Pm-940m-cnc (pre-assembled)

[phazertwo]

The VFD also needs a signal to tell it to run and what direction to run. There are two replays in the cabinet for this.... I think they are KA1 and KA2, but I can't remember and don't have my diagram with me.

You have to make sure that your outputs are addressed correctly, then it should work. I would start there, then check to make sure the outputs are actually lighting up.

PZ

 

[Sal_the_man]

The VFD also needs a signal to tell it to run and what direction to run. There are two replays in the cabinet for this.... I think they are KA1 and KA2, but I can't remember and don't have my diagram with me.

You have to make sure that your outputs are addressed correctly, then it should work. I would start there, then check to make sure the outputs are actually lighting up.

PZ

Roger that. KA1 is to have it turn CW and KA2 is for it to turn CCW.

KA1 is getting power and is activating correctly. Haven't tried KA2.

 

[phazertwo]

A signal wire comes from the VFD to KA1 and is jumped to KA2, and which ever relay is activated feeds that signal back to the VFD. Make sure that it's making the whole trip. I would be willing to put money on a loose connection.

PZ

 

[Sal_the_man]

Hey shout out to @phazertwo and @B2 ! It was indeed a poorly connected ground wire (blue #011) located at one the fuses. I was able to pull it out by hand actually, so just re-tightened it and voila the VFD fired up!

Did our carving which seems more like an oval than a circle. But hey something is better than nothing.

Spindle seems to be spinning slower than we previously had it so it's probably my doing in the software settings. Going to revisit that again.

But man you guys are awesome. @chocadile and I are feeling pretty good today about our first cut using @B2 's file!

 

[B2]

Sal,
Great News!

I think you used the "ArcCutpocket - Copy.txt" file I posted.
Check out the path display in Mach3 and see if it looks oval verse round..... Maybe it is oval? I think this is the set of code that came from the wizard, I never actually ran it, but the simulation looked good. Anyway, there is no simple G code to actually make a true spiral pocket so they typically use a series of round arcs with the origin effectively moving. I think the code calls for a series of 180 arcs each one progressively smaller but starting from where the last one left off. This is common. Anyway, I wanted to make a spiral shaped cone and never found a simple G code to do so.

So go to path, highlight the code in the left window and step down through the code line by line. In the path window you should see the individual cuts lighting up as you go. Hence, you can follow the 180 arcs.

Anyway, a single G2 command will essentially generate a circle for you. use a point and see if it comes back to where it started on the circle. If not an axis maybe missing steps. Why missing steps: motor coupling loose? mechanical binding? etc. Poor electrical connection? motor traverse profile acceleration or velocity too high? (P2 and I were discussing max velocities earlier in this post , so you can see our numbers there, Feb 22, 2019 .) etc.

 

[Sal_the_man]

Sal,
Great News!

I think you used the "ArcCutpocket - Copy.txt" file I posted.
Check out the path display in Mach3 and see if it looks oval verse round..... Maybe it is oval? I think this is the set of code that came from the wizard, I never actually ran it, but the simulation looked good. Anyway, there is no simple G code to actually make a true spiral pocket so they typically use a series of round arcs with the origin effectively moving. I think the code calls for a series of 180 arcs each one progressively smaller but starting from where the last one left off. This is common. Anyway, I wanted to make a spiral shaped cone and never found a simple G code to do so.

So go to path, highlight the code in the left window and step down through the code line by line. In the path window you should see the individual cuts lighting up as you go. Hence, you can follow the 180 arcs.

Anyway, a single G2 command will essentially generate a circle for you. use a point and see if it comes back to where it started on the circle. If not an axis maybe missing steps. Why missing steps: motor coupling loose? mechanical binding? etc. Poor electrical connection? motor traverse profile acceleration or velocity too high? (P2 and I were discussing max velocities earlier in this post , so you can see our numbers there, Feb 22, 2019 .) etc.

@B2 your hyperlink regarding max velocities and the motor settings was an absolute gem. Fixed our travel settings to a tee.

I also fixed out physical E-stop button, the wrong port & pin were specified.

