Thank you, sir!

While I've got your attention I have another burning question, though slightly off topic.

As I mentioned I've been out of the loop for several years now. When I was last here plasmac (pre qtplasmac) was in heavy development and rpi4 support was "expiremental" and plasmac a no go.

Is the rpi a viable option now for a plasma table?

Look honestly unless there is some feature you absolutely must have that is the later versions I would stick with what you have. Even more so if you are using the parallel port. As the later installs do not use an RTAI kernel, which is best for parallel ports.
I think JT runs a lathe that is still on a version of Linuxcnc that runs on Ubuntu 8 or something like that back when the project was called emc2.
Unless you have a download of the image file that passes the md5sum test you are on the road to nowhere. Get that sorted first if you want to proceed.
Before anything back up your Linuxcnc folder that is in your home folder so you don't lose any of your Configs if things go bad.

It may help if you can give some info regarding the machine, are you using a parallel port or not, the CPU on the computer you wish to use, I don't want to look up the specs of the computer you are using as the same model can have different CPU, memory HDD and so forth.

Oh hang on you have a working Linuxcnc install ?

If so you can use that to make the USB stick.

This is a very comprehensive article on how to do that
www.cyberciti.biz/faq/creating-a-bootabl...k-on-a-debian-linux/

Or you can search for WSL dd to USB.
WSL is windows subsystem for linux

learn.microsoft.com/en-us/windows/wsl/install

The image needs to be written to the USB stick byte by byte. The ISO format does not have a partition scheme.
I would have looked into why the program wouldn't run

A properly written USB stick for booting Linuxcnc does not have a "partition" scheme.
I think Belana Etcher has a "raw mode" that writes the image file to the USB stick as win32diskimager would.

Hello,

Since you don't describe your detailed workflow, it's difficult to answer correctly.
There may be an offset entered in the tool table, but it's not actually necessary, since the tool length doesn't matter with this procedure.
For my part, I have put together a few routines that do a manual tool change with automatic measurement.
The whole thing assumes that there is a tool in the spindle at the beginning, regardless of whether it is actually used or not, and that this is measured and then used to measure the workpiece height.

I hope I'm doing this correctly.

Many greetings, Frank

That did not boot. I am trying to boot from DVD again. Is there any upgrade path from 2.7.15 to the modern versions that does involve booting an ISO? This desktop is apparently a legacy BIOS.