taper vs plug taps

Original Tap Magic, with trichlor, was still available a couple of years ago. I've got a pint or so of it in my shop now, bought from Scott Logan during one of his open houses.

Mike

Reply to
Mike Henry
Loading thread data ...

Hey Robin, Which kind of tap was this "thread" made with? :-) ...lew...

Reply to
Lew Hartswick

Greetings Harold, It's too bad you never used form taps. I use them whenever possible. They are good in gummy materials, such as stainless and mild steels. They excel in aluminum. Even though they work well in half hard brass I'm not sure that the threads are as strong as cut threads. This is only because half hard brass tends to crack and flake when deformed, as when being knurled. But knurling deforms the material more and for a longer time. Tapping 304 with form taps is scary and taps will break if proper lube isn't used or if the tap has done too many holes. The proper form of form tap also makes a difference. Some taps have three lobes, others have 5 lobes, some have a groove ground the length of the threaded portion, etc. One of the best reasons for using form taps is a blind hole. No chips to worry about. And my personal best at tapping is with a form tap. Over 11,000 holes with the same tap. A

6-32 tap and the material was 1/8" die cast aluminum. Cheers, Eric
Reply to
Eric R Snow

That point on the tap is for the foreman's use. He counts the little dents left by that point when you miss the hole when production tapping. That way he can tell if you are paying attention. ERS

Reply to
Eric R Snow

And a roll or form tap will make no chips and a stronger thread. Thus they are faster and better if the material can be formed. ERS

Reply to
Eric R Snow

Gentlemen, a while ago I saw a manual tapping machine that worked by simply forcing the tap to go along a particular straight line (ie prevented it from twisting sideways). You would still tap by hand., but the tap holder can only slide up and down. Which is very nice. I forgot what these things are called. I have been tapping quite a few things lately and would love to have one, but unfortunately I forgot what they are called.

i
Reply to
Ignoramus23763

The material that we machine is usually 28HC cast in the annealed condition or the same material with "soft plugs" inserted in the casting. The soft plugs are 316 stainless. We do use form taps in some applications.

John

Reply to
John

A tap? Thread rollers or formers work this way. But only on the OD of stuff.

Gunner

Political Correctness

A doctrine fostered by a delusional, illogical liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Reply to
Gunner

It's not a tap, it is a tap guide, kind of, that prevents the tap from going off center. It is shaped like letter C, with the tap guide going from top right of that C, down.

i
Reply to
Ignoramus23763

Kinda like a drill press thingy? Hand Tapper.

Like this?

formatting link
Ive got a couple of them here and there, bolted to work benches. Best thing since sliced bread. You can still bust a tap..but you have to work at it a bit harder

Gunner

Political Correctness

A doctrine fostered by a delusional, illogical liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Reply to
Gunner

Yep, that's it. I will look for one -- I have not busted taps in a while, but I would like to tap in a better way.

i
Reply to
Ignoramus23763

Though that being said..I usually tap em in the mill. Drill the hole, install the tap, tap, move to the next hole position and so forth. But for rework and so forth..they are right handy.

Gunner

Political Correctness

A doctrine fostered by a delusional, illogical liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

Reply to
Gunner

Great report, Eric. I don't doubt anything you've said--it all makes perfect sense. The 11,000 holes with one tap is exceedingly impressive-----

I'm only vaguely familiar with those taps----but I do happen to have one in my toolbox, the three lobed type. I've never had the courage to give it a go. Fast is, I don't have a clue about tap drill size. Is there a rule of thumb?

Harold

Reply to
Harold and Susan Vordos

I had my first experience with a form tap about a month ago. Had some knobs to make with two set screw holes (at 90*) into a fairly small central hole (knobs were 2" dia). Thought to self "why not try these form taps" so bought one. A little expensive comared to regular taps. BUT Wow! was that slick. did it on a Bridgeport. Material was 6061 so maybe that part of the ease but sure was even better than sliced bread. :-) ...lew...

Reply to
Lew Hartswick

They are great for the right use. One thing to be aware of with these taps is that since they deform the metal the entrance and exit of a hole will have material pushed out. And when tapping a blind hole the metal pushed ahead of the tap shrinks the hole and the tap can bind before it actually hits bottom. ERS

Reply to
Eric R Snow

impressive-----

formatting link

Reply to
Roger Shoaf

Thanks, Roger. I've saved the link for future use.

Harold

Reply to
Harold and Susan Vordos

According to Harold and Susan Vordos :

[ ... ]

There is a table in _Machinery's Handbook_ -- at least in the recent editions -- 24th and later -- which lists proper tap size for thread forming taps. My guess is that the proper size is really critical for those, since they select from fractional, letter, number, and metric sizes to get the closest to whatever they calculated.

IIRC, both the 1/4-20 and the 10-32 sizes want metric tap drill sizes, but I would have to look it up again to be sure.

Enjoy, DoN.

Reply to
DoN. Nichols

Greetings DoN, Drill size is indeed critical for from taps because the metal is only displaced. A little too big and the minor dia. will be oversize and a little too small will crowd the tap completely and break it. ERS

Reply to
Eric R Snow

Exactly why I've never played with the one I have. Not having a clue, I knew that I'd screw up-----from which the only thing I'd learn is to not use them.

Ever tried one in tough materials, Eric? Stainless (300 series), maybe chrome-moly?

Sure chuckled when DoN mentioned the 24th edition of the handbook. I'm still using the first one I ever bought-----new-------15th. edition. Talk about feeling old!

Harold

Reply to
Harold and Susan Vordos

PolyTech Forum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.