Attaching wood to edge of MDF question.

[Mike Monroe]

Here’s my situation... I have 6’ long by 2’ deep base cabinet I’m installing in my shop. The base cabinet came from my wife’s work place; they were going to throw it away. It’s a little beat up, but perfectly fine for a workshop. I wasn’t able to recover the counter top that was originally on the cabinet.

Here’s what I’m doing for a countertop... I took a 4x8 sheet of ¾” mdf and cut it in half length ways, so I have 2 2x8 sheets of mdf. These 2 layers will be the base of the countertop; I’ll top it with 1/8” tempered hardboard. Since the cabinet is 2’ deep, the mdf will end up roughly flush to the front of the cabinet; but I’d like to have a 1 ½” overhang. So I’m planning on permently attaching a 1 ½” x 2” piece of wood to the edge of the mdf. This will give me an overhang, the appearance of a thicker counter top and something solid to attach oak trim to. The replaceable hardboard top would cover the mdf and the wood overhang. I would end up with a 25 ½” deep countertop wrapped with oak.

The question is: What’s the best method for attaching solid wood to the edge of 2 sandwiched layers of ¾” mdf?

I’ve thought of two ways; biscuits and glue, or 1” dowels, drill a 1” hole 1” deep into the edge of mdf sandwich and glue in a 1” section of 1” dowel, then attached the real wood overhang to the wood dowels with screws. The way I see it, biscuit would be easier and quicker, but perhaps not as strong as the dowels. Anyone see any issues with using biscuits?

Thanks for any and all responses.

[Bart Sharp]

Here’s my situation... I have 6’ long by 2’ deep base cabinet I’m installing in my shop. The base cabinet came from my wife’s work place; they were going to throw it away. It’s a little beat up, but perfectly fine for a workshop. I wasn’t able to recover the counter top that was originally on the cabinet.

Here’s what I’m doing for a countertop... I took a 4x8 sheet of ¾” mdf and cut it in half length ways, so I have 2 2x8 sheets of mdf. These 2 layers will be the base of the countertop; I’ll top it with 1/8” tempered hardboard. Since the cabinet is 2’ deep, the mdf will end up roughly flush to the front of the cabinet; but I’d like to have a 1 ½” overhang. So I’m planning on permently attaching a 1 ½” x 2” piece of wood to the edge of the mdf. This will give me an overhang, the appearance of a thicker counter top and something solid to attach oak trim to. The replaceable hardboard top would cover the mdf and the wood overhang. I would end up with a 25 ½” deep countertop wrapped with oak.

The question is: What’s the best method for attaching solid wood to the edge of 2 sandwiched layers of ¾” mdf?

I’ve thought of two ways; biscuits and glue, or 1” dowels, drill a 1” hole 1” deep into the edge of mdf sandwich and glue in a 1” section of 1” dowel, then attached the real wood overhang to the wood dowels with screws. The way I see it, biscuit would be easier and quicker, but perhaps not as strong as the dowels. Anyone see any issues with using biscuits?

Thanks for any and all responses.

I'm not sure I understand what you're getting at with gluing in dowels and then screwing into them, but it sounds complicated. I built a quick and dirty bookcase for my office from MDF with solid cherry edging on the front. The procedure was complex, but let me see if I can explain it:

1. Smear ordinary wood glue on the edge of the MDF and the back of the cherry
2. Put them together and apply clamps
3. Wait 20 minutes and remove clamps
4. Repeat (I only had two clamps at the time)

It worked great and looks nice!

[Allen Bookout]

I think that ordinary wood glue with no biscuits or dowels would be plenty good. Whenever I am in doubt I always use two part epoxy for glue. I just finished a router table and covered the edges of two 3/4 mdf sheets glued togeather and use epoxy. Will never come apart---ever. If you used epoxy and biscuits you could use it for a bomb shelter. Allen

[Larry Browning]

Glue, biscuits and clamps. The glue will be plenty strong to hold the edging, the biscuits are just used for alignment. Don't overthink this, just "Get er done!"

Larry

[Michael Ballent]

I would avoid the dowels like I would avoid the bird flu ;) If you decide to go the biscuits it will be mostly there to help you in aligning the edging to he MDF. The other option would be to use pocket screws :D Quick and dirty and no clamps needed :)


I think that ordinary wood glue with no biscuits or dowels would be plenty good. Whenever I am in doubt I always use two part epoxy for glue. I just finished a router table and covered the edges of two 3/4 mdf sheets glued togeather and use epoxy. Will never come apart---ever. If you used epoxy and biscuits you could use it for a bomb shelter. Allen

[Mike Monroe]

Bart,

Thank you so very much for such an insightful post. But your stunningly complex bookcase application just doesn't meet the requirements for a countertop.

