Chris wrote this article on Mar 4, 2014. It was listed as incomplete.
So just how much can be said about a tap wrench? It turns out, a bunch more than I thought just a week ago.
A couple of weeks ago I made my Z-setter. I was pretty happy with it even if I did make a couple of mistakes. The Z-setter has 5 tapped holes, four of them blind. I was originally going to go with #8 screws but those were too big, so instead I choose to use #6 screws. Because of the blind holes, I stopped at the local industrial supply store and tried to buy a set of #6-32 taps. Since they only sold them individually, I picked up the taper and bottom taps and planned on using the plug tap from my “tap and die kit”.
Well these are slightly smaller taps than I normally use. My normal “small” size is 1/4-20 and those never give me a problem. Well in this case the T-handle tap wrench in my kit wasn’t able to close on the tap. And this is suppose to be the “small” wrench. In the end I used the flat wrench which just barely worked.
To tap the holes I first drilled them to depth then switched to holding the tap in the drill chuck. I then took the mill out of gear and turned the spindle by hand to tap the first part of the holes. I wasn’t sure of the “feel” so I was worried about bottoming the tap and stripping the threads or breaking the tap so I didn’t go very deep.
Once all the holes on the top had been drilled and the threads started, I removed the part from the vise and attempted to tap them by hand. It was at that point where the limit of this particular tap wrench showed itself.
This is the T-handled tap wrench that came with the kit. Starting at the top we can see different features of its construction.
- The handle is chromed with grooves at both ends to act as a detent for the ball latch in the body.
- The body is also chromed. At the top is the hole for the handle.
- A hole has been drilled through the top to the handle hole and then counter drilled. The counter drilled part has been tapped.
- Handle retaining system. A ball has been placed in the hole at the top, a spring is placed on top of that and the pair is captured with a set screw.
- The chuck is blackened and may be hardened, I’ve not checked. It has a fairly coarse knurl with two decorative grooves cut in it. The inside is tapered but the quality is nothing special.
- The jaws are an integral part of the body. A hole is drilled from the mouth of the body and then the body is slit so there are four jaws. The jaws seem to be designed to hold a round and not square shaft.
When using this tap wrench, as you loosen or tighten the chuck the smoothness changes depending on how and where the chuck is on the body. It does not matter if there is a tap in the wrench or not. It is difficult to tell if the tension felt is because the jaws are squeezing the tap or if it is just the spring in the jaws.
In the case of the #6 tap, it felt like there was a good purchase on the tap but as soon as there was any tension the tap slipped. In other words this tap wrench is a low cost imported pseudo tool.
Now we come to the point of this review. The orgasm inducing (or at least helping to get there) Starrett 93A T-handled Tap Wrench.
The first thing I noticed was that the handle didn’t have the retaining grooves I’m used to. Instead it was a simple steel rod, slightly tapered at both ends with the corners nicely rounded/broken. It had a nice heft to it. At first the fact that it wasn’t chromed sort of made me wonder.
Then I slid the handle into the body of the wrench. The handle stayed where I put it. It doesn’t slide around like “normal” tap wrenches. I slid the handle around and it had just the right amount of friction. I could center the handle and it stayed put. I could move it to one side and it stayed put. When I removed it the friction was constant until I reached the taper.
Examination of the handle hole revealed why. While the body had the same handle hole and top hole as the import, the top hole was there for centering, not for the retention hole. Instead of the “normal” ball retention Starrett cut a small grove for a retainer spring clip just inside the handle hole. When the handle is inserted the retainer expands into the groove while holding onto the handle.
The reason the handle is not chromed is that this retainer system would likely scrape the chrome off if there was ever a chip or scratch made to the handle.
The centering hole means you can use a tap follower to guide the tap as needed when starting the tap. Instead of putting the tap in the drill chuck and then turning the chuck by hand I could have placed a center point in the chuck and then used that to hold the tap vertical as I started the tap. This would have given me exactly the feel I needed to make good threads. It also means that if I had multiple taps (taper, plug and bottom) I could have the ones I needed in different wrenches and instead of having to change out the tap in the chuck I could just remove the one wrench and use the second wrench with the other tap. Much faster.
Next we move to the chuck itself. Unlike the import this has a medium knurl and it is beautifully done. The chuck is also blackened and it looks to be hardened. I’ve not tested but given that it is a Starrett I trust it to be what it looks like.
Side note: I bought a tool kit for the office. It came with a set of hex wrenches. The wrenches are blackened which normally tells me that the tool is hardened. The first time I went to use one to tighten the nuts holding the desks together the wrench twisted rather than the screw moving. While the blackened color said “hardened” the reality was, “Not much better than pot metal.”
When you look into the mouth of the wrench you can see that there are two jaws. The jaws have 90deg V’s cut in them and are blackened and hardened. When you turn the chuck on the body the motion is very smooth and the tension stays constant from fully closed to fully opened. The threading is what you would expect from a company that made their name by providing precision threaded tools (micrometers).
When the chuck is removed the first thing you notice is that the body has a slot milled in it. This slot is wide enough to hold the jaws and the jaws ride within this slot. The body does not flex as the chuck is screwed off or on.
The jaws are spring loaded so that they move outward. In another tap wrench I own there is a standard coil spring between the two jaws. When the chuck is removed the jaws want to fly apart with the jaws going in two different directions and the spring a third. It is important to make sure you don’t let the jaws spring apart like that as you take the chuck off the body to free the jaws.
Well, on the Starrett tap wrenches I didn’t really have to worry about the spring or jaws flying apart. Instead of a coil spring there is a bent wire spring. At the end of the milled slot the body is drilled. The bend of the spring slides into that hole. The other two ends have a hook at the end and these are press fitted to the jaws. When the chuck is removed the two jaws and the spring remain as a single unit attached to the body.
The jaws and spring unit can then be removed. The entire tool can be cleaned and lubricated and put back together.
There is a reason why Starrett 93A sells for $29.14 on Amazon and the Irwin tap wrench for the same size range sells for $8.50.
I’ve added the next two sizes of Starrett T-handled tap wrenches to my wish list, the 93B and the 93C
Jaw sizes for the three Starrett T handled tap wrenches are:
93A – 1/16-5/32
93B – 5/32-1/4
93C – 1/4-1/2