Particle Board Mortise and Tenon

[Mike Prentice]

I am planning on taking a desktop (1 1/4" PB with veneer) and making a credenza out of it. My plan is to rip it in half and take one half and cross cut it for the legs. Instead of attaching the top to the legs I would like to mortise the top to the sides. Any thoughts in doing that? If the top thickness is 1 1/4" how long / deep should I make the mortis/tenon?

I only plan on having a stretcher towards the bottom on the back side and a triangle piece of steel triangle on the back corners.

[Jason Beam]

The only way i'd recommend you do this with particle board is with hardwood floating tenons -- a particle board tenon will be pretty useless if it even holds together long enough for you to get it assembled.

[Von Bickley]

Welcome to the creek.....
I can't help you with your question..... I don't use particle board.

[Rich Riddle]

Mike,

Is this particle board (like OSB) or MDF? You can easily mill/route MDF including a mortise/tenon, but not OSB. I would certainly not use either material as legs. I have seen others do it, but I don't. It gets into the strength of the material and water for me. In regards to the depth of the mortise/tenon, if you don't want a through variety, I typically go 1/2 the depth so in your case 5/8".

http://www.displays2go.com/Guide/Comparing-Building-Materials-Particle-Board-MDF-Plywood-17

[Mike Prentice]

I'm new to doing this type of stuff. The wood is the cabinet grade particle board. I plan on the legs being 30" tall by 17.5 wide.

I know PB is not ideal for some types of projects but I'm just trying to repurpose an old desk top that has veneer that matches other furniture I have.

[John Blazy]

Ive made a ton of low cost furniture using just decorative stone texture melamine - PB core - you just have to use gluing cleats in your joints to expand the glue surface area, and never cut a dado or biscuit, and especially never cut mortice and tenon because the only strength in veneer or melamine faced PB is the actual face material and the outer .090" of the PB core.

So dont cut mortice and tenon at all. Just butt join the legs (or miter) to the top, and add gluing cleats to both sides of the 17" wide leg (if mitering, then cleat the inside corner).

This assumes you use polyurethane glue. No real joint strength using PVA wood glue, because it soaks in, starves the joint from the porosity of the PB core, and shrinks.

Polyurethane like Gorilla or PL Premium construction adhesive is all I use for any porous core sheet products, because it soaks in a bit, then expands during cure, not shrinks. As a bonus, PL Premium nearly welds to melamine surfaces. I know you have veneer face, but try bonding PL to melamine, then break the joint. It will rip the melamine right off, and never fails at the glue line.

Mitering with PUR glue is perfect for porous core material when you tape the miter and fold - see below:
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[John TenEyck]

You have even more options. Lots of European cabinets are made with veneered particle board. I have some that are almost 40 years old and still work fine. Those were made with doweled butt joints. Lots of dowels. No cleats anywhere.

I made my kitchen cabinets out of Melamine, which is a coated particle board. I used butt joints and biscuits with glue for all the boxes, even the drawer boxes. For the cabinet boxes, I added screws between the biscuits where they wouldn't show, but just biscuits and glue on exposed panels. After 20 years not one joint has opened.

I've made other PB cabinets using the ready to assemble approach so that I could assemble them on site because they were too heavy or large to transport. I used Blum's RTA fittings. Some of those cabinets are 25 years old and doing just fine.

As long as the design has inherent rigidity any of the above work fine.

John

[Davis Young]

You might have considered this already, but 1-1/4" is pretty thick for solid particle board. Could this possibly be a hollow core/torsion box? I just don't want you ripping your table top up and getting an understructured surprise.

[Mike Prentice]

You might have considered this already, but 1-1/4" is pretty thick for solid particle board. Could this possibly be a hollow core/torsion box? I just don't want you ripping your table top up and getting an understructured surprise.


I thought so to, but when I ripped it, it was solid. A bank I used to work at years ago had their own cabinet shop, so no expense was sparred!

[Mike Prentice]

Thanks for the ideas. I'm glad I joined the group. I originally thought the top was sold wood but after I ripped it and found out it was PB I was worried about doing a mortise and tenon joint.

[Tom Ewell]

As John mentions, follow the Ikea/Euro mode of fabrication, they've produced engineered/veneered material stuff for eons.

Hardware designed for this type of construction is available at most any online hardware vendor and some locals have caught on.

[Gerry Grzadzinski]

You might have considered this already, but 1-1/4" is pretty thick for solid particle board. Could this possibly be a hollow core/torsion box?


1-1/8" particle board is a standard thickness that's used all the time in office type furniture, for countertops and legs or end panels.
You can get particle board 1-1/2" thick if you want. It's awfully heavy.