Teach me about taps

[theoldwizard1]

I have a "Made in the USA" Craftsman SAE and Metric tap and die set. It serves me well for the few time I have needed it.

I now have a need for a couple of "bottom" taps and have run into a few terms I don't understand.

Spiral point, taper, plug and bottom. I'm guessing spiral point is the most common and what is in my Craftsman set and bottom is for blind holes. What about taper and plug ?

HSS means "high speed steel" (whatever that means) but what does GH3 mean ? What is best for mild steel ? What do you need for 4130/4140 ?

What else do I need to know ?


Does all of this apply to dies ?

 

[OccupantRJ]

http://www.newmantools.com/taps/taptech.htm

 

[ChevyEFI]

More snippets of info

http://www.garagejournal.com/forum/showthread.php?t=178522

http://www.garagejournal.com/forum/showthread.php?t=182026

 

[wafrederick]

Don't use them to clean up threads,they are made to make new threads only.There are rethreading taps and dies to clean up threads including damaged threads.I had the bad habit of doing this,bought a rethreading set today.

 

[theoldwizard1]

More snippets of info

http://www.garagejournal.com/forum/showthread.php?t=178522

http://www.garagejournal.com/forum/showthread.php?t=182026

Okay, I'm learning. For general use in mild steel

• Stay away from 4 flute taps if you can. They are more likely to break
• Stay away from powdered metal taps (sounds like a bad idea anyway)
• Don't use taps to "chase" existing threads (Guilty !)
• If tapping a thru hole, just use a taper tap
• For blind holes, start with taper tap, then a plug tap and finish with a bottom tap

What does "high speed steel" really mean ? (Or does it just mean not PW ?)

What is a "gun tap" ?

 

[OccupantRJ]

If you use a tap to clear a threaded hole you will die tomorrow.....I should have died a long time ago.

 

[woody 73]

Most of the cheaper tap & die sets, (not all) are made out of carbon steel, which over the long haul will only hold up for just so long before they are not very useful.

On the other hand HS/HSS will last for much longer, and they will cost many times more then the carbon steel sets; that is why most people only buy them when they need them and not in set form, more like one tap at a time.

The above reading from some of the other posters should help you out and if you look at youtube look for the user name of Tubal cain, he is a shop teacher that will help you better understand about taps and dies.

 

[woody 73]

Maybe this will give you a good start:

 

[Pudge87]

I think all the links above will provide you with enough info, but I will recommend a good tap fluid. We started using Tap Magic Xtra Heavy at work, and its cut tool wear in half. I've even used the stuff to drill and ream in a pinch.

Also at work, 95% of the time we're working with 4140qt or 4340qt.

 

[thebeekeeper1]

Tag for those links, as I have much to learn.

 

[Murphy4570]

I use taps to clean up goobered up threads all the time. Have yet to have any problems.

I used one last night to clean up a M8x1.25 threaded hole. Old bolt decided to eff up the threads on its way out. C'est la vie!

 

[spacedoutbob]

Same with me, Any time I have a bolt that was difficult to come out, I run a tap in the hole to clean it up, Doing this in over 40 years, has never come back to haunt me. In fact, it made reassembly easier.

Bob

 

[OccupantRJ]

Same with me, Any time I have a bolt that was difficult to come out, I run a tap in the hole to clean it up, Doing this in over 40 years, has never come back to haunt me. In fact, it made reassembly easier.

Bob

And you likely never WILL have a problem. Since no one without the original thread gauge in their hand will know what tolerance any hole is tapped to, it is a **** shoot at best, no matter whether a tap or a thread restore device is run into the hole. Stay away from taps marked H2 and above, and you will very likely never have an issue, since the guy happily and proudly screwing his thread restore device into the hole doesn't have a clue WHAT the hell thread fit he started with, or will end up with either.
Read this.

http://www.cutting-tool-supply.com/TechTips/Tapping/HLimitsClass/HLimitsClass.htm

 

[CWP1616L]

What does "high speed steel" really mean ? (Or does it just mean not PW ?)

