Unified. Size #10, 32 tpi. See... https://en.wikipedia.org/wiki/Unified_Thread_Standard Metric M5 also works.
I guess I don't quite understand the question, but 10-32 is a sizing specification that comes from an SAE definition (I believe), but is now defined in the Unified Thread Standard. 10 - 32 = diameter - pitch (TPI) = 0.1900 in / 4.8260 mm - 0.031250 in / 0.7938 mm Is that what you are looking for?
Quoting from another forum: "Most modern razors use M5 x 0.8 threads except for Fatip who use M4.5 x 0.75 threads. The old Gillettes used #10-32(SAE) which has a pitch of 0.8 so close to M5 x 0.8." and "The metric size would be M5x0.8. The 0.8mm pitch is .0315" compared to the 32/inch or .03125. So no problem on that score. But the M5 diameter is a little larger than the #10, so what usually happens is that a 10-32 head mates to an M5 handle OK, there's just a bit less mating surface on the flanks od the thread. An M5 head on a 10-32 handle can be more of an issue with the threaded post on the head being slightly too large for the handle. Sometimes it orks, sometimes it doesn't - it all depends on the tolerances for that individual sample."
That. ^^^ Almost all modern DE razors still use 10-32 or M5, a testament to the endurance of the Gillette legacy. Edit: especially since there are thread sizes that are easier, cheaper to make and will last longer than 10-32. Pipe threads would be better choices for razor handles and heads in my opinion. It would keep water out of the places there shouldn't be water.
Pipe threads are a good idea but I think you need dope or Teflon tape to seal them properly and of course that would be a pain to fix up every time you change a blade. A regular thread with a simple silicone rubber O-ring should provide a water tight seal though with minimal maintenance issues.
If you want to make a universal handle make it a 2 piece with the neck piece as an adapter. One adapter can then have a thread for 10/32 SAE and the second adapter for M5 X 8.0 Metric. Depending the shave head just slap on the appropriate adapter. If you want to take it a step further use a ball end on the neck piece with 10/32 on one side and M5 on the other. It will allow you to also angle the head like a gem micromatic.
This is the reason I asked - I am designing some new handles - - Comments? 65mm tall 8mm diameter. 10 mm at bottom #10-32 threading (or is it better to use M5 x 0.8?)- "The Max Grip".
Sounds right up my alley. I'm a fan of the smaller handles like the single ring and ball-end tech. I have used handles with metric threads on old Gillettes. It works, just not as snug as it could be. I don't know whether tightening slightly sloppy threads does bad things over time. My minimally informed guess would be that it does. Less metal making contact = easier to deform.
Thats a nice looking handle, it has a modern look but still somewhat retro, im not a fan of some of the space age looking handles out there. But that looks amazing.
2 Questions you need to answer for yourself. 1st. Are you going to use this with SAE thread based heads aka Gillettes or Metric thread based heads aka any chinese made razor for example? If you plan to do both my suggestion is don't mix thread types you run the risk of heads unscrewing while shaving and/or wobble in the head at the same time. It is an issue of sufficient torquing something no one considers until hand tight fails. Just make a universal or 2 handles and mark the metric one with a m either stamped or etched somewhere on the handle. 2nd. Do you want a balanced handle or not? If you finger shave you want a balanced handle. To check take any handle with a head on it and see if it balances on your index finger. The balance point should be right at the neck the more balanced the easier it is to hold it there with wanting to roll etc. Examples of balanced handles are a Merkur progress short handle razor, Gillette 40s style super speeds. Unbalanced the razorock radio handle or the Gillette 3 piece tech fat handles. If you can't hold a balanced handle this way then this is a good exercise to do to build up finger strength and coordination balancing a razor your index, middle and thumb, walk around with it that way, move your hand and arm up and down, sit and stand still balancing the razor on your fingers etc.
