Re: [CAD_CAM_EDM_DRO] More on servo motor selection

Jon Elson wrote:

> But, we're really going around in circles, here. Let's start from the
> beginning. You want to use 1/2 Hp with up to 1/2" end mills, at what
> RPM? In aluminum, 600 SFPM is recommended, so that comes out to about
> 4300 RPM. A dirty worst case cutting force calculation would show that
> the torque to turn the tool was .5 Hp x 550 Ft-Lb/Sec = 275 ft-Lb/sec
> A 1/2" end mill has a circumference of .5 X Pi = 1.571" or .131 Ft, and
> is turning 4300 times a minute, or 71.7 times a second. So, the peripheral
> velocity is 71.7 x .131 = 9.388 Ft/Sec. To get equivalent torque under these
> circumstances, (275 Ft-Lb/Sec) / (9.388 Ft/Sec) = 29.3 Lbs.

Jon,

Sorry for being so dense but this is all new to me. Is the part
of your mail I've referenced above the "worst case cutting force
calculation" you mentioned?

Also did you base the initial .5 Hp requirement on my calculation of
removing 1.5 cu. in. of al. per minute?

I also wanted to mention that I found a page on your web site that
also helps to explain some of this. The URL is:

http://206.19.206.56/motor.htm

Thanks again,
Drew

--
Drew Rogge
drew@...