Interrupted thread pipe taps

[Black_Moons]

Hi, im wondering if interrupt thread pipe taps are going to be easyer to use? Im planing to buy some 3/8 and 1/2" NPT taps, mainly for taping in aluminum and UHMW plastic and other soft materials.. maybe with a very low desire to one day tap in mild steel. Right now taping just a 1/4" NPT hole in aluminum sorta stresses my tap wrench and arms.. im wondering if a interrupted thread pipe tap (shown here: http://ecx.images-amazon.com/images/...500_AA280_.jpg ) will be easyer to tap with since it has less teeth cutting at once? Or am I just being dilusional?
Should I just buy a bigger tap wrench (or make one) and buy normal pipe taps? the interrupted thread ones are a little more expensive.. not much however.

[.RC.]

That looks like a normal tap to me???

The feed rate when tapping/threading is fixed so it is going to take the same amount of power to cut the thread regardless....

[doc-zeus]

Several questions? I sure hope you are using a quality cutting fluid?

(I'm still surprised at how many "do-it-your-self'ers" come into our shop looking for help to remove broken taps or bolts, and act surprised when asked about cutting/tapping fluid. Others complain about dullling drills when drilling some metals, and seem surprised when we suggest a cutting fluid when drilling!)

? How small is your tap wrench? Usually if it's bigg enough to engage the tap, it is big anough to give you adequate leverage.

? Did you use a reamer prior to using the tap? There are special pipe tap reamers that should be used first! This will cut the taper first, so your tap isn't also doing that work!

If the answer to any or all of these questions were "What?", you may want to back up and start again.

[Black_Moons]

Tap wrench is about 12" across, yes I use cutting fluid and back off the tap

No I did'nt use a tapered reamer as I read that NPT taps did'nt need them, but I guess thats only true of 1/8 and maybe 1/4 in soft metals. I guess I should buy one for 3/8 and 1/2" NPT. (I have a project or two that involves NPT pipe taps into something 'kinda' blind (not throughhole) so I guess that means I need seperate reamers for each size)

ringer: its 5 flutes and every other thread 'tooth' is removed. but yea I guess I was being dilusional now that I think about it more...

Using 'rapidtap' general perpose taping fluid (says good for aluminum on the front...) I could get an exact name if you want.


but yea lol. when I was young I used to think metal was undrillable, after all, your drilling metal with metal! that can't work very well can it? And time and time again as a kid I proved myself correct when trying to drill steel, without lube, with my dads old bits that had been used extensively on wood... Id say it was more of a grinding operation then a cutting operation and that was when I was lucky enough to make progress.

Nowdays I ALLWAYS use oil to help conserve my drill bits, my only dulled bit so far was one that had an encounter with a weld lip, and even welds I have manage to drill through without much fuss as long as I remember not to drill an uneven weld (ruins the drill cutting lips with the impact). Mild steel drills like butter.