On Wed, 21 Mar 2007 16:26:24 GMT, with neither quill nor qualm, Gunner
I haven't yet needed to use it, but it was missing some tap sizes if
you have extras. If so, I'll figure out what wasn't there.
Love the moment, and energy of that moment will spread beyond all boundaries.
-- Corita Kent
Great list of products, Unca George! I can add but little to it.
Brownells' sells a nice little tapping block similar to the OMW except the
shank holders fit individually into the block. www.brownells.com Taprite
Kit (tap guide), item # 357-001-000 $27.15
George has some really good advice on the depth of thread. I am not
sure where to find the information, but as the thickness of the
material increases you can decrease the depth of thread and still
break the fastner before stripping the treads.
Also on work hardening material as stainless, you really don't want to
back the tap up. Use a spiral tap or a gun tap.
As far as using a drill press............ I drilled a hole in the
back of a tap wrench and chuck a bit of rod that is the same diameter
as the hole in the drill press. The rod goes in the hole in the tap
wrench and keeps every thing aligned. Using the tap wrench to turn
the tap is easier ( in my opinion ) than turning the drill press by
If I have to drill and tap without using the drill press, I use the
drill press to drill a hole thru some scrap 2 by 4. Then use that to
guide the drill and the tap. You can just use the tap drill in the 2
I gotta say it again: VFD! A 3-phase motor & VFD are perfect for drill
presses. Being able to dial in the speed in an instant is obvious, but
none of the gizmo's mentioned are as good as a VFD for tapping. Put
the VFD on 5 Hz, chuck up a tap, and power it in! It's as simple as
changing the drill bit to a tap and turning down the speed! Spiral
point taps are best, but reversing is something a VFD does also, so
regular taps are almost as easy. I have a forward-reverse foot switch
that is nice, but not necessary.
V-F-D, V-F-D, V-F-D ....
Speaking of breaking taps, the other day I broke a 3/8" tap! This was a
3/8-16 (NC), HSS, H3 fit, almost new, Cleveland brand, spiral point, in
mild steel, 5/16 hole. The work was in a vise, so no unusual motion was
required, that might result in side force. I finished the job with an
Ace brand backup tap without any problems. Do you think that this might
have been a defective tap?
I spent the extra bux for a brand name & I shoulda saved my money.
HSS taps don't break as easily as carbon steel taps. Good taps (NOT
found at Ace) cut better and more easily than not-so-good taps. The
biggest key to avoid breakage is get the tap started centered and
straight, and apply only torque -- never bending moment. Always
lightly c'sink a hole before tapping. I haven't broken a tap from
00-80 up thru 3/4 in recent memory. The most fragile of the lot are
6-32, a terrible thread! Others have mentioned lube: always!
Enco makes a cheap device that is enormously helpful: look at
#325-5179. $12.06, now on sale for less. It's a spring-loaded guide
with a 1/2" shank. Many tap wrenches and some larger taps have a
centered dimple in the back. Stick the 1/2" shank into a collet in
the mill (need not be tight), or chuck it in a DP or tailstock chuck
in lathe. In the case of mill or DP, center the spindle over the hole
-- which it already is if you just drilled the hole. I have a chuck on
a 1/2" shank so it's easy to drop the chuck used for drilling and
insert this device, often without changing any heights. Set the tap
in the hole, lower spindle until the point on this dingus engages the
dimple in the tap wrench, then lower a bit more to compress the
spring. Now you can tap the hole, turning the tap to and fro at will
to clear chips. The spring-loaded guide will keep the tap straight,
resist bending or side forces, and will "follow" the tap so you need
only adjust height occasionally if at all. Result: far, far fewer
broken taps. Another advantage of this is that you don't lose the
"feel" of the tap because you're operating the (low mass) tap wrench
This is obviously not a "production" setup, but it works great for a
BTW, I have had this thing longer than I can remember and only
discovered tonight that it is reversable! Oy din't knew that! The
other end is a recessed hole to engage the pointy shank on some
smaller taps, don't know how you turn 'em then. Maybe a small wrench,
or perhaps a shop-made shank-grabber of some sort.
Don, this is very nice. Thanks for a good idea. I do not have a spring
loaded center, but I found a solid center that I can hold in the
chuck. Seems to work quite well, though getting it into the right
position is not as easy as with the tap chucked in the chuck.
