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)?
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
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'.
formatting link
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.
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
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:
formatting link
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. $99.00. There are other models for
auction of course. #1 style E is what you want. It should come with
collets.
ERic
Eric
bobm46 fired this volley in news:jjt1in$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.
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