How bad is 0-80 to tap in aluminum?

Spehro Pefhany fired this volley in news: snipped-for-privacy@4ax.com:
Maybe with a 65% thread clearance hole, but I wouldn't. Hell! 0-80 is small enough to break just by thinking about tilting it off-axis. How would you get it straight with a hand-held drill?
What's the matter with chucking it up in a finger vise, and doing it that way? At least, then you could use a drill press to get your initial alignment.
LLoyd

Mostly to save time, and because I've gotten away with it on larger taps, but your point is well taken.. much off-axis force is going to be fatal, and there won't be much 'feel' with a heavy drill.

I tapped quite a bit of 2-56 in 6061 using Alum-Tap fluid on a CNC with rigid tapping. I used some $8 spiral-point taps to push the chips ahead. The CNC guaranteed alignment straight over the hole.
There is a limit to how deep the hole can be for any particular tap size, or the chips start to pack up and that's when you break the taps. The tap manufacturer should have data on that.
The smaller the tap, the more critical the alignment parallel to the hole becomes.
Jon

You're giving me stomach cramps just thinking about it.
Unless, of course, your goal is broken taps -- in that case, go ahead and have fun!

A roll tap wouldn't produce any chips.

SmallParts used to (maybe still does) sell some magic wax that you put down a blind hole, then tapped. The idea was that as you tapped the wax would be deformed and push up the tap flutes, taking the chips with it.
Cool (and expensive) as all get out. I have no idea how well it works, or if it's available in #0.

I took the handle off a tap wrench and then pressed a 3/8 socket on the end. Then I use a speed wrench for the handle. Holds the tap nice and square. I can't remeber *ever* breaking a tap with this, haven't went 0-80 but i wouldn't be afraid to have you try it
Karl

One of those offset handle things? That's REALLY scary.
But if I could find a way to fit to my little 3.6V Hitachi DB30L (hex shank drive)... it might be okay. It has a clutch, rocker reverse and is light enough that there could be enough 'feel'.
Thanks, off to the drawing board (well, CAD package).
Best regards, Spehro Pefhany

I occiasionally have to do a few hundred M2 threads into some small 2mm ally plates for mounting some optical encoders onto.
The M2 is only a little bigger than what you have to tap.......
I have mounted the guts (motor & chuck) from an old battery drill to a piece of wood.
In line with the axis I have a ball bearing drawer slide with a right angle bracket attached.
The bracket has a hole in it for the tap to go through.
The drill motor is wired via a reversing toggle switch to a PSU.
I hold the part to be tapped against the bracket and use the draw slide to feed it "on and off" the tap. I can tap a hole in probably 3 seconds. The drill motor is probably dong a few hundred RPM. It works a treat.

Spehro Pefhany wrote in news: snipped-for-privacy@4ax.com:
Unless you have ton of them, I'd do 'em by hand with one of these:
Doug White

Yep. I like it. Got the idea here when I had a about a zillion taps to do in an electric panel. I found it fastest to have a drill for the holes and the speed wrench tap. better than two drills. I did a fair amount of 4-40 nothing smaller for my experience.
YMMV
Karl

6061-T6 or a softer version?
First off -- unless you include spiral point (or "gun tap") in your description of "good quality coated tap" -- forget it. You need a tap designed to chase the chips ahead of the tip, or a spiral flute tap designed to chase the chips back out the starting side to go continuous feed. Other taps need to be reversed every half turn or so to break the chips or they will clog and break.
Second -- you need something which will hold the tap straight (especially for something as fragile as an 0-80) (which, BTW, you only mentioned in the "Subject: " header, and some newsreaders stop displaying the "Subject: " header once you are into composing a reply).
The ideal thing is a smaller (say 30X) TapMatic tapping head, which can be set to limit the torque so when a tap dulls it will stop turning. And when you set it up, use the depth stop to stop the feed of the assembly at a proper point. The tap will self-feed for another couple of turns or so (maybe four with 80 TPI) and then disengage a dog clutch so the motor keeps spinning but the tap stops. When you withdraw the quill the tapping head will switch into reverse, and back the tap out faster than it went in. It works fine in a drill press (once you set up a stop for the reaction arm sticking out the side of the head).
eBay auction # 280843542733 has an example of the right size, 30X -- #0 through 1/4" taps. This one has a break in the collet closing cone, and I would probably go for a different one, but this is an early one with good photos. No clue as to what size arbor it has, but those can be replaced.
To get a tap a little less fragile, look into "thread forming" or "thread rolling" taps (which need a different size tap drill, BTW. But in 0-80 size, I still doubt that you could hold the drill stable enough to avoid breaking it. Especially considering that you need to reverse the drill motor to back the chip out, and many have reverse switches which are hard to switch without joggling the angle of the drill motor and thus breaking the tap.
Good luck, DoN.

Thanks for the comprehensive reply, DoN. I agree about the reverse switch- the little guy has a rocker, which is a lot smoother.
My local guy has a self-reversing head for

While I could be wrong on this, given the fairly thin material, I suspect you might get away with it.

Spehro,
The sanity, or lack thereof, is more likely associated with runout and hand shake of cordless drill.
Bob Swinney
Looking at using some relatively small screws tapped into (probably) 6061 aluminum. Through holes, maybe 0.08" of material. Is it insanity to think about using a cordless hand drill and run them right through without backing off (assuming a good quality coated tap and aluminum cutting fluid)?

Greetings Spehro, If you're gonna use a tapping head check out a Procunier head. These heads only have cone clutches in them and do not self feed. The harder you press the more torque to the tap. Though I have Tapmatic, import Tapmatic copies, Ettco, and Procunier heads in my shop I use the Procuniers the most. One Procunier head I have is over 50 years old and still works great. It's the smallest size and it has tapped many 0-80 holes. This head might be perfect: bolts up to an electric motor. Procunier heads will run horizontally without problems. In fact, if you don't but it I may. It's the correct size, number 1. And instead of collets uses adrill chuck. You just hold the parts in your hands and push them onto the tap and then pull them back off. $99.00. There are other models for auction of course. #1 style E is what you want. It should come with collets. ERic Eric

You could try chucking the tap in a drill press (NO POWER) to get straight then turning the chuck by hand.

bobm46 fired this volley in news:jjt1in$sep$1@dont- email.me:
You won't have much 'feel' there on something that small.
Better to loosely chuck a pin vise in a drill press, and simply use the press as a tapping stand.
LLoyd

Looking at using some relatively small screws tapped into (probably) 6061 aluminum. Through holes, maybe 0.08" of material. Is it insanity to think about using a cordless hand drill and run them right through without backing off (assuming a good quality coated tap and aluminum cutting fluid)? __________________________________________
Go for it! Removing broken taps won't be that bad. Try a drill guide to keep them straight. Even wit broken taps it will be faster than any other method.