Thread: Mdf Drawers

G'day Squirrel.
Mdf has a queer habit when you screw into the side of it (like end grain in real wood) that it expands by roughly the diameter of the screw you put into it.
There is a way out of this problem by drilling a hole smaller in diameter than the screw thread, but longer thaan the screw thread, and then using screws with no taper.
Straight buggers..like gypsum screws.
Dunno if this helps, and I shouldn't post after 9PM
Regards,
Noel

A simple butt joint with battons(increase glue area) and lots of pva glue, no screws needed just a brad gun.

Ply is a much better choice for drawers.
MDF particularly thin MDF has a habit of bowing and stretching when supported round its edge.
Not good for spanning gaps.

You need to use much thicker material than you would with ply or even chip board.

I have some storage shelves sheeted in MDF supported arround the perimiter, they have sagged consiiderably.

MDF is a great material but it isn't very strong.

cheers

Oh

The strongest joints in MDF are rebated and glued.

If you want to screw into edge grain of MDF or chip board you want "director screws" which are a weirdo screw designed for the purpose.
They have a deep paralell thread and a paralell shank ner the head.
You drill a steped hole. They hang on like buggery.

cheers

Thanks guys,

It was only after I bought the material that I realised it was going to be a problem. I only bought it because the one I was copying had MDF drawers.

I like the idea of the battons and if the screws blow out the material I will use a brad gun.

Regards
Squirrel

Hi All,

I just built a new computer desk and drawers out of mdf. Frame for Drawers were 18mm the carcass were made out of 18mm(fronts) and 12mm Sides and backs. Instead of screwing them together I used lots of glue and biscuit joints.

All worked very well.

Cheers

Michael.

I have a biscuiter, might just over engineer these suckers and throw in a couple of biscuites as well.

Squirrel

The drawers in one of my workbenches are MDF.
The sides are 19mm with a 12mm base.
They are 900 X 500
They are screwed butt joints and the bottom sits in a rebate.
One of the drawers holds about 20 planes, and another is full of screws, bolts, nails etc.
They have no sag
I pre drill all screw holes and use particleboard screws, never had a problem

Cheers, Jack

My oldest set of MDF drawers are on my 5 year old computer desk.
The drawers are in excellent shape, no sagging and still slide in-out very smoothly on simple candle waxed "jarrah on jarrah" runners.
They are 450 mm wide x 600 mm (yes, 600!) deep and between 150 - 300 mm high.
The drawer bodies made of 15 mm thick MDF held together with particle board screws in predrilled holes and glue. The bottoms are 3mm MDF rebated into the bottoms and held in place by the waxed jarrah runner. No battons, just butt joints.
Each drawer has a front face of 19mm thick polished jarrah floor board screwed to it.
They are full of the usual office crap, pencils, paper, envelopes, manila files, tools, ancient computer cables and peripherals, and I think there are still some half eaten packets of biscuits and potato chips in there somewhere.

My take on this:

Make the drawer bottoms the full width & length out of thick-ish MDF, then fix the sides and ends to this platform. Use an 'overlay' drawer front glued/screwed or bolted on with the drawer handles to the front of the drawer.

If worried about the MDF 'blowing out' due to screws, just make sure that the sides overlap the front and rear, then glue & drill right thru' the sides, then glue some old bamboo chopsticks into the holes & cut off flush (I save all the 'throw away' bamboo chopsticks that I get when eating out) - this is what the Japapnese did with 'Tansu' chests, and they are still hanging together a hunderd or so years later. OK, you could use thin dowel pins, but throw away chopsticks are free

If worried about the bottoms wearing or not sliding smoothly, then rebat some hardwood runners underneath, very much like the 'Enco' drawers beloved of some high end furniture makers in FWW.

Thanks again for the great response, at first I felt like a bit of a dork with this type of question.

Final plan of attack is, 12mm front, back & sides, 6mm bottom (all MDF).

Joints will be glued and screwed with pre-drilled holes.

Front will be 17-18mm ply with edges dresses.

This should last a couple of years (5 I hope) by this time the young tyke will be close to teen years and will probably want a change.

Thanks again and will definitely post some pictures when finished.

Squirrel

You are not a 'dork' for asking a reasonable question, specially in a place set up for people to ask questions & discuss things.

I get far more peeved at 'experts' who answer questions with something like 'Oh yes, I answered that question 20 years ago, go find it' - this was very common with magazines trying to shift their back issues, even if the issue was long out of print. Compterised search facilities are still very flakey - I often can't find something that I have read a few weeks ago.

I've made a lot of drawers out of MDF, including melamine covered, and went throught the anxst that you are now experiencing. I found that the best way is to ensure that the joints are unloaded, ie no stress across the joint.
The easiest way is to make the 4 sides of the drawer and joint them any way you want (I now just butt join (glue) and screw) and then fit metal drawer slides of the type that fit under the sides and make sure that they fit under the full length of the drawer. In this way the drawer slide takes the load and supports the side joints and base.
Can post pics tonight if needed
Fletty

PS; BSR, what were you doing up at 12.23am??