[ceaser902]

High im new to this forum and i wasnt quite sure where to post this.
I have been recently working on tapping a 3/8-18 npt pipe thread in a piece of plate steel .497'' thick. my program first drills a 9/16 inch hole, then a special tapered carbide endmill reams the hole tapered. then a
3/8-18, hss, interrupted, tin coated tap cuts the treads in one shot. the problem is the tap tears out the threads about one out of ten parts. I got out the programming manual (we normally wright programs by hand for the mills) and tryed to use a rapid peck tapping cycle g84.2 instead of normal g84 rigid tap cycle, but the machine did not recognize the g code and allarmed. Ill put my code examples below btw i think the machine has a fanuc 15 or 16 control.

All my other coworkers are baffled and confused and the engineers got no clue and left it in my hands I suggested a form tap, but have never heard of one for pipe theads.

WORKING CODE(cant remember my spindle speed but im sure speed and feed is correct as machine has no trouble with other parts during tapping)

N1 G??M29
N2 G98 G84 Z-.8 F5. R.1

CODE THAT ALARMS

N1 G??M29
N2 G98 G84.2 Z-.8 F5. R.1 Q.1

alarm comes up as invalid g-code

any help would be appreciated as we really would like the machine to have a chip breaking tapping cycle . the book lists the g84.2 as standard option with a vauge citation about 15 controls. only thing i can think of is manually pecking in and out then dropping my z. but its a large batch size and thats a lot of time. Maybe a parameter is set wrong?

[Praymond1209]

You might try thread milling instead of tapping