# Tap Question



## PEU (Jul 13, 2004)

I want to know the difference between these kinds of taps:

Taper / Plug / Bottoming travers catalog page 

I found these descriptions in the travers.com catalog for the tap 15/32-32 (arc aaa)

Which should I buy?

I need advice. Thanks

Pablo


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## wasabe64 (Jul 13, 2004)

I'm sure there is a better explanation somewhere (or someone else will post it), but here's my understanding of the tap profiles based around how I tend to use the different types of taps.

Taper - best for tapping through entire length of hole, the tapered profile helps keep the tap straight while tapping. Not good for blind holes since the taper means a significant portion of the tap must be tapped into the hole to cut the correct profile thread.

Plug - has a faster taper than a standard taper tap, which means less metal will be cut before thread is cut to correct profile (this also means that it is trickier to align the tap). I use them for tapping partial distances in a hole.

Bottoming - very little to no taper, for tapping blind holes.

I usually use plug taps for tapping flashlight bodies.


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## KC2IXE (Jul 14, 2004)

Taper taps are really only useful in a through hole situation, and the fisrt something like 10-12 threads are not fully cut - if you are only worried about topping the top part of a DEEP hole they are also OK. Their advantange is that they are the easiest to start, and to drive

Bottoming taps - they can NOT be used to start threads, but can tap all the way to the bottom of a whole.

Plug taps - in between the other two - probably the must used type


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## PEU (Jul 14, 2004)

thanks!! a friend of mine is flying from USA, and I must hurry if I want them on time. I'm going for the plug.

Pablo


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## MoonRise (Jul 15, 2004)

CPF motto - Buy them all!!!

At least get the plug tap and the bottoming tap. Start the threads with the plug tap and then use the bottoming tap for short blind holes.


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## wptski (Jul 15, 2004)

You also have 3 and 4 fluted taps plus spiral flutes too! Three flute is used for taping with a drill press or lathe under power, it has a chip breaker. Four flute is for hand taping. The spiral flutes are normally used for production applications, better chip control and allows cutting fluids to get into the hole better.


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## KC2IXE (Jul 15, 2004)

RE: N-Flute taps (2,3,4 etc)

It's NOT the number of flutes, in fact I've seen 3 flute tapes that were hand taps

Spiral POINT taps (aka "gun taps") are usually designed to be machine driven - they push the chip foward - they are NOT good for blind holes

Spiral FLUTE taps are also designed to be machine driven, and I would NOT risk hand driving them - They are meant for blind holes

Of course, there is the oddball, which most folks have never used: Thread forming taps - they are great if you are working in material that is ductile enough to form threads - no chip!


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## wptski (Jul 15, 2004)

[ QUOTE ]
*KC2IXE said:*
RE: N-Flute taps (2,3,4 etc)

It's NOT the number of flutes, in fact I've seen 3 flute tapes that were hand taps

Spiral POINT taps (aka "gun taps") are usually designed to be machine driven - they push the chip foward - they are NOT good for blind holes

Spiral FLUTE taps are also designed to be machine driven, and I would NOT risk hand driving them - They are meant for blind holes

Of course, there is the oddball, which most folks have never used: Thread forming taps - they are great if you are working in material that is ductile enough to form threads - no chip! 

[/ QUOTE ]
I don't think that I've ever seen a three flute hand tap. We use what my employer stocks and sometimes that isn't too much. We do as best we can!

Don't see much two fluters either, although I have some at home, small ones and a 2-56 comes to mind as one I have.


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## wasabe64 (Jul 15, 2004)

I have a tendency to only buy taps as I need them, so I have an assortment of 3,4,6-fluted hand taps.

I've seen the thread-forming taps, basically an unfluted tap.


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## tvodrd (Jul 15, 2004)

Just some of my own experience. I don't think I even own a taper tap. Don't have any at the shop at work either. Plugs are the workhorse for hand tapping. If you need the depth, plug followed by bottoming. Spiral points are fine for hand tapping and best for power tapping. They push the chips ahead of them where a conventional tap will pack-up chips in its grooves. You can use them in blind holes, but make sure the hole is deeper than you intend to tap it so the chips have somewhere to go! With a spiral-point, you don't reverse it every turn or so to bread the chip(s). With conventional taps, this is a must- 1-2 turns in, back it out 1/2 turn, repeat... Oh, Make yourself a "bench block"- some 3/4 thick aluminum with some holes drilled to just clear your tap's O.D. It makes starting taps straight a lot easier.

Larry


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## MoonRise (Jul 16, 2004)

[ QUOTE ]
*tvodrd said:*
(snip-snip-snip)
*... every turn or so to bread the chip(s). *
(snip-snip-snip)
*Larry 

[/ QUOTE ]*

Mmmmm, breaded chips and breaded fish makes Fish-n-Chips!!!! Serve with malt vinegar and a nice cold beer, delicious! Dinner at Larry's house!

