Differences between taps

Is there a practical difference between taps with flat points like this:

http://www.grainger.com/Grainger/WIDIA-GTD-Gun-Tap-4AKK0

And taps with sharp points like this:

http://www.sears.com/craftsman-tap-drill-combo-set-1-4-20-tap/p-00952847000P

The pointed style is usually used as a starter tap. I usually use the flatter style to clean threads. There is also one called the bottom tap, its cutting edges are closer the end of the tap. The end is more square and not as tappered as the flat style.

Taper taps are for threw holes
Plug Taps are for blind holes
Bottoming taps are for finishing up the last few threads not cut from the plug tap.

Pointed taps, like stated are for starting or through holes. Flat bottom taps are for blind holes, or holes that do not goo through the part. Once you get into larger sizes though, some may look like a bottom tap but are in actuality a starter tap. The larger ones just don't need the point on it.

Another thing about taps, stay away from 4 flutes. More trouble than what they are worth due to not having enough chip clearance. The best bet for home use, is get two or three flute Gun Taps. I think the three flute gun taps start at either 5/16" or 3/8" in size. Most small 4 flutes, you'll snap them off and they are a real ***** to get out. I've had to remove hundreds over the years for production departments. And if you bind a tap or hear a snap while it's in the hole, good luck on getting one out. They make "tap extractors" but I have never had any luck with them. When you bind and snap a tap, it's stronger than the tap extractor anyways.

And never use a rusty tap. 90% of the time it's dull from rust, or it's an older tap that has been laying around after being used quite a few times. Taps are cheap until you get into the larger sizes. Once you get a tap, don't let them bang around one another and don't loan any out, so you'll always know what you have.

Also, ! some of the 4 flute and spiral flute taps are made of Powdered metal, so TREAD LIGHTLY if you end up having to try to hand tap something with them .

Spiral point taps are for best for through holes and shoot the chips ahead of the tap. Apparently these are gun taps, altho I was never taught that way.

Spiral flute taps are better for blind holes and feed the chips back out towards you, much like a drill bit. These are probably my favorite but are more expensive. I once bought a no-name import 8-32 that did nothing but strip the hole, so now I only buy quality taps, especially in spiral flute.

For general, all-around use I prefer hand taps (which might be the 4 flutes Kevin refers to?). I've personally had no problems with them over the years, you just gotta use the right technique of back and forth to break your chip. Hand taps pretty much don't feed the chips one way or another, which sounds like a bad idea but works out fine in practice.

Your Craftsman link looks like a basic hand tap to me. The Grainger link specifies it's a gun tap, thus spiral point.

Ign said:

Spiral point taps are for best for through holes and shoot the chips ahead of the tap. Apparently these are gun taps, altho I was never taught that way.

Spiral flute taps are better for blind holes and feed the chips back out towards you, much like a drill bit. These are probably my favorite but are more expensive. I once bought a no-name import 8-32 that did nothing but strip the hole, so now I only buy quality taps, especially in spiral flute.

For general, all-around use I prefer hand taps (which might be the 4 flutes Kevin refers to?). I've personally had no problems with them over the years, you just gotta use the right technique of back and forth to break your chip. Hand taps pretty much don't feed the chips one way or another, which sounds like a bad idea but works out fine in practice.

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^^^ This. I always recommend against spiral point taps for home use as they can quickly get you into trouble on blind holes. Learn to use a regular 4 flute hand tap well as that is what you will likely be buying upon the occasion of needing a special thread.

I believe calling spiral point taps "gun taps" is a relatively recent misnomer. I was always taught that gun taps are like gun drills - for tapping/drilling DEEP holes.

While we're here;

Can someone clarify the different between a thread-chasing tap and a cutting tap?

I was under the impression a thread-chaser was less likely to over-size a given thread.

There are 4 different thread tolerances, that is the easiest way to put it. They are each classified as a "Class".

So an average retail Irwin plug tap is a 3.5? And an avg. thread chaser is a 1 or 2? And a bolt would be a 0?

lilredex said:

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That image came from my site...

http://shopngarage.com/2012/04/types-of-taps/

Stephenw said:

That image came from my site...

http://shopngarage.com/2012/04/types-of-taps/

Click to expand...

I save all the good stuff, yours included. Neglected to reference your site.....corrected.

jcriss said:

Also, ! some of the 4 flute and spiral flute taps are made of Powdered metal, so TREAD LIGHTLY if you end up having to try to hand tap something with them .

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Examples?

Just a little more information:
Taper taps cut a little easier because each tooth is removing less metal than the other types. Plug taps are a compromise and are the most likely type you will find. Bottoming taps should only be used to clean up the last threads in the bottom of a hole left by the more tapered plug tap. Bottoming taps are very hard to turn if you are cutting fresh threads in a drilled hole. They also dull faster because the cutting action is concentrated on the fewer teeth.

Most taps can be sharpened, but it is not economical to do this on smaller sizes, as you can buy a new tap for less money.

It takes experience to "feel" when a tap is binding and close to breaking. A dull tap breaks easier, probably because of uneven wear on the cutting edges making one tooth experience more pressure, and you can't tell it - only the overall pressure it it taking to turn the tap. It is much cheaper to replace taps often than to deal with a broken one!

Always use a wrench that has a T-shaped handle to turn a tap, and apply pressure to both sides of the T evenly. Uneven or side pressure on a tap is the most common reason for broken taps, followed by dull taps.

Make sure the tap starts square with the hole, and doesn't tip off line as it enters the hole. You can back off and restart the tap to square it up if you don't apply a lot of side pressure, just back up and take a small bite in the proper direction, perhaps repeating a few times until you get it square again.

Some taps are made for tapping plastics that "give" and contract back after the tap is removed. They will cut an oversized thread if used on harder materials. I believe that taps for powdered metal may be more aggressive and you can overload the teeth by using them on harder materials, leading to tap breakage.

Most taps found at retailers (like Craftsman or the auto parts stores) are designed to tap mild steel and cast iron. Industrial surplus taps may be designed for more exotic materials (especially aerospace surplus) and may not work well on common materials.

Here you go. Here is an A-Z on taps. Different styles, how they are used, plus a tap chart
http://www.newmantools.com/taps/styles.htm

ChevyEFI said:

While we're here;

Can someone clarify the different between a thread-chasing tap and a cutting tap?

I was under the impression a thread-chaser was less likely to over-size a given thread.

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Chase will clean pre-existing threads much better than a die or tap. It's more for cleaning rust off threads, burrs, debris of any sort. Where-as a cutting tap or die is for creating new threads.

Keep in mind that some tap designs are optimized for high speed/volume production environments where all process paramters are tightly controlled. Yes, you can use them by hand but they are more expensive and will easily break. I would consider all the more advanced designs such as spiral fluted, spiral pointed, 4 flutes, carbide, etc, etc as production taps. My opinion is that for homeuse a standard coated tap is the best choice

The tap in your first link is a Machine tap it is designed for power tapping and pushes the chip ahead of the tap primarily for through holes. The second link is a Hand tap