John It would help if we knew what it is you want to attach this focuser to, ie thread on your scope.
There are several stepdown rings that have M46 p 0.75 threads but they usually fit common camera filters M52, M55, M62 etc.
I went through a similar situation recently trying to fit an SCT 2" 24tpi threaded item to a Tak FS60 (M55.9 x0.75 thread) in the end I got a Takahashi extension tube and had a 2" SCT thread cut to the other end of it.
A reasonable question you ask. But I've been asking the question in reverse: "What, if anything, will this focuser thread into? Please tell me."
When you say, "There are several stepdown rings that have M46 p 0.75 threads..", I'm betting you probably mean male
M46 x 0.75, not female
. Please tell me I'm wrong!
I want any
female M46 part, so that I can modify it to mount on a base plate of my own construction. I just want the female M46. My telescope has no ready-made threads of either gender to mount the focuser on.
The focuser will then thread into my DYI base plate (made from wood or metal plus any female M46 that I can get my hands on!) on the side of my 7" newt OTA.
I only bought the focuser because the seller made the application sound common. Now I see that this is not turing out to be the case.