Mach 3 Kernel Speed

[saabman]

So what is the collective wisdom on the speed that the Mach 3 Kernel should be run with IH Turnkeys (and kits)

[ger21]

The author of Mach3 has always recommended using the lowest kernel that will allow you to get you're maximum velocity.

Some say they get smoother running motors by using faster speeds. Results can vary from PC to PC.

As you increase the kernel speed, Windows get's less CPU time for itself.

[saabman]

I understand the basic relationship between the pulses per inch (in the case of an IH mill this is 20,000) and velocity. So the basic math for the IH Turnkey mill is

kernel freq/20000 = max ips

so 25000/20000 = 1.25 IPS or 75 IPM

My conclusion is 25000 is to slow for fast rapids above 75 IPM.

35,000/20000 = 1.75 IPS or 105 IPM

So 35,000 would seem to be the floor frequency. This is sufficient to drive the speed controller which requires 25khz

Servo good to 4000 rpm, so lets check the RPM of the motor.

At 1 IPS the ball screw makes 5 revolutions per second as does the large pulley. The small pulley (motor shaft) makes 20 revolutions per second. Or 1200 RPM.

So at 25,000 pulses = 1500 RPM and 35,000 pulses is 2100 RPM. Either of these well within motors speed range.

The max Kernel Freq would then be 66, 666 with a theoretical max travel rate of 200 IPM.

So for 100 IPM velocity it seem I can do that with 35k kernel. Not a stretch for a modern computer.

Anyone running a faster kernel?

[RustedOut]

Mine is running at 45,000 and has been since I first got it going. A couple weeks ago I was cutting a long MDF blank at 80 ipm with rapids of just under 140 ipm. Program ran nearly an hour each side and the mill ran wonderfully the whole time.

I tried it at 25,000 and 35,000 at first, but the higher 45,000 just seems to make the mill respond nicely so I left it there. I really would like to get my hands on an oscilloscope to finish tune the drives, but they are running cool and quiet so I haven't lost any sleep over it.

Bob

[ozzie34231]

Let me pop my nose in here and ask what acceleration works well for users?

Ozzie