Raspbery Pi 4 - 4GB or 8GB - which one or both?

Thank you Andy.

We are also picking up issues now with the RPi freezing.
Will try the 64bit shared below by elovalvo. Hopefully it is resolved.

Mine doesn't freeze with Andy's image. I suspect you have a power supply problem.

So with Elovalvo's image it doesn't freeze, however we cannot get G71 working on the 2.9 pre-release available for the RPis.

We have checked the power and no issue with power. 3A and 5V from the recommended RPi power supply.

G71 not working is almost certainly unrelated to power supply.

How does it not work. Have you tested with known-good sample files?

There should be three files in ~/linuxnc/nc_files/(sample?)/lathe_G7*