Newbie questions about CNC workflow

Hi

A friend has purchased a Sherline 4410 CNC lathe with computer (supplied with the lathe) running Linux. I am trying to help him get started as I know about Linux, but I know nothing about CNC. I need to understand the workflow. I guess the best way to understand is to ask some questions.

1) I believe the starting point is to write some g-code. Is that typical or would you expect to use a CAD package for that?

2) I've heard that the g-code must be compiled into machine code. Is that correct?

3) My friend was thinking of using Mach3 but I believe that only runs on Windows. Would LinuxCNC be a sensible choice?

4) Any other advice please? Such as how to use Windows for part of the workflow (he is more familiar with Windows than Linux).

Best regards

David

Welcome to the forum!

1. Normally you would design your part in a Cad/cam package, then load the gcode from the cam package to the machine package, so mach3 (windows) LinuxCNC (linux).

2. In this instance the gcode would be your machine code, as that is what your machine control software (machine package) reads/proccess (mach3 or LinuxCNC).

3. He has the choice really, see above.

4. I would go with a windows supported cad/cam package then, again mach3 may be the better choice on the host machine as well.

.Me

Hi Lee

Thanks for your reply. I think the issue is that the PC supplied by Sherline has built-in drives for the CNC lathe's motors. Something like this:

http://www.sherline.com/8540pg.htm

(although he has a lathe not a mill).

So I guess he really is tied to a Linux environment - unless he can develop g-code on Windows and copy it to Linux for running on the Lathe.

David

I think that he already has LinuxCNC, although the web site refers to it under its old name, EMC2. Same thing but name changed due to trademark or some such issue a while ago.

You can develop gcode wherever you like. You can hand-write it, but most people use some kind of CAM package that takes a CAD drawing as input and gives gcode as output. It can be a bit more complicated than that, but that is the basic principle. As Lee says, your friend would then run LinuxCNC which takes the gcode file and turns it into actual motor control signals. Because the gcode is portable (pretty standard with minor variations depending on whether LinuxCNC or Mach3 or some other machine control package will read it - you tell the CAM package which flavour of gcode you want) then you don't have to run CAD or CAM or machine control on the same platform. Mix and match as you will. I use Windows for CAD and CAM but copy files over the network to my LinuxCNC/Ubuntu machine in the garage. That kind of thing is pretty standard practice.

That's a pretty high-level description. Someone will be able to fill in details if you would like to go down a level or two.

Hi, no problem !

The drivers maybe inside the pc case but I dont think they will be part of the pc system its self, they probably fitted them in the case because they had room to do so and so on.

Drivers are usually independent of the host machine such that they "talk" to the host machine via the printer port or via usb. So what I'm really trying to say is, I doubt the pc has any special software drivers on it specifically for the motor drivers they use, such that without them the lathe cant be used. So this means anything past a physical connection to the pc via a port, can be considered irrelevant.

This then, should mean it dosnt matter what os or control software you use, however I've never worked with anything from sherline so I have no idea if they use any proprietary software, but my experience so far is suggesting they probably dont.

To be honest, if the system was setup and working when he got it then there really isn't any need to change to the os or control software, so all you really need to know at this point is how to generate gcode and then pass it to LinuxCNC/EMC and start the job, as gcode is universal in that sense.

.Me

Thanks Neale, i'm currently mobile so slow typing for me and trying to multi task, didn't see your reply till after posting...

Side stepping a little, what/how do you go about doing the network share, Samba ?

.Me

Yes, Samba. The client is bundled with the Ubuntu version that is part of the LinuxCNC distribution, so it's pretty easy to use. Curiously, it used to work well, then it stopped being able to map drives for a few weeks, but last night it was fine again. I suspect problems with an update somewhere. I also use Ethernet-over-mains adaptors to get a network connection to the garage. Tends to be a bit flaky if the router control electronics are powered up but very useful otherwise.

Hi Lee and Neale

Thanks very much for your replies. They were very helpful.

Best regards

David

Quote:

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Originally Posted by Neale

Yes, Samba. The client is bundled with the Ubuntu version that is part of the LinuxCNC distribution, so it's pretty easy to use. Curiously, it used to work well, then it stopped being able to map drives for a few weeks, but last night it was fine again. I suspect problems with an update somewhere. I also use Ethernet-over-mains adaptors to get a network connection to the garage. Tends to be a bit flaky if the router control electronics are powered up but very useful otherwise.

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Cool, I usb most stuff at the mo as the boxs around the network are only a flight of stairs or a gardens lenth away, when I get my new shed/workshop built I will be moving the file server to there so think it will be samba I go with for that, didn't know they bundled it with LinuxCNC/emc...

.Me