I'm looking to save some cash and considering buying 2x10 fir boards from a big-box store. I have a couple of questions:
a) If the boards are relatively straight, how much of the thickness can I expect to plane off to achieve a perfectly flat surface? They currently measure 1.5" thick—once I've prepped them, what thickness should I anticipate remaining?
b) I've been storing lumber indoors, yet I often face bowing issues. Here's my usual process: I joint one side, then plane the other side to thickness. But when I return a couple of days later, the board has bowed. Should I be removing equal amounts from both sides while planing to solve this issue?
5 Answers
As for your first question, it’s really a bit of a gamble and depends on how 'perfect' flat is for you. One of the key things to remove is the roundover on the edges to avoid splinters, which can also be done by planing the profile of the sides. For the bowing, box store wood is notorious for high humidity, so try letting it acclimate in your workshop before you start planing—this could save you some headaches!
I always try to take off the same amount from both sides when milling. It seems to help reduce warping. Regarding wood from big-box stores, I highly recommend selecting the best pieces and letting them acclimate in your shop for as long as you can. If you notice your supply dwindling, grabbing a few extra boards can really help for future projects.
I usually work with yellow cedar that’s pretty rough and wet. I take a little off each side, then sticker it for drying. After the moisture imbalance settles down, I can pick the best parts for my projects. The leftover pieces still find their use in smaller projects!
When milling, you're likely exposing moist inner fibers, which can quickly dry out and shrink. If you don’t plane evenly, one side may dry faster, leading to warp. Remember to always plane off material evenly from both sides to avoid this issue.
I recently worked on some fir 2x4s for shop furniture, so my experience might be helpful. After milling, I ended up with a thickness of around 1 3/8". As for the bowing, it’s often due to the wood's internal stresses being released during milling. Your approach—jointing one side, planing the other—is correct, but make sure not to plane both faces simultaneously. Just stick to planing the side you’ve jointed—it’ll help keep everything even and minimize warping.
That's what I thought too! I’ve heard from others that planing the same side too many times could expose wetter fibers, causing issues.
Interesting, I didn’t realize humidity would affect that! I had similar issues even with hardwood from the lumberyard.