Archive for the ‘Lumber’ Category

EMC Calculator

Friday, June 7th, 2019

A few years ago I created an online calculator for predicting how much lumber will expand or contract based on its percent moisture content (MC). I personally use it quite a bit! The calculator requires a starting %MC and a final %MC in order to calculate how much wood movement will occur. Unfortunately, sometimes it can tricky to predict a final %MC based on where in the country the piece of furniture will live.

In order to help with deciding on a final %MC there are equations that one can use (the equations have been previously published link). In order to simplify the calculations, I created an online calculator which allows you to enter your ambient air temperature and the relative humidity; the calculator will provide the %EMC (equilibrium moisture content) from these values. You could, in theory, use a relative humidity and temperature that would represent the largest deviation based on where your piece of furniture will live.

So if you know your starting %MC via the use of a moisture meter, you could then use the EMC calculator to come up with a final %MC in order to calculate how much expansion or contraction the wood might incur.

If you have any questions please let me know below.

Adventures in Lumber

Saturday, October 10th, 2015

For me, my lumber adventures always start early on a Saturday (they close at noon).  The lumberyard I purchase from (The Hardwood Store in Gibsonville NC) is 30 miles away, so when I go I always make sure to get everything I need for a project to avoid another trip.

Bring Stuff:  Here’s a list of things that I bring with me to the lumberyard:

  1. Chalk – this helps when measuring parts onto long boards.
  2. Tape measure – I’ve forgotten to bring this in the past, but my lumberyard has loaners available.
  3. Cheap handplane – To help see the figure in rough boards. This is something that I think am going to start bringing.  My lumberyard skip planes so this isn’t always necessary.
  4. Cut/parts list – This is absolutely necessary unless you plan on over-buying for every thickness that you’ll need.

Picking: Here’s some helpful advice for picking through lumber.  First, let me say that not all lumberyards tolerate picking; some will jump on you.  The lumberyard I go to now (The Hardwood Store) is very tolerant of picking, but be courteous.  I don’t think it’s a good idea to get on the bad side of those that work at the lumberyard so you might want to leave the stack of lumber the way you found it.  Sometimes when I go to the lumberyard the stack of lumber in some bins will look heavily picked through.  All that you might find are the discarded boards from those before you – lots of sapwood, curved, or knotty.   When this happens I’ve found that if you ask politely they’ll bring out a fresh pallet of lumber if they have it available; just ask nicely.  My lumberyard never has a problem with this and the guys that work there are super nice.

Finding figure:  The lumberyard that I go to skip planes all of their lumber.  Skip planing is the process of lightly planing lumber in order to expose the figure; this also helps with grading lumber.  My lumberyard does this and I really like it.  It’s a great way to see what you’re getting.  All of the beauty as well as any sapwood and imperfections are exposed so there are no surprises after you start milling at home.  If your lumberyard doesn’t do this you can bring a cheap handplane or a scraper with you.  Just expose a little bit of the figure with your scraper or handplane, but don’t go nuts in case you don’t buy it (you might want to check if they are ok with this).

“The Hardwood Store” (Gibsonville NC)    lumberyard

Warping and Waiting

Tuesday, September 22nd, 2015

When I first started woodworking it was usually on the weekends because that’s when I had the most time (like most people).  So, when I started a project on a weekend, it might not be until the following weekend before I could work on it again.  Very early on in my quest to be a woodworking Jedi (a path I hope I am still on – but one I don’t really expect to reach) I noticed that if pieces sat for a few days that they would warp.  Naturally, this made me panic every time I started a new project to get everything assembled as quickly as possible.  This, unfortunately, wasn’t very enjoyable.  So, I asked around to find out what other woodworkers do to keep everything flat without freaking out.  What I found out was that with careful milling (assuming your stock is adequately dry), the warping can be significantly reduced and you can assemble more at your leisure.  In practice, this appears to hold water.  What is careful milling?  When planing stock at the planer (thicknesser for those across the pond) one should be careful not to remove too much from one side only.  This has the dramatic effect of reducing warp.  Another thing I do, when it’s appropriate and fitting to the project, is to leave my material as thick as possible.  By not planing to a pre-determined thickness I’ll simply stop when both faces are flat and smooth.  I’ve found that the thicker the board, the less prone it is to warp.  And from a physics stand-point, this makes sense.  One factor that also seems to influence warping, and one that can’t be eliminated by careful milling, is the length of the component.  For example, the longer a rail the more prone it is to warp with prolonged standing – in my experience.

Now I don’t worry about warping like I used to; I can usually prevent it from happening to any significant amount.  I’ve waited as long as two weeks to assemble a large project with no warping troubles.

Relax!  This is supposed to be fun.

**Edit:  Stickering your milled lumber also helps to prevent warping.  I always sticker my lumber after milling (place sticks between boards to allow adequate air exposure on both faces).