00-90 cutting tap versus forming tap

[peteski]

I'm no expert but with such a small cutting area, Rods tap looks to me like a forming (not a cutting) tap.

[BuddyBorders]

That's a spiral point tap (aka - Gun Tap) Should work just fine if used carefully. Recommended tap drill is #62 (.038" dia)

Regards,

Buddy

[peteski]

That's a spiral point tap (aka - Gun Tap) Should work just fine if used carefully. Recommended tap drill is #62 (.038" dia)

Regards,

Buddy

My mistake. On second look I see that there is a groove along the entire length of the threads.   Barely visible in the photo.

[Lemosteam]

A forming tap would only work in very soft material. Cutting taps are all I use .

This depends on the tap drill size used.

In my example I was tapping 2-56 thread in a 3D printed steel tender chassis after using the proper tap drill (which also wore very quickly).  The steel is mush harder that mill steel, aluminum or hard brass. The prints were $30+ each and I could not get the broken tap out no matter what I tried.

The MT tap dulled too quickly and the "chips" it produced would bind in the grooves and would eventually snap.  Cutting taps were worse because of the reduced cross section (A below) at the center of a fluted tap (B below, a little better with two flutes) as compared to the MT Tap:



In the end I went with a true forming (plug) tap which is primarily a hardened threaded rod and the cross section is simply the rood diameter of the thread.  But instead of using the "proper" tap drill size I went with a larger size that still left a reasonable amount of thread, especially since the forming tap is designed to displace metal into the threads.  Let's face it; in our scale a full thread depth is not really needed as we will never need to apply full load on the thread anyway, nor will the operational load be enough to pull those threads out. 

It's still tough to tap, but I haven't broken a tap since and as far as I know no customer has complained to me of a stripped thread or loose joint in the kit.

I use these but unfortunately I do not see a 00-90:

[Chris333]

I've seen kits to remove broken tabs that fit into the 3 flutes to grab the broke part, but I suspect the smaller the size the further up the creek you are.

When I tapped all those hole in aluminum for my printer...   

[Lemosteam]

Yeah I even tried a diamond burr to grind the remainder out of there.  No dice.

[rodsup9000]

This depends on the tap drill size used.

In my example I was tapping 2-56 thread in a 3D printed steel tender chassis after using the proper tap drill (which also wore very quickly).  The steel is mush harder that mill steel, aluminum or hard brass. The prints were $30+ each and I could not get the broken tap out no matter what I tried.

The MT tap dulled too quickly and the "chips" it produced would bind in the grooves and would eventually snap.  Cutting taps were worse because of the reduced cross section (A below) at the center of a fluted tap (B below, a little better with two flutes) as compared to the MT Tap:



In the end I went with a true forming (plug) tap which is primarily a hardened threaded rod and the cross section is simply the rood diameter of the thread.  But instead of using the "proper" tap drill size I went with a larger size that still left a reasonable amount of thread, especially since the forming tap is designed to displace metal into the threads.  Let's face it; in our scale a full thread depth is not really needed as we will never need to apply full load on the thread anyway, nor will the operational load be enough to pull those threads out. 

It's still tough to tap, but I haven't broken a tap since and as far as I know no customer has complained to me of a stripped thread or loose joint in the kit.

I use these but unfortunately I do not see a 00-90:

 Is this stuff harder than A2 tool steel??? I've used American made 2-56 gun taps with TiN finish to power tap 1/4" thick A2 (in the Bridgeport) and never had a problem with breakage.

[mmagliaro]

Lemosteam,
Some of the 00-90 taps I just bought are "bottom forming" taps, and they look as you describe:
just a piece of 00-90 threaded rod in hardened steel.  They are made by Regal in the USA and
were available on eBay very cheaply (about 8 bucks).  They are not tapered, which would make them tricky to
start in a hole to make a new thread.  You can find them by looking for:

USA 00-90 Thread Form Bottom Tap GH8 HSS NS

[rodsup9000]

 Update on using these taps
 As of now, I've tapped over 1000 holes in Kadee/Micro Trains metal frames and using beewax for lub.  I just taped 2 holes in a piece of .165 thick brass with ease.

[thomasjmdavis]

Got the taps yesterday and they are made in Korea. It took 4 business days to ship and USPS 3 days to deliver.
They look nice and hope the HHS is of quality.

I note that, while the graphic on the product page shows the shaft of the tool approximately the same outer diameter as the threads, the photo of your tap show that the upper part of the shaft is of much larger diameter.  This will make it easier to find a tap wrench to fit.  What diameter  is it?  And is it square on top? 
(PS- as is obvious in my phrasing, I am not a machinist by trade, and I'm sure there are more precise names for the parts of the tool than "shaft" or "top")

[Lemosteam]

Update on using these taps
 As of now, I've tapped over 1000 holes in Kadee/Micro Trains metal frames and using beewax for lub.  I just taped 2 holes in a piece of .165 thick brass with ease.

That's awesome- have you tried tapping any form of cast iron or steel?

[rodsup9000]

I note that, while the graphic on the product page shows the shaft of the tool approximately the same outer diameter as the threads, the photo of your tap show that the upper part of the shaft is of much larger diameter.  This will make it easier to find a tap wrench to fit.  What diameter  is it?  And is it square on top? 
(PS- as is obvious in my phrasing, I am not a machinist by trade, and I'm sure there are more precise names for the parts of the tool than "shaft" or "top")

  It does have a square end.  It's .096" in diameter and measures .075" across the flats..  I've done all my tapping with it mounted in a pin vise.

That's awesome- have you tried tapping any form of cast iron or steel?

I have not tried it on anything that hard yet.

[u18b]

As stated.... always... always use oil.

And work slowly.  Forward a quarter turn, back a quarter turn.
Forward, back.   Very slow and tedious process.

[rodsup9000]

As stated.... always... always use oil.

And work slowly.  Forward a quarter turn, back a quarter turn.
Forward, back.   Very slow and tedious process.

  Was taught in machine tool school (mid '70's), to use beeswax for soft gummy metals (like the Kadee/MT frames). Kerosene for harder gummy metals like aluminum. I'm sure things have changed over the years, But I've had good luck with the beeswax.
 
 With a gun (spiral point) tap, no need to back it out like a hand tap. Also the HHS is stronger and not as brittle as the common carbon taps.

[randgust]

I'm intrigued by the tapping oil or liquid.

I've always lubricated my taps, just with a drop of LaBelle 108, and I've never broken one.  Come close to jamming them, but never broke one.  I've learned that in a pin vise it's not the smartest thing to tighten it down 100%, settle for 90% and it you do jam it,  go for the extra 10% to get it out.

I've had more trouble with soft metals than steel, actually, as the particles jam so easily on stuff like pewter.