/ubbthreads/images/graemlins/wink2.gif /ubbthreads/images/graemlins/crackup.gif /ubbthreads/images/graemlins/crackup.gif /ubbthreads/images/graemlins/crackup.gif /ubbthreads/images/graemlins/crackup.gif


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## tvodrd (Jul 16, 2004)

Gotta get new glasses! /ubbthreads/images/graemlins/icon23.gif

Larry


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## gadget_lover (Aug 22, 2004)

Ok, I'm playing with some lights and find that I've wanted to tap several aluminium (or plastic) bodies for use with a kroll switch. That's 5/8x28 thread. It's a hassle to chuck a finished flashlight without getting jaw marks on the finish. So I start thinking to myself....

How well does a home made tap work? I assume that I could cut a threaded rod to the correct thread, then taper it and cut slots the length of the thread to create the cutting edges. The last step would be to temper it.

Or should that be taper, then cut the threads and then slots?

Can you get decent threads this way? The nylon body of the kroll is pretty forgiving.

Thanks

Daniel


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## tvodrd (Aug 22, 2004)

Daniel,

I think a factory-ground tap will do a much better job. A US-made 5/8-28 from McMaster is $30.41+. My recollection is that Travers sells import ones for around $15 I think. Interestingly, it is only the first few threads on a tap that do the cutting.

Larry


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## gadget_lover (Aug 22, 2004)

I notice you did not say it would not work /ubbthreads/images/graemlins/smile.gif

I guess I could just go to the garage and cut one, to see if I can make it work.

Would the procedure I laid out sound about right?

Daniel


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## tvodrd (Aug 22, 2004)

Daniel,

Yes, it will work and well if you get the geometry right. You won't need to heat treat it for tapping plastic, but it will dull after a dozen uses in acrylic. For tapping aluminum, I suspect there will be problems unless you can harden it. In order to harden properly, the steel will need to be "high carbon" (~1%) and you will need to heat it cherry red and quench it in water or oil. It then needs to be drawn/tempered to reduce the brittleness, but too much will soften it too much. Of course some A2 tool steel would make heat treat easier. When I need heat treating, I send it out. You seem to be bent on going about this the hard way. /ubbthreads/images/graemlins/grin.gif
Travers again

Larry


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## Doug S (Aug 22, 2004)

Larry, sometimes the hard way is more fun /ubbthreads/images/graemlins/banghead.gif
It seems to me that the method proposed by Daniel may produce an excessively tight fit. Isn't a standard tap a fraction of a RCH bigger than threaded stock to produce the necessary clearance between the two mating threaded objects? OK, going back to electrical stuff now.


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## gadget_lover (Aug 22, 2004)

I was actually thinking about it more as an exercise in tool making than as a substitute for commercial grade equipment.

Every once in a while I want to make just half a dozen of of something to mate with a part that has oddball threads. Sometimes I just don't want to wait for mailorder of until Monday when businesses open. Some of the lights from China don't really fit any of the thread gauges that I have.


I will be getting a 5/8 x 28 tap from Travers, but.... I may try making one too. The production of a tap does not seem too much different from the idea of making a broach. I want to try making some of those too.

Thanks for the info Larry and Doug. 

Daniel


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## tvodrd (Aug 22, 2004)

From what I've seen, fractional taps are typically a .002" to .004" Over their nominal fractional sizes. Machinery's Handbook is not light reading on the subject of unified threads! Percent engagement, class of fit limits, etc. I'm not remotely a master of the subject. I don't even know how they make an 0-80 tap for a couple of bucks! Gotta be redressing their wheels a lot. /ubbthreads/images/graemlins/grin.gif I don't understand why a US-made 5/8" endmill goes for $15 and getting it reground to .605" dia costs $60. /ubbthreads/images/graemlins/icon3.gif Gotta be interesting to actually work in the field. (I don't.)

Larry


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## NewBie (Aug 23, 2004)

You ever try case hardening on something like this tvodrd, instead of the steps you mentioned?


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## gadget_lover (Aug 23, 2004)

[ QUOTE ]
*tvodrd said:*
From what I've seen, fractional taps are typically a .002" to .004" Over their nominal fractional sizes. Machinery's Handbook is not light reading on the subject of unified threads! Percent engagement, class of fit limits, etc. I'm not remotely a master of the subject. I don't even know how they make an 0-80 tap for a couple of bucks! Gotta be redressing their wheels a lot. /ubbthreads/images/graemlins/grin.gif I don't understand why a US-made 5/8" endmill goes for $15 and getting it reground to .605" dia costs $60. /ubbthreads/images/graemlins/icon3.gif Gotta be interesting to actually work in the field. (I don't.)

Larry 

[/ QUOTE ]

I never thought of trying to get a custom ground end mill. I'd probably adjust my design to use 5/8. /ubbthreads/images/graemlins/smile.gif 

Does it really cost $60 to get .01 inch (radius) ground off? What type of shop whould you go to get such work done?

So much to learn and only another 50 years to learn it.

Daniel


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## lgl_olephart (Aug 25, 2004)

Get a hardened bolt and grind it to look like a tap. Won't be pretty, but it will work.


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