Thursday, February 5, 2015

The great wood screw debate

Over on my buddy's blog, http://themodelrailwayshow.com/cn1950s/, a conversation has started about drywall screws vs proper wood screws for layout construction. Started in part by me when I built Trevor's benchwork in one day and I convinced him to save his collection of drywall screws for hanging drywall.
I have a few reasons for this attitude, which I'll share with you.
Study a flathead wood screw head vs a drywall head. The wood screw should be a simple straight taper, whereas the drywall screw is a buglehead shape. The buglehead will have a greater tendency to split the grain when being seated, especially near the end of a board. The buglehead was carefully designed to create the dimple needed in drywall for taping and not pierce the paper.
Drywall screws are casehardened, to prevent them from rusting when buried in wet drywall mud. Doesn't always work, but that's the intent. The end result is a screw shaft that is very brittle and far more likely to snap if you over torque it while trying to draw 2 pieces of wood together. The only upside of this is the greater depth of your foul language vocabulary that develops when you try to extract a broken shaft.
Most wood screws over 1" long will have a blank shaft above the threads and below the head, while drywall screws tend to threaded to full shaft length. The reason for the blank portion is to prevent bridging of the screw while drawing 2 pieces together. If you have thread all the way up the screw you basically have to strip the screw out of the first board to suck it into the second board, which greatly increases the chance of stripping the threads in the second board, and why would you go to all the work?
Wood screws are available in a far greater variety of lengths, thicknesses, styles, head shapes, thread designs, etc than a basic drywall screw. Go visit a fastener specialty outlet and have a gander. No doubt you'll be amazed as to what's out there.
And for you non-Canadians, shop for square drive screws. We know it as the Robertson screw. Hands down the best drive design for screws period.
See the chart
Everything else aside, the simple joy of working with Robertson screws over anything else settles the argument for me. I have driven 100s of thousands of woodscrews in my work and only once did I have do a job for 3 days with all Phillips screws. It was 3 days from hell. Screws constantly falling off the drivers, drivers camming out of the sockets. It was a fight to do basic work, compared to what I'd been used to.
So the right tool, fastener for the right job. Would you solder your DCC decoder into that loco with a torch? Use a hammer drill to install working signal bases?
I can hear it now, "I've used drywall screws for years on my layout with great success." Good for you, and I can drive my car 20,000 miles without changing the oil. Doesn't make it right.
Besides, visiting the fastener store may expand your knowledge base and show you something that you didn't know existed and may solve that little problem you were having. The construction world doesn't begin and end in the Home Depot or Lowes.

3 comments:

Anonymous said...

A few years ago, Model Railroader magazine paid me money for telling American modellers to use Robertson screws.

Steve Lucas.

bestsnowman said...

Great information to know! I just need to figure out what to do with my extra drywall screws... I bought a 40lb box to finish my basement but really ended up only needing about 5lbs.

Anonymous said...

Pierre,

I'm with you man! One of the last owners of my (almost) 120 year old house must have had stock in a drywall screw company. The idiot used them for EVERYTHING! It's bad enough dealing with them inside the house, where it is dry; but he even used them to assemble the wood fence (among other things). I don't think I have removed even one screw in one piece. Due to moisture rusting the tiny shaft of the drywall screw, the head snaps off every time.

gary