Drill holes for bookshelves before or after paint?

Question

I am building a set of built in bookshelves with floating shelves set on pins. The bookshelves will be painted, so I'm assuming 1 coat of primer and 2 coats of finish.

Should I drill the holes for the floating shelves before assembly or after painting?

I figure that if I drill before paint, the paint will change the dimensions of the holes. I'd like to paint after assembly and before installing the cases to the wall, so if I drill after paint, access to the holes will be limited.

This particular problem is about the order of operations:

1. Glue Up
   
2. Paint
   
3. Drill

or

1. Glue Up
   
2. Drill
   
3. Paint

Answer 1

Put simply, it depends. 3 coats of paint can be quite a bit, depending on how you apply it. How tight are the tolerances for the holes? Are you brushing it or spraying it? If you're spraying it, you shouldn't have much problem. it would also depend on the kind of paint you're using. Latex may be a problem but acrylic might not and alcohol/shellac shouldn't have any problem. Here's what I would do:

• Get 2 pieces of scrap
• Drill one and paint it (vertically) and paint the other and drill it.
• See which one works out better.

That said, if you decide to drill post-paint, I would put painters tape down before you drill to mitigate some of the tear out. If you're using a template that lays completely on the wood (not the commercial plastic one) and clamp it in place, you shouldn't have much problem. If you're using a plastic template or a piece of peg board, you might.