Confusion Of Style Of Taps To Purchase

In addition to the types mentioned, there are two others that I use often.
The first is a spiral flute for blind holes. The chips are pulled out of the hole.
The other, and my favorite for smaller size holes are form taps. Unlike the other types mentioned, the form tap presses or forms the thread with no chip. They use a different tap drill size chart. My experience has been with Balax form taps and (fingers crossed), I've never broken one even at 0-80 or 1-72.
 
Enco has Hertal HSS taps in 3 pc sets one each bottom, tapered, and plug, from 12-20 dollars a set from 4-40 up to 3/8-24. after that they get pricey. Almost always can find a 20% off coupon, and if your willing to wait a bit you can also get free shipping. Keep in mind it is hard to find plug and bottom taps at the big box stores.
Mark
 
i am not qualified to give a dissertation on the correct tap for every possible application. i will point out two things however. first is that taps are made in different dimensions for tighter or looser threads and second that i have never had a cnc (necked style) tap break. that is the only style i will buy
 
The nature of the metal determines the amount of money to spend on tap and dies. If most of your tapping is aluminum or brass, cheap is perfect.
If you are doing stainless steel you need to buy several high end high speed steel taps and dies of the same size because they will wear out fast.

4130 4140 will wear them down as well.

I used cheap taps on aluminum and brass and they never seem to wear out. A Chinese set for 2o bucks will outlast you with alum and brass.

Much of my "work" lately is 316 stainless because of the environment and stresses of these parts. Brittle metal taps will break, so I don't use carbide taps. It is better to use high quality high speed steel for stainless steel, in my opinion. But you will need to by at least two if you have many holes to tap. 16 bucks a piece for best quality is normal for 10mm or so taps.

P.S. Bottom taps will not actually " bottom" in the hole. This is why I use two bottom taps for holes that I need the threads to go deep. I use a normal bottom tap , then on my grinder I make a "real" bottom tap that takes me to the actual bottom with threads and I mean threads to the bottom. I grind it so that there is only no speck of taper on the real bottom tap.

First tap with a full taper for good cutting. Then use the normal bottom tap, then use the special custom tap with NO taper for a real bottom tap that goes all the way down with threads.

Unless you are cutting very tight threads, normal taps and dies are fine. They have some "wiggle" and gaps in the thread contact. The only time you need super tight is if you are making a special "lead screw" and need close to no backlash.

In machine work, if you need tighter threads it is because of extreme heat that would change the contact of the metals.
 
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Stanshire said:
In addition to the types mentioned, there are two others that I use often.
The first is a spiral flute for blind holes. The chips are pulled out of the hole.
The other, and my favorite for smaller size holes are form taps. Unlike the other types mentioned, the form tap presses or forms the thread with no chip. They use a different tap drill size chart. My experience has been with Balax form taps and (fingers crossed), I've never broken one even at 0-80 or 1-72.
Click to expand...
If you’re not breaking 0-80 roll form taps. Then the tapping gods must like you! Hats off to you!
 
All of the advice is pretty good. For general, all-around hand tapping, a plug tap is adequate. Bottoming, if you need to get down in a blind hole. Taper, if you are having trouble starting a plug. Spiral point for production (power) tapping. Also, don't forget the lube: kerosene for aluminum, sulfurized or lard for steel, dry for brass, mineral oil for wood (yes, you can tap hard woods easily). Starting a tap in a drill press or a lathe (by hand) is a nice way to get good alignment. Backing out every half turn on stringy materials to break the chip is good. Blowing chip out of bottomed holes helps, too. Don't force a tap. Don't use dull taps for new threads (OK for cleaning up, though). Get good quality tools.
 
Look for a used MADE IN USA set on ebay. You can do well to buy a used Blue Point on your budget. Here are a couple of examples to bid on. One is metric and one is SAE :

http://www.ebay.com/itm/Blue-Point-...:g:B3QAAOSwLVZV5xfM&item=111813596142&vxp=mtr

and:

http://www.ebay.com/itm/Blue-Point-...435246?hash=item235c99bf6e:g:XrwAAOSwT5tWPS-k

It is extremely wise to invest in an aid to get your tap straight when you start tapping. Suggest this one:

http://www.ebay.com/itm/NEW-SPRING-...335117?hash=item1e9a18cb8d:g:zHYAAOSwqu9VUP6N
 
There are several books out there on tapping, find one and read through it. I have tapped 7050T8651 aluminum, and had good USA taps seize and break. I was using rapid tap and tap majic for aluminum, sometimes even a good tap will break if used in the wrong application. Tim
 
I have a set of three M6 taps that I bought in a regular German hardware store around 1969. I still usem them and they are still working really well. They do not have spiral points and are 4 fluted.
However, unlike any taps I've found and bought in English speaking countries, this set has a 'first cut' (my expression) or taper tap which cuts a very shallow thread over its full lenth above the relatively short taper section. The 'second cut' tap has next to no taper, and cuts the thread a bit deeper, but with visible flat bottoms of the thread for it's entire length. The 'final cut' tap has just one or two tapered threads at the end and cuts the final thread for its full length.
I have been able to cut very deep thread in pretty hard steel and stainless without any issues whatsoever. I also use them in a cordless drill to make deep threads. Of course they need backing out to break and clear swarf from blind holes.
Are those taps available in the US, UK or Australia, and what are they called in English?
Cheers,
Joe
 
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