Now...one last problem before we're 100% functional! The spindle speed RPM does not register on mach 3. It spins at an arbitrary value. I do not have it set to the PWM controller, so I presume this is another port/pin issue?

Our VFD is functioning of course since I am able to spin the spindle

 

[B2]

Hi Sal,

I am glad my velocity settings were of use. WRT to the spindle speed, I will not be near my 940 until next week. However, if you have specific measurements or Mach3 setting observations you would like for me to make I will try to do so. Just let me know.

If you have a volt ohm meter (VOM) you could measure the speed input voltage (DC voltage) at the VFD to see what it is set at. You did not mention what rpm your spindle was turning at, but from your first cut photo it is obviously turning at some reasonable speed. The VFD input voltage is suppose to be between 0 and 10 volts (DC) for min to max speed, respectively. If it happened to be connected in error to one of the logic level pins it might be around 4-5 volts and would cause the spindle to turn at roughly 1/2 max speed. If you do not have a VOM you can get a cheap one at Harbor Freight or on the internet. Harbor Freight has a poor quality one that they some times promote for around $5, but it works for most simple measurements. Amazon probably has be better one for $11-$25. A really good one would cost several hundred $ (Fluke).

When I first got my 940 I checked my spindle speed against the Mach3 settings. Of course Mach3 does not know about the mechanical gearing and so just reads between 0 and 1000 rpm even if the gears are changed to cause the spindle to be 3200 rpm max. Nevertheless, I found that the speed displayed by Mach3 was about 10% off from the actual speed.

To do this measurement I used an optical strobe. I had a digital function generator which yields an accurate square wave or pulse wave frequency reading. I used the generator to drive a bright LED and put a piece of white tape on one of the splines on the spindle shaft. I turned on the spindle and then adjusted the generator frequency until the optically strobed white tape appeared to be stationary. With one measurement made I then could change the Mach3 settings and adjust the generator frequency to the speed it should be and see if the strobed tape was again stationary. Things were not perfect, but were reasonable given that everything is open loop and analog.

If you want to get a function generator or a pulse counter you can purchase a cheap one from Banggood or Aliexpress, but shipping from China will take a month or so. Ihave no idea if they are any good. I do not know what Harbor freight might have. Amazon will have a digital function generator, but will cost at least $60-70. A really good one will cost a lot more. Here is a generator URL that might work. The specs do not say anything about the load that it would drive except TTL. Normally a funciton generator would drive a 50 Ohm load. From this one can calculate how to connect a raw LED. https://www.amazon.com/KKmoon-Preci...l+function,aps,188&sr=8-5#feature-bullets-btf

Example LEDs: https://www.amazon.com/DiCUNO-Emitt...lectronic+led&qid=1553746085&s=gateway&sr=8-3

If you want to pursue all of this and do not have an electronics background I can provide more details.

Dave L.

PS. I another Amazon search for a tachometer. This might be a better method for measuring the rotational speed and only costs $17. Amazon has a review movie where someone was measuring spindle speed!!! it only appears to go up to 1000 rpm, but that is probably good enough.
https://www.amazon.com/AGPtek®-Prof...&qid=1553746280&s=gateway&sr=8-26-spons&psc=1

 

[Sal_the_man]

Hi Sal,

I am glad my velocity settings were of use. WRT to the spindle speed, I will not be near my 940 until next week. However, if you have specific measurements or Mach3 setting observations you would like for me to make I will try to do so. Just let me know.

If you have a volt ohm meter (VOM) you could measure the speed input voltage (DC voltage) at the VFD to see what it is set at. You did not mention what rpm your spindle was turning at, but from your first cut photo it is obviously turning at some reasonable speed. The VFD input voltage is suppose to be between 0 and 10 volts (DC) for min to max speed, respectively. If it happened to be connected in error to one of the logic level pins it might be around 4-5 volts and would cause the spindle to turn at roughly 1/2 max speed. If you do not have a VOM you can get a cheap one at Harbor Freight or on the internet. Harbor Freight has a poor quality one that they some times promote for around $5, but it works for most simple measurements. Amazon probably has be better one for $11-$25. A really good one would cost several hundred $ (Fluke).

