Can't control my spindle speed

[Vogavt]

LONG POST - Apologies

(somewhat of a cross-post here...)


Using Mach 3, Version R3.043.022
Using xylotex XS-3525/8S-4
Using cnc4pc C11 Rev 7.2 board
Using Harbor Freight Mini-Mill (44991) with stock DC motor

Over the holidays I got a hand-held tachometer and decided to check the spindle speed of my Mini-mill (HF-44991) against what it was showing in Mach3. Now mind you I had control in the ability to increase or decrease the rpm's before all this started.

I noticed that the speed was off by a several hundred rpm and decided to tune it. So here we go. I tried the automatic spindle calibration within Mach3 R3.043.022, but decided to cancel before I got to far since it seemed to be taking way too long. I then began just typing in the speed and checking against the tach and created a table of corresponding spindle rpms vs tach rpms.

I've restarted Mach3, I've saved settings, etc., but I can't seem to get the changes to take place.

Not sure how the AutoCal works since I don't have any feedback to system regarding RPM. I did note that when selecting AutoCal the software does in fact cause the speed to increase gradually, but I always stop before it ends due to the latter reason.

On the motor tuning of the spindle, I have:
Steps per: 1000
Velocity: 1500
Accel: 161.25
Step Pulse: 4
Dir Pulse: 4

Odd thing is, I can't change the Velocity. I can type in new numbers but when I click somewhere else on the dialog, the number reverts to 1500. (found out later it's because of the acceleration number, change that and you can change the velocity; posting here for someone else's benefit).

On the Ports and Pins, Spindle Tab:
Motor Control is set to Use Spindle Motor Output and Step/Dir. If I disable it, I can't get the spindle to turn at all.
"ModBus Spindle - Use Step/Dir as well" is disabled
"Special Functions - Use Spindle Feedback in Sync Mode" is disabled

Since I didn't know where to go about making changes, I started with adjusting the pulley, but later found this is only a scaling for what's displayed in Mach.(posting here for someone else's benefit).

THE ISSUE: I can't control the speed at all. I can see an increase in voltage from the C11 output as I increase the speed in Mach3, but now the motor only comes on at around 5V and runs max speed. Even increasing the voltage doesn't make an increase in actual motor rpm. In fact it starts the spindle motor to grunting like the brushes are about to come out.

I reinstalled Mach3 and created a whole new config file from scratch, but it didn't resolve the issue, unless I still have my spindle motor tuning incorrect.

I tested the rpm's with two other DC motors (tread mill type) and the issue is the same.

I tested with another speed controller with both DC motors and again the issue is the same.

All three motors were acting just like my mill motor in that they both made a grunting type sound due to the inconsistent voltage that is being applied. I had always thought it was the crappy brushes of the original mill motor, but now I know that it's related to the constant on/off voltage or something.

I say something because both speed controllers are indicating 95v to 100v coming out of them going to the connected spindle motor. Once I get the output voltage of the C11 up to around 5V (by adjusting in Mach3, not the pot), the motor will come on. I still can't get any increase in rpm by increasing the spindle speed in Mach3. What's really odd is that when I continue to increase the speed in Mach3, that's when the slight decrease in RPM starts to occur and consequently the grunting starts.

I believe I have adequately proved to myself that it isn't my motors and it isn't my speed controllers.

Again, the only thing I changed on the C11 was rotating the potentiometer. I don't see any discoloration anywhere on the C11 board, chips or otherwise. I pushed on all the chips to check for tightness to be sure there weren’t any issues with them being loose.

I now have the spindle tuning set to 1000 steps/per, the velocity maxed out (~6000) and the acceleration set to 6.25, and the spindle motor still runs wide open regardless of the spindle motor tuning settings.

I've contacted Arturo and he's looked at the xml I sent him, but I said the xml looks fine. Hood, over in the Mach3 forum said the xml looked fine as well.

That's why I'm posting here since I don't know whether it's Mach or the C11 board.

Any help would be immensely appreciated! I would gladly call anyone willing to talk to me. Send me a PM with your phone number and I'd make the call.

Thanks in advance,

Vogavt

[Vogavt]

Okay, just an update. I totally uninstalled Mach via the control panel - Add Remove Programs, deleted my C:\Mach3 folder and started from scratch (other than my saved license and xml file).

Still no joy....

Anyone?

[Vogavt]

Has anyone used the C3 - INDEX PULSE BOARD with the C11?

Arturo thinks this will resolve the issue. Not sure why I'd need to by an additional board when the C11 was working before all this started and the C11 already has a "built-in" Variable Speed Control.

Anyone?

