I have a handful of broken power tools that have functioning drive motors. They parts I needed to fix them cost more than a replacement, so I replaced them and hung on to them for parts. I'm wondering if I can use the motors for a custom R/C build while using a standard, off the shelf, 1/10th or 1/8th scale speed control, and 2S/3S/4S LiPos. I'm not sure how to determine/convert the specs of the motors in my power tools into something comparable to the standard parameters used for R/C ESCs.

If it's a brushed motor, maybe. If it's brushless, highly unlikely.

Look for brushes in the motor. If their are none look for hall affect sensors. How many sensors?
Confirm they are dc or ac.
measure the current to accelerate the motor and the steady state current while running under load.
chances arent good but this is where you start looking first.

not uncommon for battle robots to use the motors from drills and grinders to use for their RC application, HobbyWing sells a 4S capable brushed ESC too!

If its a cordless tool, then its a dc motor, and can be used. Some of them are large though. It used to be common to use dewalts cordless motors (12v ones i believe) on a summit or even a crawler. I know the 18v ones are 775 sized motors, i ripped one of my drills apart to see. And the newer brushless motors are really tall and thin. So i doubt they'd fit in anything.
if its a corded tool, then no it wont work, as it'll be an ac motor.

on the surface it might seem like you can’t run an ac motor on a brushless esc but it is done. it can be done with and without sensors or even back emf. early robot servos were permanent magnet motors and the shape of the electricity to rotate these motors was identical to the shape our esc deliver. a bunch of small pulses that simulate an ac waveform. a trapezoid. travel 30 years into the future and those same systems are still dicing up dc but doing a better job of chopping it up and it looks like a sin wave. when a company i worked for discontinued the old (esc) servo drive of 30 years ago auto manufacturer F forced us to design the new systems to work on the old motors because they had 100s of millions in motors buried in every corner of every machine globally. well, the first step was to plug it in and run the old motors on the new sin wave systems and watch what happened. nothing happened except the motors had less torque and ran cooler.

all precision motor controllers take ac and turn it into dc and then chop it up into ac again. im not suggesting that it’s easy but its interesting to know that our hobby is very much connected to some of the highest technology available today.

You could get a controller to do it, but it's not likely to work with off the shelf RC ESCs as per the original post.

These power tools have for 99.99% a brushed motor and yoes, a decent ESC capable of those voltages will work but you need to add a servo tester to controll it by hand.

If you look arround on Ebay, Aliexpress and Banggood you will find cheap high rated voltage/current PWM controlers which are directly controled by a potmeter.

I dont think I said anything to the contrary. I post to generate interest and understanding. Id prefer not to go back and forth with you.

On the off chance that its a cordless apparatus, at that point its a dc engine, and can be utilized. Some of them are huge however. It used to be basic to utilize dewalts cordless engines (12v ones I accept) on a summit or even a crawler. I realize the 18v ones are 775 measured engines, I tore one of my drills separated to see. What's more, the fresher brushless engines are extremely tall and slender. So I question they'd fit in anything.