Trying an alternative way to create the Chess Board trim - but a problem arises

[Kevin_Giles]

I eventually got the original method mentioned in the course to work. Then I thought I would try another method.
This is what I did : -
extruded the chessboard face by exactly 1 in z
centred the cursor,
Created a cube and scaled to 30303 (x,y,z)
Made the top face at z=1 (now it clashes with the chessboard face)
Now I selected the “cube” (the trim)) and applied a “difference” boolean operation with the chessboard.

Unfortunately, this created some weird geometry (as seen in teh wireframe mode) and did NOT cut out the chessboard.

Can someone tell me why ths- is so, please?

[LucidityOfPower]

Any chance you could show exactly what you’re trying to do / what is happening? It’s a lot easier to help if you have images