Why are tap wrenches so weird?

dbooksta · Jun 24, 2017

Even when I had a shop with Starrett tap wrenches I didn't understand: Why don't we have something like a socket wrench, where each socket is sized to a standard tap shank, and has a 1/2" square wrench hole that can accept wrench handles of arbitrary lengths, with optional ratcheting features, etc.?

Now that I'm using cheaper wrenches it's weirder: They have two opposing sliding bits, one of which is left-hand threaded and held by the handle. I can't imagine why this would ever be useful, except maybe to replace the bit. But I'd sooner throw the whole thing away, and that extra bit and threaded handle just increases slop. Am I not using these correctly?

ewlsey · Jun 24, 2017

Mcmaster Carr 2604A35. These are great for repair type work or chasing a thread.

The regular tap wrench is better for cutting new threads with a traditional hand tap where you need to constantly reverse the tap to break the chip.

L Vanice · Jun 24, 2017

There are a great many different designs of tap wrench, past and present. About anything you can imagine has been made at one time or another. There are always reasons to select one design over another because there are many different situations in which taps are used. The best designs have been around for a long time because people have found that they are, in fact, the best designs. Some designs have survived just because they are cheap and mostly work, not because they work well. There are people who will always favor cheap over good.

Larry

msimard · Jun 24, 2017

For a tool to drive taps by hand, the most important design trait should be symmetrical drive arms to eliminate the force that pushes the tap off path and results in wobbly/sloppy threaded holes.

bryan_machine · Jun 24, 2017

ewlsey for the win.

also, if you put a sliding t-style wrench handle on it, it will behave like a regular tap wrench.
mcmaster "sliding t-style wrench handles" if you somehow don't have one....

Bill D · Jun 24, 2017

Lisle makes a set of square sockets sized to hold standard tap shanks. Are metric tap shanks English sizes or are they metric ? Metric sockets use standard 1/4, 3/8 1/2 inch square drive handles.
Bill D

Lisle Corporation

Mud · Jun 24, 2017

These from snap on have o rings to hold the tap in.

My new favorite for big taps, from GearWrench

tnmgcarbide · Jun 24, 2017

the only 'weird' tap wrenches i've encountered were the pieces of dogshit disguised as real tools- as
advertised-with steel vee jaws,
and steel threaded handles ....(they conveniently did not mention zinc potmetal bodies). WTF? i bought a "set" of three of them, about 15 years
ago . i threw them in the trash about 14 yrs, 11 months ago .

i like the Greenfield/GTD sliding jaw wrenches a lot .

the ratcheting general tee handles i bought 10 years ago are very good for smaller taps- they ratchet for machine taps or can lock if you're using hand taps (almost never)

for large taps over 5/8" , i have a shop made wrench - which is nothing more than two opposing square bars with vees, and two 5/16 capscrews .

this is the idea - http://www.oocities.org/elmgrove1765/project5/tapwrench.jpg

i also like these ratcheting, square drive refrigeration wrenches
Refrigeration square Ratchet wrench set - Google Search
they fit taps from 1/4" to 1/2"

D Dubeau · Jun 24, 2017

I made these for taps up to 1/4". I can drive them with my 12v 1/4" hex drill/driver (not impact), 1/4" hex extensions to get into tight spaces, or a ratcheting palm driver (or any 1/4" he turning device you could think of....). Most of the time I use the cordless driver. The taps, are a nice snug "snap" fit, and will come out easily if you want, but will stay in, in all positions.

They also come in very handy with a right angle drive for hard to reach places.

EPAIII · Jun 24, 2017

..... Or broken taps.

msimard said:
for a tool to drive taps by hand, the most important design trait should be symmetrical drive arms to eliminate the force that pushes the tap off path and results in wobbly/sloppy threaded holes.

ewlsey · Jun 24, 2017

Bill D said:
Lisle makes a set of square sockets sized to hold standard tap shanks. Are metric tap shanks English sizes or are they metric ?

Inch and metric taps are all ground from the same standard blank and similar sizes have the same shank and square diameter. I.E. 6mm and 1/4, 8mm and 5/16, 10mm and 3/8, etc.

EPAIII · Jun 24, 2017

Looks like a great way to break a tap, usually even with the surface so you can't easily extract it.

Mud said:
These from snap on have o rings to hold the tap in.

My new favorite for big taps, from GearWrench

tnmgcarbide · Jun 24, 2017

that's what these things are for :
http://www.practicalmachinist.com/v...ical-projects-new-machinists-handtapblock.jpg

Mud · Jun 24, 2017

EPAIII said:
Looks like a great way to break a tap, usually even with the surface so you can't easily extract it.

I posted that to illustrate the sockets. You are not required to use a ratchet in rough fashion in conjunction with those sockets. I've used them quite a bit without ever breaking a tap, including with a ratchet at times. Try using both hands next time.

MattiJ · Jun 24, 2017

Bill D said:
Lisle makes a set of square sockets sized to hold standard tap shanks. Are metric tap shanks English sizes or are they metric ? Metric sockets use standard 1/4, 3/8 1/2 inch square drive handles.
Bill D

Lisle Corporation

Most of my metric taps match the M.C.T.I standard but to make things more confusing I have also one or two oddball size from SKF and some german brand.

M10 tap can have probably half a dozen shank and square drive sizes.

Ratcheting tap wrench is good donor for cordless drill/driver adapter:

Scottl · Jun 24, 2017

I've had a set of the Lisle tap sockets for years and their greatest strength is getting in to restricted areas where readily available square drive extensions can give added length.

rons · Jun 24, 2017

Took longer to take the picture than dream this up. A nice off-cut of Superstrut and two channel nuts.
OSG 1/2-14NPT tap with 1/2" square shank.

Davis In SC · Jun 24, 2017

msimard said:
For a tool to drive taps by hand, the most important design trait should be symmetrical drive arms to eliminate the force that pushes the tap off path and results in wobbly/sloppy threaded holes.

But there always the doofus that tries to use a Crescent wrench on a tap, then complains that the "Defective" tap broke...

art.h · Jun 24, 2017

EPAIII said:
Looks like a great way to break a tap, usually even with the surface so you can't easily extract it.

Might be okay if the ratchet has a centre for hand tapping in a mlathe or mill.

John Welden · Jun 24, 2017

Use a cordless drill when possible.

Why are tap wrenches so weird?

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