Hello all, I am preparing to build two freestanding painted bookcases using MDF. These bookcases will have fixed shelves that will be let into dadoes cut into the sides of the bookcase.
I would prefer to glue the fixed shelves into the dadoes, but I am concerned about the glues effectiveness on the milled part of the MDF. Will the glue soak in and be useless? Should I glue size it?
If I glue size, will the glue/water mixture swell the end of the fixed shelf to the point of creating fitment issues with the dado?
Thanks for any advice. I am very new to MDF.
Replies
Glue size isn't necessary.
Just glue it up as usual, no special preparations.
DR
Since they'll be painted, you could always use some finish nails to hold it till the glue dries. Butt joints aren't the strongest when it comes to MDF but dado joints are very good. Also, the edges swell a bit when the glue soaks in so they'll be nice and tight.
Thanks to all for the replies. I appreciate the help.
I use 'good-old-yellow-wood-glue' and it works just fine. What I'm more concerned about is the SPAN of the shelf. Two to three feet is really maximum for an end-supported shelf, even with a stiffener across the front. Four footers will definitely sag within months. Also be aware that MDF generates a nasty dust when cutting with either a saw or a router (for the dados). USE a decent dust mask, not the 50 cent 'sneeze masks.'
SawdustSteve
Thanks for the heads up. The fixed shelves will be 32" (for efficient use of the sheets) and will be supported by a poplar 1x2 nosing and nailed to the sheet backing. Hopefully that will be sufficient.On the topic of sheet backing for bookcases, would beadboard wainscot panel look better than plain 1/4" mdf or luan ply? I had originally planned on just using some thin mdf or 1/4" ply for the back, but as I searched through some old threads here I read a couple of posts that mentioned using the beadboard wainscot paneling for backing.I think it would add a nice detail to a budget piece, but are there any drawbacks that I am not thinking of?
Hi Ryan.... If I remember correctly, you said in your original post that you were going to paint the finished unit. 1/4" beadboard pannel is only slightly more expensive than plain old ugly luan plywood, and has much more character to it. BUT... there is a tremendous difference in the LOOK of real (1/2 or 3/4") beadboard and the 1/4" panneling that is supposed to look like beadboard. There is also a huge difference in price. BUT when it comes to esthetics (the look), if you like it, then go for it. The 32 inch span should be good, especially if you're putting 1 x 2 nosing on the shelves. I've built a series of cabinet units for my 'museum of un-natural history'. The first one I built had one slight flaw in it. I did not leave enough height from shelf to shelf, winding up with a snug fit for the three ring binders that were going to be stored in them. The next unit had the extra 1/2". It sure makes a difference! SawdustSteve
Thanks again. I would imagine that real beadboard would look better but this is a budget project, so I'll pick up some of the beadboard paneling. I am only using one sheet of mdf for each case (six 32" pieces of stock for shelves) so that should leave plenty of room for space between shelves on a case near 8' tall. Thanks again.
I cut a 3/8" dado for 3/4 shelves and route both sides of the shelf ends to 3/8". The assembled joint will cover up any flaws in the dado and the joint will look like a perfect fit. This joint also helps prevent glue squeeze out.
You can also just rabbet the shelf ends to 3/8" and join to verticals with the rabbet up to hide any flaws.
Yeah, I've seen something similar to what you are describing before (if I understand you correctly). You are saying that only a portion of the thickness of the shelf gets let into a dado, right? And the rabbet is left up?Too late for me though because earlier today I ordered a 3/4" straight bit from whiteside because I didn't have one. Oh well, still very useful info. Thanks for the help.
Sorry Ryan if you already know this..........If you are going to use latex paint be sure to use a clear top coat like a water based poly. Books and such will stick to latex. If you are going to use oil based paint you will be ok. I learned the hard way! I didn't want to use oil because it yellows. Here is a book case I built recently that incorporated our TV. This was a built-in. I used latex, SW Monarch paint then top coated with poly water based any areas that was going to be in contact with a paper product.
Semper Fi
Jarhead, no I did not know that fact about latex paint. Thanks for mentioning it. I was planning on using an oil based primer and topcoat, just because I've always been told that oil paint dries harder and is more durable over the long haul for things like trim and built-ins. But I did not consider the yellowing issue. Is there anything that I can do to avoid or delay the yellowing? I was planning on using a quality paint like Ben Moore or SW, do you think I will still get yellowing?
since jarhead is elsewhere...
there's nothing to stop yellowing, it's a product of titanium replacing lead in oil based paints since 1978. the only resolve is to use latex. and top coat it, for durability.Expert since 10 am.
jarhead,came across this article in my search for oil based primer.thanks so much for the poly over latex tip! i have some old (valuable) books i was going to put on the shelves with just latex. you saved me!one last question, have you had any issues with oil primer under latex? theres no "special" latex for over oil primer is there?thanks again
I was taught that this is OK. The reverse is a problem.
Put them in the dados and make them tight, glue it with titebond or any decent yellow glue, shoot a couple crown staplers in the side of each shelf put a screw or two if you want. Bondo all your holes, prime and paint. Easy?
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