Super-PID new low-cost router speed controller

[CarveOne]

CarveOne- When I said rough edges that's basically saying these initial units are made here in the design workshop and the overall finish is not representative of a proper production batch. But they are complete and fully functional with all the stuff that matters (as is your workshop I bet!).

I was just joking with you. Everything around here has rough edges on it, including the owner. I know how engineering lab work goes as well. Been there and done that for too many years.

CarveOne

[ger21]

Ger21-
As for running the speed control from Mach3, I'm glad you wanted to test that because it's something I can't do here. The middle wire of the pot goes from 0v to 5v, and that gives speed control of 5000 to 30000 RPM. However it's not totally linear as the scale was carefully adjusted to a semi-log scale to give better "feel" of the pot. It can still be controlled from any 0v-5v analog source if Mach3 has that type of analog output.

Actually, I can't test it either. I'll need to add a parallel port and an additional board to generate the 0-5V signal. Something like this:
DC-03 DigiSpeed GX V3 [DC-03] - US$38.00 : Homann Designs, The Preferred CNC Component supplier

or this:
CNC4PC

Not sure if I have room in my box, though.

Looks like the voltage is linear, so I'm not sure if or how Mach3 can compensate.

[Al_The_Man]

Looks like the voltage is linear, so I'm not sure if or how Mach3 can compensate.

Don't these BOB's that offer Mach (PWM) to VFD analogue, provide this?
They usually offer 0-10vdc, but I believe it can be scaled in Mach just going by an Email I got some years ago from Art when I looked into making one.
Al.

[CarveOne]

My CNC4PC C11G breakout board has the 0-10vdc spindle speed control function on it. I'll see if I can make it work.

Maybe future boards can have a switch or jumper to select linear (Mach3) or nonlinear (potentiometer) mode options.

CarveOne

[ger21]

Don't these BOB's that offer Mach (PWM) to VFD analogue, provide this?
They usually offer 0-10vdc, but I believe it can be scaled in Mach just going by an Email I got some years ago from Art when I looked into making one.
Al.

I just spent over an hour reading, and don't see where or how this can be done.

[RomanLini]

Can you suggest reading for me Gerry or Al re the Mach PWM output?

I already have some excessive RC filtering (integration) on the pot input inside the super-PID, so it may accept the PWM signal directly or just require 2 resistors (for 10v to 5v conversion) and if needed, a 100uF cap (cap for extra PWM filtering).

CarveOne- great point about adding some type of option, thanks for that. At this point the SuperPID microcontroller has a spare pin that would only require tying HI or LO to select the linear/log pot option. But there is no terminal on the PCB so the wire would require soldering to the bottom of the PCB on the micro pins, which is a little clumsy.

It's very simple for me to just produce 2 firmware versions, one with the log system for manual pot use and one linear for external 0v-5v control, but I'm not sure Val would like that as the manufacturer as it adds complexity at his end, ie programming 2 versions, testing 2 versions, shipping the right version etc... Which is the reason the original design spec autoselects 50/60 Hz mains so it's never a manufacturing issue.

My limited understanding of Mach3 is that is uses "plug-ins" so can't this be coded as a plug-in? And what would be the down side if the speed range is not exactly linear, it would still be 5000 - 30000 RPM, and have a tacho display...

I forgot to mention the SuperPID comes standard with a logic-level "tacho" output as I had heard some PC software displays RPM on the PC screen, I don't know if this has any bearing.

(edit)Gerry, I juest checked out the Homann Designs DC-03, it looks like a nice product but I don't think that it would be necessary as it seems to be an isolation board and the Super-PID already has the low voltage stuff (typically) attached to the PC ground. At this point it looks like the Mach3 PWM output can just be attached directly to the Super-PID, maybe with an additional cap needed.

[H.O]

Hi,
Out of the box Mach3 offers On/Off, PWM and step and direction control of the spindle.

On/Off is simply a signal you can tie to relay, turning the spindle on and off.

PWM is just that, a low(ish) frequency PWM signal is generated on the output pin of your choise. The frequency can be specified but the higher you go the lower resolution (available number of discrete speeds) are available. If you run Mach3 at 25kHz and set the PWM frequency to 25Hz you'll have 1000 discrete "steps" or speeds and the PWM signal can be integrated by a simple RC filter to get an analog voltage. This will likely not be very linear over the whole range but that might be able to be corrected with the Calibrate Spindle feature in Mach3 (never tried it personally).