When I first got my 940 I checked my spindle speed against the Mach3 settings. Of course Mach3 does not know about the mechanical gearing and so just reads between 0 and 1000 rpm even if the gears are changed to cause the spindle to be 3200 rpm max. Nevertheless, I found that the speed displayed by Mach3 was about 10% off from the actual speed.

To do this measurement I used an optical strobe. I had a digital function generator which yields an accurate square wave or pulse wave frequency reading. I used the generator to drive a bright LED and put a piece of white tape on one of the splines on the spindle shaft. I turned on the spindle and then adjusted the generator frequency until the optically strobed white tape appeared to be stationary. With one measurement made I then could change the Mach3 settings and adjust the generator frequency to the speed it should be and see if the strobed tape was again stationary. Things were not perfect, but were reasonable given that everything is open loop and analog.

If you want to get a function generator or a pulse counter you can purchase a cheap one from Banggood or Aliexpress, but shipping from China will take a month or so. Ihave no idea if they are any good. I do not know what Harbor freight might have. Amazon will have a digital function generator, but will cost at least $60-70. A really good one will cost a lot more. Here is a generator URL that might work. The specs do not say anything about the load that it would drive except TTL. Normally a funciton generator would drive a 50 Ohm load. From this one can calculate how to connect a raw LED. https://www.amazon.com/KKmoon-Precision-Dual-channel-Generator-Arbitrary/dp/B014KT3IT6/ref=sr_1_5?crid=188CMPJLMZUXV&keywords=digital+function+signal+generator&qid=1553745100&s=gateway&sprefix=digital+function,aps,188&sr=8-5#feature-bullets-btf

Example LEDs: https://www.amazon.com/DiCUNO-Emitt...lectronic+led&qid=1553746085&s=gateway&sr=8-3

If you want to pursue all of this and do not have an electronics background I can provide more details.

Dave L.

PS. I another Amazon search for a tachometer. This might be a better method for measuring the rotational speed and only costs $17. Amazon has a review movie where someone was measuring spindle speed!!! it only appears to go up to 1000 rpm, but that is probably good enough.
https://www.amazon.com/AGPtek®-Professional-Digital-Tachometer-Contact/dp/B004Q8L894/ref=sr_1_26_sspa?keywords=optical+strobe&qid=1553746280&s=gateway&sr=8-26-spons&psc=1

Thanks Dave.

Would you kindly share the ports & pins table with us? I think that is our root cause.

If I'm interpreting the wiring diagram correctly, all my limit & home switches are wired to port 1 in our CNC controller. However, in the Mach software I have to configure it to port 2 in order for it to operate. So I'm guessing the spindle, VFD controller is also wrongly specified in our software even though it is correctly wired to the controller and in the cabinet.

 

[B2]

Hi Sal,
Took a lot (34) of photos for you today showing settings in Mach3 as well as some of the wiring in my PM-940M CNC. However, just in case your machine's wiring is different I will first post my PM-940M CNC "Owner's Manual" which I got when my machine was shipped. From your Feb26 photos the 940M components in the control box are laid out in a little different geometry than are mine, this causes my nMotion box to be mounted upside down from the word nMotion. Likewise, some of the wiring control wire numbers differ. It looks like most of your limit switch wire numbers are inverted from mine as well as being different in color. For example, 059 and 057 are interchanged. This seems to be true for each pair of these! Likewise, some of the output wire numbers differ. For the most part, I think my machine is wired up as the wiring diagrams show in my manual. I inserted a few comments in the pdf manual file.

In my photos, I tired to turn the wire labels so that the numbers would show. Interestingly, when I tugged on one of the wires going to the VFD the wire pulled right out of the crimp connector! You may want to go from connection to connection and simply tug on the wire a little!!!!

I have never posted this many photos before, so I am going to do one first and see if the thumbnail versions come through as full resolution.

Dave

 

[B2]

Hi Sal,
I am still a newbie at Forum postings and so do not know if there is a better way to post these photos. Because there were so many images I will not post them as individual images. Because the resolution maybe important for you to be able to see the finer details of the images I did not want to simply upload them as thumbnails. So, I have put them into pdf files. As I said before, there are 34 photos, so you can determine if you got all that I posted.

Good luck,
Dave