After posting about Lee Valley’s new thread ID tool, we started thinking about other thread-identification tools that we’re familiar with. Identifying a thread is usually done in one of two ways – by matching an unknown thread to a fastener of known thread, or by measuring and comparing the diamater and thread pitch of a fastener.
Following are a few types of thread identification tools:
Pictured here is the (made in USA) Thread Checker by S&W Manufacturing. Loosely threaded about a wire, these beaded fasteners can be used to identify tapped holes, nuts, and bolts. This type of thread ID tool offers similar flexibility to Lee Valley’s ID tool, but eliminates the risk of losing a stud. S&W Manufacturing also offers a wall mounted Thread Checker.
Nearly identical to the Thread Checker, Rockler’s Thread Detective Screw Gauge is as versatile, but a bit more economical. SAE and metric gauges are sold separately.
Then of course, you have bolt and machine identification gauges where you match fasteners to holes of known size. For these gauges to be used most effectively, you may want to have a screw pitch gauge handy to measure a fastener’s thread count. Of course, you could always hold the fastener up to a scale or calipers and count the thread density yourself.
Most hardware and tool stores will typically carry screw ID tools of this kind, and they’re quite affordable at $10-15, although you may be able to find a cheaper one. These types of gauges are available from several brands in a very similar layout (suggesting a common OEM).
Some time ago we noticed a similarly styled ID tool by Woodcraft that can be used for sizing anchors and wood screws – Anchor & Screw Gauge (via Woodcraft).
Finally, a screw thread pitch gauge is used to measure the TPI, or threads per inch, of SAE fasteners. Metric thread gauges work in a slightly different manner and instead measure the separation between threads. Screw pitch gauges can be found at larger home improvement stores, and many well stocked online retailers.
Here are several gauges available via Amazon.
If you know of any great thread identification tool styles that we might have missed, please let us know via a comment!