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Forum Index : Microcontroller and PC projects : Pi based CNC anyone?
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Hiya My CNC died  It was using a old Pentium mainboard with WinXP, and using Mach2 as the software. The mainboard has died. Tried swapping for another, and once I got past the WinXP licensing issues, it also died, old hardware. 3rd main board and now XP is stuck in a licencing loop " You need to activate Windows ", " Your Windows is already activated ", "You need to activate Windows ", etc. Time to modernise. I've started researching and see the Raspberry Pi is used as a hobby CNC controller these days. But before I spend money, just wondering if anyone else has experience with this? My motors and microsteppers are fine, so I just want to use the Pi GPIO pins directly via optocouplers to isolate the different logic levels, as the Pi is 3.3 but my microsteppers are 5.1. I'm hoping the Pi CNC software can be configured this way. Thanks Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Rickard5 Guru  Joined: 31/03/2022 Location: United StatesPosts: 463 |
Gizmo What are you controlling? I mean I've seen guys make it work, but I wouldn't run my Bridgeport off it I may be Vulgar, but , while I'm poor, I'm Industrious, Honest, and trustworthy! I Know my Place |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Its a CNC table, 500*500*150mm. I use it for timber, making circuit boards, some light aluminum work. The stepper controllers are microsteppers and only need a Dir and Step signal at 5.1v I've got a spare Pi4, going to try out the software later today. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Personally, I wouldn't bother, just because I have one lying around. If you follow the forums, they still have lots of issues with latency and jitter. I would go straight for one of the Fanuc clones on Aliexpress; they are dirt-cheap, fully featured, robust and can hit 500KHz step-rate. I am currently building a 6-axis (infinitely expandable) motion controller but I have no intention of incorporating G-Code interpretation. I'll simply take pulses from the clones as position/velocity commands for the closed-loop servo-motors. If I wanted to go "high-end" with a sexy HMI, I would consider a PC or RPi or Odroid but I would do it properly. Craig Edited 2022-05-26 14:49 by Tinine |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
G'Day Glenn (and Craig) I have probably misunderstood the problem but 3.3V signals can usually drive 5V logic. If not there are several cheap devices to boost / reduce levels. Good luck. Peter(B) |
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OA47 Guru Joined: 11/04/2012 Location: AustraliaPosts: 986 |
Glenn, If you want to take the less adventurous route, I can gift you a mainboard, cpu & RAM with an activation key for WIN XP Pro from old stock I had when I was manufacturing PC's. PM me if interested. OA47 |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Yup, never had a problem driving 5V but for me, the problem is the other way and I don't really care for voltage dividers. I grabbed a bunch of those level-shifters that Mick (Mixtel90) uses and they seem to get the job done. I use lots of MAX491 xceivers which were fine with the 5v-tolerant Rx pins of the PICs but with the Pico, I have to stick with 3.3v and so level-shifting it is. There exists 3.3v alternatives for pretty much everything but right now, they fall into the unobtanium category. Cheers! Craig |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
I suspect OA47 has solved the problem. I have a spare XP machine in the cupboard for when my systam fails. Peter(B) |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Watching lots of youtube videos. Maybe a arduino based option would be better. The Uno runs at 5v and can talk directly to the microsteppers, http://kalaakaar.in/cnc-controller-with-arduino-tb6600-and-grbl/. Its also dirt cheap. I have a arduino as the brains of my 3d printer I built a few years ago. It was surprisingly fast. My CNC table is just 3 axis drivers and a spindle on/off, pretty simple. There are homing switches, but I never use them. Thanks for the offer OA47, but I do have a couple spare laptops I could use to run the software. I was trying to use the original WinXP installation as its been set up with the drivers etc to drive the parallel port at high speed, and all the non essential windows stuff was removed. I didn't want to go through that setup process again. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| PeterB Guru Joined: 05/02/2015 Location: AustraliaPosts: 655 |
I think some people have experienced problems trying to drive 5V logic with a laptop. Peter(B) |
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Chopperp Guru Joined: 03/01/2018 Location: AustraliaPosts: 1097 |
