Replies

1. 
   jim_"crazy_legs"_blodg | Mar 06, 2002 12:58am | #1

   *
   MDF is about 1/2 the cost, takes paint beautifully and is actually stronger than plywood in at least one way.

   Plywood is easier to work with, stands up better to moisture and the edges will take more abuse before denting.

   If you know how to work with wood, you can work with plywood. The same is not true for MDF. There are some special tools and fasteners you'll want to investigate, like confirmat screws, stepped drill bits and dust collection systems for your shop. But I've used it quite a bit the past 2 or 3 years and I'm convinced, it definately has a place in building fine homes.

1. 
   Michael_Rimoldi | Mar 06, 2002 01:04am | #2

   *bobl, I just got done building mine and I used cabinet grade plywood for the carcasses and MDF for the doors. As Jim said, MDF is usable but I had reservations on fastening and strength so I went with the ply. It wasn't cheap as its around $45 a sheet but I'm very satisfied with the results.Mike

1. 
   bobl_ | Mar 06, 2002 01:33am | #3

   *The cabinets will be painted (presently planning Schroeder paints $$$ bought a euro qt for $25) and I have conformat screws with the step drill bit. Been reading up some. having second thoughts, so that's why I ask.Long range plans are addition, but kitchen is circa 1960, so have to do something now.thanks for input

1. 
   Mongo_ | Mar 06, 2002 01:51am | #4

   *I'm not at all "anti-MDF." I agree with others that MDF does have a place in cabinetmaking. I still prefer birch ply for cabinet carcasses. I can close yesterday though...but ended up ordering another stack of birch ply. though the pocketbook took a hit, my back and lungs were greatful.My biggest uses for MDF? I use 3/4" for large paint-grade raised panels for wainscotting. I've used it some for raised panels in doors, but not a whole lot. I use half-inch for the backs of some cabinet carcasses. I run the half-inch through the table saw with a dado blade set on a 45, and plow a "V" groove every 4-5 inches. Gives a bit of insexpensive detail to the back of a cabinet.Adrian has some great ideas for MDF in cabinets, if I recall I think he uses a lot of MDF-core sheet goods. He's probably the most knowledgable one here. He may be able to help you if you need ideas for fasteners that work or don't work in MDF.

1. 
   Jamie_Buxton_ | Mar 06, 2002 03:16am | #5

   *The biggest drawback to MDF is that it is not as stiff as the same thickness of plywood. If you use it for shelves, it may sag under heavy loads. Furthermore, it cold creeps, so that while the initial sag may be acceptable, it'll slowly sag more over time. For vertical panels, of course, this isn't an issue.

2. 
   RonTeti | Mar 06, 2002 06:37am | #6

   *Bob, for paint grade MDF is the bomb but there is some limitations, keep it away from moisture and when you mill it make sure you have good make that great ventilation. I think I read somewhere that the glue used for MDF is phormalihyde(sp) which is definatly not very good for you.

3. 
   Tim_Mooney | Mar 06, 2002 02:40pm | #7

   *I painted 136 work stations in a plant that was all made from mdf. It finishes very easy, minimal sanding,and it saved material [lacquer] over plywoood.Time and materials are probably 40 percent cheaper to paint mdf, as opposed to plywood.

4. 
   Dave_Riggs | Mar 07, 2002 11:11am | #8

   *Sink cabinets are bad for mdf. Even a small leak causes swelling and warping.

5. 
   taylorf | Mar 07, 2002 05:36pm | #9

   *I am making some cabinets for the family room and they will be painted. I was thinking of using MDF for the raised panels instead of gluing up poplar. Will this be ok?Thanks,Forrest

6. 
   Mongo_ | Mar 07, 2002 05:56pm | #10

   *Perfect application.

7. 
   Adrian_Wilson | Mar 07, 2002 11:19pm | #11

   *One of these days, I'm going to convince you.....keep walking towards the light, Mongo.yeah, I think the particle core and MDF core sheetgoods are superior to any plywoods on the market (flatter, more stable, no telegraphing of defects and voids to deal with, better veneers), as long as you design with their shortcomings in mind....everything has some shortcomings. Like being careful around water, and letting raw particleboard reach to the floor, common sense things.For fastners, confirmats or particle board screws, NOT wood screws. Or RTA (ready to assemble) fastners. Butt joints, not dadoes. There is a thread somewhere where I went into a lot more detail on 'why I hate plywood' (my students are trained to exclaim 'it's crap!' at this point).Mongo; that detail you describe for cabinet backs....there are sheets available that have those details already routed....v-grooves or beads...just cut 'em up on the saw and install.The light is this way, Mongo.....just come a little closer....keep walking....

8. 
   Adrian_Wilson | Mar 07, 2002 11:19pm | #12

   *Architects usually spec 1" for shelves....less sag, looks nice and substantial.

9. 
   bobl_ | Mar 07, 2002 11:23pm | #13

   *Already have the confirmats. Have one of your threads bookmarked somewhere, just have to find it (he says shamelessly suckingup)Glue?

10. 
    Don_Papenburg | Mar 08, 2002 04:57am | #14

    *Look out Mongo I think that light is coming from the fast freight rumbling down the track!

