Messages

1631

General Mach Discussion / Re: After using the “Steps Per Unit” in “Axis Calibration” my CNC wont run properly

« on: September 03, 2008, 09:27:25 PM »

Problem is, his error is not constant, even if we ignore the 32000 setting.  If it were, he should be seeing 0.986, 0.493 and 0.247.  Something is very wrong there.  As he reduces the steps/unit, the error, as a percentage, is increasing! 

 

Regards,
Ray L.

1632

General Mach Discussion / Re: After using the “Steps Per Unit” in “Axis Calibration” my CNC wont run properly

« on: September 02, 2008, 08:46:44 PM »

Nice looking machine!  Mid-band resonance occurs at moderate speeds, and when you hit it, motor torque falls drastically.  One way to deal with it (sometimes) is to just power your way through it - accelerate fast enough that you get through it, to higher RPM, before the motor has a chance to stall.  But, that isn't always practical.  Mechanical dampers are another way to deal with it, and can be quite effective.  Micro-stepping can also help, as it reduced vibration.  From what you've described, I do think this is likely your problem.

Regards,
Ray L.

1633

General Mach Discussion / Re: After using the “Steps Per Unit” in “Axis Calibration” my CNC wont run properly

« on: September 02, 2008, 07:43:43 PM »

Acceleration is a function of the motors, the machine, the drivers, etc., etc., and will be different for every axis, and every machine.  X will generally be quite different from Y, because it's fighting a higher mass and hence inertia.  Start low, and work your way up, checking at each step that it will reliably rapid to the correct position.  If you go too far, you'll find you lose position randomly.  There's really little to be gained by going to max acceleration except for bragging rights, so I wouldn't push it.
You may also be hitting mid-band resonance.  Are you using Geckos?  If so, you should adjust the resonance compensation.  It will be different for the two axes.

Regards,
Ray L.

1634

General Mach Discussion / Re: After using the “Steps Per Unit” in “Axis Calibration” my CNC wont run properly

« on: September 02, 2008, 05:45:53 PM »

The buzzing is undoubtedly the stepper stalling because you're trying to step too fast.  You doubled the steps/unit, but didn't change the max speed, so the step rate during jog was doubled, and the motors can't handle it.  First, reduce the max speed on the motor tuning dialog to a low number, like 10IPM.  Then check the jog operation.  I think you'll find it works fine, just slow.  While you're there, check the move distance is correct.  Once both of those are OK, then play with max speed and acceleration, and set them low enough that the motors don't stall.
But, sounds to me like you're really in half-step mode, not full step.  Either that, or you have a 2:1 mechanical reduction you've left out of the calculation.  For 10-pitch screws, full-step 200PPR motors, steps/unit *will* be 2000 in inch mode.

Regards,
Ray L.

1635

General Mach Discussion / Re: VFD and noise questions

« on: September 01, 2008, 11:15:53 PM »

So what was causing the E-stop???

Regards,
Ray L.

1636

General Mach Discussion / Re: VFD and noise questions

« on: September 01, 2008, 09:31:00 PM »

I am going to drop him a line in a few minutes but to be honest his BOB is doing everything correctly , when i call out m3 it closes the contacts on the mechanical relay just like its supposed to and it properly adjust the analog out put thru the full range from 0-10volts depending on the s value so I really dont think its a problem with the board. I have 2 other identical boards purchased at the same time wired just the same that are working perfectly. The only diff is both those machines are running much earlier versions of mach and teco VFD , this one has a 30hp automation direct VFD . I was also running a much later version of mach.

When I installed the earlier version of mach 2.** after the later version 3**is there anything special I need to do to uninstall the newer version ? or is it ok to install as if I am upgrading

You're not connecting the VFD ground (from the VFD control voltage power supply to the BOB) to the system ground, are you?  The VFD control voltage ground needs to be separate from the system ground, just like for the PC.

Regards,
Ray L.

1637

General Mach Discussion / Re: VFD and noise questions

« on: September 01, 2008, 08:14:21 PM »

So, if I'm understanding this correctly, the only thing the M3 is doing is setting one of the PP outputs to command the motor on, but that signal is basically going nowhere, right?  That sounds like a flaky BOB....  I did have that kind of problem with my (really old) Rev 2.0 C11 board, but since getting a Rev 7, no problems at all.  I wonder what the differences are between my Rev 7.0 and your rev 5.4?

Regards,
Ray L.

1638

General Mach Discussion / Re: Microstepping & Torque

« on: September 01, 2008, 07:40:28 PM »

Kristin,

    The surge rating means it will tolerate that voltage for a *brief* period, not long-term.  You'll need to find something with a higher voltage rating.  While you're at it, better pick up a new battery for the ol' calculator.  25 * 1.414 = 35.35V , not 28.535V :-)
    Your plan for sorting the phase on the secondaries is spot on.

Regards,
Ray L.

1639

Brains Development / Re: Suffering From Brain Damage....

« on: September 01, 2008, 06:26:04 PM »

post up your brains here and I will look at them........

Well, I'd have to recreate them.  I didn't save the ones that didn't work.

Regards,
Ray L.

1640

Brains Development / Re: Suffering From Brain Damage....

« on: September 01, 2008, 10:52:29 AM »

Ray,

 Use TWO brains, one that is your input condition brain, in your case you %jogDRO, and write that to a user dro, or set a logic condition LED.

BTW: It would help GREATLY if you would explain exactly what and how you want to do the brain and why.............

In the second Brain, pull in the user dro value, and work your formula or formula(s), in single or multiple rungs depending on what you want to do.

scott

Scott,

    I tried doing basically what you suggested, but using a variable rather than a user DRO.  Does that matter?  I basically set it up so a falling edge on a pendant button (button pressed) would trigger a brain that looked at the current setting of a parameter, such as jog %, and set a variable to the desired new value.  Another brain watched for a rising edge on the same pendant button (button released), and set jog % to the value in the variable.  This still resulted in a loop that locked the machine up solid.
    "BTW: It would help GREATLY if you would explain exactly what and how you want to do the brain and why............." - I believe I did that in great detail in my first post in this thread....

Regards,
Ray L.