deep hole tapping problem

[ak_crabber]

well i started this new job the other day and they give me this part. its a simple turnbuckle.

its either 306 stainless or 318 stainless....not extremely hard metal. But i have to tap 2 holes on each end of the short rod....and the holes are to be tapped 3 1/2 inches deep.

the machine is a smaller Mazak mill and I'm a gcode programmer so naturally i had an issue from the get go. i guess EIA is ok. i found out there was no peck tapping canned cycle.

its to be tapped 1/2 inch -13. predrilling 27/64 was putting too much pressure on the tap so i went to 7/16. had it running fine with a special made tap (left hand tap that was 7 1/2 inches long)


anyway, i ended up breaking taps after about 3-4 parts

can you recommend me a tap that i can straight g84 it to the bottom without having to manually write out a peck tap cycle

basically my prog went like this

n3g00g90g54x0y0;
t18m06;
s70m4;
g43h18z1.m08;
g84g95g98z-.5r.1f.0769;
(repeated this line all the way to -3.5


should i try a hypro tap????

give me a recommendation of something that will pull the chips out and not break

[little bubba]

I really want to be a jackass, but EIA/ISO is G-CODE. You can't count on every machine having every little canned cycle your used to. They all differ, I wish they would standardize, but its not going to happen. Its all just syntax.

Your using multiple cycles to get to depth, thats fine, that is exactly what I would do.

To cure your problem, form tap it. No chips, no problem. I know its "stainless" but your in the 300 series, its about as hard as snot until you start moving it around. Run that sucker in there, one shot and done. You're probably in the custom tap size and length, plus the left hand, but the damn things last.

[Mitsui Seiki]

Try to add a Q value to G84 to get a peck tapping cycle.

[davereagan]

I tapped 160 1/2"-13 blind holes 1" deep in 316 stainless using a Vega Vanadium, Tin coated hi performance tap. I ran it around 70 rpm and pecked every .2" I would not dream of tapping deep without pecking, even if it was just cold rolled steel. I used Tap Magic Heavy but I think Tap Magic w/EP extra would have been ok. Flood coolant is out on stainless except 303.

[ak_crabber]

Originally Posted by little bubba I really want to be a jackass, but EIA/ISO is G-CODE.

understood......

Originally Posted by little bubba Run that sucker in there, one shot and done. You're probably in the custom tap size and length, plus the left hand, but the damn things last.

if it was that easy i wouldnt have made the post in the first place....

[ak_crabber]

Originally Posted by Mitsui Seiki Try to add a Q value to G84 to get a peck tapping cycle.

tried that but no....mazaks get mad unless you use mazatrol

[fuzzyracing1967]

I have what may seem a dumb question,but when are your taps breaking? The reason I ask is I had a simular problem once,( deep hole,stainless ).What was happining for me was the tap was breaking on the way out,the hole would close back up just enough that the tap would have to back tap on the way out.What ended up working was using trimtap heavy,(the stuff is like honey)to tap the parts,was a pain but it worked.

[HamerHead]

Use a roll tap.
I taped titanium 2" deep, with 1/4-20 roll tap on a Hardinge CNC lathe!
Used this white grease like compound for lubricant.
Forgot the name of it, it's been years.

[pdoherty]

Used this white grease like compound for lubricant

If it was many years ago, it was probably white lead. Works wonders on stainless tapping jobs, but obviously not a good plan from a heath & regulatory standpoint.

We use a product called 'white lead replacement' that is about 20% as good as the real thing.

[coolantman]

EnviroCut 2524 works great on stainless. Use straight!!