Step and direction. This outputs step-pulses just as if the spindle was another axis. To get an analog signal the step pulses is run thru a F/V converter chip such as the LM2907 which outputs a voltage proportionally to the frequency of the step-pulses. This is the type of circuit available on the CNC4PC C11 board for example. (It offers better lineratiy and better resolution than the PWM option)

Then of course you have all sorts of more "exotic" ways of controlling the spindle speed, like MODBUS and things like that.

Finally you can attach a one pulse per revolution signal to an input and have Mach3 display the true speed. The pulse must be at least 1/kernel frequency long in order for Mach3 to see properly.

/Henrik.

[Al_The_Man]

I just spent over an hour reading, and don't see where or how this can be done.

Gerry - Roman, I will see if I can dredge up the old emails, they ,may have been deleted, I will post what I find.
Al.

[ger21]

Can you suggest reading for me Gerry or Al re the Mach PWM output?

http://www.machsupport.com/docs/Mach...all_Config.pdf

Section 5, towards the end I think.

And what would be the down side if the speed range is not exactly linear, it would still be 5000 - 30000 RPM, and have a tacho display...

You program the rpm using the S word in G-code. S20000 for 20K rpm. Downside is you wouldn't get what you expect. But it might be close enough.

If the PWM works straight from Mach3 into the SuperPID, that would be great.

[RomanLini]

Hi,
Out of the box Mach3 offers On/Off, PWM and step and direction control of the spindle.

On/Off is simply a signal you can tie to relay, turning the spindle on and off.

That is directly compatible with the "RUN" input of the Super-PID.

PWM is just that, a low(ish) frequency PWM signal is generated on the output pin of your choise. The frequency can be specified but the higher you go the lower resolution (available number of discrete speeds) are available. If you run Mach3 at 25kHz and set the PWM frequency to 25Hz you'll have 1000 discrete "steps" or speeds and the PWM signal can be integrated by a simple RC filter to get an analog voltage.

Good information, thanks! That should connect ok direct to the Super-PID instead of the pot. I would suggest a change of the existing 2.2uF in the SuperPID to (say) 220uF.

This will likely not be very linear over the whole range but that might be able to be corrected with the Calibrate Spindle feature in Mach3 (never tried it personally).

I will look into the calibrate feature.

Step and direction. This outputs step-pulses just as if the spindle was another axis. To get an analog signal the step pulses is run thru a F/V converter chip such as the LM2907 which outputs a voltage proportionally to the frequency of the step-pulses. This is the type of circuit available on the CNC4PC C11 board for example. (It offers better lineratiy and better resolution than the PWM option)

More good info thanks. It may be possible for the SuperPID to directly interpret the pulse frequency but it's microcontroller is already worked pretty hard running the PID, phase control and LCD all in real time!

Finally you can attach a one pulse per revolution signal to an input and have Mach3 display the true speed. The pulse must be at least 1/kernel frequency long in order for Mach3 to see properly.

This shouldn't be a problem, the Super-PID "TACHO" output is logic level and 1 pulse per spindle rotation, somewhere near 50:50 duty so at 30000 RPM will be (worse case) 500uS pulse width which is well within your 1/25kHz needs. So it looks like you get tacho display on Mach3 with the standard SuperPID.


Al- thanks, any info you can provide will be appreciated, particularly on how the "racalibrate spindle" feature works, and if the PWM RPM must be 0-30000 RPM or if it can be offset to 5000-30000 RPM.

Ger21- Thanks I've downloaded the PDF you suggested and will check it out.

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Here are a couple of pictures of my Super-PID display unit, it was just cut from black and clear acrylic with a tongue and slot design. The switch on the right is "RUN" and the two switches on the left are for "STABLE MODE" and "OPEN LOOP MODE" which are two inbuilt features you can connect if you choose.

The lead shows how I just bought a $5.95 mains extension lead and cut it in the middle to provide the mains in/out plugs and some mains rated cable. There's no way I could have bought the 2 mains plugs and 3 metres of good cable for $5.95!

Videos of operation have been taken, I just need to work out how to use that Youtube thing and I will post links then.

[ger21]

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Here are a couple of pictures of my Super-PID display unit, it was just cut from black and clear acrylic with a tongue and slot design. The switch on the right is "RUN" and the two switches on the left are for "STABLE MODE" and "OPEN LOOP MODE" which are two inbuilt features you can connect if you choose.

I'm guessing the run is On/Off? We can probably control that with mach3 as well?

Is "Open Loop" basically bypassing the Super-PID?

What does "Stable Mode" do?

Hope we get a manual with this.

Right now I plug my router in above the machine. I'm going to have run a shielded cable through my E-chain.

