stepper motor rule of thumb

I really could not find a good spot on the web that gave typical dimensions of NEMA motor frame sizes, so I dug into a bunch of high-torque Lin engineering PDFs and came up with the following:

frame size     bolt square          body square
NEMA size 8     .64” (16.4 mm)          .80” (20.3 mm)
NEMA size 11     .91” (23.1 mm)          1.1” (27.9 mm)
NEMA size 14 	1.02” (25.9mm)          1.39” (35.3 mm)
NEMA size 17 	1.22” (31.0 mm) 	1.67” (42.4 mm)
NEMA size 23 	1.86” (47.2 mm) 	2.25” (57.2 mm)
NEMA size 34 	2.74” (69.6 mm) 	3.37” (85.6 mm)

Then I noticed that if you took the distance between two bolt-holes on the motor frame in millimeters and divided that by 2 you would get very close to the advertised frame size.

I was going to add this to
//www.reprap.org/wiki/StepperMotor#Unscientific_rules_of_thumb_for_motor_purchases
but I figured it would be good to vet it here first. Does anyone have an "official" frame dimensions reference?

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My blog's Reprap feed: [blog.markbova.com]
I'm currently working on a stock Mendel build with a Seeeduino Mega and four Pololu A4983 stepper controllers.

The NEMA number is the body square dimension in 1/10 of an inch. If you round all those to the nearest tenth they are spot on.

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[www.hydraraptor.blogspot.com]

That's even more obvious. I wonder why I missed that compiling the table or web searching for an answer.

Have you tried the NEMA website?

Found one document "ics16" that had some info but couldn't find anything for the smaller steppers

The registration fro download is free

found this today, doesn't attribute the source

[www.numberfactory.com]