Oversized plywood sheet for a corner desk

[Fanous]

Hello dustmakers,

I'd like to brainstorm best way forward for getting my desk top board sorted for a corner desk.

Here is the rough design - wanted thick plywood, 20-30mm thick ish, and either buy veneered, or veneer it later. That's a minor detail. Some leg system, probably castle joints, with screws, so I can dismatle and assemble per needs.

My question is how to best get this plywood top sorted. Problem is the dimensions are larger than standard sheet of ply. Namely 170x170cm max dimensions, and 70cm for depth of each wing.

Idea 1) 6mm ply, and buld it up in 4 layers.
Layer 1 and 3:

Layer 2 and 4:

I think that' mechanically sound, can cut out of standard size sheets, and glue it up. Challenge here is having good flat surface to do it on, and have even clamping forces, to end up with a flat table.

Idea 2) Find out a company that stocks Jumbo plywood - found some online in roughly 3.5x1.5m dimensions. So still a bit short on the final dimensions, but perhaps missus would get on board (pun not intended).
This will be a challenge to ship, probably costly too. Some company might do CNC to dimensions, which would help a lot. It seems difficult to fins something of good quality (birch or marine ply) and thick enough (I'd say 18mm not enough. Would be happy with 24mm or thereabouts)

Idea 3) butt-joint - least favourite optoin to me, just don't know I can trust the glue to that extend, without some reinforcing, perhapr flat finger joint, bow ties, large domino and such. This joint just screams I'm going to break.

I'd be happy to hear your thoughts and ideas for all points above. Many thanks.

 

[profchris]

It seems to me you'll want some reinforcement under the joint, as you have no leg on the internal corner.

If so, that would keep the two edges of a butt joint aligned.

I suspect those who know tables will suggest some kind of frame and maybe thinner ply, so hold on for more expert views.

 

[Fanous]

Thanks Chris, just for sake of completness, here is the view from beneath:

Yes I didn't put a leg in the corner. Don't want missus kicking it with her toe, as whe rotates on chair from one wing to the other.

 

[Sachakins]

Have you considered using 2 solid wood 38mm or 43mm worktops, butt jointed with worktop bolts to keep joint aligned and secure?

 

[Hornbeam]

If you are going to veneer it later it is extremely likely that the joint will telegraph through. If you went with your option 1 you could do the outer sheets with a mitre internal to external corner and then veneer to that pattern as well
I would also consider some rails at the front to prevent sag

 

[ChaiLatte]

Idea 1) 6mm ply, and buld it up in 4 layers.

Just to throw another complicating factor into your calculations, standard plywood is made from an odd number of layers, so is stiffer in one direction than in the other. Hence you may be able to play with the orientation of each piece of each layer to achieve optimum results.

Whatever the trim piece is on the front, if you can rebate that and inset a piece of metal, it will stiffen it up a lot.

 

[Jacob]

Make it as one normal 4 legged table with a 2 leg extension joined on. Or a drop down flap extension.

 

[Sachakins]

Try here
https://www.wood-cut-to-size.co.uk/index.php?id_product=66&controller=product

 

[Fanous]

Have you considered using 2 solid wood 38mm or 43mm worktops, butt jointed with worktop bolts to keep joint aligned and secure?

I have not - I quite like that idea

 

[TheUnicorn]

As per sachakins, I'd joint the top like a kitchen worktop, however I still think you need some additional structure below to prevent sag

 

[Fitzroy]

I built this earlier in the year, it’s 1800mm on each long side, and 32mm thick. There is a long mortice and tenon (correct term?) along the edge between the two pieces, which is 13mm x 13mm, and has bed bolts to pull together. The frame has no rail on the front edge as I did not want anything that interferes with the users knees. The top is buttoned to the frame, there is no sag.

Fitz

 

[Richard_C]

That's nice, beyond the skills of many (including me).

