Stop in for a cup of coffee

I'll have to dig through some books or old prints to find photos .
Concept is a small guide that attaches to the bar and fits a 2 x 4.
The 2x is temporarily attached to the the log with some screws. I recall cross pieces were used but why ecapes me right now.
Something like this
upload_2022-6-12_17-44-50.png

edit
something like this
51qNc51pCNL._SS300_.jpg