Just for interest, I just fired up my old Athalon desktop PC with XP (+ Mint). Still goes. It is available for nix if you want it Glenn, but it sounds like you want to go a different route. I'm at Cotswold Hills BTW. Brian ChopperP |
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| matherp Guru Joined: 11/12/2012 Location: United KingdomPosts: 10315 |
Grbl on an Uno works well. Tried many things and this is as good as anything |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
Grbl Controller Look interesting  Site Edited 2022-05-26 18:17 by Tinine |
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| ElectroPI Newbie  Joined: 27/04/2012 Location: AustraliaPosts: 37 |
1. latency & jitter are problems which need to be handled well by programs that run under Windows. Something like Mach3 or Mach4 work well but are not free. https://www.machsupport.com/software/mach4/ 2. as Peter mentioned, grbl on an Uno works very well and is free. https://github.com/gnea/grbl/releases Click the wiki button at the top of the page for lots of setup info. Basically the Uno running grbl sits between the computer/laptop and your CNC motor controller. It receives gcode commands from the computer/laptop and controls the CNC machine with built-in ramping of speed, curves, limit switch checking, etc. Load grbl into an Uno & connect it to your CNC motor controller - the minimum you'll need are pins 2 -> 7 and 0V.  3. plug the Uno into a PC or raspi4 with a USB cable (raspi3B+ and below run too slow so stick with a raspi4 or raspi400). Use a short USB cable (I've had problems in the past with spindle motor noise being picked up by a long USB cable causing the computer to lockup). 4. there's a choice of CNC software to run, eg linuxCNC, Universal Gcode Sender (UGS), Candle, etc (there's lots more in the grbl wiki). Note - for testing if you connect to the Uno using a Terminal program like PuTTY you can type gcode commands and grbl will execute each one in real time. My favourite program is Candle https://github.com/Denvi/Candle for Windows or https://github.com/pihnat/rpi-Candle for raspi4 |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5119 |
Thanks Looks like there is a port to the ESP32, which is a bit faster than the Uno. I've been using the ESP32 on a few projects lately and have a spare one here, so might have a play. The Uno can get to 30,000 steps per second without jitter, the ESP32 over 60,000 it seams. Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Revlac Guru Joined: 31/12/2016 Location: AustraliaPosts: 1154 |
I bought a CNC 3018 pro some time back, Yes its a toy but its ok to practice and learn with. It come with an offline controller, just looked at it and it has the ESP32-wroom-32E, haven't used that controller or the GRBL app. Candle is very straight forward sender, and the view of the cutting track has shown me a few mistakes I have made and could go back and correct it before cutting.  Cheers Aaron Off The Grid |
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| Tinine Guru Joined: 30/03/2016 Location: United KingdomPosts: 1646 |
I for one, would like to follow this project  Craig |
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| Rickard5 Guru Joined: 31/03/2022 Location: United StatesPosts: 463 |
I got one of these 3018 machines and outside of having to remake the spindle mount they are pretty amazing ! I may be Vulgar, but , while I'm poor, I'm Industrious, Honest, and trustworthy! I Know my Place |
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| Rickard5 Guru Joined: 31/03/2022 Location: United StatesPosts: 463 |
I got one of these 3018 machines and outside of having to remake the spindle mount they are pretty amazing ! I may be Vulgar, but , while I'm poor, I'm Industrious, Honest, and trustworthy! I Know my Place |
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bigmik Guru Joined: 20/06/2011 Location: AustraliaPosts: 2950 |
Lads, I also have a 3018 cnc and am happy enough with it with the standard controller that came with it. The only thing is the supplied 24v brick they supplied (and replacement they sent as well) is not up to the task. I bought a decent 5A 24vdc caged PSU from digikey for about $28AU and no problems there. I have heard many reports of the 3018 stopping mid stream but not experienced it myself so I suspect those issues would be power brick related. In my case I couldn’t power the spindle to 1000 (RPM??) using any grbl program without having to first go to 600 then 1000. For about $200AU I think they are pretty good but not easy to assemble Regards, Mick Edited 2022-05-27 06:26 by bigmik Mick's uMite Stuff can be found >>> HERE (Kindly hosted by Dontronics) <<< |
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