Hi all, I am on rebuild of one old plasma oxy fuel gantry machine. Still need to buy the gearboxes for the longitudnal axe but I have already the servo motors.
Machine is 5m large and have about 10m long rails. On the longitudnal axe I plan to have 2 servo motors of 1kw each, I bought the dmm-tech dyn4 drives and DST servos. On the transversal axe I plan to have a single servo of about 750w also from dmm-tech.
Now I woul like suggestions on which cnc controller to buy for this machine ?
I thought about using linuxcnc initially maybe wire together some arduino with grbl or buy some
plasma cutting cnc controller on aliexpress ?
At that size, I’d default to looking at LinuxCNC even though I haven’t used it yet. A machine that substantial probably would reward the substantial configuration effort. It’s been used in a lot of complex “big iron” CNC conversions for years. We have a few LinuxCNC users here; @dougl has been most recently vocal and if you look at his recent posts you’ll see several comments across multiple posts about his LinuxCNC experience worth reading.
That’s nothing against smoothie! But I would not rule LinuxCNC out without learning more about it.
I’d go for Linuxcnc with a Mesanet FPGA card.
This combination removes the need for a PC that can handle the timing requirements as these are passed off to the Mesa board.
Have a look at the Linuxcnc forum.
Gecko Drives are hard to beat for both stepper and servo drivers.
Hi all and thanks for your suggestions, I am also more inclined to go with linuxcnc, I have installed it few times but never had a chance to use it on a real machine. I know thee is some external components which fit better together. Will dig more into it. Right now the first plan is to make the
supporting table and the mechanical part to work. There is a lot of things to do still.
@GeoffS do you have maybe a specific model of that FPGA card ? Theres is a lot of them on the site.
The site does give a list of Linux compatible Plug and Play board combinations i.e a card that goes in the PC and an external connection module.
My suggestion is to join the Linucnc forums and check the Drivers section. The developer of the Mesanet range is a regular contributor.
This post might help: Mesa FAQ - LinuxCNC
Yeah, will try to. The machine as it was when I bought it is like on the pictures over here
on this link: http://www.brastrak.com.br/files/cnc
But its state right now is not much different. We just repaint it now I need to find time and money to get the correct gearboxes, and of course most probably all the linear guides and racks. Probably will put on the helicoidal racks and pinions. Will keep posting here, but the story is still long.
If you want to experiment with LinuxCNC on an rPi for cheap you can try the Remora project which puts Step Generation on a standard LPC1768/LPC1769 based 3D printer board(SKR v1.4, v1.4 turbo, v1.3, MKS Sbase v1.3 and probably other Smoothieboard type boards ). https://remora-docs.readthedocs.io/en/latest/
I’ve got it working with a SKR v1.4 turbon on my Creality Ender 3 3D printer, on my K40 laser cutter using a MKS Sbase v1.3. It also works on CNC machines and has closed loop control capabilities via encoders and even a high speed encoder for a CNC spindle.
It uses a SPI bus connection between the rPi and the 3DP controller. A pretty inexpensive platform even if just experimenting.
Dougl many thanks. In fact my initial idea was to use linuxcnc on a computermounted on the machine, but then I started to play with RPi and similar boards and then I tought it could be a worth to try. After all then I was thinking about cncjs interface. I am not very experienced , but I know my way on linux, although I have no much clue on how to connect all those servos and make the control panel. Still studying that part. I think its nothing very difficult to do but surely there is a lot of things to be careful on. I plan to use that machine for simple shape cuts we need to do for our products. Most probably will be more used as oxy fuel than plasma as we work with steels from 25mm up.
Hi all,time passes fast. I am about to start the rebuild of this machine. I would like to ask what would be the correct ratio of the gearboxes for this kind of machine. I did some calculations and I plan to buy the gearboxes with 1:25 ratio, with a spur gear of about 50mm diameter i can achieve from 13-15m/min as max speed. One of the questions is what would be the appropriate maximum speed for such a big machine ? I know many things are to be considered, as the weight of the machine, how it is railed etc… but of course the machine maximum speed is probably good only once you have to move the gantry from one side to another. Is it probably better to have a bigger ratio of 1:30 or 1:40 and have the machine do a better precise moves ?
Another question is about the suggestions of the CNC controller. I maybe go with some chinese controllers with ARM chip specific for plasma oxyfuel cutting machines. But there is also a MASO Australian company I was considering. Any comments suggestions ?
Is the cnc controller frequency for PWM generation very important ?
Another option is to use an arduino raspi setup with Grbl sender or cncjs or some other software.This is also one of my doubts so far.
But I would not rule LinuxCNC out without learning more about it.
