Need some help with a G84 Rigid Tap *Left Hand*

Hi guys (and gals),

This is my first post, theres definitely alot good info on this forum, and hopefully someone can help me out.

I've been using a G84 cycle for rigid RH tapping for a while. Now I need to do a LH tap. When I try and make the spindle direction CCW with M4 ahead of the G84 line, it starts in CCW and threads to Z stop, but then it doesnt stop and reverse the spindle. Naturally when it retracts it then pulls the tap and the part out of their holders/chuck. I've used the G32 and a floating tap collet, but the tap always comes loose from the set screws in the collet, and breaking taps is no fun. I really dont want to use the G32 cycle.

Example for a 1/2-20 RH Thread: (Works great)
/N300T0707(TAP)
/M8
/G0Z.400
/X0
/G99
/M29S300
/G84Z-1.375R-.200F.050
/G0Z1.0
/G28U0
/G28W0
/M1
/M5
/M9

Example Ive been trying for 1/2-20 LH Thread:
/N300T0707(TAP)
/M8
/G0Z.400
/X0
/G99
/M29S300M4
/G84Z-1.375R-.200F.050
/G0Z1.0
/G28U0
/G28W0
/M1
/M5
/M9

The machine is a DMC DL8T Turning Center. The control is a Fanuc Oi Mate-TD

Thanks for any help, Mike

Try G74.

Sent from my SAMSUNG-SGH-I747 using Tapatalk

G74 is a Peck Drill Cycle on this machine. Just tried again. Any other suggestions? The manuals that came with the machine say nothing of how to control the tapping direction.

You may just need to do it long hand

M4
G1 Z-1.375 F.05
M5
M3
Z0


Sent from my SAMSUNG-SGH-I747 using Tapatalk

You may also need to add a dwell after the M5

Sent from my SAMSUNG-SGH-I747 using Tapatalk

I tried running it manually like that as well. The sync on accel and decel of the spindle is off enough to pull the tap out of an er32 tap collet on retract. about .010 - .015" per cycle. it didnt hurt anything on steel parts until the tap came out far enough to crash into the workpiece. On the aluminum parts im running now I have the chuck pressure lower so it doesnt crush the backside of the part, and it pulls the part in the chuck rather than the tap now, but marrs up the finish pretty good.

Are you using a floating tap holder?

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I'm not currently as the machine supports rigid tapping. I do have a floating tap collet for this, but would rather not use it. The set screws failed me on previous attempts. But I may be stuck with using one if I cant find a solution

Try this. Air cut it first so you don't damage any part or tool.

/N300T0707(TAP)
/G97M4S300
/M8
/G0Z.400
/X0
/G99
/G84.3Z-1.375R-.200F.050
/G0Z1.0
/G28U0
/G28W0
/M1
/M5
/M9
..


Uly



*Edit: Nope, just tried it. Didn't work.

I tried this as well. Improper G-Code is stated.

There may be an M-code for inverse spindle rotation. Some of the Doosan lathes I'm familiar with use an M72 to reverse the spindle rotation for LH tapping then M73 to cancel when finished. This code may be different on you lathe.

/N300T0707(TAP)
/M8
/G0Z.400
/X0
/G99 M72
/M29S300
/G84Z-1.375R-.200F.050
/G0Z1.0M73
/G28U0
/G28W0
/M1
/M5
/M9

That sounds interesting. The M72 and M73 dont work on this machine, it just pauses the program at that point. I wish I could find a complete list of M-codes for this DMC. The manual doesnt have everything listed, like the M29 for rigid tap mode.

Quote:

---

Originally Posted by Mbraasch

That sounds interesting. The M72 and M73 dont work on this machine, it just pauses the program at that point. I wish I could find a complete list of M-codes for this DMC. The manual doesnt have everything listed, like the M29 for rigid tap mode.

---

Like I said... may be different...

Have you tried contacting DMC? I think the phone # is 847-741-7100.

Update, Got it working!

I did try contacting DMC, with no luck. I asked my machinery sales company to get some info, they got back to them real quick, which in turn was forwarded to me immediately.

Turns out I needed to change a keep relay to an on position. Keep Relay 5.1 needs to be 1 instead of 0, for anyone's future need.
This change activated Rigid Left hand Tapping. It also then made my M29 command, which was rigid RH tap enable, become the LH thread command. And now, M28 is rigid RH.

The G84 commands work exactly the same.

dcoupar and uperez, thanks for contributing, and trying to help some. I really appreciate it.

Quote:

---

Originally Posted by Mbraasch

That sounds interesting. The M72 and M73 dont work on this machine, it just pauses the program at that point. I wish I could find a complete list of M-codes for this DMC. The manual doesnt have everything listed, like the M29 for rigid tap mode.

---

Tapping is operation of making internal threading in existing hole. It is similar to drilling process , only there is requirement of existing hole to perform the operation . friends here we see the fanuc G74 left hand peck tapping cycle . It is also known as reverse tapping cycle and counter tapping cycle.

Parameter of left hand peck tapping cycle :-
XY- XY position where operation will perform .
Z - Operation perform depth .
Q - Depth of each cut .
R - R plane position .
F - Cutting feed rate
G74 and G84 cycle are used for tapping operation but difference is G74 is used for left hand tapping and G84 is used for right hand tapping .
O4231

N10 M06 T07 ;

N20 G90 G80 G17 G00 G54 X20 Y20 ;
N30 G43 Z100 H11 ;
N40 M04 S1500 ;
N50 M08 ;
N60 G99 G74 Z-55 R5 Q20 F2.5 ;
N70 G98 G80 G00 Z100 ;
N80 M05 M09 M30 ;

FOR DETAILS MY LINK IS -
WWW.HDKNOWLEDGE.COM