Big Picture: From CAD to Spinning Motors
17 Jul 2014 16:45 - 17 Jul 2014 16:49 #48871
by ArcEye
Replied by ArcEye on topic Big Picture: From CAD to Spinning Motors
Hi
CAD - draw a part (optional)
CAM - create gcode which describes that part in the form of a file (optional)
Linuxcnc - runs the gcode file, which tells a cutting tool how to move to describe that part and thus cut it from solid
It does this by telling each axis motor how much to move, as per the gcode, to achieve the movement that describes that bit of the part.
The method by which Linuxcnc is connected to the motor drivers, is not part of the process, it is just the electronics / mechanics of that particular machine.
The motors can be servos and the interface can be a PCI card, but the first 3 still maintain. (But in fact you do not need the first 2.)
The difficulty in conceptualising is probably symptomatic of how people come to CNC these days.
I grew up without any computers (except main frame monliths) and started engineering with manual machines.
I later converted machines to CNC and started by effectively machining manually, except by using the MDI line instead of hand wheels.
Gradually I started writing gcode programs and canned routines to achieve the jobs I needed to do, especially on a lathe, where I could program
arcs that would be very difficult to accurately turn by hand.
Only recently have I moved to converting jpg's and dxf's for engraving and drawing parts in CAD and then converting to gcode.
The difference is that I am nowhere near as good as the current generation at creating parts in CAD etc, but when it spits the code out, I can look at it and say 'That won't work' and have a good idea why, because I have done it from the ground up in the opposite direction.
My advice, decide what machine you want (lathe, mill, router etc), decide how you want to power the axes (steppers, servos ) and your paths to control the machine with Linuxcnc will be clearer, probably just a couple of choices.
Once you have the machine working, going where it is told accurately, you can build up from the jog buttons, MDI commands, simple programs, to full CAD and CAM
with a proper appreciation of what is happening.
Then when you get an error message, it will be just that, a message telling you where the error is, not an apocolyptic failure of the black art CAM god
regards
CAD - draw a part (optional)
CAM - create gcode which describes that part in the form of a file (optional)
Linuxcnc - runs the gcode file, which tells a cutting tool how to move to describe that part and thus cut it from solid
It does this by telling each axis motor how much to move, as per the gcode, to achieve the movement that describes that bit of the part.
The method by which Linuxcnc is connected to the motor drivers, is not part of the process, it is just the electronics / mechanics of that particular machine.
The motors can be servos and the interface can be a PCI card, but the first 3 still maintain. (But in fact you do not need the first 2.)
The difficulty in conceptualising is probably symptomatic of how people come to CNC these days.
I grew up without any computers (except main frame monliths) and started engineering with manual machines.
I later converted machines to CNC and started by effectively machining manually, except by using the MDI line instead of hand wheels.
Gradually I started writing gcode programs and canned routines to achieve the jobs I needed to do, especially on a lathe, where I could program
arcs that would be very difficult to accurately turn by hand.
Only recently have I moved to converting jpg's and dxf's for engraving and drawing parts in CAD and then converting to gcode.
The difference is that I am nowhere near as good as the current generation at creating parts in CAD etc, but when it spits the code out, I can look at it and say 'That won't work' and have a good idea why, because I have done it from the ground up in the opposite direction.
My advice, decide what machine you want (lathe, mill, router etc), decide how you want to power the axes (steppers, servos ) and your paths to control the machine with Linuxcnc will be clearer, probably just a couple of choices.
Once you have the machine working, going where it is told accurately, you can build up from the jog buttons, MDI commands, simple programs, to full CAD and CAM
with a proper appreciation of what is happening.
Then when you get an error message, it will be just that, a message telling you where the error is, not an apocolyptic failure of the black art CAM god
regards
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