Living with wood movement
Since we cannot avoid wood movement, we need to live with it. Now that your joinery takes it into account, are there other areas we need to worry about? Kinda.
Drawers: and here we’re talking about drawers in furniture, not tidy-whities.
- Have you wondered why the front often is higher than the sides? One of the reasons is to allow for the sides to expand/contract so that the drawer won’t bind up in the opening – or in a chest of drawers where the rail for the drawer above is the “roof” of the drawer compartment below. A snug fit would lock your drawer shut in the summer. There are other methods to lock a drawer, really…
- The grain runs around the drawer, never from bottom to top! This means that a drawer will stay almost dead stable in width and depth, but the height will differ through the seasons. Factor that in. In addition to dimensional stability, this is of course the strongest way you can build the drawer. Wood is very hard to split across the grain, but it is very easy to snap it apart along the annual rings. If you have seen more than 9 woodworking videos, you have seen a bundle of straws. If not, you will. And then you will understand, young padawan!
- Gaps around the drawer front will keep it from binding up. You can omit the gaps on the sides if the grain runs across the front. Remember to allow for wood movement if the drawer fronts are stacked, like this Ib Kofod Larsen chest of drawers:
- The drawer bottom could be made from plywood, since it won’t move. The drawer sides, front and back will all be long grain in relation to the bottom, so a solid wood drawer bottom needs room for movement. That movement should be front-to-back not side-to-side. That way, the bottom can be made to fit rather snug between the sides, which will aid in keeping the drawer square and true over decades of use – combined with dovetail joints, it’ll be a very strong and stable construction. You can fix the bottom to the front with glue, and I would put a screw through an oblong slot in the bottom into the back of the drawer to keep the bottom from sagging and rattling.
- Add a false front to an all- plywood drawer. The front will move, but the rest of the drawer won’t. Here you can secure the front with fasteners that locks the front in the center but allows for movement elsewhere.
- Wooden drawer runners? They’ll move, so choose grail wisely! Rift sawn and quarter sawn wood will benefit you here, although the difference in movement to flat sawn is negligible. But if you have a choice…
Panels and raised panel doors
Panels is perhaps the most problematic parts when it comes to wood movement. You want that raised panel to stay in place, so you make sure the frame is snug. Right? Wrong! Just look at the top of the page to see what’s going to happen.
Just make sure the groove for the panel is wide enough / that the panel is narrow enough. Secure it in the middle with a drop of glue if you want to; that way it will stay more or less in place and not be offset to one side – which may happen over the years. Or you can just let it float in there.
Pro tip: make a tab in the bottom and / or top rabbet to lock the panel in place without using any glue or fasteners.
Framing your stuff: You might want to have a nice mitered frame around the perimeter of your table, cutting board or door. It may look nice, but unless that frame is made of something that does not move you’ll most likely head into trouble. Remember that wood moves a lot more tangentially than radially? You want quarter sawn or rift sawn wood for your frame in order to minimize problems. And even then, you should be cautious! A wide, mitered frame is a really bad idea in solid wood. You might have done your homework and accounted for the table top movement, but did you remember to account for movement in the frame itself? More precisely, the fact that a 45° miter will move differently on the inside than the outside?
This is not a very big problem if your wood is dry enough. Usually we see this when installing baseboards and trim moldings from construction grade materials – you go to the big store, get your stuff and painstakingly you frame your door with dead tight mitered corners. The next day, a hairline appears. In a month, you can hide contraband in there! The culprit? Ya din’t dry the material, Jack! (practice your Nicholson here).
Here are two simple ways you can avoid this issue: Either use a splined miter or make a mitered half lap joint. A mitered tongue and groove joint works even better, but will be more complicated to make.
Wood will move and there are lost of things you can do to avoid issues. I’ve given you a few, but the main goal for me is to edumacate my fellow woodworkers about the issue. Do your research. I have seen way too many soon-to-be-failures posted on Facebook by people who haven’t learned about this. I could’ve gathered dozens of images off of there, but I would have to get consent from each individual – and I don’t think it would be fair to show someones hard work as an example of what not to do.
So let me just use myself as the bad example. Years ago, I made a score stand for my digital pipe organ (when will I ever find time to finish that one?). I did not know any better, so I glued – with dowels – long grain to end grain as sort of a breadboard end. It has actually held up rather well, thanks to me using PU glue for some reason I don’t remember. Happy accident. But this shows what will happen if you ignore wood movement – or do/did not know about it:
At this point, the central part is just a gnat’s nadger wider than the side rail, but the failed glue line clearly shows the issue. Oh, well – we learn.
I’ll finish this article with a piece of advice many of us has learned the hard way: Do not let your parts and joints sit there for a long time. If you cut your joints and leave them for half a year, expect problems. If you don’t have any other options, I would suggest that you make your joinery slightly large if you need to wait a long time before assembly. Then fettle the joints right before final assembly, and you should be good. A person I follow on Instagram had this experience – the parts laid there for well over six months, and they were twisted, bowed and the joints did not fit anymore.
Place your parts in such a way that as much of the surface on as many faces as possible has good airflow. Use sticks to stacker parts, leave them on end on your work bench or leaned against the wall. That way they’ll change uniformly, hopefully without moving too much on you. With a bit of consideration you should not have any major issues with wood movement.
In a way, knowing about it is liberating. If it is going to move, maybe fussing about that half a millimeter or 1/32” really is moo. Like a cow’s opinion. Does not matter. It’s moo.
I usually close off the articles with a bad phun (I am a dad, after all), but there are just soooo many options. Wood, shrinkage, expansion, growth, movement…. I am not going there. No, I wood not move in that direction at all…
(Next page: tables over wood movement coefficients)