A lot of home made CNC machines are made of MDF. There are things to recommend it:
- It is fairly stable.
- It is cheap.
- It is pretty uniform.
- The big box stores carry it.
Now, on the downside:
- It's heavy.
- It doesn't hold fasteners well.
- It isn't very strong.
- It will sag over time.
- It starts to deteriorate with humidity.
Well, there are lots of other materials but let's not drag this on too long. Hardwood plywood is a much better material. It is lighter than MDF. Stronger. Relatively cheap. Easy to get. Glues well. Holds fasteners well. Maintains its strength and shape well. Less susceptible to moisture. Finishes well. All in, it is a much better material to use for building anything. Softwood ply would be OK but the grades that you can get easily are crap.
MDF has it's uses. It is wonderful for a sacrificial cutting surface. It works well where there is a dry environment and there is no real structural load. It also makes really nice speaker cabinets. For CNC machines, forget about it.
Hi David,
ReplyDeleteNot to mention that MDF is an mould-magnet - all sorts of fungi (well, here in Sydney, Oz anyway ;) love attacking it, ans I suspect that one of said fungi is _Aspergillus flavus_, a very poisonous and also carcinogen-prodocuing organism. Although I could of course be wrong and it's another one altogether. Unless I smother the stuff in anti-fungal paint (for the moulds) and upmteen layers of top-coat (to keep the water out) it doesn't last very long.
Horrible stuff - it might be a good way of recycling waste wood fibres, but I loathe it. And it doesn't have a lot of structural strength built in, either - that has to come form joint engineering and (composite) coatings.
Give me plywood - or even chipboard - any day!
Cheers,
Alex.
I do wonder about tempered hardboard though. I really like it for a replaceable work surface on my workbench.
ReplyDeleteWhat thickness is that? I think that "hardboard" (tempered or untempered) over here is usually called "masonite" but I could be wrong. My current "replaceable" work surface is to sheets of 0.75"/19 mm formply. When one side is wrecked you turn it over and use the other side - but so far it has been pretty good and even (up until recently) rejects epoxy pretty well.
ReplyDeleteI use a 1/4 in on my workbench. Takes a beating and if I cut into it, spill oil on it, set a cold drink down, I really don't care. We used to call it masonite here as well but I think that was a brand name.
ReplyDeleteAnother thing they do with it oddly enough is use it for a substrate for painting with oils and acrylics. Go figure.