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Messages - Ken226

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General Mach Discussion / Re: PWM vs Analog output for spindle control?
« on: November 23, 2020, 09:04:16 PM »

My question is:. If bypass the 0-10v converter, and feed the PWM signal directly to the 1200BWD driver and use PWM duty cycle to control the speed, would I get better linearity?   

I doubt it, the non linearity is largely because the controller is actually a 'phase controlled rectifier bridge' and the transfer function ( the mathematical description
of the output verses the input) is highly non-linear with phase controlled bridges. It is in fact approximately linear to sin2 over a range of 0 to 90 degrees.

Is precise speed control that important?  For years a and years we used manual mills and lathes which which not adjustable so had to accommodate whatever gear
ratio that was available.....so why the fixation on spindle speed now?


Thanks for the reply, that's the info I was looking for and approximately what I expected.

It's not so much a fixation with spindle speed, more a mild nagging curiosity.  I get by fine with it as-is.   

The reason I decided to explore it further, is because while reading the bldc driver manual, I realized the same terminals are used for both Analog and PWM inputs.   Bypassing the Analog would be a simple matter of moving two wires on the breakout board and changing a setting in the bldc driver.  I wouldn't have to do anything to the wiring harness.

Thanks for the response.

General Mach Discussion / Re: PWM vs Analog output for spindle control?
« on: November 23, 2020, 09:33:18 AM »
I believe so.

My motor is a 1-1 ratio belt drive BLDC 1.5hp 8000rpm.   My index pulse tachometer is an optical trigger with 2 slots.

My pulley setup in mach 3 is min=0, max=8000, ratio=2

The actual RPM read by mach 3 from the pulse card matches the RPM read by my motor driver perfectly.

Boy do I feel stupid, that is what I should have done from the start. Geese I bet my old board is not doa either. :o . I did as you suggested ken226 and I am back in business, go figure.
Thanks again.

No worries. I've been there. 

My machine acts weird with some versions of mach3, and runs like  a Swiss clock with version 3.043

It's running so good now that I posted some videos in the cnc machine show n tell section.  Check em out.

Glad I could help.

Start with the easy stuff.   Save your profile file, then delete and reinstall mach 3.   Put the profile folder back in the new mach 3 installation, and test it out.

If that doesn't work, look at your pc to breakout board connection.  Check the breakout board for power, etc.  Check each component. 

Any recent pc hardware changes or software updates?

Show"N"Tell ( Your Machines) / Re: Show and tell videos.
« on: November 22, 2020, 05:03:00 PM »
Next gadget is a cover plate for an electrical switch

Setting z for contouring

Contour roughing

Drilling pilot holes

Drilling holes

Setting z to engrave



Show"N"Tell ( Your Machines) / Show and tell videos.
« on: November 22, 2020, 04:53:17 PM »
I have a few of my G0704 CNC,. So I thought I'd post up a few links.

A knife sharpener I designed and built:

The first couple parts.

A few more

Making more parts.




Touching off Z for engraving


More engraving

Assembled gadget

Testing gadget

General Mach Discussion / PWM vs Analog output for spindle control?
« on: November 22, 2020, 04:13:26 PM »
I have a G0704 cnc that I built about 8 years ago.  It uses mach3, an ethernet smooth stepper and a C11g  breakout board.

For the spindle I'm using a 1.5hp bldc motor and a GlockCNC 1200 watt 1200WBD driver. The speed is controlled via the C11g breakout boards onboard 0-10v Analog converter, connected to the 1200WBDs Analog input terminals.  The breakout board converts PWM into a 0-10v Analog signal.

My spindle works well enough,  but either the Analog converters output isn't very linear, or the 1200WBD driver doesn't convert the voltage to RPM in a linear manner. 

I can easily tune the spindle speed to match the mach3 commanded speed using the C11g onboard potentiometer,. But it only ever matches @ that specific speed.  For example, if I enter 4000rpm into mach3, and adjust the potentiometer untill I have 4000 RPM at the spindle, entering 3000rpm in mach3 will get me about 2700rpm at the spindle.  The closer I get to 4000, the better they match.  Above 4000, they will start to diverge again.    This same non-linearity manifests no matter which RPM I use as the base for tuning.

My 1200WBD can also accept a 5v 1khz-2khz PWM signal to control the speed via PWM duty cycle.

My question is:. If bypass the 0-10v converter, and feed the PWM signal directly to the 1200BWD driver and use PWM duty cycle to control the speed, would I get better linearity?   

It's not difficult to bump the commanded RPM up/down untill the tachometer is where I want,. But it would be nice if I didn't have to do that.

I don't mean to resurrect such a long dead post, but i found a solution to a problem and want to post it in case anyone else has the same problem.  Perhaps in a few years, someone will be running google searches and come across this thread like i did.

i have been plagued with this random "estop requested" error for quite awhile.  Yesterday it pissed me off enough that i devoted half the day to fixing it.

I'm running mach3 with an ethernet smoothstepper, on a windows 7 machine on a G0704 conversion.  I had tried ferrite beads all over pretty much everything (did nothing to help).  I rerouted wires to keep high voltage away from low voltage wires (didn't work either).  I set my various debounce settings in the smoothstepper plugin to as high as 200,000 (no effect whatsoever).

It started working fine after i deleted mach3 version 3.043.066 and installed version 3.043.062. 

Suddenly, mysteriously, in the exact same machine with the same wiring, Mach 3 version 3.043.062 cured the random estop triggering. 

My clue that it was a software issue and not a hardware issue was that it, in a 30,000 line program, it kept triggering the estop, on the exact same line of code. Every single time.  I could reset the Estop, and "run from here", continuing from the same line of code and finish the program fine.  but on many programs, it would trigger the estop, on the exact same line of code every single time i ran the program.  Yesterday i ran the same program 10 times, and got the estop on that same line of code ( x 2.3, Y1.125, z-.125)  Thats it, just a simple linear interpolation line amongst thousands of similar lines.  but it estopped on that same line, every single time.

Mach4 General Discussion / Re: Mach 4 demo?
« on: January 18, 2019, 09:48:56 AM »
Thank you Bryanna,

That is an excellent guide, very easy to follow.

Mach4 General Discussion / Re: Mach 4 demo?
« on: January 17, 2019, 11:37:40 PM »
Great, thank you Steve.

Ill try your suggestions in the morning.

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