[hoss2006]

Does the motor run correctly using the original manual pot?
Might be a problem with the motor controller.
Here's a troubleshooting guide.
http://www.littlemachineshop.com/Ref...leshooting.pdf
The c3 will input a pulse to mach to give real world rpm on the spindle screen.
Hoss

[pete from TN]

Please understand that I am really not good with this stuff but I did however have the similar setup to yours. I have an CNC RF45 machine that uses a sensorless vector drive and it is running off the CNC4PC C11G board. I have full control of my spindle and while the speeds are not exactly what I type in they are very close. My machine has two tier pulleys on it so I do use the pulley setups in mach as that is what they are for. Basically from what I understand the spindle in mach is setup like another drive. The computer outputs a stream of pulses and the C11g Board converts the stream into a steady DC voltage that is then used to control a speed control device on a DC or 3ph AC motor like mine. It took me quite awhile of poking around to get mine to do what I wanted and it was not without frustration. I found that finding the steps per and velocity settings that output the max 10v and then working from there was the easiest way to get what I needed. I can crank up my machine to see what I have in there if it will help you but I doubt it will. It would seem to me that with just one pulley it would be simpler to say the least. I would just try to adjust the settings until you read 10vdc on the output at your desired max rpm. I fiddled with it trying to get the upper and lower settings to jibe but to be honest I never could get it spot on. It is probably within a hundred rpm or so and my max is in the 6k range now. I can spin it as slow as 140 rpm using the slower pulley setup. You might also borrow an Oscilloscope and see what the output looks like on it going to your motor. To check your machine and it;s controller, that is pretty simple, just temporarily put it back to stock and try it.....

Again I do not completely understand how it works but there are a bunch of tutorial videos on the machsupport website about setting this up,they did help me to get it where it is now. Good luck and if there is anything I can check for you on my machine let me know.... peace

If none of that works perhaps this will:
[nomedia="http://www.youtube.com/watch?v=TsRenyiXh_A"]YouTube - mach3C6setup[/nomedia]

Pete

[Vogavt]

Does the motor run correctly using the original manual pot?
Might be a problem with the motor controller. Hoss

Well I did test with another controller and had the same issue. I looked at the troubleshooting guide as well and tested the MOSFETs, but they all seemed to be okay.

I can see an increase in voltage as I make changes to the rpm in Mach, but the DC motor won't turn until the voltage gets up to ~5v, then even increasing the voltage doesn't change the speed of the motor.

Still stumped here.... maybe I can actually talk to Arturo tomorrow.

Thanks for the suggestions!

[Vogavt]

After talking to Arturo (briefly), he suggested I look for lack of grounding of the spindle motor. So I started down the task of drawing out my wiring schematic and am posting it here for everyone's review.

IMPORTANT LEGALESE NOTICE: This drawing is what works for my machine and as such I will not be responsible for your use if you choose to follow what works for me.

Having said that, can someone provide some feedback as to what/where there might be an issue? With Arturo's grounding comment in mind, notice how I've got the machine/chassis/spindle motor grounded. I'm using the input to pin 11 as the ground which is also part of the touch probe. I'm not certain this is not adequate because I could control the spindle rpm before all this started. Just want someone else's opinion as well. I sent this drawing to Arturo yesterday but haven't heard back from him yet. Maybe today he and I can hook up.

Thanks in advance,
Vogavt

[john_100]

Hi Vogavt ,

it looks like the two wires connecting the C11 board to the MC 60 speed controller
are crossed

i'd expect P3 on the MC60 to be connected to the C11 ground
and the P2 connect to the C11 0 to 10V

disconnect the wires
check the voltage between analogue GND and "0 to 10v" terminals on the C11 board
changes as expected
min speed = 0V , max speed + 10V WRT gnd terminal
if not is the external power supply OK ?
+12V at the 12V input WRT Analogue GND

if you have the 5K0 potentiometer that originally set the speed
connect it to test the MC 60 speed control
P3 min speed end , P2 middle and P1 max speed end is about + 10V WRT P3
treat this wiring as live

on the FC250J board it is ( speed control on my lathe )
P1 is connected to the positive terminal of the mains rectifier !!!

if you don't have a potentiometer
connecting P3 and P2 should give you zero volts to the motor terminals
connecting P1 and P2 should be the maximum

to make it easier to test on your bench
use an ordinary 20W to 100W mains GLS bulb ( tungsten filament not fluoresent eco bulb)
as a load instead of the motor

John

[Vogavt]

Hi Vogavt ,

it looks like the two wires connecting the C11 board to the MC 60 speed controller are crossed

i'd expect P3 on the MC60 to be connected to the C11 ground
and the P2 connect to the C11 0 to 10V

John

Switched the wires!



@ john_100

You're a genius! I looked at that, but you know sometimes 4 + 4 is 9 no matter what someone tells you (until it finally sinks in)

I'll be revising the drawing shortly to reflect the switch. I looked at another drawing that I believe I got from Hoss's website and it showed the P2 and the P3 configured just like you said it needed to be. So I took a deep breath, switched the wires and voila! I can even make the spindle turn at 0.8Volts, at 9.9V I'm getting 4000 rpm.

I did a belt drive upgrade. Different thread.

Thanks for looking at it!

[john_100]

Hi Vogavt ,

I'm happy that I could help

John

[Vogavt]

IMPORTANT LEGALESE NOTICE: This drawing is what works for my machine and as such I will not be responsible for your use if you choose to follow what works for me.

Updated Rev 5.

For anyone wanting to look at it. I've cleaned it up a little as well since there may have been some confusion about the FC350BJ-110 board showing in the drawing (which is no longer used since it's blown).