Pocket holes and MDF

[fred woltersdorf]

Do pocket hole screws work on MDF? what screws, coarse thread? I'm making a built in and I'm using MDF for the carcasses as this is a paint grade cabinet.

[Bill White]

Pan head or washer head screws. Don't over drive them, and fine threads only. I've used glue with the pocket screws on mdf for added insurance.
Bill

[keith ouellette]

MDf does not hold fasteners very well. I have used my kreg pocket hole jig with mdf and it will work but the bond is not strong like it is foe plywood or wood.

glue helps but remember mdf is saw dust and glue. its not strong and gouges very very easy.

I would use plywood even if you are painting the carcass.

[Jamie Buxton]

Pocket screws don't work well in MDF. The heads pull through the MDF very easily -- either at installation time, or later if the joint is stressed at all.

[Scott Loven]

Kreg recommends washer head coarse thread screws for MDF.
http://www.kregtool.com/products/ka/ScrewChart.pdf
Try it with scrap first. There is also a conformant screw that people recommend that is made for MDF.
Scott

Scott

[Chris Padilla]

Scott confirmed my guess at a decent "pocket hole screw" to use for MDF: washer head and coarse.

A couple of points here:

(1) Do NOT overdrive the screw--put them in by hand or use a very light clutch setting on your drill.

(2) Clamp the two mating pieces together VERY WELL.

(3) Glue the mating pieces...the pocket holes screws will simply be like clamps holding things together while the glue dries. Don't rely on only pocket holes in MDF--they simply won't last.

[Russ Boyd]

I use course thread and like another post said DON'T OVER TIGHTEN. It works fine. Of course it isn't as strong as wood like others said, but it does work. Back it up with glue to make a good bond (both surfaces would work best). I've done plenty without glue too.

[Prashun Patel]

Pocketscrews are good for fastening MDF to wood, but not when MDF is the material you're screwing INTO. It makes a reasonable clamp until the glue dries.

Use a coarse thread.

If you have trouble getting tight joints, try making a counterbore recess on the receiving piece. Since the screws are self drilling, they rely on the wood being able to compress to absorb the removed material. That doesn't happen well with mdf of composite materials which is why you can get mushrooming...

You might consider making the sides of the carcass out of plywood. You can make the top/bottom slats out of mdf. The ply will be better for the carcass, IMHO. I'd reserve the mdf for non-structural uprights, panels, and short spans of shelving.

[Chris Tsutsui]

I hate pocket screws in MDF.

Just remember to be very delicate putting the screw in and PRE-DRILL.

Otherwise the MDF splits like the cardboard it is... :(

I put in a sketch of how it will split.

[Chris Ricker]

These are great answers but, (not to be hijack a thread) do these rules also apply to the "new" plywood which has a mdf type core to it?
I was thinking of building some shop cabinets with this type of ply and Kreg screws.

[Jack Ellis]

An alternative to MDF-core material is A-B Arauco ply. It's made from South American softwood, it's relatively inexpensive, it machines easily, and the good face looks fine for shop cabinets. I'm going to be making 12 linear feet of uppers and 12 linear feet of lowers with it shortly.

In this photo, the carcase for the bottom cabinet and the drawer sides are Arauco (drawer faces are ash). The upper cabinet is all Arauco. (Excuse the mess)

[fred woltersdorf]

An alternative to MDF-core material is A-B Arauco ply. It's made from South American softwood, it's relatively inexpensive, it machines easily, and the good face looks fine for shop cabinets. I'm going to be making 12 linear feet of uppers and 12 linear feet of lowers with it shortly.

In this photo, the carcase for the bottom cabinet and the drawer sides are Arauco (drawer faces are ash). The upper cabinet is all Arauco. (Excuse the mess)

Jack, where did you get this ply and what does a sheet cost? thanks fred.

[Jack Ellis]

I buy it at Lowes. Price is in the low 30s for 3/4 (18 MM) stock. I've also found it at a local lumber yard in Tahoe City, California but have not purchased any there just yet.