I started building a toy box to go in the pipsqueaks' playroom today. It's going pretty well, if you ask me. I would like to credit the progress on practicing drilling countersunk holes into the scrap MDF that I had leftover after making my project cuts. Best decision I have ever made. EVER. Had I not, I would be one mad momma, and out $30.
I got the toy box plans from Ana White, who is a woodworking SHEnius. I decided to go with MDF, since I was planning on painting it when it was all built. MDF however, does not like when you try and screw things into the end grain, because the screw acts as a wedge and the MDF just splits apart. Drilling a pilot hole is KEY. However, I found that unless I drilled a pilot hole that was at least the length of the screw, it wanted to split. EVERY TIME. Some splits weren't as bad as others, but I didn't want ANY. So, here are my tips for keeping MDF from splitting when drilling into end grain, all in one spot, so you don't have to spend hours on Google like I did.
• You can use drywall screws, but SPAX brand MDF screws are awesome. A little more, but worth it, IMO, and it comes with a bit in the box.
• Stay AT LEAST 2 INCHES away from the end of the board. If your cuts are straight, not having a corner screw is not a problem, especially since you should (see bullet #3)
• Always use wood glue. I use Elmer's.
• Pre-drill your holes (pilot hole) the length of the screw your using. Use a bit that is as close to the size of the shank (imagine the long part of the screw with no threads, that's the shank)of your screw, no bigger. The threads will dig into the MDF, which is what you want.
For these plans, since I wanted to countersink the screws, I laid the boards that I was joining together as if they were already joined. I then used a countersink bit (looked like a bit with a countersink part at the top) and drilled my holes through the top board and a little into the bottom board. I moved the top board and further drilled the shallow holes that were made with the countersink bit until they were plenty deep enough for my 2" SPAX MDF screws. I then applied glue and drilled everything together. I suppose it took a little more time than usual, but I wanted it done right. I couldn't be happier with the results.
Sorry about the pic quality, I used my phone. Better pictures to come.
I would also like to mention, though, that in the future, I most likely will forego the MDF and use a Kreg Jig to join planks of wood into larger pieces to use for projects where MDF or plywood is suggested.
I still have lots more to do, including trim, sealing, sanding and painting. I'll post more pictures of this progress as it happens. Until then, I'm off to watch All Dogs Go To Heaven with the boys. It is H.O.T. outside.