MDF or Plywood

[etc92guy]

I second what tdubnik wrote. Put together a garage cabinet last summer. Sides were 3/4" mdf 21" x 86". Bottom shelf 3/4" plywood set in 3/8" deep dado with a 1x3 under the back edge. Dadoed edges are glue/with (3) 2 1/2" drywall screws. Shelf has not moved in 6 months
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[a1gutterman]

I am planning to build a few book shelves and also storage cabinets.

Looking for suggestions. Is there several grades of MDF?

I remeber an unfortunate experience five years back with some material I bought at HD and the books were too much weight and cracked the material all the way through.



Dave C.

Hi Dave,
MDF is a grade]http://www.google.com/search?hl=en&rls= ... ision&cd=3[/URL]
MDF (Medium Density Fiberboard)
http://en.wikipedia.org/wiki/Medium-density_fiberboard
HDF (High Density Fiberboard)
http://www.google.com/search?q=High+Density+Fiberboard&rls=com.microsoft:en-us:IE-SearchBox&ie=UTF-8&oe=UTF-8&sourceid=ie7&rlz=1I7ADBF_en
I prefer plywood to any of those other choices. IMHO, it looks better and is stronger. Even so, it wood be wise to follow the advice already posted. I will say that I used to work for a company that used metal/MDF shelving systems. The metal was beefy and supported the shelves across the back and front (knot the ends), and the shelves were made from 1/2" X 24" X 48" sheets of MDF. We put hundreds of pounds of weight on these shelves with never a problem. The only other thing that I wood add is that if you are making an "heirloom" piece of furniture, you may want to consider solid wood shelves. I have seen some very nice "heirloom" book shelves.

[drl]

I don't know where I came across this link but it may be helpful.
http://www.woodbin.com/calcs/sagulator.htm
Regards,
Dwight

[bobgroh]

Adding more detail from that article in Fine Woodworking: adding a 2" support board basically increased the weight carrying capability from (same woods etc as my original email) 21, 17, 14, 13, and 4 lbs to 47, 39, 32, 39 and 30 lbs.

[Gene Howe]

If you move your book shelf unit much. don't use MDF. It weighs close to 100 lbs per 3/4" sheet.

[etc92guy]

Good point, Gene. That explains why I had to "walk" my cabinet from the middle of the garage stall to where I bolted it to the wall.

[Ed in Tampa]

Tim did a fairly good job of defining MDF versus particle board.
Let me add I have found no real good use for particle board.
MDF on the other hand I think is great. I consider using it instead of the junk the Big Boxes call plywood that comes from China.

MDF is heavy and properly coated or used in dry applications is excellent, it is easily cut, can be routed to an almost polished edge and perfect for anything that is going to be painted. Also I really like the look of MDF with a Tung Oil finish, almost leather like.

If you use ply wood find a cabinet shop and find out where they get their ply. There is bound to be a wholesaler some where near you that you can buy cabinet quality ply from, if the local lumber yards don't carry any.

To decide which product to use you must decide what your going to do with it. Furniture quality cabinet, storage cabinet, painted cabinet, heirloom cabinet.

Storage quality I would probably use big box ply.
Painted furniture I would probably use MDF
Furniture quality I would use cabinet grade ply
Heirloom I would solid wood.

[robinson46176]

There are always "variations" in terminology from company to company and area to area. Its pretty common with tool names and apparently in this case to materials.
I see what I would call a low density "particle board" often used in cheap wood cabinets to block off empty space. What I would call a very high density "particle board" is commonly sold and used here in 3/4" as a floor surface on top of 1/2" CDX. There is nothing low density about it. It is extremely heavy and very hard.
In my mind particle board means just that, "particles" (grains, if you will). Fiber means just that, "fibers". Now there is a low density fiber board commonly referred to by builders as "white Celotex" It is even softer than the old black Celotex sheathing, is painted white and used to be used as a ceiling material in cheap houses built in the 1930's to the 1950's. I have used it for dropped ceilings in closets. Otherwise it is pretty useless to me.
What I call a low density particle board is individual particles that you can see, not broken down fibers. It is firm but can be broken easily. It comes all apart if it gets wet much and while it did get used a lot for under-layment I would never put it down.
I don''t consider low density particle board to be a fiberboard. Yes, I know some guys use it interchangably but I don't. It just isn't the same thing. If you walk into most lumber yards and ask for low density fiberboard they will either look at you like a deer into headlights or will lead you to a stack of white Celotex.
There used to be a difference between "wafer board" and "OSB" but I don't know if they even make the old original wafer board of the late 1950's anymore.

Then of course there is Homosote... A whole other class of fiberboard. And a whole family of "hardboards" (Masonite). Back in the really old days there was a product commonly called "beaverboard" and that name was frequently slapped onto a number of products in later years long after the old beaverboard was long gone from the scene.
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I constantly rib my brother-in-laws about their constant reference to any kind of a wood pallet as a "skid". That word is sustained by factory workers and dates mostly back to the 1940's or before and I believe originated with the US Army. Of course several pallet factories make a certain kind of platform that they sell as a skid. One thing that makes pulling their leg about it more fun is that one of my BILs drove a semi delivering for a pallet factory for years. I keep kidding them to show me in any catalog where they can buy a "skid truck". You won't find a "skid factory" in many phone books. If you want to buy a wooden platform to ship goods on you better look under "pallets"... I know it has become common terminology but I still enjoy giving them a rough time about it. We have a good relationship going back 47 years now.

[hudsonmiller]

I've banished MDF from my shop. It's awful stuff made by Satan himself. Use plywood or hardwood.

[beeg]

I've banished MDF from my shop. It's awful stuff made by Satan himself. Use plywood or hardwood.

IF MDF is what I think it is. I DON'T blame ya one bit.