11. 
    Adrian_Wilson | Mar 08, 2002 05:19am | #15

    *Generally, my opinion is butt joints are best for most cabinetry (but there are exceptions). Dadoes are great for solid wood....they got 'imported' to cabinetmaking with sheet goods....they are often recomended as a preferred joint with plywood, but I think that's just habit. It's difficult to get a really quality dado joint with the inconsistent thickness of plywood....and it isn't recommended with particlecores. Ply or particlecores, any dado weakens the gable as far as shear strength goes....I can get you the link to an article about it, if you are really interested. And, yeah, I know, when the shelf or whatever gets inserted, it's supposed to strengthen the gable back up, but the gable itself has still been compromised IMO. Depends on the situation if this is a major factor or not.Anyway, bottom line is, I think butt joints with proper fasteners are best for most cabinetry....which means....no glue. And you can prefinish all the parts flat and then assemble, if you want. Inconsistent thickness becomes less important. Most cabinetry is tied into other cabinets, and then into the frame, and often made more rigid with counters also, so you have to look at the big picture.

12. 
    Adrian_Wilson | Mar 08, 2002 05:19am | #16

    *Whatever works.

13. 
    GACC_DAllas | Mar 08, 2002 07:51am | #17

    *Adrian,Got a question. I don't mean to hijack the thread. This is MDF related.We finished a mahogany break front for a client here last December. My supplier was out of veneer core 4x8's so we had to go with MDF core for the case work and shelves. The shelves are WAY too long, about 44" with a 1 1/4" moulded drop edge.The sag, just like I told him they would. Way too long.Will the 1" MDF sag over this span? I'm trying to find the guy a cheaper way to fix his shelves. Solid 1 1/4" mahogany shleves will run about $3000.00. Two layers of veneer plywood (one layer 3/4" and one layer 1/2") is still pretty pricy for the amount of sheves he needs.Got any suggestions?Ed.

14. 
    Robert_Hedlund | Mar 08, 2002 08:04am | #18

    *Fine Homebuilding No. 103, page 101 has a little ditty on shelves and sagging. If anyone out there doesn't have this issue from '96 I can write up some details.

15. 
    diddidit_ | Mar 08, 2002 03:33pm | #19

    *Let me add some info; my noble employer uses MDF extensively for desk work surfaces, and in one case, we use it just painted (powder-coated, actually). Even at 1 1/8" thick, we don't span over 36" without adding steel reinforcements underneath. Adding veneer and backer or laminate and backer stiffens it considerably, but still not as much as a particleboard or flakeboard core of the same thickness. The powder-coated MDF looks fantastic, though.did

16. 
    Bill_Hartmann | Mar 08, 2002 06:11pm | #20

    *EdYou might want to try the Sagulator.http://www.woodbin.com/calcs/sagulator.htmAnd did has one solution. Hide some angle iron behind the drop edge.

17. 
    Adrian_Wilson | Mar 08, 2002 09:48pm | #21

    *That sagulator looks interesting....here's some info I have, from AWI...I'm synthesising here, but it should give you something to go on....these are 'estimated total distributed loads in pounds' (to cause a 1/4" deflection. They have numbers for 8" and 12" shelves. and the nearest spans to your 44" are 42 and 48...I'll use 42", and 12" shelves:medium density particleboard (raw or melamine)3/4"=43 lbs1"=102MDF (raw or melamine)3/4= 541=128birch faced ply, veneer core3/4= 81birch faced particlecore3/4=68partcleboard with p/lam two sides, one edge3/4=96-129, depending on thickness of p/lampartclboard with 1/8 lumber edge3/4=50particleboard with 3/4 lumber edge3/4=63particleboard with 1 1/2" dropped edge3/4= 152There is an equation I could give you, but you need to know things like modulus of elasticity. You'll have to extrapolate some from the above, there aren't values for every material in use in the chart I'm using.Suggestions: maybe add a drop edge front and back....pretty big difference when you add one just to the front, it has to go up a lot if you double it. You could use a thicker, wider drop edge.1" material. Steel, but it's hard to hide angle iron of the size that would do anything. Any or all of the above.

18. 
    Pete_Draganic | Mar 09, 2002 02:12am | #22

    *I have to agree with Jim. MDF is a great product for many applications. I've used it here and there and it has always given better than expected results. It is an excellent choice for any interior trim type work that will be painted because it has no grain or knots to contend with. It has a very crisp and clean, smooth surface.The downside is that it does chip easily on sharp exposed edges and ends, so some softening of them may be a good idea in certain applications. Also, like Jim said, it doesn't take well to moisture. Using it for a cabinet sidewall that'll touch the kitchen floor where mop water and spills may get to it may need some reconsideration or a little ingenuity in application style.Oh yeah, it makes the most dust you've ever seen when being cut... and it isn't like sawdust.... it's more like powder. Looks like cocoa powder and almost smells like it too.Pete

19. 
    Pete_Draganic | Mar 09, 2002 02:20am | #23

    *Replace the drip edge with something more substantial perhaps. It may help to stiffen up your shelves. Glue it and fasten. Although you may get the sag out now, wait till the 700 lbs of books go onto each shelf!Maybe you better just swap them out with some solid wood.... thick solid wood.OR..... remove the edge and customize it to accept some angle iron so that it remains mostly concealed.Just thinking out loud.Pete

20. 
    Pete_Draganic | Mar 09, 2002 02:46am | #24

    *Ed,here's an idea that I drew out in cad.Pete

21. 
    GACC_DAllas | Mar 10, 2002 04:24am | #25

    *Pete,Great idea. I hadn't thought about putting the iron on that way.I'll see if I can sell it to the customer.Thanks,Ed.