There’s a thread on the end of many common handles including mop handles and the extension grippers for changing light bulbs. There’s a similar but smaller thread on toilet plunger handles. What is this thread?
I’ve seen mop handles sold with “ACME Thread” ends. ACME threads are square-profile threads that are used on many machine parts; generally they are for linear motion devices (like the carriage on a lathe that can travel up and down the ways) rather than fasteners. But none of the mop handle ads say what size ACME thread they are. Moreover, mop handle threads are typically more rounded, almost like the very shallow and round threads on light bulb bases.
I want to buy nuts or other items to interface to long extending handles that have these threads, but haven’t found how to do so.
A engineer’s hand book on standards will contain specs for all standard threads and standards on how you are to specify custom threads. The threads on those handles will be one of the sloppy fit threads. ACME is a type of thread, so if that’s what is one the part, that is what it is. Different types and standaeds are needed for different applications or the thread will fail. Some plumbing threads have a bilt in interference so that they produce a water tight seal in a determined number of threads. You don’t want that thread for attaching hard drives to computer cases. The screww needs to keep turning until the two parts are snug, not until a set number of threads stop it from going further.
ACME is the thread used by many things using a rough fit thread to join. They do have many standard variances though, and finding the exact thread used if you don’t know is a pain in the ass. You need major and minor diamaters, threads per inch and lots of other stuff to start. Your best bet is to take a handle in and try on ACME Bolts at the hardware store.
>finding the exact thread used if you don’t know is a pain in the ass
Yes, just so. In fact 30 years ago I worked as a machinist and I have several references such as the Machinery’s Handbook and Mark’s Mechanical Engineering Handbook laying about me right now. Trouble is, the exact thread used is exactly what I don’t know.
I don’t think I’ve ever seen ACME threads at the hardware store. Well, maybe on the better made C-clamps, but not anyplace I can test them. But I’ll look.
Somebody oughta start a business making brackets, adapters, and so forth that are compatible with mop handles. These threads are becoming ubiquitous, if ill-documented. I bought a 40’ handheld extension handle with these threads for less than $40 at Home Depot - the possibities are almost endless!
One of the handles I have has especially nice threads in what looks to me like cast zinc. They are definitely rectangular in profile, have an OD of about 0.745", and have 5 threads per inch within a few thou measured with calipers over 3 threads. Trouble is, the source I was using listed only 6 threads per inch and 4.5 threads per inch, no 5, for 3/4" ACME threads.
So I went to another vendor and found 3/4" ACME threads with 5 per inch. This resolves an apparent contradiction. My nuts will be out this morning. The shipment, I mean…