10-Inch Student Slide Rule
Frederick Post model 1446 [1949-1950]

Hemmi model 40
1949 Frederick Post General Catalog,  Pages 68-69

Top and bottom edges are vertical bare bamboo
Back:  Bare bamboo with table on thin plastic
This model was discontinued about the same time Hemmi introduced date codes.
I don't expect to find a Post model 1446 with a date code but it's not impossible.