'Bout 6 months ago I went through this nightmare of a special project of making a quite intricate device to fit on the end of a plain ol' broomstick handle. Customer had no idea what the handle was going to be made out of, but he absolutely needed that interface.
I can tell you that after testing approximately 20 different makes and models of female devices ( brooms, pushbrooms, cheap paintrollers, expensive paintrollers, polesanders, brushes and you name it ) by far the most were the closest to a 3/4-5 ACME.
The only problem was that using the ACME thread specs, they did not tighten up. My app was 1" deep blind hole, so imagine the chip issue.
Nonetheless, what I came up with was to reduce the major dia by .02 and give it a 5 degree taper.
Since the handles are made of all kinds of garbage using all kinds of garbage specs ( if any ), the taper had allowed something ( and I could not care less what part of ) the thread to lock up and tighten.
Anyway, this was my experience with the broomstick female thread. Straight bore, .02 under spec for the major and a 5 deg. taper.
If this is an internal application, I've found Micro100 the only supplier of a tool which can fit inside the bore and create the thread. Found no taps or threadmills to make a blind 3/4-5 ACME.
And lastly, my app was in Aluminum. If you have steel or anything else, either walk away from it or kiss your butt goodbye! This thing is one deep thread for it's size and the tool!!!
On Edit:::
Sorry guys, I've just checked my notes on the program and noticed that the minor dia also had to be opened by .03! Still straight bore, but .03 over the spec.
Courtesy of ME Thread Pal, these are the specs I've used a starting point:
0.7500-5-ACME-4G
Allowance,--
Minor Diameter Min,0.5500
Minor Diameter Max,0.5600
Pitch Diameter Min,0.6500
Pitch Diameter Max,0.6562
Major Diameter Min,0.7700
Major Diameter Max (Ref),0.7900
Flat At Root,0.0690
Thread Height (Basic),0.1100
Pitch,0.2000
Lead,0.2000
Starts,1
Lead Angle,5.624