2014
M176 is motor polarity reverse. M177 is Motor polarity forward. On 2011 and newer Doosan's you would put the M176 on a line by itself BEFORE the M29, then, AFTER you cancel with a G80, you have an M177 on a line by itself.

On the Mits it "might" be different, check your M code list for "Motor Polarity."

I should have mentioned, this is a 1997 Daewoo. It doesn't appear to have any M codes > 99, and it doesn't appear to have motor polarity codes.

I was about to move this job over to a Haas, but I went and talked to the guy that I bought this machine from. He doesn't think it can do it, but he loaned me a floating tap head so I can use G32 instead.

I'm off to the races, but I'm bewildered that they would make a machine with rigid tapping to only do RH threads. I really like the mechanical elements of this Puma, but I very much dislike the Mitsubishi control.
 

Vancbiker

Diamond
Joined
Jan 5, 2014
Location
Vancouver, WA. USA
Did you include D-1 in your code? Here is a clip from a Meldas lathe programming manual.....

Whether to carry out forward tapping or reverse tapping when executing the synchronous
tap cycle is determined by the sign for address D. (Positive: forward tapping, negative:
reverse tapping) If there is no address D command, forward tapping will take place with
the 1st spindle. If the 1st spindle is not serially connected, a program error (P182) will
occur.
 

runninwideopen

Aluminum
Joined
Oct 31, 2014
You nailed it! Thanks. I do see the D shown as a variable in the book for G84 but I do not see a description anywhere, what it means, or what range it would be.

Did you include D-1 in your code? Here is a clip from a Meldas lathe programming manual.....

Whether to carry out forward tapping or reverse tapping when executing the synchronous
tap cycle is determined by the sign for address D. (Positive: forward tapping, negative:
reverse tapping) If there is no address D command, forward tapping will take place with
the 1st spindle. If the 1st spindle is not serially connected, a program error (P182) will
occur.
 








 
Top