On Thu, 22 Mar 2007 23:36:10 -0500, Ignoramus15474
Some sort of cutting fluid anyway. I prefer the proprietary
cutting/tapping juices like Tap-A-Matic, etc. Kerosene works quite
well in aluminum. Ernie has reported that limonene works beautifully.
I've not tried it simply because I've not yet found any. Oil works
well on larger coarser threading, as when threading pipe.
If the concentration need not be high, I think I recall that "Goof-off"
paint error remover is a mix of mineral spirits and A-Limonene.
I'll try some. I'm all the time tapping 6061 in 10-24 or smaller.
"Tap-Magic" doesn't really do the trick. I haven't broken a tap in a while,
but I'm always feeling like I'm on the verge, taking 1/8-turn cuts and
". . .I haven't broken a tap in a while,
Careful here. IMO (though not backed up with a great deal of tappping
experience) it would appear that the notion of "small turn and backup" can
be overdone. Intuition tells me that very small turns might leave fractured
metal ahead of the tap's cutting surface. It seems these unbroken chips
would be prone to jam between the tap and hole when backing up. ymmv.
Bob (taps like he lives, hard) Swinney
Yeah, I agree. I only take such tiny cuts when I have the feeling the
cutter is "gumming up" in the work. Usually, I'm working about 1/2-3/4 turn
per cut, but some slabs of 6061 have a whole different "feel" than others.
I think it must be the variations in temper between lots. But it scares me,
working on a piece that's got 10 hours of machining in it, and knowing -
just KNOWING - that if I break off a tap in it, that will be the very one I
can't get back out. And there aren't any EDM shops within 60 miles of me.
I almost always use spiral point gun taps, which don't require backing up. One
exception is when power tapping M8 holes in the ends of extruded aluminum Item
framing, which also exhibits the sort of variability you describe. While a gun
tap would sometimes seize in a particularly gummy spot, spiral flute taps have
taken all the worry out of the operation.
On Fri, 23 Mar 2007 11:13:47 -0400, Lloyd E. Sponenburgh wrote:
One cure for this is alter your order of operations. Do the riskier stuff
first (if possible), then if you ruin the part, you aren't as invested in
It's also possible to remove a broken tap from aluminum chemically. I
don't recall the liquid you'd use, but I'm sure someone here will know.
This has been discussed here in the past.
I know vinegar will remove steel, but I don't know if it would bother the
On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA
My hobby pages are here:
Visit the castinghobby FAQ:
The member map is here:
Absolutely the worst! It has too deep a thread for its
diameter, thanks to someone deciding to keep 32 TPI through three
consecutive common sizes. (Perhaps too lazy to change the gearing in
their lathe. :-)
Also -- yes.
[ ... ]
I've got one of these (came in an eBay lot of tools in an old
machinst's toolbox). But I haven't used it yet.
Yep -- the reversible feature is documented in the "manual"
which was still with this one -- suggesting that the original machinist
had not used it much either. :-)
I did recently drill and tap for 42 1/4-20 holes in some 1/4"
thick mild steel plate. I used the drill press, and for the tapping a
TapMatic tapping head. I also used some "TapMagic" original formula
(thanks Scott) as the tapping lube.
If anyone cares -- it was to make a new "apron" for a DiAcro 24"
bench shear. The apron and the back stops were both missing. I adapted
the stops from a much smaller (8", IIRC) shear, and had to make the
apron from scratch. I had to guess at a reasonable grid for the
threaded holes -- it was obvious that the pattern from the much smaller
shear would not work.
FWIW -- I can also say that the Acme threaded rod from MSC
machines nicely. I had to machine a 7/8" long 1/2-13 thread on one end
to fit the holes in the casting -- much larger than those in the tiny
shear, and I had to drill and tap the other end, to install stops to
keep the backstop adjusters from sliding off the end of the rods.
The finish on the Acme rod from MSC is black, FWIW.
Email: < firstname.lastname@example.org> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
I busted a brand new 1/2-13 Sossner tap last weekend while tapping a 1"
piece of 6061 in my Lassy Tapper.
Sossner is one of my preferred brands so I was extremely surprised.
Inspection under a micrscope showed it had been cracked prior to me
getting it and I simply finished it off.
"Liberalism is a philosophy of consolation for Western civilization as it
- James Burnham
Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here.
All logos and trade names are the property of their respective owners.