Retrofitting a 3-axis VMC with DC servos - guidance needed

Finally, after a long wait, the boards have arrived! Now I'm looking to buy the PC to control the machine. Checking all the models you shared before, I couldn't find any of them available in my country for under $700 USD.

However, I found two options: a Dell Optiplex 790 with an i5-2400, and another refurbished PC with an i5-4400 (the seller didn't specify the exact model, just that it could be an Optiplex, HP, Lenovo, or Bangho).

Which one would recommend? Both rely on integrated graphics. Is that going to be an issue in my case? From what I've read, a dedicated GPU is usually recommended, but I'm not sure if that's only for software pulse generation or if it's recommended for hardware-assisted setups too.

Thanks in advance!

I've never used anything other than integrated graphics. no need for a seperate GPU

Hi everyone,

I've just purchased the host PC and I'm waiting for it to arrive so I can set up the RT-OS and start digging into the retrofit.

To practice on the bench and learn the ins and outs of LinuxCNC, I put together a Mesa hardware stack: 7i97T + 7i74 + 7i84U + 7i73.

I have a quick question regarding the initial configuration workflow. From what I’ve gathered reading through the forum and docs, the easiest path forward seems to be:

Use mesaflash to flash the proper binary (.bin) to the 7i97T so it supports the Smart Serial expansion through the 7i74.

Once the main FPGA board has that specific firmware, use mesact to configure the machine basics, pinout, and closed-loop settings.

Regarding step 1: Is mesaflash strictly necessary for this, or can I flash the firmware directly from within mesact? From what I've seen in recent updates, it looks like mesact has a built-in flashing utility that might work for this. Is that correct and reliable for ethernet cards?

Lastly, I’d love to get your advice on the best learning path to fully grasp how Mesa cards interface with LinuxCNC. Should I just wire everything up on the test bench and learn by trial and error, or is there a specific documentation, manual, or forum thread you'd recommend reading first to avoid spinning my wheels?

Thanks a lot for all the help!

I've just finished installing the system, disabled all power-saving features (C-states, SpeedStep, etc.) in the BIOS, and isolated a CPU core using isolcpus.

Here are my latency test results while stressing the system with 4 instances of glxgears and a YouTube video playing in the background

Note: I am currently running this test using an old VGA monitor. I suspect the analog output/Xorg driver might be causing some minor latency spikes compared to using a pure digital connection, but I'm not entirely sure.

What do you think of these numbers? Are they good enough to move forward with my Mesa setup, and what should my next steps be?

Thanks in advance for your feedback!

Looks fine but for mesa its better to run: latency-histogram --nobase --sbins 1000 --show to get rid of the base thread window which gets in the road. and can suppress results. Run that and reshare.

This are the results
for what i understand are good for mesa Ethernet boards
Now i´m gonna try to make connection to the board
its that okay?