Tapping is something I've needed to do very little of. The usual 40-pc standard Tap Set from the likes of Grainger, et al, include tap wrenches that are underwhelming in efficiency.
A number of weeks back, I began a project that required not only numerous 1/4" taps but taps that required exacting precision re perpendicularity on a narrow (1/2") surface.
In my search for the proper tool(s), I came across a little, relatively inexpensive unit outsourced by
Grizzly Industrial (to India), designated as
H5607 Tap Wrench With Fixture http://www.grizzly.com/products/Tap-Wrench-w-Fixture/H5607
It used to be carried by Amazon but no longer, and reviews are hard to come by. Noteworthy is the conspicuous divergence of opinions, i.e. really good or next-to-useless. It appeared as if something obscure clouded the issue pertaining to the spring nibs (seen to the left above).
I decided to take a chance (along with procuring other "helps"!) since this unit would be VERY suitable for the application.
I couldn't have been more pleased with the results. The two images below show 1) the parts, including 2 sets of nips for 2 different size-range of taps, and 2) the unit laid out, ready to be assembled for use.
The problem with the spring nibs appears to be one of unfamiliarity, since no hint of how-to-use is provided. Key here is the tightening capacity for the nibs holding the inserted tap end, as evinced by the flat, wrench-application surface at the base of the female-thread case that slips over the nib holder. Apparently, some people keep breaking these nips , thereby completely disabling the tool! As far as I can tell, the only way to defeat this tool is to NOT tighten appreciably the nibs to the tap end, resulting in slippage/breakage once the wrench is turned fully to engage the tap.
The fix is simple:
tighten to ~ 144 in-lb (I wouldn't go over 150 in-lb.....). For those that usually relate to torque in terms of ft-lb, the value here is
12 ft-lb - a value that should not be exceeded, near as I can tell. However, except for an unusual, interchangeable-head type of torque wrench, one cannot apply a torque wrench directly.
Here's one way to determine just how tight 144 in-lb is:
Find a convenient, attached-bolt head of equivalent size to that of the flat-wrench surface on the H5607, that being
9/16" - and ONLY that, metric sizes can't be used (unless you have a 16 mm on hand, and that is still a little sloppy!)
Loosen the bolt, set torque wrench to
132-in lb (11 ft-lb), tighten until the head releases (clicks). Now, use the flat wrench to
tighten the bolt SLIGHTLY, paying close attention to how much strength your wrist-forearm is using. If you're unsure, or not used to gauging like that, repeat the entire exercise.
Finally, apply the 9/16" wrench to the H5607 until you reach the same degree of exertion as used with the bolt-tightening exercise. This will be sufficient.
The reason for listing values in
in-lb: most ft-lb graduated torque wrenches are of the 1/2" drive variety, commonly reaching values of 150 ft-lb (the best ones up to ~ 300 ft-lb). The problem with ALL torque wrenches is that they become quite unreliable at their extreme bottom or top end.
3/8" drive torque wrenches, in contrast, are graduated across a much lower range of values, usually up to ~ 250 in-lb, which barely equals 20.5 ft-lb. More appropriate still, is the fact that the handle-length of a 3/8" drive torque wrench is significantly shorter than that of its larger iteration, and much closer to the length of the flat-wrench used to correlate your physical strength, an
important consideration when taking into account the "distorting" of sensation when applying physical strength with greater leverage, i.e. using a longer handle!
The point is: torque values required for this exercise are well within the comfort range of a 3/8"drive torque wrench, and that's what should be used.
For my purpose, the H5607's primary function was to provide a dead-on-perpendicular start for the tap. Once into the material, say ~ 1/4-3/8", other means to complete the tap can be used - although I see nothing wrong with making sole use of the H5607.
To complete the taps, I made use of a
GearWrench 3880 5 pc set which is an absolute JOY! to use, along with a
Gator Tap Wrench Guide (both available on Amazon):
The GearWrench set is made in Taiwan with the customary quality associated with the island, the ratcheting wrench having a fine-toothed gear (72 teeth) that permits excellent depth control. Completing 9 taps was
completely pain-free, i.e. no hassle, simple, the wrench lets you almost sleep through to the finish.
The Gator Tap Guide came in very handy. However, without the initial, straight hole provided by the H5607, the process to completion would have been more awkward, given the requirement for working on a 1/2" wide surface.
Be it an awkward surface, like a round one, or any normal work, that Grizzly tool sure can make our day!
Edit: I've included changes that make this rather arcane topic more explicit, more easily digestible.