(superseeded) Linuxcnc on Linux Mint 19.3 quick and easy installation

Disabled UEFI and I am in!! Thanks so much. Now, on to more learning.

Just thinking aloud.......

Could a so called “meta package” be built so installing kernel and linuxcnc be installed by one package ?

I am trying this on Linux mint mate 19.1 and downloaded all the files as per your instructions but don't know how to load the rt kernel. boot menu shows it is there but when I select it I get error saying I need to load kernel first. I have to select the regular kernel to boot. Don't know what to do. New to this even though I have been using linuxcnc on my router for over a year. Thought in would be nice to enjoy mint out in my work shed when not running cnc. Help!

Ok will need a picture of the boot menu message you are getting, the way you are describing is a little confusing to me.
Will need you to post the contents of /boot/grub/grub.cfg

Download 4.16.12-rt5-kona-rt_amd64.deb used gdebi to install ,Reboot shift/ctrl grub2 menu ,Not showing it only see 5.3.8.28 generic .I also did the the three sudo line, reboot same thing NO 4.16.12rt5Kona rt amd64 again only shows Linux 5.3.8.28 generic.
What am I doing wrong ?? Not a happy camper right now with this .

I did that, both image and headers, 4.16.12rt5-kona-rt amd64.deb and then the rt kernel. Same message at boot, you need to load kernel first. I am going to recheck again but no luck yet. I am sure I got the right files.

Does grub have an "Advanced Options" menu ?
If you delve into that it may have your rt kernel come up.

If you want to wait an hour or son from this post I'll have my Linux Mint 19.2 iso with an RT kernel and Linuxcnc 2.9 installed already to do a fresh install with.

Yes and Advanced options menu only show 5.3.8.28.
Would be nice to download a iso all set up with LinuxMint & CNC ?
It would stop a lot of people from using a lot of aspirin as one fig it out

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