The problem I have is when running a program my cnc will not run faster than 58 ipm, even if I manually increase the feed rate. So is there something in mach 3 that puts a limit on how fast your feed rate is? If so how do I change the limit?

Thank You
Dennis Killian AKA capdenny

Hi,
we can't possibly answer your question without some details. There is no limitation in Mach that prevents you
from going as fast as you tune your motors, or as fast as your motors will physically go or the kernel speed it exceeded.

What is the steps per unit value in your motor tuning?
What is the max velocity in your motor tuning?
What microstepping regime have you in place?

Craig

The problem I have is when running a program my cnc will not run faster than 58 ipm, even if I manually increase the feed rate. So is there something in mach 3 that puts a limit on how fast your feed rate is? If so how do I change the limit?

Thank You
Dennis Killian AKA capdenny

MACH3 do limit the speed but only for the DEMO version limiting the kernel engine to a MAX. of 25,000Hz.
If you have MACH3 full license, you should NOT be running the kernel at 25,000Hz.
I built a new PC with win7 32bits with I5 7600 36MHZ CPU and my MACH3 kernel speed was able to reach 100,000Hz with STILL excellent results.
(But for balanced stability I intentionally reduced the kernel speed to 60,000Hz.)
Result was my router that previously with core2duo 24MHz could not run faster than 40ipm now can run at 100ipm. This is the max speed my router can run physically design.
To run even faster, I would have to increase the driver voltages from 24volts to 48volts and use steppers with higher torque that also requires higher current to run. $$$$ required.

Many make the mistake of buying OLD PC with XP or Win 7 to run MACH3. 
Even with old PCs you may be able to increase the kernel Engine to run at 36,000Hz or 48,000HZ if you can tune it up or just upgrade the CPU and RAM and video card reducing background programs and interruptions.

Step pulse and DIR pulse under Motor tuning can affect the speed too.
Default is 5 and 5us though some people even use 15 and 5 for stability because they have inferior hardware.   
BUT with my faster PC, I could reduce Step pulse and DIR pulse to 1us and 1us have no known issue yet

Hi,

(steps/unit) x (max velocity, units/min) / 60 = required step pulse rate at max motor tune velocity and must
be less than or equal to the kernel speed.

If you answer the questions we could soon work out whether Mach is limiting the speed by virtue of kernel speed limitation.
Without answers no one knows.

Craig