recommended controller board

Full disclosure, I know absolutely nothing about CNCs.

I love electronics and automation, and I recently acquired a Unimat SL100 and I decided what a great spare time project.  All my research points me to LinuxCNC, which brings me to my question...  What are some recommendations for USB controller boards compatible with LinuxCNC?

**QUICK EDIT...  I am looking for something inexpensive and entry level to get my feet wet so to speak.  I am not super concerned about performance yet, this is more of a proof of concept.  Once I get basic functionality working, then I will jump in with both feet and sink some $$ into it.

Any guidance is greatly appreciated!

Thank you

USB devices in general do not work with LinuxCNC for motion control as they do
not support real time communications.

The most basic starting system is probably a PC with a parallel port (and perhaps a simple
breakout board like the common "Mach3 5 Axis CNC" breakout)

Nest step would probably be an LinuxCNC specific Ethernet connected card or EtherCAT
 

I'm also pretty new regarding LinuxCNC, and in the process of orienting for the direction to control my machine.
A quick search:
duckduckgo.com/?t=h_&q=Unimat+SL100+&iax=images&ia=images

SL1000 (with three zero's) is a hobby level lathe.

Do you already have a PC for controlling your machine?
LinuxCNC needs a specially crafted OS with a real time kernel and quick I/O capabilities, because it does all calcualtions on the PC side. If you want to use USB, something like GRBL may be more appropriate. With GRBL, you send the G-code to a microcontroller, and the microcontroller does all the real time stuff. This makes the communication between the PC and the controller very tolerant of timing issues, the PC also does not need to meet real time performance, and any PC can be used. Have a look at the GrblHAL project, where you can choose from quite a lot of different microcontroller families.

For LinuxCNC
Parallel ports are mostly obsolete as PC hardware, but there are still motherboards where an LPT port is available on an internal header, but does not have a connector on the outside of the PC.

The lowest cost option (except the 2nd hand PC from the attic) for LinuxCNC is probably one of those SBC's I once had a working machine with machinekit on a Beaglebone Black, but it was headless and X-forwarding over SSH was atrociously slow (about a 2Hz display update rate. In the meantime Machinekit has mostly died too, but a Raspi 5 combined with Remora is an option. This uses an SPI bus to communicate with a microcontroller that does the step generation, but it still needs a low latency communication channel to exchange data with a servo thread. Apparently it's untested or not supported to attempt to use an SPI bus from another SBC then the Raspi 5.

SPI is supposed to be unavailable on regular PC's, but as far as I know it's often available on the TPM module, together with the LPC bus. But I have not seen any hint of LinuxCNC being able to work with those communication channels.

I should note that PCI and PCIE parallel port cards are still available if you motherboard has a PCI or PCIE slot

Does remora use the spidev interface ? Whilst ai haven’t looked at the remora driver code lately I noticed a ref to bcm2835 headers which ties it to the RPi4. The RPi5 is a different kettle of fish.

Best bang for buck is going to be an ex corporate PC that has a PCIe for a Parallel Port card.

If just for a proof of concept, the Wheezy image of Linuxcnc with an RTAI kernel wouldn’t be a bad choice, ok it runs linuxcnc 2.7 and an old version of Debian that has been EOL for a few years, but it still works.

I ran my mill with a BBB using the Wheezy image of MK so no having to work over ssh. Was a decent setup for a while.

Linuxcnc-RIO is well worth looking at.

User_paulvdh_42 wrote:

but a Raspi 5 combined with Remora is an option. This uses an SPI bus to communicate with a microcontroller that does the step generation, but it still needs a low latency communication channel to exchange data with a servo thread. Apparently it's untested or not supported to attempt to use an SPI bus from another SBC then the Raspi 5.

SPI is supposed to be unavailable on regular PC's, but as far as I know it's often available on the TPM module, together with the LPC bus. But I have not seen any hint of LinuxCNC being able to work with those communication channels.

The drivers are made specifically for the RPi3/4 and 5, so they dont use spidev and wont work with other sbc. It wont work on a PC with TPM unless someone makes some kind of hardware driver. If you dont want to use an Rpi, you can try out the remora ethernet board