TotalBeginner: Is the edge grain of plywood still long grain

[Ihaveadream]

Hi Everyone,

I am an absolute beginner to woodworking and hope to make a sturdy 2000mm x 1600mm x 600mm cabinet on casters that will hold heavy equipment.

Short question is:

Is the edge grain of plywood still classed as long grain for gluing purposes.

The reason im asking:

I plan to just use glue and a saw for my cabinet. Im going to try and make mortice and tenons by gluing 4 x 6mm plywood planks together and cutting the two middle planks longer to make the tenon.

These planks will be the 1600mm pieces.

Then cut a section out of the middle two of another 4 planks and gluing them together leaving space for a through tenon in the 2000mm tall piece. Thats how i want to construct the front and back of the cabinet.

But to join the front and back pieces together i wanted to do a half lap joint by leaving the outer two of a 4 plank glue up longer and then gluing the exposed faces to the edge grain of the joint that has the mortice in it. I know if i screw into this i risk separating the ply sheets so im wondering if a glue joint, face to edge grain will hold and be strong enough to hold the front and back together.

Sorry for the extremely long post hopefully you can visualise what I mean.

 

[custard]

You can glue to the edge of ply, it's not quite as strong as true long grain to long grain glued joints...but it's strong enough!

Having said that i think you need to reconsider your plans for using only glue and a saw.

If you're using PVA glue then you need added pressure for optimum strength. You'll also have the problem of locating the components as glue makes things very slippy. You could think about screws or dowels as cost effective options.

If at all possible try making something a bit smaller first, you'll find you pick up all sorts of little tricks the will stand you in good stead for a larger job. Decent quality ply isn't a cheap raw material, so you don't want to waste a load through inexperience.

 

[Ihaveadream]

Thanks for your quick reply and good advice!

I should clarify the glue and saw statement a bit and say that i won't have a workshop full of power tools (tablesaw, router etc).

I own a drill so can screw the planks in place whilst the glue dries or buy clamps but I have watched videos of glue ups and I know what you mean it looks like it could be infuriating for someone with no experience getting everything lined up.

A good thing about the project is it is solely for practical use so looks aren't important. I considered using pocket hole joinery but can't figure out if it would be a rickety mess when I move it.

I think you're right about a smaller project, ive been thinking about a prototype version of this cabinet on a smaller scale to practice.

 

[profchris]

Have I understood - this cabinet is big enough to hold two people standing up? (2m X 1.6m X .6m)

If so, 6mm plywood is barely strong enough to hold it up, let alone putting heavy things inside!

Not sure whether you want 12mm or 18mm, but certainly go thicker.

And if it doesn't have to look pretty, why glue up complex joints? The simplest is a 25 X 25 mm batten screwed and glued along each joint. Or a thicker batten if the contents are really heavy.

 

[Aquachiefofficer]

I was in your position about 2 years ago and I'm impressed by your self-confidence and ambition, but Custard is right. I made ruinously expensive mistakes when starting out. Locals with wood burning stoves were eternally grateful for my endeavours. I also found that glue alone is not a good choice for load-bearing construction - I bought a dowel jig.
It's a steep learning curve. Start small and work up.
Regards, Paul

 

[Ihaveadream]

The 6mm ply would be glued up x 4 so would be 24mm planks once glued!

At first i was just going to glue and screw timber battens together to make the frame and then line it with ply but I read that butt joints are weak enough to break by hand.

And glueing and screwing the battens through the face into the end grain would be the only way i can think of joining the right angles. Unless im missing something obvious.

If there is in easier way to achieve this then id be greatful for your advice.

Confused!

 

[Lazurus]

There are a myriad of hand cut joints and simple jointing aids - pocket hole is a good example, I cant picture what you are trying to make, perhaps a googled image of something similar may assist with suggestions?

 

[Stanleymonkey]

+1 for above

Nothing fancy required - can you draw what you think and snap it with your phone and add the picture as an attachment to your post.

Cabinet sounds huge - any hints on what is going inside?

 

[profchris]

And glueing and screwing the battens through the face into the end grain would be the only way i can think of joining the right angles. Unless im missing something obvious.

By cabinet I thought you had in mind a box with base, sides and top, with a door at the front.

Along every right angle (except the door, obviously!) run a batten (on the inside of the right angle, or if you don't want them seen, recess base, top and back and place them on the outside where they won't be visible). Screw and glue in from both pieces of plywood. Presto! your right angle is joined. Back, top and base hold it all square.

But I'm guessing you have something more complex in mind where this wouldn't work? Some kind of sketch would help a lot.

 

[Ihaveadream]

OK so I'm terrible at sketch up but even worse at drawing.

If you imagine that this is the front of the cabinet frame:

These are the mortise and tenons:

and this is the lap joint that will hold the front and back frames together:

I am thinking of adding another upward support beam in the middle of the 1600mm width beam on each side with another mortice and tenon for support. Then the back, sides and top will be lined with ply and I will figure out how to add doors in the front.

The cabinet will be being wheeled out onto a van for transport and will mostly be carrying instruments and tube amps. It fits in a very specific space in my pokey house and will make moving all the equipment at once so much easier than it is currently. The height will actually be 1850mm rather than 2000mm so as to allow me to wheel it through my front door with a small ramp.

 

[Stanleymonkey]

Cool - thanks for the pictures

Silly question - if you are moving everything at once - can you actually lift, push, steer, shove all that weight plus the wooden box along and up ramps into vans etc.

Not being sarcastic. Just a classic error where you build everything and then discover it weighs a ton! Can it be split into two smaller 1 metre boxes?

 

[Stanleymonkey]

If the equipment is heavy - you will end up making a frame and skinning it with thick material - especially the floor.

Maybe head to B&Q, get some 18mm ply cut accurately to size for free and then big square timbers along the inside to glue and screw the butt joints together. Looking at the 1.2 x 2.4 metre boards will also give you an idea of the scale of your project.

 

[Ihaveadream]

Cheers for your advice Stanleymonkey. I will do this this weekend. I have only just realised that if I secure the battens to the ply all along their length with glue and screws they will be secured all along the length of the ply rather than just the corners. In my head I was thinking that the corner butt joints would be the only thing keeping the thing together.