"Ignoramus11290" wrote in message
...
With the original Bosch drives, my 145v motors, etc, the mill was
capable of 200 IPM rapids. Right now I have a 70v power supply with
30A8 drives and the top speed is 60-70 IPM.

My question is how much am I losing, in reality, but having faster top
speed. My feeling is not much, but I want to know.

This is not an entirely idle question, as I could install drives that
match motor voltage (30A20AC or 25A20AC or some such). They would use
120 VAC as power source.

So, would I see any improvement in anything valuable with higher top
speed or no?


I guess it depends on what you are doing. I suspect probably not. That
being said, if you are doing some really long programs ( I just did one that
took almost 2 days) rapid speed can make a difference of several hours. If
most of your jobs are only a few hours probably not at all. Not enough
savings to risk crashes as others have said.

HOWEVER, if you are making fifty of something with a small cutter out of
aluminum you might be cutting at that speed or higher... once you get your
high speed spindle all figured out. I was just doing some speeds and feeds
calculations today that were giving me (wishful thinking) suggested feed
rates of over 100 IPM using a max spindle speed for the calculation of 21000
RPM.

Seriously though 60 IPM is pretty darn fast for most of us. I can get that
speed on my Taig with the Gecko controller, but I backed it off to 52
(mathematical speed based on kernel speed that works really well with my PC)
and cut at 30 or less and I am thrilled with the performance.