Beginner Desk Joinery

[Safinn]

So I'm wanting to put myself a desk together but I am a total beginner. I guessing that 18mm plywood should be good to go with for all panels. If you can suggest something else please do! The plan is to have 4 panels, 1 being the table top, 2 being the side panels (legs) on either side of the table top and a support panel under the table top connecting to each side panel.

The best would be around 1500mm in length but the issue is I have no idea what the best method of joining the panels together to have a strong desk that can take plenty of weight.

Please guide me in the right direction. Thanks.

[promhandicam]

Welcome to the forum. 18mm plywood should be ok for what you are proposing but it would be worth going to a timber merchant and buying birch ply, or whatever their best quality one is as a lot of the ply from the likes of B&Q is poor quality with filled knots / holes and voids in the core. Most timber merchants will also cut the panel for you if you work out the sizes in advance. As to joining the bits together, If you have a cordless drill or can borrow one, invest in a kreg k3 pocket hole jig for about £30 and a speed clamp and you should have everything you need.

[Safinn]

Thank you. So that would be a pocket join right? Seems easy enough to start. Is glue not needed for extra strength?

[promhandicam]

Technically I guess the joints would be butt joints, held together with pocket screws. You could glue the edges as well, but the strength will come from the correct design rather than the glue. I'd suggest that what you are calling the support panel or stretcher between the legs also butts up against the underside of the desk top and is screwed up into the top as well as into the 'legs'.

[jake]

Even easier would be screws straight down through the top into the legs. If you were to space, mark and drill the screws accurately, you could either use some smart looking screws (for eg look at spax stainless decking and timber cladding screws, or their washer head screws, etc) or you could counter-bore and hide the screws with contrasting wooden plugs. As long as you are a bit OCD about spacing and so on and spend on the right fixings (or plugs though you might be able to find someone willing to cut you some), this would end up looking very honest in a modernist structural expression way.

Structurally, you need to think about legs splaying inwards or outwards under weight. So anything you can do to brace the legs to stop them doing that is vital - be that simply thicker bigger stronger metal fixings (maybe have a look at some of the really technical timber framing fixings by the likes of Knapp, but I would not be confident with 18mm ply, 25mm seems more likely to survive this to me), brackets to brace the joints, or better still revolving the panel underneath the top 90 degrees backwards so it becomes something which fixes upright between or to the back-side of the legs (doesn't necessarily have to be full height, even 150mm would help prolong life a bit, the more the better though structurally). In an old-fashioned wooden desk the horizontals between the legs running under the drawers did the same structural work.

[Safinn]

Thank you for the advice. I think thicker wood looks better also. Will take a look and hope the pricing is not too much more. Also them spax decking screws look very solid. Which would provide a stonger joint? The pocket screws or going in through the top? Don't mind either but would like a solid, lasting piece.

[will1983]

axminster do a UJK pocket hole set for about £50 which includes two pocket hole guides, the drill bit with stop collar and a box of screws. i got one the other week and its very good. you will need a clamp to hold the guides in place while you drill the holes, i think they are about £16 for the UJK branded one..

[promhandicam]

Even easier would be screws straight down through the top into the legs.

The only problem with this is that if the ply isn't good quality then it will probably delaminate as the screw goes down between the plys. With the pocket holes you are screwing into the face of the board. 25mm ply won't be so bad but for birch ply you'd better be sitting down when the tell you how much it is going to cost

[jake]

Cost of birch ply is true, I don't think the ply would delaminate as long as you pilot drilled.

[Safinn]

So I'm going with BB grade hardwood 25mm plywood already cut to size. I think I'm going to go with screws straight in from the top. Been looking into screws and pilot holes. Looking at these screws here:

Spax single-thread woodscrews 5-x-70mm
http://www.screwfix.com/p/spax-single-t ... -100/55868

Are they good to go with? Also not sure about how to do pilot holes. How deep and wide should it be if I'm using the screws linked? Should it be as deep as the screw (70mm) and how wide? Is there like a cheatsheet or chart that gives recommendations?

Do like the look of these: http://www.screwfix.com/p/spax-t-star-h ... -100/7244f
As @jake suggested but would need to make a counterbore to get flush right which makes it harder for me.

Sorry for all the noob question. Sounds like such a simple task but i'v never done anything like this before and want to get it as best as i can.
Thanks.

[Tomyjoiner]

If your screwing then personally id be using a no 3.5 or a 4 at the most, a no 5 is far too severe to go into the edge of ply even with a pilot.

[Safinn]

If your screwing then personally id be using a no 3.5 or a 4 at the most, a no 5 is far too severe to go into the edge of ply even with a pilot.

Ahh ok. I read that the length of the screw should be around 2-2.5 time the depth of the wood so for me that would be around 50mm-60mm. I can get 4x50mm, 4x60mm or 3.5x50mm. Which is recommended?

[promhandicam]

4 x 70 screw. 4mm hole through the top then 2.5mm pilot as deep as the drill bit will go. Brad point bits would be best.