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Small-Scale Question Sunday for November 12, 2023

Do you have a dumb question that you're kind of embarrassed to ask in the main thread? Is there something you're just not sure about?

This is your opportunity to ask questions. No question too simple or too silly.

Culture war topics are accepted, and proposals for a better intro post are appreciated.

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There's a little bit of that, where midwits (myself included) tend to think of MDF- and plywood-heavy designs as fake or insufficiently sexy. It used to be more popular for entry-level projects about ten years ago, where the price difference between MDF and S4S softwoods was much greater.

For the complete beginner, MDF does have its place. It's mostly flat, incredibly dimensionally stable, and accepts paint well so long as you prep the edges correctly. You have to be trying aggressively to get any tearout, and the stuff sands almost embarrassingly well. If you want to learn about dados and rabits joins, especially by hand, it's an excellent option. You'll have to buy a number of good drill bits because predrilling to exact sizes is so important, but that's not an awful habit and these days you can get some decent HarborFreightium drill bits for cheap.

But MDF does have a lot of awkward tradeoffs: you're really limited in joinery, the material is both brittle and has little stress resistance, the dust is slippery as ice and almost as bad as walnut for your lungs, the material is very abrasive on cutting blades, and even small amounts of water or high humidity before it's got some finish on it will turn it into sludge. These aren't big deals at smaller scales or with starter tools, but as you start to do bigger projects they can exceed a lot of the savings you might have gotten from the raw panels. Meanwhile, once you have a real planer, you'll find that you're often going to want to plane down (non-pre-primed) MDF to get rid of shipping marks (and sometimes to get a more precise thickness for a project); if you want an MDF-heavy project to stay stable and rigid you'll start supplementing it with hardwood edge banding. You'll start looking at finish quality, and for MDF you're pretty much restricted to sand-and-prime-and-sand-and-paint or veneer, and when working with hand tools those are a lot more tedious than varnish or polyurethane or Odie's oil.

But there's also a specific place where those tradeoffs are extremely worthwhile, and that's bulk cabinetry. You buy planer blades in bulk and have a resharpening contract, so the tool wear matters but it's a line item. You're going to be using an airless or HLVP gun, not a thousand paint rollers, so painting is a lot easier and you can get a uniform coat in minutes, not days. You and your employees are totally wearing those mandatory safety masks cough cough, and if you don't have a big dust collection system your shop will literally explode. Obnoxious and complex glue-ups. The cabinets are going to be permanently installed once (and the installation itself will lend a ton of strength), so it doesn't matter if your fixtures will tear themselves apart if moved. In return, you basically can ignore dimensional stability, and the extent that simplifies your project when you're trying to keep 1/8th inch accuracy over eight or twelve or sixteen feet is a big deal.

And bulk manufactured wood cabinets are not-so-coincidentally also a big money maker for large-business wood shops. (These same forces also drive flatpakable furniture, though the margins there are smaller and a lot of it's overseas stuff.) Not the only one, and if you have the buyers have the cash for conventional wood you'll definitely try to upsell them. But it's as close to a reliable demand as it gets.

There are still some places for MDF (and to a lesser extent, OSB) for hobbyist and small businesses. It's excellent for CNC work you intend to paint later, for example, and sometimes you can do things there that real lumber won't tolerate. If you're installing into drywall, not having to care about seasonal movement can be really convenient. There's a few situations where the extra weight and heft is enough of a bonus you'll throw a bit of MDF paneling in even when using real wood for the framing.

That's pretty much what I assumed. Most of the flatpack and flatpack adjacent furniture I've had has been chipboard with a laminate or veneer surface, but I'm pretty sure our kitchen cupboard doors are MDF underneath the protective thermofoil finish because like you say they're from a place that prioritises volume and efficiency over craftsmanship. The galaxy brain is building that bulk business and the brainlet is shrugging and saying "it's a cupboard door, what else matters" while us midwits seethe about how phony it is.

I've been warming to plywood on the basis of cost x simplicity x skill level but unless I found a niche use for MDF like complex shaping (I remember using it to build terrain for WH40k when I was a kid) then I just can't bring myself to willingly choose it. It's so soft and heavy, and the moment it gets a drop of water on it it turns into cardboard. That's before having to worry about the clouds of hazardous dust. But yeah, maybe if I was building cupboard doors that would get painted anyway or a sacrificial top for a workbench it might be the sound choice. OSB I just think of as subfloor or a very quick and dirty wall material.