# Joining MDF



## CoolDavion (Dec 6, 2007)

At my wife's request I've got an MDF project coming up.

In looking on line, I've found a mryid of answers to the question:

What works the best for joining / connecting MDF? Screws, biscuts what?

Basicaly I'll be making several large boxes. 
I read that you need to prdrill and fill when using screws.
I'm thinking that biscuts would be the way to[new tool  ].

What works best in your experence.


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## gwurst (Nov 28, 2007)

You can get-by with standard coarse-thread woodscrews, but you really need to pre-drill the holes fairly close to the thread diameter since MDF does not give and tends to split. I haven't tried biscuits with MDF, but I don't see why it wouldn't work off the top of my head. They do make specific connectors for MDF and particle board:

http://www.mcfeelys.com/product/7050-CSP/7mm-x-50mm-Connecting-Screw


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## PurpLev (May 30, 2008)

MDF is particles- so there are no grains for screws to 'latch on to' much, you should use Confirmat screws that have a thicker rod, and a coarser threading.

I wouldn't think biscuits would work too well with MDF as the edges tend to split, and chatter and dont have much strength to them - but if you do choose that route - I'm sure many (me included) would be interested to hear as to how it went, and how the MDF held on to that?

PS. isn't MDS a serious health hazzard material based on it's very fine and cancerous sawdust? just curious… I usually tend to stay off from working with this material, but there seem to be plenty of people that like it.


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## EEngineer (Jul 4, 2008)

I just started working with MDF. Basically, I just made 3 drawers for a tool stand. But I can tell you what doesn't work.

First off, I don't like MDF; it splits way too easy, no where near as rugged as solid wood or even plywood. I dadoed the drawers just like I have a dozen times with plywood and managed to split the MDF in a number of places. On successful dadoes, I glued and then nailed brads to hold until the glue dried. Even the smallest brads split the MDF. If I ever use MDF again, I will make the dadoes slightly wider (a pain since I just used standard 1/2" router bits before) and pre-drill any brad holes before nailing. I strongly suspect that slots for biscuits would have to be widened, too; part of the reason biscuits work so well is that they swell under the influence of the moisture in the glue. This is almost certain to split MDF.


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## dennis (Aug 3, 2006)

I love MDF. I guess it just has it's uses. I probably would not turn it on a lathe. Wouldn't use it for a face frame or table legs. Side walls, shelves, corbels that are getting "painted" great. I use screws and biscuits with no problems. I'm not a fan of nailing it. If I used it every day i might be worried about the health risk, but 1 or 2 projects a year won't kill me.


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## FatherHooligan (Mar 27, 2008)

I've just made the one project with MDF, the Thomas the Tank Engine table that I've just about completed and I used glue to adhere the mdf table top to the frame. I am going to try and make some boxes out of it and I am leaning toward gluing these as well. Maybe its LJs new sponsor 'Gorilla glue', but I like gluing stuff.


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## wilsonsk (Feb 12, 2008)

Confirmant screws are definitely the way to go. I have had virtually no cracking/splitting with them. Confirmant screws coupled with glue make a pretty strong joint. But MDF does throw off A LOT of fine sawdust so take precautions when cutting or routing, especially in a closed shop (dust mask, dust collection, etc).


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## joey (Sep 17, 2007)

MDF isn't that hard to work with just watch out driving screws to close to the edge it can cause the board to split. I always countersink the underside of the hole to keep the joint flat when you screw it together. use low speed on your drill or a low clutch setting to keep the screw from stripping out which it will do easily in MDF even with course threads. bondo, or auto body filler makes a great filler if you have a blow out or to fill a seam. be careful sanding because it will flash and show spots that you sanded if you paint the piece. I always prime painted pieces with auto primer you can get a really nice paint job that way. hope some of this helps
Joey
http://sleepydogwoodworking.blogspot.com/


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## motthunter (Dec 31, 2007)

the stuff glues great with Titebond. MDF is basically glue and dust… some screws and glue and you are good.