I'll also need to run the sensor through there. You said it's pre-wired, but I'll probably need 4-5 meters. I'm guessing this should be shielded as well?

[RomanLini]

Hi Gerry, the manual is basically written but waiting on some trimmings like a few diagrams and photos etc. It will be a .PDF very shortly.

To answer your questions;
1. The "RUN" is indeed for turning the router on/off, it is a logic level input and meant to be connected to your PC, Mach3 or EMC etc. I used a switch for the display unit for convenience.
2. "OPEN-LOOP MODE" bypasses the spindle sensor and just turns the power up/down to the router like an old fashioned speed control. It still has the tacho RPM display and still shows the power bargraph display, but there is no PID closed-loop system controlling things, just a simple knob. This is useful for testing, or if you need to use the speed control with no spindle sensor (or if the sensor fails you can switch straight to open loop and maybe finish the job). It won't give the low RPM power of the PID system but it might be useful for some cases.
3. "STABLE MODE" changes the PID settings to more heavily damped settings. The normal settings are very stable and specifically tuned for routers for the best power and stability, but if for some reason there is evidence of oscillation you can use the "stable" setting. This mode, being heavily damped, gives slightly slower response to loads and less perfect speed regulation but it is still speed regulated and offers similar high power. Generally it should not be needed but I thought it was a pro type feature even if only for testing or special cases.

The unit I sent to you has 3 metres of shielded cable (2 core + shield) attached to the sensor. Sorry if I had known you needed 5 I could have supplied it that way! I have tested the sensor wire next to the router power and stepper wires and not seen any interference so far as it has numerous layers of hardware and software filtering for the sensor signal but like any device I can't speak for every case! You should not need to shield the router power wires as the phase angle system used doesn't generate the amount of nasty noise that some PWM spindle controllers do. Maybe I can check your build log photos and suggest a wiring scheme based on that?

It's official! I'm a TERRIBLE cameraman...

Video of Super-PID booting up, then the "Spindle View" mode showing LCD bargraph that changes as the spindle is turned. This feature is active anytime the router is stopped, so you can always see the spindle sensor output.
[nomedia="http://www.youtube.com/watch?v=L8IsjkTxAs0"]YouTube - Super-PID CNC spindle view mode[/nomedia]

Video of "Pot View" mode. If you turn the pot fast when the router is stopped the bargraph shows the pot position, to see the pot is functioning perfectly (in case of remote pot mounting or to see an external speed vontrol voltage etc).
[nomedia="http://www.youtube.com/watch?v=NYvStyUbeII"]YouTube - Super-PID CNC pot view mode[/nomedia]

Video of open-loop test. The spindle is set to about 10% power, which settles out about 5800 RPM. Then when a chunk of wood is mashed into the 5mm endmill the spindle speed drops down to stall. This video demonstrates the very poor router power at low RPMs, ie before the PID system is turned on.
[nomedia="http://www.youtube.com/watch?v=qJdOAj0hei0"]YouTube - Super-PID CNC open-loop spindle test[/nomedia]

The video shows the Super-PID set to its lowest speed of 5000 RPM, you can see the tacho 4998-5002 or so, keeping speed within a fraction of a percent. Even at this low speed when the wood is again mashed into the tool (a nasty test!) the speed barely droops (maybe 2%) then recovers back to 5000 and chews the wood right up now it has some decent power. Then the speeds 5000-10000-15000-20000-30000 etc are shown and you can see the power bargraph rise to show the increase in power sent to the router. Then a 8000 RPM wood mash test.
[nomedia="http://www.youtube.com/watch?v=85L050QcsYI"]YouTube - Super-PID CNC 5000 to 30000 RPM PID[/nomedia]

Fun video of cutting some oval pockets in acrylic with a 5mm 4-flute endmill at 8000 RPM, giving no melt and sharp clear edges.
[nomedia="http://www.youtube.com/watch?v=NIHa6_MpN7A"]YouTube - Super-PID CNC cutting acrylic 8000 RPM[/nomedia]

Second video of that job, this time drilling the acrylic at 5000 RPM with a 1/8" standard drill bit. No coolant or pecking is needed and due to the reliable RPM, the swarf is beautiful constant long swirls. The holes are again sharp and clean with no evidence of melt. (I'm very happy with the SuperPID for drilling!)
[nomedia="http://www.youtube.com/watch?v=oBJ4Ebo-_HU"]YouTube - Super-PID drilling acrylic at 5000 RPM[/nomedia]

Here's a photo of the oval pocket and drill test after I cleaned it you can see the neat walls and almost glass-like cut surfaces;
(and sorry for the long post and for the wobby camera work!)