Hi Lorenz
Yes, this is a story many folks will follow.

Quote
I'm assuming the diameter of the cutting blades is 20" ? Just so I know when I fabricate a cutter for mine.
These machines were made in 20" and 24".
The 26" machines were self-propelled.

The diameter will be the tip-to-tip measurement.
If you fabricate a bar holder, the tip-to-tip will include the blades,
as in the image above. The stepped down bar holder was designed to
protect wear on the holder bolt heads.

Hope this helps.
----------------------
Jack

Triangular blades are still available.

However, I'm not sure whether the original holder on your machine
was a steel triangular job, with same triangular blades.

I see no problem with fabricating a bar holder for swing-back blades
of your choice - if you would prefer that.