Back to the original questions. When I started to work from home 25 years ago I needed a similar L shaped workplace. I hade a very tight budget and it didn't need to be moved so I didn't build a frame. Softwood batterns on the wall supported the far sides. Rather than legs I bought 2 slim budget price under desk units, one with drawers, one a side-on filing cabinet. Both were modified (wheels pulled off, and a simple plinth underneath to raise them to the exact height I needed. Top was MDF (sorry all, money was tight), 2 pieces butt jointed with a slim strip underneath ending short of the front edge so it wasn't seen. Staained and varnished. Gravity held it in place on the battens/cabinets. It wasn't 'precious' so I could drill cable holes where they were needed. I had thought carefully about how it would be used, back then you needed printer/scanner and fax machine. The fax machine was parked in the corner so the joint was just about invisible .

It served me well for over 15 years then as technology changed and we needed less space I threw it all out and got a nice old (100 year perhaps) desk instead. I can see that the OP is 'aiming higher' but a big L shaped desk is unlikely to fit in any other location so why not use the wall if you can?

Main thing is to sit and contemplate how it will actually be used in everyday real life. We all differ. Often the short 'L' is never worked at, its just a place for kit, stuff and things so an additional leg might not be an issue.

 

[Fitzroy]

That's nice, beyond the skills of many (including me).

Back to the original questions. When I started to work from home 25 years ago I needed a similar L shaped workplace. I hade a very tight budget and it didn't need to be moved so I didn't build a frame. Softwood batterns on the wall supported the far sides. Rather than legs I bought 2 slim budget price under desk units, one with drawers, one a side-on filing cabinet. Both were modified (wheels pulled off, and a simple plinth underneath to raise them to the exact height I needed. Top was MDF (sorry all, money was tight), 2 pieces butt jointed with a slim strip underneath ending short of the front edge so it wasn't seen. Staained and varnished. Gravity held it in place on the battens/cabinets. It wasn't 'precious' so I could drill cable holes where they were needed. I had thought carefully about how it would be used, back then you needed printer/scanner and fax machine. The fax machine was parked in the corner so the joint was just about invisible .

It served me well for over 15 years then as technology changed and we needed less space I threw it all out and got a nice old (100 year perhaps) desk instead. I can see that the OP is 'aiming higher' but a big L shaped desk is unlikely to fit in any other location so why not use the wall if you can?

Main thing is to sit and contemplate how it will actually be used in everyday real life. We all differ. Often the short 'L' is never worked at, its just a place for kit, stuff and things so an additional leg might not be an issue.

It is a huge thing, it was a 50th present for my brother and his office at his company so he had the space. Making it took every inch of my 3mx6m workshop.

As you said if it’s going to end up in a specific corner for its whole life then can you use the same walls for structure?

Nothing wrong with MDF use, although it can be a bit droopy overtime of not supported.

 

[Samkilby]

If I was making it I would be looking at incorporating a front rail (or mid/front ?) of some variety. Possibly it would be annoying but it will last.. and I’m sure there is some way to design around it.
If not an option two bits of 24mm birch with large floating tenons and worktop joiner bolts might do the trick, but I would probably still want some underside supports

 

[Fanous]

Thanks All for contributions, much appreciated.

I took the suggestion from Sachakins, which then later got reinforced by Fitz - going to use kitchen top (3m x 720mm x 40mm oak), cut to size, most likely a butt-joint, if I can borrow the router jig for it, and figure out how to use it. If not, not really feeling like buying the jig for one-off, so could do a large miter with a track saw. I think using the largest domino I have in the box (10mm?) for alignment and reinforcement, and actually glue it. Should be able to make it through doors, with only 170cm length. Would you guys still add the mechanical machine screws on the butt (maybe miter) joint if it's glued with TB3?

Still want to skip the front rails (where the knees will be) - can't really see the 40mm oak sagging..? Will have the rails elsewhere mainly for the legs to have some support, and stay 90deg to the top.

