7/16-14 thread chaser

Pete,

Is class 2 anything special or is this a "normal" 7/16-14 tap that would come in a thread & die kit let's say?
 
Pete said:
It is physically IMPOSSIBLE for a standard tap to remove parent metal unless the thread is damaged.
Click to expand...

Hi Pete, you'd have to define a "standard" tap here, there's really no such thing!

I'm assuming you mean the type of tap that you might possibly purchase at a typical hardware store maybe??

Thanks, Gary in N.Y.

P.S. It all boils down to the "H-limits" of each individual tap. Conventional hardware store taps are generally the H-3 series! For tighter threads you would use an H-1 or maybe an H-2? It all depends, the taps come as high as H-5's, maybe more, not 100% sure!
 
GOSFAST said:
Hi Pete, you'd have to define a "standard" tap here, there's really no such thing!

>A class 2 tap is what you get at a hardware store, tool store, or tool truck.
They are in the common tap and die "kits". Some people refer to them as
"standard". It cuts a 77% thread.
>Class 1 is looser. Class 3 is tighter.

I'm assuming you mean the type of tap that you might possibly purchase at a typical hardware store maybe??

Thanks, Gary in N.Y.

P.S. It all boils down to the "H-limits" of each individual tap. Conventional hardware store taps are generally the H-3 series! For tighter threads you would use an H-1 or maybe an H-2? It all depends, the taps come as high as H-5's, maybe more, not 100% sure!
Click to expand...

> Here are the H specs.
Class of Threads, H Limits
Classes Of Threads
There are (3) established Classes of Thread, designated in the unified series by adding: "A" for Screws and "B" for Nuts (or other intenal threads) to show definite limits and tolerances.

Class 1B Thread
Is wherea 1A screw can run in readily for quick and easy assembly. The hole is classified as 1B. The fit is a 1B thread, (very seldom used in modern metal working)

Class 2B Thread
Consists of a 2A screw in a 2B hole. 2B thread has wide applications. It is used to accomodate plating, finishing and coating to a limited extent and threfore, has fair tolerance allowances.

Class 3B Thread
3A screw in a 3B nut or internal threaded hole, used where tolerance limits are close.

GH Numbers
GH Numbers are listed below. "G" designates Ground Thread. "H" designates the pitch diameter is on high side of basic. These two letters (GH) are followed by a numeral indicating the Tolerance of Pitch diameter oversize.




H1 = Basic to Plus .0005
H2 = Basic Plus .0005 to Plus .0010
H3 = Basic Plus .0010 to Plus .0015
H4 = Basic Plus .0015 to Plus .0020
H5 = Basic Plus .0020 to Plus .0025
H6 = Basic Plus .0025 to Plus .0030 H=Above Basic
H7 = Basic Plus .0030 to Plus .0035 L=Below Basic
 
I'm staying with my incredibly well modified 8Ba head bolt with 5 (not 4) carefully filed grooves in it. It has served me well for the last 20 years and I'm stickin' with it.
 
GOSFAST said:
Hi Pete, you'd have to define a "standard" tap here, there's really no such thing!

I'm assuming you mean the type of tap that you might possibly purchase at a typical hardware store maybe??

Thanks, Gary in N.Y.

P.S. It all boils down to the "H-limits" of each individual tap. Conventional hardware store taps are generally the H-3 series! For tighter threads you would use an H-1 or maybe an H-2? It all depends, the taps come as high as H-5's, maybe more, not 100% sure!
Click to expand...

According to the Grainger catalog, they list taps with a H12 rating. Talk about sloppy!

Does anyone know where to get a 7/16-14 H1 rated tap? A quick Google search did not find any places that sell them. Now I want one.
 
Thanks to Pete again for setting us straight on the #2 class fit threads can cleaned with the proper class thread tap.
 
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