I've seen "carbon steel", "heat treated carbon steel" (is that same as
HSS?), and "alloy steel" tap & die sets. For relatively low-use, does it
matter which type I buy? Any suggested sets/sources?
The material I will work on is cast iron (as in TS top), sheet steel (as in
the legs of the TS), and aluminum bar. The most critical use will be to
cut threads in sheet steel for adjustable feet on heavy tool tables.
Along same lines, is titanium worth 20% extra or so on fortsner bits?
TIA. -- Igor
You can't have too much quality in taps and dies. Shop around and perhaps
buy just the sizes you need. One rarely uses all the sizes in a set. You
may also save on handles, even find them at yardsales, since they don't do
the cutting. My best taps actually came from yardsales...quality I'd hardly
be able to afford.
Cast iron is very hard.
Get some good real cutting oil.
Yes - all except HSS are rubbish.
My advice on taps and dies is to only buy _top_ quality (Presto in
the UK) and to buy them as you need them. A single die, or a set of
three taps (taper, second and plug) aren't that expensive and they
last well. These days threads are pretty standardised (especially in
Europe) and so you just don't need many. I do all my work with maybe
four different thread sizes, even though I've a full range to choose
If this was rec.model-steam-engines, then it would be a different
story. Then you need a full set, just to get coverage.
Three flute taps are less easily broken than two or four flute. spiral
flute are just for machine tapping and are hard to use by hand.
Always use a good tapping lubricant on steel. Use the right action too
- half turn forward, quarter turn back to break the chip. M3 and
smaller are consumables - buy a couple of second taps at a time,
because they are easily broken.
No. In principle it is, except that you don't need it on woodworking
tools, and that these days it's just shorthand for "tarted up
rubbish". When buying Forstners, buy some that are _sharp_ - this is
a hard thing to find these days.
Properly called "starting", second & plug (or bottoming). A true
taper tap cuts threads on a tapered hole, e.g. for a boiler stud.
(this is a pet peeve of mine, and given that both boiler studs &
taper taps have been obsolete for 50 years, a moot point).
What about tapered taps for pipe thread? That is still a common beast.
But also from McMaster Carr:
The chamfer is the reduced thread height at the front of the tap that helps
guide the tap into the hole. There are three types:
Taper Chamfer- Has 7 to 10 chamfered threads. Commonly used in
through-holes and for starting threads.
Plug Chamfer- Has 3 to 5 chamfered threads. Use them in through-holes
as well as in blind holes with sufficient space at the bottom for chips to
Bottoming Chamfer- Has 1 to 2 chamfered threads. Use in blind holes
where threads must come as close to the hole's bottom as possible.
Semibottoming and modified bottoming chamfers are similar, but have 2 to 2
1/2 and 3 to 4 threads respectively.
Looks like Andy was correct.
About the time I had mastered getting the toothpaste back in the tube, then
All steels contain some amount of carbon. All steel needs to be heat
treated to be hard enough to cut more than one thread, so all carbon steels
used in tools need to be heat-treated to make them worthwhile.. All steels
have some "alloying" metals in them, so all steels are alloy steels. "HSS"
usually means "high speed steel", or a steel that has the correct properties
to allow use in high-speed machinery (clearly overkill for hand tools).
I think this is a good example of "you get what you pay for." If you buy a
"made in China" set from Harbor Freight of the like, you can't really expect
too much. On the other hand, top quality taps & dies are VERY expensive.
The approach that I took was to buy a cheap set, then as I used them over
the years, those that I used a lot (not many, as it turns out), got replaced
as they wore.
This seemed to work for my low usage level.
The steel is going to be the worst to tap. Cast Iron and Aluminum are the
easiest on your list although you should ALWAYS use some type of cutting
fluid. Motor oil works just fine if you have nothing else around. Aluminum
will break any tap without fluid. It sticks real bad.
Now... As for teh taps. Buy the highest quality you can but try to get
only the sizes you need or you'll be spending a fortune. See if you can get
them all with teh same size handle "interface" so you only need a single
handle. Use smaller handles than required to avoid accidentally beraking
taps from too much manual torque.
Careful and slow is better than fast, efficient and a broken tap.
Joe Agro, Jr.
My eBay: http://tinyurl.com/4hpnc
Get the high speed steel. For starters you can just buy the taps and the
tap drills. If you have a machine shop supply house in your area this is
the place to go, you will find better prices than the hardware store. Also
for your tap drills buy stub drills. These are shorter than jobbers length
so they tend to wander less.
It also helps start the taps if you make a tapping block. What this is, is
a block of steel or aluminum that you drill holes into on your drill press.
The holes are sized just to clear the major diameter of the tap. you hold
this flat against your work piece and insert your tap in the hole. This
allows your tap to start straight.
You mentioned tapping sheet steel. You don't get real good results when the
material you are cutting thread on is much less than one diameter thick.
Often you are better off using a screw and a nut or a product called a
riv-nut. A riv-nut is kind of like a pop rivet but it has threads inside.
About the time I had mastered getting the toothpaste back in the tube, then
After reading all the stuff said about taps/dies I would add my very
cheap 2 cents worth. Buy the best you can afford if you are cutting
new threads in stuff, but the real cheap sets are great for chasing
threads. I used to use a very cheap chiwanese set on the farm for
cleaning up threads on equipment. They got lost and broken a lot so
cheap was good. It is rather hard on a good die to run it down a rusty
bolt with munged threads that has been down in the dirt and manure.
I would also add that, while you may only really need a couple of
sizes consistently, I found that I used virtually every size out of a
65 piece set over the course of a couple of years. YMMV
There's nothing wrong with the advice you've been given so far. It always
pays in the long run to buy quality. However, I feel it bears mentioning
that I've been using the same el-cheapo Vermont American tap and die set
from Lowe's for, I don't know, maybe 6-7 years.
I'd say mine qualifies as "relatively low-use" but not "low use." I use
them fairly often, but not often enough to make it easy to justify going
out to spend $100 or so for good stuff. By "fairly often" call it "I use
them an average of about 25 times a year."
I've gotten quite a lot of use out of the thing, and I'm surprised it has
lasted this well. I've been meaning to get a new set, or get some quality
individual pieces for years, but really it's a low priority back burner
Michael McIntyre ---- Silvan < firstname.lastname@example.org>
Linux fanatic, and certified Geek; registered Linux user #243621
Speaking of taps...
I got tired of not being able to find my tap/drill/screw
reference card (I think I must have put it in some "safe" place.)
When I finally did find it I saved a copy on my web site with a
link at http://www.iedu.com/DeSoto/CNC /
Now if I can just find my drill size chart, I think I'll do the
same with that...
Normally that'd be a great idea. The problem is that this shop is
wide open during warm weather and between the breeze and my
neighbors' propellers, paper doesn't seem to want to stay where I
put it - especially if I put it on a wall.
By stuffing it out on the web, I get to look at it when I need
to; and it's there for other people to use, too. B'sides, now it
lives in someone else's (server) shop. (-8
I long ago put this one in the forget it mode.
For all taps, #4 thru 1/2", I've made the problem go away.
Took a scrap piece of walnut, then drilled two lines of holes, front and
back, to accept the tap drill and the tap as a pair, in the sizes mentioned
Life is too short to sweat the small stuff.
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