Taps and pocket clip screws that match?

David Mary

David Mary

pass the mustard - after you cut it
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I've been having a bear of a time trying to find both taps and screws that I can be sure will match, for the purpose of tapping handles for pocket clips. If anyone can recommend me where to find such, I would be most grateful.
 
Haven't bought taps in a while, going off what I remember there are different grades like 1 - 3.Two beening the most common.

A great place to find taps is KBC Tools
 
View attachment 1099935 Machine screw taps are usually offered in three shapes: Starting, Plug, and Bottoming. A plug tap is good for most applications. A bottoming tap is needed for blind holes. Machine threads do not do well in soft materials like plastic. Threaded inserts like Helicoils solve this problem. Not my picture.
 
Taper taps are very rarely used these days. A plug tap will suffice for pretty much everything. Bottoming taps are only used for the last few threads after a plug tap has already been run to the bottom of the hole as far as it will go. Even then they're usually only used when there isn't space to drill the hole deeper than the necessary thread depth and just use a plug tap.

Regardless, any of these will produce the exact same thread that the same screw will screw into, so they have nothing to do with thread mismatch.
 
eKretz said:
Taper taps are very rarely used these days. A plug tap will suffice for pretty much everything. Bottoming taps are only used for the last few threads after a plug tap has already been run to the bottom of the hole as far as it will go. Even then they're usually only used when there isn't space to drill the hole deeper than the necessary thread depth and just use a plug tap.

Regardless, any of these will produce the exact same thread that the same screw will screw into, so they have nothing to do with thread mismatch.
Click to expand...
Good posts. I wonder if he's referring to 2b vs 3b threads and making sure that matches?
 
Classes of fit for threaded fasteners are #1, #2, and #3. A applies to male threads and B applies to female threads.
1A & 1B have the loosest tolerances and are seldom specified. 2A & 2B are the normal use standards and are suitable for pocket clip screws. 3A & 3B have the tightest tolerances and are used for more critical applications (Moon Shots).
 
tiguy7 said:
Classes of fit for threaded fasteners are #1, #2, and #3. A applies to male threads and B applies to female threads.
1A & 1B have the loosest tolerances and are seldom specified. 2A & 2B are the normal use standards and are suitable for pocket clip screws. 3A & 3B have the tightest tolerances and are used for more critical applications (Moon Shots).
Click to expand...
So will a 3a screw fit in a 2a thread? I've always been curious about that
 
Yep, class 1 is usually reserved for stuff like hardware store stamped steel wingnuts. Class 3 is more for precision stuff - in many cases with class 3 threads any damage like a scratch or nick can result in a thread that won't screw in. The vast majority of fasteners used today will be class 2, and any standard tap you order will automatically be a class 2 unless you special order it otherwise.

A 3A will thread into a 2B, yep. The tolerance is mostly on maximum pitch diameter for the B (internal, or female, thread) and
minimum pitch diameter for the A (external, or male, thread).

So generally, a 3A (male) will be slightly larger in pitch diameter than a 2A. A 3B (female) will be slightly smaller in pitch diameter than a 2B.

Keep in mind that there's still a range within all classes that is deemed acceptable, so you can actually have a class 2 or even a class 1 that fits like a class 3.

Edit: here's a demonstration for a 3/4" thread as an example - so a class 1 mating thread could have a maximum of about .032" slop in the fit, with a minimum of .002". A class 3 about .010" maximum slop and a minimum of almost nothing. Smaller threads have correspondingly smaller tolerances.

20190328_165646.jpg
 
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There is a handy tool you can get at many hardware stores or machinist tool supplies. It is a thread checker and the ones for fine threads are either thicker hunks of high grade plastic or metal like in this photo at this LINK > > >
Or like this LINK > > >

Be sure to take a screw to the vendor so you get a small enough checker.

More conventionally one can just use a thread pitch gauge but for that fine of threads you may need some magnification to see if the pitch gauge fits right. For larger threads there is no question the blade of the pitch gauge really seats into the threads with a tactile YEP-THAT-FITS sensation. If you try a gauge that is the wrong pitch it just wallows around and never feels right. LINK > > > to thread pitch gauge.
And here LINK> > >
I have and use both just depends on the situation.

PS: if you get two links to the same photo try again (I corrected my post / link).
PPS : takes a while to load those last two images for some reason.
 
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Wow, you guys brought me up to speed in no time flat! Thank you one and all.
 
eKretz said:
Yep, class 1 is usually reserved for stuff like hardware store stamped steel wingnuts. Class 3 is more for precision stuff - in many cases with class 3 threads any damage like a scratch or nick can result in a thread that won't screw in. The vast majority of fasteners used today will be class 2, and any standard tap you order will automatically be a class 2 unless you special order it otherwise.

A 3A will thread into a 2B, yep. The tolerance is mostly on maximum pitch diameter for the B (internal, or female, thread) and
minimum pitch diameter for the A (external, or male, thread).

So generally, a 3A (male) will be slightly larger in pitch diameter than a 2A. A 3B (female) will be slightly smaller in pitch diameter than a 2B.

Keep in mind that there's still a range within all classes that is deemed acceptable, so you can actually have a class 2 or even a class 1 that fits like a class 3.

Edit: here's a demonstration for a 3/4" thread as an example - so a class 1 mating thread could have a maximum of about .032" slop in the fit, with a minimum of .002". A class 3 about .010" maximum slop and a minimum of almost nothing. Smaller threads have correspondingly smaller tolerances.

20190328_165646.jpg
Click to expand...
That's great info thank you! Especially since I'm trying to have 500qty of 3 different 2-56 ti screws made :)
 
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