Loading different configurations during startup.

I'm planning on building a CNC machine (euhm, more then one actually), and one of my goals is to be able to load wildly different configurations for the same machine hardware. Both locations and directions of X, Y, Z and rotation axis may change. How easy is it to do this with LinuxCNC? For hardware, I'm probably going for an Ethernet based MESA card, maybe also into EtherCAT, but that is for later concern. Can a different configuration be loaded when LinuxCNC starts? Can this be done on the fly, or does it require a restart?

I guess it would work to make a custom startup command, that first copies one of the configurations to a default location before LinuxCNC is started, but I'm hoping for a more elegant solution.

This may sound weird. To give a better Idea of the direction I want to go into, I've added a picture of the Hommel UWG2. This is essentially a flat base plate, and depending on how bolt-on accessories  are configured, it can be used as either a horizontal or vertical milling machine, or even as a lathe. One of the accesssories is a rotary table, which can also be bolted on in various positions. Other examples of such universal machines are the Koelsch/Beichle Comined universal, Aldrin universal machine and Meyer & Burger UW1 (Both Hommel and Meyer & Burger were later sold as (bought by?) Astoba.


 

 

tommylight wrote:

... and frankly i see no need for it, you would have to change stuff mechanically first then start a config for that setup.
No restart of the PC required for running different configs.

 

Indeed. That is the intention.

The old machines such as the Hommel require quite a lot of work to setup, because everything is mechanical, and drive axles for auto feed and such have to be reconfigured manually too. In my modernized version accessories such as for example a rotary table or an XY table get their own built in stepper motor(s), and you just plug it into the control box and load the fitting configuration. So you first reconfigure the hardware, and you load the (preconfigured) corresponding configuration. Goal is to have 4 to 8 different configurations. For example for:

1. Vertical milling.
2. Horizontal milling.
3. Line Boring.
4. 4th / possible 5th axis configuration.

Below a picture of the same Hommel machine, but configured as a lathe.
 

So you can start with a 3 axis machine, use it to make a rotary table, and then extend it to 4 or even full 5 axis, but also go back to 3 axis, because that allows for more rigidity and heavier machining. Andysmachines has made some excellent youtube tutorials on gear milling, and this has a lot of error prone manual machining, which also gets boring very quickly. And this begs for more automation. The goal is not to work with mechanical CAD that spits out a big G code file, but to write some python code that generates some G code for special applications. For example gear cutting with a disk mill, or with a profile mill. The number of teeth for the gear is then just a number in a for loop (and a radius change).

So the question still is: How do you load different configurations in LinuxCNC? Is this a command line option, do you have to fiddle with configuration files outside of LinuxCNC? Does a configuration change also reprogram the Mesa card without a hard reset?

My experience with LinuxCNC is very limited. I did some short tests with Machinekit some 10 years ago, and recently I tried it on 3 different PC's, but latency tests were atrocious, so I need better hardware. I'm also still in doubt to whether go with LinuxCNC or to stick with something simpler such as GRBL. Worst case scenario for multiple configurations, is to write a script that interprets G code, and then swaps axis and direction, and write it back to another file.