Epoxy granite vertical mill build log

[Nick]

I'll take some pictures for you to see how they are made up.

That would be great. I've put some rubber sheeting in for the moment.

Do you have any experience of Linux CNC.? If not then get ready for a massive learning curve because with servos and closed-loop it's a different ballgame to Steppers. I'm very experienced with lots of controllers and I'm struggling big time with Linux CNC. Luckily I've got a Linux Guru in my camp working on it, hey Clive S . .

Nope, It's been a massive learning cure. Very slow progress, hours of scanning the Linux CNC forum. You get stuck on silly things like setting up the home switches for what seems like hours. I gave up with stepconf and pcnconf wizard and just played around with the "hal" and "ini" files. I have however got Linux CNC working with steppers via a computer parallel port.



I have made my first chips and broken my first end mill on the servo mount for the X-axis. There were lots of issues milling this the X-axis pulley keep slipping. It looks a bit rough, I left 0.5mm of axial so I had to file it down, no finish pass but I think it will be functional. Waiting for a new belt to try it out.



5mm 2 flute end mill: RPM: 8000-10000 WOC 1mm, DOC 4mm, chip load per tooth around 0.04mm, feed 600mm/min
8mm 2 flute: RPM 8000-10000, WOC 1.6mm, DOC 8mm, chip load 0.05?, feed around 1m/min

I have got the china servo motors (analog) working with Linux CNC on the desk, closing the loop in control, it wasn't too painful to figure out. The mesa 7i77 card is really nicely made, nice manual, lots of IO.

If anyone is interested I will write a tutorial on getting the china servos working with Linux CNC, it might help with small things like I got stuck for a a good few hours before I realised I needed to set Pn146 to 0 on the servo.

Very brief video of first'ish chips

https://www.youtube.com/watch?v=WzXHVFuu-qo

[JAZZCNC]

I have got the china servo motors (analog) working with Linux CNC on the desk, closing the loop in control, it wasn't too painful to figure out. The mesa 7i77 card is really nicely made, nice manual, lots of IO.

If anyone is interested I will write a tutorial on getting the china servos working with Linux CNC, it might help with small things like I got stuck for a a good few hours before I realised I needed to set Pn146 to 0 on the servo.

Very brief video of first'ish chips

Bloody hell not joking when said video was brief I blinked and was done. . .


Regards Linux and Servo's how's the following error, have you checked it in hal scope.? . . . We are struggling (well not me but my guru) with the Step/dir to get full speed without throwing a following error.

[JAZZCNC]

Hi Nick,

Here's those way covers I was talking about, pictures didn't do it justice so a little video shows it better. Hope it helps

[Nick]

Hi Nick,

Here's those way covers I was talking about, pictures didn't do it justice so a little video shows it better. Hope it helps

Ah thank you very much, I see what you mean now, those look great, really simple design, just sheet metal and a few welds. I will give making some a go.

Following error wise. What speed are you aiming for? How have you found tuning the internal PI loops? I'm struggling to tune the servos. I'm just about at less than 10 microns f-error now on the X and Y, I am cheating slightly acceleration dropped a bit, speed reduced to 1500mm/m. I think my main issue is the servo speed and torque loops aren't tuned. The error got a lot better when I put in the inertia load into Pn257 after I ran the Fn018 mode to get the inertia ratio. I'm using gain adjustment mode 1 (Pn258) and then adjusting the "rigid grade selection" until I get oscillations / vibration. I found the linuxCNC tune very sensitive to FF1

I haven't worked out how to properly tune the internal PI's because I can't work out how to bring linuxCNC into open loop and then command a specific speed in LinuxCNC. I am thinking about using the internal speed command function and toggling this with push buttons. Say set it to 250, -250rpm and then I will be able to jog it back and fourth while looking at the HAL scope.

[Clive S]

I haven't worked out how to properly tune the internal PI's because I can't work out how to bring linuxCNC into open loop and then command a specific speed in LinuxCNC. I am thinking about using the internal speed command function and toggling this with push buttons. Say set it to 250, -250rpm and then I will be able to jog it back and fourth while looking at the HAL scope.

Nick. What mode are you using ie position or torque etc. Have you seen or read this:-

https://forum.linuxcnc.org/10-advanc...etailed-how-to

I am in the same boat as you and struggling with a following error when using closed loop. Changing closed to open loop is just one change in the hal file.
This is also my first time with halscope

[Nick]

Nick. What mode are you using ie position or torque etc. Have you seen or read this:-

https://forum.linuxcnc.org/10-advanc...etailed-how-to

I am in the same boat as you and struggling with a following error when using closed loop. Changing closed to open loop is just one change in the hal file.
This is also my first time with halscope

Yeah, that's what i've been following, really useful. I also found the John Thornton guide's. Using speed mode, via a mesa 7i77, so linuxCNC is running the position loop.

I will try torque at some point I think. I'm sure the issue is with the drive speed and torque PI loops. How have you gotten on with setting the drive PI settings? I'f i put it in open loop I think the axis will drift and I don't think I could command an analog signal? or maybe I could?

[JAZZCNC]

Nick, Clive is using Step & Dir Mesa card not Analog +/-10v using Position mode in the drive. He's using the same AASD Drive as you but 30A with 1.8Kw servo.

[Clive S]

Yeah, that's what i've been following, really useful. I also found the John Thornton guide's. Using speed mode, via a mesa 7i77, so linuxCNC is running the position loop.

I will try torque at some point I think. I'm sure the issue is with the drive speed and torque PI loops. How have you gotten on with setting the drive PI settings? I'f i put it in open loop I think the axis will drift and I don't think I could command an analog signal? or maybe I could?

I believe that torque mode is more difficult . I am using step/dir not analogue which should be easier.

I will be away for a few days but will catch up on my return.

[Nick]

Quick update:

Control box nearly done, MPG installed one of the cheap aliexpress ones, finally got an E-Stop. Its got space for 5 servos and 1 servo for a spindle, 3 installed. The 7i77 and one cheap parallel breakout board to drive 1 stepper (currently the Z axis, will hopefully rotate the tool changer)



I tried to keep AC separated from low voltage, the 7i77 to servo connections are using twisted pairs, I ended up hand soldering these. I have tried to ground everything in one place. Some thoughts:

Those cheap ebay "crimp tools" are really effective. The "DB25 solderless connectors" on ebay were invaluable for checking the wiring to the AC servos and the MPG. I got a 800x600x210mm box, I wish I had gone for a 250mm depth the door is catching on the AC servo encoder connectors when closed. I will have to swap the cable trunking out for a deeper version I used 40mm, think I will go for 60mm or deeper.

Z-axis counterweight system next

[Chaz]

Nice Nick.

I'm keen to hear your thoughts on those drivers / servos. Been looking them myself for whatever I build next.