Linux CNC

[RayStoner]

I know this is a popular choice among the hobby machinist for control of lathes/mills/routers/plasma cutters, etc. One of the challenges of using Linux CNC has always been the limitations of the parallel port. The latency of a PC is pretty critical to the success of the build.

In the world of Mach3 there are many options to take the burden of step generation off the processor of the PC and move it to a controller...smoothstepper, Galil, UC100 and the like.

Mesa Electronics offers a step generation/control solution that is pretty cost effective. The 5i25 is $89 and is a pretty straight forward installation, there is a configuration manager in LinuxCNC that will help you set the system up to use the 5i25. If you don't have a PCI slot to use, they have the 6i25, essentially the same card in PCI-E.

The offer configurations firmware for most of the popular breakout boards, the G540 is a pretty popular one.

They offer breakout boards too, including a 5 axis step and direction card (7i76) that offers 48 general purpose I/O pins, isolated spindle speed control with encoder feedback. A 6 axis +-10V (7i77) analog servo interface with a ton of general purpose I/O and spindle speed control, etc.

One of the really cool aspects of these boards is that they are a the boards that Tormach chooses for their pro-sumer level CNC machines. They recently converted to LinuxCNC and set up one of the best conversational front ends I've ever seen. They call it path pilot and with some minor effort, it is usable outside of their machines. Tormach offers the "Path Pilot Restore Disk" for $30 here.

The linux CNC forums have a good description on how to get path pilot to work with your machine.

You can find many videos of using path pilot, installing it, etc on Youtube too.

Thought others might be interested.

[IdeaMakers]

Thanks for all the information about these parallel port upgrades and alternative software. Linux CNC has a learning curve but I know there are several people familiar with it at SC and we'll be using it with the laser engraver so it is already in house. I went with Mach for my machine just to get up and running quickly along with the Gecko 540, nice system since it is all serial cable hookups and pretty idiot proof. Along with a PCI parellel port upgrade it runs very smooth

I always get Tormach confused with Torchmate, what a mistake that is. The Path Pilot does look to improve on Mach having watch a quick video from NYC CNC. Seems quite a bit quicker on controlling the machine and more intuitive at visualizing the operation.

I'm not sure where we are with the mill though. We had talked about upgrading the internal boards to boost the speed and memory and these upgrades seem to be on the computer side rather then the mill. Are we looking at controlling the mill from the PC through drip feed thus negating the other upgrades? And I'm not sure what a Restore disk is for the Path Pilot although $30 sounds pretty cheap for the software.

[RayStoner]

The restore disk installs linuxCNC and path pilot. Some hacking involved in making it work on machines other than Tormach, but the effort seems pretty worth it.

It would be really nice to have the big mill controlled with LinuxCNC/Path Pilot, but some additional research is required. I believe the feedback on that mill is tachometer based, rather than encoder based. I don't know the implications of that at this point. I know that such a conversion is possible, but I'm not very aware of the exact requirements. I'll have to look around on the forums and internets to find out what others have done. I don't know if there are any local resources.

Drip feed does make this less critical. I still don't trust it very much though. There isn't any sort of check to ensure that there aren't errors in the code, that could end in ruined parts when it comes to a malformed line of code. It seems like there are dropped bits sometimes, Slowing the communication down may fix that...I'll keep experimenting.

I called BobCAD yesterday about registering the software. They said there would be a "technician" calling me back to figure out the details of how to get it registered...I haven't heard back from them. I did find some stuff that may solve the problem for us though, I'll try it out Saturday.

[IdeaMakers]

Make sense now, Path Pilot is what they call a screen set in Mach. Thanks for calling BobCad, we'll wait to see how that goes.

Seems like the internals of the mill are the oldest so the bottleneck of the system with connection speeds of only 9600 (??) so I'm thinking the internal board upgrade would be good along with a front end like Linux CNC.

Right after we get a vise though!

John