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## jcash3 (Dec 15, 2007)

check out my kithen cabinets under my projects, all the doors and drawers are mdf. raised panel, glued cope and stick joints, the hinges are blum and are screwed in. i predrilled and have not had any trouble with them. MDF is harder on blades and router bits, but offsets the price. it's inexpensive, works easily, sands good and takes paint great. it's like anyting else, you have to learn the tricks to working with it.


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## CoolDavion (Dec 6, 2007)

Thanks all.

We are redoing my 9 year old daughter's bedroom as her birthday persent in a "more grown up style", and the reason for MDF is in case she wants to re-paint it in a few years. The idea is a fairly large wall unit desk/dresser/book case combo so cost of wood is a big factor. Also I'm not up to fine woodworking status yet and do not want to ruin alot of nice wood.

I've read alot the dust, I plan to do most of the cutting outside if possible, and have wear the respieratior.

I found a few hints about having a screw block of real wood if possible, and there are a couple places where I think I'll be adding them for extra support.

Joey - if you hadn't had said anything I would not have thought that was MDF cabinets.

I've already gotten a edge guide out of this project, and i do believe that a Kreg pocket hole jig will be necessary, so some additions to the tool collection.

Also I plan on getting one of the small "project boards" of MDF at HD to to something small to get my feet wet this weekend if possible.


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## SenatorCletusScoffpossum (Jul 18, 2008)

I have had pretty good luck with pocket screws and lots of glue. The pocket screw drill bit seems to create enough of a hole to prevent the end from splitting apart; that is assuming that you don't over tighten the screws, which is quite easy to do. I use the pine plugs to plug the pocket holes and then paint the whole piece. Seems to work pretty good so far, though I have my doubts as to whether it would stand up to heavy abuse.


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## Grumpy (Nov 9, 2007)

There are screws especially designed for MDF, should be available at any decent hardware store. biscuits are great for strength & alignment.


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## Frank (Nov 19, 2006)

Back in the days when I used to do a lot of kitchen, den//library and living room remodels….if a customer wanted painted cabinets or bookcases, MDF was the way to go. My favorite and most succesful tried and true method was screws and biscuits, matter of fact one today can still not beat those biscuits for strength and durability, plus no-returns.

....also Grumpy brings forth a great point above about 'alignment'.

Thank you.
GODSPEED,
Frank


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## edp (Jul 23, 2007)

I use (TiteBond II) glue and screws on MDF regularly. I also dado wherever I can for shelves and bottoms/tops. The dados generate a lot of mechanical strength when cut properly. The screws I use are the promax from mcfeeleys.com. They have small nibs under the heads which will countersink their own hole as they go in and the saw style thread pattern doesn't split the material when using them on edges. For attaching face frames, Kreg all the way using the coarse thread screws and low torque. Any shelves over about 18" will require a solid wood front edge to prevent bowing which doesn't take long to show up. Here, I typically use a shallow rabbet on the back of the edging and pocket screws to hold it together until the glue cures. Like Joey says above, MDF is great for door components. It machines well and holds a crisp edge. Rail & Stile joints glue up well and the raised panels are very realistic after being painted. Remember that the paint will look better after the parts have been primed and sanded. The primer will seal the pores on the machined areas so they more closely resemble the paper coated surface of the unmachined surfaces and cause a more uniform paint film. Make sure that any tall work fabricated from MDF is securely attached to the wall because it is very heavy.

Ed


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## sIKE (Feb 14, 2008)

If you need to screw through the edge I have found it be to bore a 1/4" hole the length of the screw I want to use and then glue a 1/4" dowel into the hole and let dry, you now have wood to screw into.


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## Mattias (Jan 27, 2008)

I would never screw mdf together.What I use are rastex fittings and wooden dowels so I always can disassemble the furniture I make from mdf. I know, It's a lot of work but at the end I'm always happy I use those things.
You can see some projects from me by my projects, but I first have to upload them.

Mattias.


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