What is a "gun tap" ?

High speed steel means it's made out of the same steel as high speed steel drill bits. High speed steel taps are going to be more durable than regular high carbon steel taps.


Gun taps are the same as taper taps. Just a different name.

 

[OccupantRJ]

For those who do not know, there are also taps used in production without cutting flutes that are called thread forming taps. They are machine forced into a hole of the proper size to create threads by expelling the metal out of the way of the desired threads. What to clean those threads out with? For that matter, how would you even know if you are dealing with formed threads? What to do? What to do?

 

[OccupantRJ]

Gun taps are the same as taper taps. Just a different name.

You might want to research that one a bit.......

 

[CWP1616L]

You might want to research that one a bit.......

I stand corrected.

 

[CWP1616L]

Would you say a gun tap is the same as a spiral point tap?

 

[OccupantRJ]

Would you say a gun tap is the same as a spiral point tap?

Now you're on the right track. I like using these for through hole tapping with a hand held power drill. But then again, I have been doing it for 40 years. Power up, run through, slam into reverse while still spinning but before bottoming out. Most small part tapping I do on the Bridgeport. That's right, I'm nuts!

 

[theoldwizard1]

Well folks Google is your friend. This is what I have learned from reading thye WIDIA-GTD Master Catalog, Experts, correct my if I am wrong.

• Greenfield Tap and Die is probably the oldest brand in the US taps and dies, dating back to the late 1800s (the name "Greenfield" GTD came along in 1912)
• GTD became part of WIDIA in 2010. (If they don't have what you need, they will MAKE IT !)
• GUN™ was patented by GTD in 1916
• GUN™ taps shoot chips ahead of the cutting action (Obviously only used for thru hole tapping)
• There are spiral flute taps for blind holes
• There are spiral point taps for thru holes
• Various type of spiral taps have different "twists per inch"

Finding 2 or 3 flute taps is difficult !

 

[A_Pmech]

Most small part tapping I do on the Bridgeport. That's right, I'm nuts!

This is one of the reasons why I'd never want a single-phase Bridgeport. Hit reverse and it keeps going forward!!!

A cordless drill is the best tap wrench ever invented.

 

[george4]

A cordless drill is the best tap wrench ever invented.

Please expand on this.

 

[wafrederick]

This is one reason why not to use taps to clean up threaded holes

 

[andywander]

For those who do not know, there are also taps used in production without cutting flutes that are called thread forming taps. They are machine forced into a hole of the proper size to create threads by expelling the metal out of the way of the desired threads. What to clean those threads out with? For that matter, how would you even know if you are dealing with formed threads? What to do? What to do?

Once the thread is formed, it is (or should be) the same form as if it were cut. So clean it out with anything you would clean out a cut thread with.

 

[andywander]

Now you're on the right track. I like using these for through hole tapping with a hand held power drill. But then again, I have been doing it for 40 years. Power up, run through, slam into reverse while still spinning but before bottoming out. Most small part tapping I do on the Bridgeport. That's right, I'm nuts!

How do you bottom out in a through hole?

 

[Gmonkee]

To a machinist making a new piece or some high tech precise machine I can see going all **** retentive. The exact correct thread for the exact correct bolt. It will make a difference.

For Billy Bob Hillbilly trying to get a starter remounted on his 400,000 mile, 1975 4 X 4 truck I'd think he'd just be happy to get it bolted back up. Hopefully with tools and hardware he has available to him at the moment.

If the tool shelves in the stores are a reflection of a reality at all, about 4% of the tool using public are machinists. The rest of us just fix things when we have to, or to get paid. Sure are a lot of adjustable wrenches, Vise-Grips as well as combination tools next to the small display of precision measuring devices.

 

[Pudge87]

How do you bottom out in a through hole?

