The Current Bread & Butter Setup?
- unknown
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01 Dec 2025 10:44 #339569
by unknown
Replied by unknown on topic The Current Bread & Butter Setup?
Ah I see, I was some what interrupted by The Hound whilst reading and responding, my apologies sir.
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- andypugh
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09 Dec 2025 12:50 #339912
by andypugh
The reason I suggested the Pi5 in this context is that if anything goes wrong with the Pi you can just slot in an identical Pi with the _same_ SD card and be back to exactly where you were.
If using PCs it can be difficult to find an exact replacement. Yes a _similar_ PC might work, and might run properly with the old SSD. But it might not.
Replied by andypugh on topic The Current Bread & Butter Setup?
The 3B wasn't very useful for LinuxCNC. The Pi4 worked a lot better (and can be used with Ethernet Mesa hardware). The Pi5 is better again.In short:
RPI can do at most 20000 steps per second, if lucky and with a bit of fiddling (this is from what i read here, i stopped using RPI since version 3B)
The reason I suggested the Pi5 in this context is that if anything goes wrong with the Pi you can just slot in an identical Pi with the _same_ SD card and be back to exactly where you were.
If using PCs it can be difficult to find an exact replacement. Yes a _similar_ PC might work, and might run properly with the old SSD. But it might not.
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09 Dec 2025 12:58 #339913
by andypugh
You will get more speed out of steppers with a Mesa card, and this is not solely down to step rate. It comes down to the resolution of the increments in step rate as the system accelerates. If the Pi can do 20kHz flat-out then the slower rates are quantised at 10Khz, 6,66kHz, 5kHz... The motor can't physically follow such large speed steps. The Mesa card can do 20kHz, but also 19.99999 kHz too. And 20.00001
But, you could start with the GPIO and see if it's acceptable for the application.
Replied by andypugh on topic The Current Bread & Butter Setup?
It depends on what you need. I don't think that the GPIO interface on the Pi is quite as good as a parallel port, and the parallel port is only supported out of habit and as a way to get new users started cheaply.Is the rPi GPIO interface considered fully baked, or is the Mesa 7i96S the smart bet? I would totally love to avoid the $150+ for the Mesa, but only if that does not then cost me an additional $300 in labor time.
You will get more speed out of steppers with a Mesa card, and this is not solely down to step rate. It comes down to the resolution of the increments in step rate as the system accelerates. If the Pi can do 20kHz flat-out then the slower rates are quantised at 10Khz, 6,66kHz, 5kHz... The motor can't physically follow such large speed steps. The Mesa card can do 20kHz, but also 19.99999 kHz too. And 20.00001
But, you could start with the GPIO and see if it's acceptable for the application.
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- hhscott
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30 Dec 2025 08:52 #340706
by hhscott
Replied by hhscott on topic The Current Bread & Butter Setup?
Somewhat of a novice here but like you it has been several years since my last retrofit/build of a LinuxCNC machine. The last machine built was back in 2020 and the pi platform was not really a good option then. Currently I just retrofitted a full size industrial CNC router and I am using the pi5 8GB with a Mesa 7i96s. So far it has been flawless and totally stable. My motivation for using the pi is basically downloading the image and go, other than a couple of minor tweaks to the OS (my preferences) it just runs out of the box. Using the pi I don't have to worry about finding another PC that would work in the event of a hardware failure and the fact that I can make multiple super cheap fully operating copies of the OS on a SD card cannot be beat. The machine that I just retrofitted is going to be used in a production environment and will need to be totally reliable day in and day out.
The following user(s) said Thank You: rodw
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25 Jan 2026 16:59 #341908
by andypugh
Replied by andypugh on topic The Current Bread & Butter Setup?
One advantage of the Pi is that it is perfectly reasonable to have an identical spare to swap in in case of trouble.
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