A workshop countertop will be subject to stresses that a bookcase simply does not experience. A countertop is a work surface, a bookcase just sits there. A countertop in a workshop will have things clamped to it and be pounded on by large implements of destruction; not to mention the large people that might lean or sit on the edge of the countertop. The majority of these abuses will be directed at the edge of the countertop, thus I do not believe that glue alone will provide sufficient holding power. I'm of the mind that additional mechanical re-enforcement is needed to withstand said pounding and clamping and sitting. To that end I was hopeful someone on this forum might have a relevant solution.

Again, thanks for the reply, I'll keep it in mind the next time I make a bookcase out of MDF.

-Mike

[Per Swenson]

Mike,

I second the motion,

No need for biscuits or dowels.

Just lots of clamps and glue.

When you glue your edging it is much easier to cut it oversize,

glue it proud to the counter top and then router and straight

bit with bearing, trim the edge flush.

Hope this helps.

Per

[Bob Winkler]

Seems like a lot of people are on edge these days.

I also think that glue alone would be adequate. Modern glues are amazing. But like you, sometimes I want a mechanical fastener as a redundant support. In your case, I would consider pocket screws through the work top from the underside. Quick and effective, and won't show.

Hope you consider this relevant.:D
Bob

[Doug Jones from Oregon]

Wow...I get to disagree with a bunch of folks on this one.

MDF is about as unstable an edge as you can get, short of possibly Particle board.

Any mechanical fastening that you do into the edge is likely to seperate the fibres of the MDF itself as you apply pressure, ie pounding on a project, clamping fixtures to it.....

I would look at possibly making this "extension" on the backside so that it would not take a beating, and then just a very thin trim on the front applied with just glue.

Just another man's thoughts!

Doug

[Bart Sharp]

Bart,

A countertop is a work surface, a bookcase just sits there. A countertop in a workshop will have things clamped to it and be pounded on by large implements of destruction; not to mention the large people that might lean or sit on the edge of the countertop. The majority of these abuses will be directed at the edge of the countertop, thus I do not believe that glue alone will provide sufficient holding power.

-Mike

If that's what you think then you, sir, have never seen me use a bookcase! :D I've always been taught that a glue joint is stronger than the wood it's holding together. That would imply that if you're beating it hard enough to bust the glue line (ignoring the potentially important difference between shearing forces versus tensile forces), then you're beating it hard enough to bust the MDF. That may be an old wive's tale (not to offend any married women of a certain age), but I'm willing to buy in.

BTW, you're welcome to get snippy with everyone else who gave you the same advice as I did, but I wouldn't recommend it. They're mostly regulars, I'm just a frequent lurker.

[Steve Clardy]

No snipy stuff from me. Lol
I would just preglue the mdf only. In other words, just a film of glue on the mdf edge. Let dry, slightly sand. This fills the mdf edge.
Then glue on the edging, clamp it up.
Biscuits will help with alignment, but not necessary.

[Andy Hoyt]

Good thing mdf is cheap. Throw it out or use it for something else.

Get a sheet of 3/4 cdx and start over. Glue the snot out of it, shoot some long finish nails into it, lay in the hardboard cover sand flush. Have a martini.

[Allen Bookout]

Mike,

Sounds like that you may be barking up the wrong tree for the abuse that your table top is going to take. I made a welding table out of angle iron and quarter inch steel sheet metal. You can bang on it all day long with your sledge hammer and not do any damage. It was not as expensive as you might think, especially if you can weld. I use an old arc welder but with the new mig welders it is a piece of cake. I used the table a lot. Metal may be the way to go for you.

Allen

[Mike Monroe]

BTW, you're welcome to get snippy with everyone else who gave you the same advice as I did, but I wouldn't recommend it. They're mostly regulars, I'm just a frequent lurker.

Snippy?? Me snippy??? I've been called a lot of things, but never snippy... maybe snipey would be better. :D

[Mike Monroe]

Many thanks to everyone that replied. I think I'll go with Steve Cardys suggestion, plus the biscuits. I'll try to post pictures of what I did for the sake posterity.

-Snipey

[Andrew Ault]

Mike (and Steve),

What glue would you use? I think that many glues will not bond to themselves as well as they do to wood.

Bob Smalser wrote about this a while back:

http://www.sawmillcreek.org/showthread.php?t=21822

Just curious.

- Andy

[Steve Clardy]

I use titebond original on about everything except my pancakes.