Before hitting the table or vise, opposite side of a bore, or maybe even before you run all the cutting edges through the part being tapped. Many possibilities, just some off the top of my head.

 

[OccupantRJ]

Before hitting the table or vise, opposite side of a bore, or maybe even before you run all the cutting edges through the part being tapped. Many possibilities, just some off the top of my head.

Correct. In that particular instance, I was referring to running out of cutting edges on the tap.

 

[A_Pmech]

Please expand on this.

Cordless drills with torque limiting clutches make great tap wrenches. Install a spiral point or spiral flute tap in the chuck, point and shoot.

For bottoming, set the clutch a few clicks higher than what is required to drive the tap. When the tap bottoms the clutch slips.

 

[OccupantRJ]

This is one of the reasons why I'd never want a single-phase Bridgeport. Hit reverse and it keeps going forward!!!

A cordless drill is the best tap wrench ever invented.

I totally agree with your sentiments. Hmmmm. I just realized that I haven't tried power tapping with my 3 speed hammer drill yet. Whadda yu think, AP? Put a 1/4-20 in and give it a shot?

 

[kythri]

Tagged as well.

 

[fredybender]

Just as a starter note, cutting tools has ben my bread & butter for the past 25 years.
I presently work for a tool company, that has been in business for over 100 years, and I can say that this is not only my income, but my true passion.

First:
When I see something like "rethreading" taps being marketed, I can only say bullcrap, and I will explain; The only way you are going to thread oversize, is if you have the tap traveling off axis: Its not the tap, its tyhe alignement.

I have also been making race engines, and rebuilding race car dog boxes, rethreading with cutting taps since the 80's, without any problems.

So for the first part: rethreading taps are a very good marketing technique.

As far as nomenclature, there are so many things:
taper, plug, and bottoming refer to the chamfer induced on the tool, to produce threads to a certain depth; That being said, a longer chamfer, will make the tap cut easier, and ease up on thread wear, on the front theeth, but will not permit to thread close to the bottom shoulder.

Spiral pointed, or gun taps, will direct the chip flow towards the bottom of the hole; great for through holes, but not good for blind holes. Spiral fute taps, will pull out the chips from the hole, but with the cutting geometry, the fact, that the tap has cutting flutes in a helical form, WILL make it very easy, to oversize a hole if alignement ins not kept throughout the tapping cycle,

As for class of threads, generally speaking GH3 is standard, but look into the tolerancing in a machinery's handbook, because the parger the diameter, the more tolerancing will be inherited on pitch diameter.

All in all, I have my tap and die set, and it gets used, for MRO most of the time without a hitch!

There is so much to teach and understand in threading, but if there is a manufacturer you can look up for info on this, you might look up these guys
http://www.sandvik.coromant.com/sit...nloads/global/catalogues/en-gb/c-2900-141.pdf

 

[fredybender]

http://www.sandvik.coromant.com/sitecollectiondocuments/downloads/global/catalogues/en-gb/c-2900-141.pdf

 

[george4]

Cordless drills with torque limiting clutches make great tap wrenches. Install a spiral point or spiral flute tap in the chuck, point and shoot.

Clever, but how does that play into the idea that one should back off the tap periodically as one is cutting threads? Do you reverse the drill or just cut all the way in one shot?

 

[TwoInch]

High speed steel means it's made out of the same steel as high speed steel drill bits. High speed steel taps are going to be more durable than regular high carbon steel taps.


Gun taps are the same as taper taps. Just a different name.

really?

when someone asks about HSS, giving another HSS application tells nothing of the material, or why its named what it is. HSS is used in many applications that deal with cutting. drill bits are usually the first HSS cutting tool that your average person will come into contact with.

the gun tap was already handled by someone else, so i wont go there.

 

[A_Pmech]

Clever, but how does that play into the idea that one should back off the tap periodically as one is cutting threads? Do you reverse the drill or just cut all the way in one shot?

With a spiral flute or spiral point tap, clearing the chip is unnecessary, the tool geometry handles that.