Making taps

[Limy Sami]

I think / pretty sure (correct me if I'm wrong ) that forming taps are tri or quad lobel as in form relieved, possible on a lathe with various gizmos- sure but not easy.

 

[Screwmachine]

No idea on forming but having been in need of a nonexistent left hand die lately might add to the thread.

Left hand threads crop up in watches fairly often. In need of a left hand die that can't be obtained in a reasonable time or cost: make a male thread that corresponds, heat treat, grind flats 180 degrees so that it's quite thin. The helix angle becomes practically non existant. Use this to make the die, turning backwards. Sounds insane but it works. In at least a couple of w atchmaking texts.

For all the hype watches, scaled, aren't so precise.

 

[Clive603]

Probably get near enough to the true form if you had a lathe capable of simultaneously relieving, screwcutting and taper turning. Sort of odd ball thing that a Holbrook B with fixed relieving gear on the head could probably manage but these days I guess its a creative CNC job.

Last time I needed a home brew forming tap thread was small enough that I could just kill a couple or three taptite screws! Which are thread formers. Getting the length was interesting. Rescue job where oversize holes had been drilled and normal thread wouldn't have held.

Clive

 

[Conrad Hoffman]

Don't have any of those capabilities, so I think I'm going to stick with a cutting style for the 1-off I need at the moment. Thanks!

 

[Cole2534]

Awesome thread Conrad.

On that tap you posted about, what size wheel were you using for the relief grind?

 

[Conrad Hoffman]

plain old 8" bench grinder.

 

[Conrad Hoffman]

The tap I needed most recently was for the draw bar of a ww collet spindle (.275 x 40). Made the tap just like the one that started this thread- worked perfectly. We're building a little bitty indexer for ww collets because we make little bitty stuff!

 

[John Welden]

The tap I needed most recently was for the draw bar of a ww collet spindle (.275 x 40). Made the tap just like the one that started this thread- worked perfectly. We're building a little bitty indexer for ww collets because we make little bitty stuff!

Get a cnc 5c rotary axis. Haas make one that's pretty cheap. Then just use a straight shank WW collet holder and pop it in a 5c collet. That's what I used to do. Manual indexing is a pain and slow. Several companies besides haas make little CNC 5c indexers. Look on eBay if you can't afford new.

 

[Chknives]

Do you think this method of making taps will work for something like a m30 size thread? I want to clean up some threads in a machine base and don't want to buy a tap if I'm only going to use it to clean up 4 holes and probably never again.

 

[jeff10049]

As for cleaning up holes just grind a flat or two on a bolt works great.

 

[daredo222]

As for cleaning up holes just grind a flat or two on a bolt works great.

And whack the bolt with a hammer every half turn.

Ray

 

[JRIowa]

so I think I'm going to stick with a cutting style for the 1-off I need at the moment.

Conrad, all of the form taps that I have ever seen have been ground. Finish is usually better than that of a ground thread tap. I'm thinking that if the form taps did not have a good finish it might seize.
JR

 

[apoc_101]

Somebody at some point, must have made the forming tap manually, when they invented it. undoubtedly not in the same quality as a Balax etc.

Then again, I suppose we've all "invented" our own forming taps from time to time, with varying degrees of failure

 

[Gordon B. Clarke]

Do you think this method of making taps will work for something like a m30 size thread? I want to clean up some threads in a machine base and don't want to buy a tap if I'm only going to use it to clean up 4 holes and probably never again.

If you're just cleaning the thread then the suggestion by jeff in post #30 should work fine as long as the bolt material is the harder of the two.

 

[partsproduction]

All the agonizing I've done over tap cutting angles,,,for nothing. Seems like sculpturing with a club. (no offense intended)

Good taps have eccentric relief ground in. Then there are "Con-eccentric" grinds, and the old concentric taps that needed so much torque to drive. I have a tap grinder, uses gears for different numbers of flutes. All that ingenuity for nothing.

But if these are form tapping then hole diameters are critical. If they are cut taps they have negative angles.

 

[Conrad Hoffman]

Get a cnc 5c rotary axis. Haas make one that's pretty cheap. Then just use a straight shank WW collet holder and pop it in a 5c collet. That's what I used to do. Manual indexing is a pain and slow. Several companies besides haas make little CNC 5c indexers. Look on eBay if you can't afford new.

Can't argue with that, if one has the space. One use here will be putting it on the table of an Accufinish diamond grinder to relieve and facet small ceramic items, so a small hand fixture is what's needed. Almost everything I do is a one-off. For me, high volume production is 3-10

 

[partsproduction]

I'll try it tomorrow, it occurs to me that with the steep angle the chip may "see" a positive cutting angle. In any case threading the blank it may benefit to make back taper so flank friction is less as it goes deeper.

Always trying to make things more complex!

 

[Cbcues]

I have been searching for the old fashioned way thread with no success. Anyone have the link to the original thread on making a tap? Thanks

 

[rjibosh]

Can you just case harden these taps with kasenet or an equivalent?