Hi. Newbie woodworker here.
I wish to make some simple bookcases & cabinets out of MDF because it’s relatively cheap and I’ll be painting them.
I’ve read that MDF doesn’t hold screws well. So, what types of fasteners work best? What about biscuits? Will the joints blow apart when these things swell? How about no fasteners at all? Are well-glued joints all I need?
Thanks.
Toolfanatic (a.k.a. The man formerly known as “Toolfreak”)
Replies
Assuming you'e talking about 3/4" MDF, biscuits with glue will work fine. You can clamp the case to keep everything together until the glue dries, but it is simpler and faster to use a few nails instead.
Even nails with an air gun will raise the surface fibers slightly, so it is a good idea to sand them smooth before you fill the nail holes.
Screws work fine too -- and coarse thread DW screws are a little better than the fine thread, but it really doesn't matter if you are also gluing the joint. MDF splits easily, so you'll want to use a drill/countersink of appropriate size to make sure the hole is almost as long as the screw.
Good luck.
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"I tend to live in the past because most of my life is there."
-- Herb Caen (1916-1997)
What about biscuits?.. Will it blow apart...???
Biscuits CAN swell the MDF a bit and may be noticable by a slight swelling on the surface.. However I have noticed this just sometimes..
I now use a lock miter bit for all my MDF corner joints (and for other woods)..
You will either HATE or LOVE a lock miter bit... No in-between's!
I've built a lot of different cabinets out of MDF. Glue and brads are all you need.
Cheers. Walker1
Do yourself a favor and get some birch plywood, the few extra dollars will be worth not eating the MDF dust and you might just be able to lift the bookcase. Using dadoes for fixed shelves and your top and bottom is the way to go, with either material. Rabbet on the face frame if you are using one. Edge band the plywood shelves and you will have something that is worth the effort.
Ditto on the birch plywood. However, it's available in 18mm OR 3/4", so if you need to buy it at different times, make sure they have the same as you used before. HD has 18mm for $29.97 and 3/4" for $36.97 per sheet. MDF is $20.97 here in Milwaukee. Birch is definitely lighter and is very stable. For particle board, there are screws called, oddly, Cabinet Screws. Whodathunkit? They have a thicker shank and the thread is very coarse. Great for making boxes. HD has these, too. They look like drywall screws on steroids.
"I cut this piece four times and it's still too short."
By birch plywood, I assume you're talking about the stuff with the veneer core. I stopped using this, in favor of plywood with a fiber (i.e. MDF) core years ago because I was tired of fighting slab doors and carcases that would warp enough to make working with them a PIA. I don't find Baltic birch much better. IMHO, MDF or fibercore ply is way easier to work with simply because it is more stable and stays flat, even though you do have to find a way to contend with the dust. What's your solution to the bending/warping problem?********************************************************
"It is what we learn after we think we know it all, that counts."
John Wooden 1910-
You must be finding some crappy plywood if you have warping problems. I'm not talking about construction plywood, which is a totally different thing than cabinet grade plywood. I don't have to do anything about warping because it just isn't an issue. Even the low grade birch at HD hasn't given me any problems. MDF is a very heavy and the edges dent easily. Fibercore veneered sheets are difficult to edgeband without a mechanical bond such as a T band. The ends don't hold glue very well and rabbets or other joints that reduce the thickness are easily broken. You can break a 12" shelf of MDF over your knee without trying. Glue a couple pieces of MDF together then try to pull them apart. The top layer will peal right off like a thin sheet of paper. It's already been mentioned how poor MDF is for attaching with fasteners. It makes a nice substrate for thermofoil and other shrink wrap type coverings but even the large manufacturers have to use specialized fasteners. Have you ever seen the little plastic screw anchors that kitchen manufacturers have to use with euro style hinges and MDF doors? It may paint well but so do many other materials. MDF dust is one of the most irritating for me and I'm not particularly sensitive. Recently there have been some offshore plywood products on the market. The word is, that some of these are very poor with thin veneers and many voids in the core. If you buy your products from a reputable supplier and know how to specify sheetgoods, there shouldn't be any issues with quality. I'm not recommending a quality plywood over MDF because of some snobbery. My thoughts are based on long term experience as a cabinetmaker using many different products. The original poster asked about a painted bookshelf in MDF and I gave my opinion. He will have to look at the pros and cons and make the decision accordingly.Beat it to fit / Paint it to match
Cabinet Screws are only necessary if you want to be able to break down the piece later, otherwise glue is best.
There is nothing wrong with using MDF, if the piece is going to be painted any way. It's excellent material to work with, and it saves a lot of trees . To completely reject MDF when it's perfectly suited to the project, is nothing more than a ridiculous ego trip.
Walker1
And, if you want a really smooth surface to paint, it doesn't get much better than MDF. There are also some sheet goods that are used in cabinet shops that have particle board at the center and as it gets closer to the surface, the particles become finer, more like MDF. It's pricey, but you get the best of both worlds.Re: cabinet screws- I should have said "for gluing and screwing the parts together". If I want to make things that are "knock-down", I would use knock-down hardware.
"I cut this piece four times and it's still too short."
Edited 8/21/2005 9:53 pm ET by highfigh
What the others have said about fasteners and glue is good. You are best off designing your joints to minimize the need for fasteners. For example, dado the sides of the bookcase to accept the shelves and you'll have great support. Then the back of the cabinet will keep the sides from spreading and you won't need any fasteners at all on the shelves, except perhaps one screw a few inches back from the front.
Practice on scrap because MDF really does split easily.
If you are just beginning and don't have a dado blade for your table saw you could use a router if you have one, or take multiple passes on the tablesaw. It takes longer, but gets the job done.
When I need to use screws in particle board or MDF, I often run my screws then back them out and drill out the screw hole for a 1/4" or 5/16" dowel. I glue in a dowel then reassemble the joint. Now, my screws are anchored in something solid.
This process takes more time, but joint failure goes way down.
WOW i am floored by some of these suggestions. I just glue and staple it. I use more staples than I would for other products. The staples are only to hold things together until the glue dries anyway. shackle the holes and sand before painting.
If you use nails or screws, instead of staples the core is weak, and you can end up with a separation or big bubble in the substrate that you are fastening to
when fastening hardware, it is good to have the system where you drill the 5 mm holes then use the system-screws. they really hold good and can be removed for painting, and then replaced. Wood or sheet-metal screws just destroy the material around them.
If you are going to use MDF for doors you should use the type of hinges that have the press-in nylon bungs if you care about the quality of your work.
I only use MDF for projects which will end up fixed into place. It is just too fragile for furniture that will be moved around. I have not had any problems with it after it was installed, unless there have been water problems. Keeping that in mind, I usually glue down a piece of plastic laminate under any sink cabinets, and caulk all around the edges, so if there is a small leak, it has to come out the front of the box to alert the home-owner.
I hate working with this crap, but I earn my living in my shop, and sometimes there are jobs that must be done fast and economically, and hopefully still look good.
I hope this helps, Good luck, K
This is what I said to begin with. Brads to hold the carcass together until the glue dries. I use MDF when it's suitable for the intended use, because it's quick and easy, and looks great painted.
I usually ease the edges with a 1/8 roundover bit, and then a couple of coats of good quality paint, makes it very durable. ( Oil primer first).
I never glue and screw, it weakens the joint. And I wouldn't use knockdown hardware on MDF unless it had lam. or ply. veneer.
Walker1
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