General Tap question....
 

The standard hardware store has one kind of tap.

If you look in a machinists catalog there is a bewildering array of
taps.

So my question is something like?

Can someone give me the 5 min class in what kinds of taps are used for
what?


Do you use a different tap for
Aluminum?
Steel?
Plastic?


When do you use a 4 flute, when do you use a
tap with other than 4 flutes?

What is the strongest tap (aka one I won't snamp off)

Any taps with a leading guide pin that aligns with the hole for hand
tapping?


What is a roll tap?

Paul

You can use a Plug tap (the common hardware-store type) for just about
anything. The chips clog it quickly so you need to remove and clean it
whenever it gets a little harder to turn. Maybe you have to break a few
to get the feel for them. I back off when I can see the flutes
twisting.

A Gun or Spiral Point tap pushes the chips forward into the hole so you
can turn it continuously in a through hole, but these chips are
difficult to pull out of a blind hole. If you have trouble getting a
plug tap to start cleanly (sometimes they just want to ream the hole)
try a gun tap for a few threads. Or replace the dull tap.

Use a Bottoming tap after the Plug tap to extend the threads nearer to
the bottom of a blind hole, if you can't drill deeper.

A Spiral Flute tap sends the chips out the top like a drill bit. I
understand that they are more brittle than straight flute taps but I
like them for aluminum.

Thread-forming or Roll taps squeeze the threads into the metal instead
of cutting it, so they are cleaner and can be run all the way into a
blind hole in one stroke. I haven't tried them myself and the one time
I got a job back where the shop had used them the threads weren't very
good.

The strongest? That may depend on the maker rather than the type. I
like Greenfield when the company is paying for them but my personal
stock is mostly cheapies or second-hand good ones that I have reground.

Simple & effective tap aligner:
http://www1.mscdirect.com/CGI/NNSRIT?PMAKA=06593016

Or you can drill shank-sized holes in a block to make your own tap
guide.

jw

Very small taps require very little cutting force, so there's little likelihood
of breaking them. Big taps are very strong and breakage usually involves just a
tooth not the whole thing. In my home shop experience I see broken taps mostly
in a small range of sizes maybe no. 10 up to 5/16" but MOSTLY 1/4-20. When I
design a project nowadays that has a lot of tapping I try to do two things:
design it with through holes and design it with 3/8-16 threads or bigger.

The Enco hand tapper at $79.95 with free shipping is really a very good deal. I
have one and although I did have to monkey with it a little to get the little
ball/spring attachment to work at all, now it works to hold the tap holders in
and the overall machine works very well. Of course, the first tap I wanted to do
was a No. 12 (dang, they didn't provide that one) and the next one was 9/16"
which they don't provide either. Go figger.

There are taps which you use by hand, and then there are taps you run with a
machine under power. Most of the exotic taps are in the latter category. Stick
with Greenfield or Cleveland or Nachi or the like and just buy 4-flute taps in
taper, plug and bottoming. Spend a little effort to make real storage for them
in your shop. I have said it many times and I'll say it one mo taps and dies
are one place where you do NOT want to buy cheap import, you want the best you
can get. Always use tapping fluid, and when it's a critical hand tapping
situation, get helpers to watch you to make sure you start the drill motor square.

GWE

wrote:
The standard hardware store has one kind of tap.

If you look in a machinists catalog there is a bewildering array of
taps.

So my question is something like?

Can someone give me the 5 min class in what kinds of taps are used for
what?


Do you use a different tap for
Aluminum?
Steel?
Plastic?


When do you use a 4 flute, when do you use a
tap with other than 4 flutes?

What is the strongest tap (aka one I won't snamp off)

Any taps with a leading guide pin that aligns with the hole for hand
tapping?


What is a roll tap?

Paul

you comment that breaking taps you've broken
MOSTLY 1/4-20.

I mostly build small stuff....
It seems like some tap sizes are more fragile than others....
I don't think I've ever broken a 4-40 or 10-32,
I have broken several 6-32 and 1/4-20's
(About the largest hole I ever tap)

Are some taps sizes more prone to breaking than others?

Paul

In article , says...

What is the strongest tap (aka one I won't snamp off)

I favor two (or three, for the larger sizes) gun taps
in HSS. These work best for through holes but often can
be used in blind holes with a bit of fiddling.

Purchase ground thread taps in this form from reputable
manufacturers like greenfield, etc and you will be suprised
at how much better they work than hardware store stuff.

If you are having trouble snapping them off, check that:

1) you are drilling with the correct size tap drill. Bigger
is easier.

2) you are using the correct cutting fluid for the job. Do
NOT use a lubricant for this like engine oil, ATF, or any other
lubricating oil. You WILL snap taps if you do that.

3) you are setting the tap up square to the hole.

4) you are backing the tap off after each turn if you
are using four flute taps to break the chips.

Give some specifics about the failures and folks can make
other suggestions.

Jim


--
==================================================
please reply to:
JRR(zero) at pkmfgvm4 (dot) vnet (dot) ibm (dot) com
==================================================

--FWIW I *never* use 4-flute taps; too prone to breakage, heh.
2-flute taps do for most everything and I use them manually or in a
Tapmatic all the time. A 1/4-20 tap is big enough that it can be held
by a VSR drill and this is damn handy for large work that needs lots of
holes tapped.
--The real secret tho is to have new, good quality taps and to
use lots of the right lubricant. For steel, brass, aluminum etc I use
Cool Tool II. For stainless I switch to Moly Dee.

--
"Steamboat Ed" Haas : You just can't beat
Hacking the Trailing Edge! : cruisin' in a steamboat
http://www.nmpproducts.com/intro.htm
---Decks a-wash in a sea of words---

Go here for a very cheap and easy to make tapping fixture.
http://www.ggls.org/TappingFixture/
Dave

wrote in message
...
The standard hardware store has one kind of tap.

If you look in a machinists catalog there is a bewildering array of
taps.

So my question is something like?

Can someone give me the 5 min class in what kinds of taps are used for
what?


Do you use a different tap for
Aluminum?
Steel?
Plastic?


When do you use a 4 flute, when do you use a
tap with other than 4 flutes?

What is the strongest tap (aka one I won't snamp off)

Any taps with a leading guide pin that aligns with the hole for hand
tapping?


What is a roll tap?

Paul

One thing not mentioned is tht H number on taps. This is the clearacne
rating of the tap with smaller numbers meaning smaller clearances. The
typical tap is a 3 and works well for most purposes.

--
Why do penguins walk so far to get to their nesting grounds?

According to :

[ ... ]

The strongest? That may depend on the maker rather than the type. I
like Greenfield when the company is paying for them but my personal
stock is mostly cheapies or second-hand good ones that I have reground.

The most likely tap to get broken is a carbon steel tap in the
6-32 size. This is because the thread is too coarse for the diameter.
Note that the 32 TPI is commonly found in three sizes -- 10-32, 8-32,
and 6-32. 6-32 should never have become a standard.

HSS is stronger than carbon steel.

Two-flute is probably the strongest of the ones available in
6-32, and for anything other than blind holes a gun tap would be my
choice.

Other than these comments, I think that the OP's questions have
already been well answered.

Enjoy,
DoN.

--
Email: | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
--- Black Holes are where God is dividing by zero ---

"Bob May" wrote in message
...
--
Why do penguins walk so far to get to their nesting grounds?



Because they can't fly, and they would swim but the water is not next to the
nesting grounds. They select nesting grounds for the climate or the fact
that there are less critters around that will eat their eggs or chicks.

That's my guess anyway.

--
Roger Shoaf

If knowledge is power, and power corrupts, what does this say about the
Congress?