Appreciare further thoughts, if the above has some things to consider (still)

 

[Samkilby]

If you do a butt joint you definitely don’t want to glue it, thinking about the directions of seasonal timber movement. In that instance the dominoes if they are what you are using would also want to be dry, and at least one side on loose setting. You could (for example) glue the back or the front domino as a reference point and everything would expand and contract from that point. You would use he dominoes for alignment and a bit of joint strength, and the worktop bolts to pull together. You could use a bought jig, you could make a jig, or you could use a forstner bit and a tenon saw for the worktop bolts.
You could also do a mitre, but I wouldn’t necessarily choose to.. often mitres are used to avoid exposed end grain, and aren’t particularly strong joints as they offer poor glueing opportunities (end grain to end grain) is not like a standard block kitchen worktop is going to have a really continuous grain as the blocks are all so short anyway, so I don’t see any benefit to a mitre.
You might also mean a masons mitre as you have mentioned worktop jigs, but I wouldn’t do that with solid.. generally used on laminate worktops.
As I said before, I would definitely be going with a rail. People get by with rails or even drawers on dining tables, or used to have those funny little keyboard pull outs on desks. I would be happy enough with no front rail if there wasn’t the problematic joint on the end. If it had to be no rail, I would probably do a sliding dovetail, which can be quite labour intensive for what I would argue could be avoided.

 

[BarbaraT]

What about using worktop bolts?
The router jig works really well, if you want to laminate sheets, I've done so in a big vacuum bag. Made from some clear plastic sheeting.

Unika Toggle Bolt 3 Pack for Compact Laminate Worktops https://amzn.eu/d/3WoKqxt

 

[Fanous]

If you do a butt joint you definitely don’t want to glue it, thinking about the directions of seasonal timber movement. In that instance the dominoes if they are what you are using would also want to be dry, and at least one side on loose setting. You could (for example) glue the back or the front domino as a reference point and everything would expand and contract from that point. You would use he dominoes for alignment and a bit of joint strength, and the worktop bolts to pull together. You could use a bought jig, you could make a jig, or you could use a forstner bit and a tenon saw for the worktop bolts.
You could also do a mitre, but I wouldn’t necessarily choose to.. often mitres are used to avoid exposed end grain, and aren’t particularly strong joints as they offer poor glueing opportunities (end grain to end grain) is not like a standard block kitchen worktop is going to have a really continuous grain as the blocks are all so short anyway, so I don’t see any benefit to a mitre.
You might also mean a masons mitre as you have mentioned worktop jigs, but I wouldn’t do that with solid.. generally used on laminate worktops.
As I said before, I would definitely be going with a rail. People get by with rails or even drawers on dining tables, or used to have those funny little keyboard pull outs on desks. I would be happy enough with no front rail if there wasn’t the problematic joint on the end. If it had to be no rail, I would probably do a sliding dovetail, which can be quite labour intensive for what I would argue could be avoided.

Lots of great points here, thanks very much. With the grain direction difference, glue is indeed a bad call. I could however cut the top in a way so it runs the same direction. Unsure if I should, something I need to think about, but probably not. At that point I would think the table would be weak (snap along the grain, if unsupported by rail in full.

One side loose domino not a problem. Will implement for alignment. Will make the very first one (from the corner) tight, so the corner stays as reference, since it will be noticable, if seasonal movement is allowed there.

Masons mitre - yes I was thinking to use that jig - another good call, the seasonal movement would mess it up. Would I want to do what Fitz did on the pics above, and have a little glue on addition to the board, which would then hold a straight plane butt joint? Trying to think of an advantage here over not doing so.

I'm considering adding a leg (close to a wall) under the butt joint. That way the bigger top would be supported on all 4 corners, and the add on wing would have it's own 2 legs. Perhaps that's robust enough to allow missing rails..?

 

[Fanous]

What about using worktop bolts?
The router jig works really well, if you want to laminate sheets, I've done so in a big vacuum bag. Made from some clear plastic sheeting.

Unika Toggle Bolt 3 Pack for Compact Laminate Worktops https://amzn.eu/d/3WoKqxt

I like those, fairly cheap too, should be simple to implement, to replace the glue. Thanks!

 

[Sachakins]

You can also get surface mounted worktop bolts, although I've never used them myself.

HARDWARE FOR YOU EASY FIT KITCHEN WORKTOP CONNECTING BOLTS (2) https://amzn.eu/d/3gTfVjf