1. Great timing I need a bin for the kitchen. Enough Beech leftover from building my bench for the carcass, however I have not been able to locally source any ¼” ply. The nominal 6mm available is actually 5.37mm.
    I am reluctant to cut ¼” grooves and mortices as that would leave up to 1mm gap.
    Any thoughts from the team?
    IoW U.K.

    1. No better than most plywood is, a few days of high humidity will take care of that gap. 🙂

      Seriously though, it seems to me that the plywood panels are simply space fillers, not essential to the structural integrity of the bin. In that case, slightly loose joins won’t compromise the object. It would be like a door with slightly loose panels. You might be able to cause them to rattle, but the door (or bin) won’t fall apart because of it.

      1. I realise they contribute less to the structural integrity of the bin but I dislike the idea of seeing significant gaps. Plywood is a pretty stable material so expecting it to expand by around 20% with humidity or water based glue I think is very optimistic. Perhaps the solution is to grind down a blade for the plough plane to the size of the available panels. Or Heresy use the router table with suitable bit, but that is hardly in the spirit of woodworking masterclass 🙂

    2. That’s a common issue. We call it 1/4″ plywood, but I don’t think I’ve ever found any that is actually 1/4″ and I doubt you will. In the US, 1/4″ plywood is normally 7/32″ nominal thickness and that’s what you have found but it varies depending on the type of plywood you’re looking for. Hardwood will be different from sanded softwood, etc. Some of our 1/4″ is actually slightly over 3/16″. It’s going to be interesting to see how Paul handles the mortises for the plywood tenons. If you look closely at the intro video you can see the slight gap in the grooves but the tenons seem to fit pretty well. I’m sure there is a plan here. FYI, the power tool guys address this by selling undersized cutters that are specifically intended for plywood. You could grind down a cutter for your plow plane if you feel you need to but I don’t think it’s worth it for this. A 3/16″ chisel might be helpful though.

      1. Hi Harry ,
        I had another look at the intro, there are indeed some hairline gaps in the grooves (dado) but the tendons are tight as one would expect from the Master.
        I’ve just read Paul’s blog where he eludes to the inconsistent thickness of ply and the use of an undersized chisel for the mortice. So I look forward watching that stage of the construction.
        For the liner I am looking at using a bespoke bag made from up-cycled Sail cloth which is moisture resistant but washable when soiled.

        1. I haven’t read Paul’s blog yet Geoff, but it stands to reason that he had to do something to account for the variability in plywood thickness. Some of that stuff has a stated tolerance of up to +/- 1mm but even the good stuff is +/- 0.2mm or so. This is the one time that a mortise will have to be fitted to the tenon which is of course backwards to the way it’s normally done. Without a doubt, Paul has a plan. The next episode will be very interesting I think.

    3. For this bin construction I don’t think the plywood plays much role in strength. So I wouldn’t worry much about the gaps of the plywood tenons. As for the gaps between the plywood and the channels, usually a moulding at the back side or even a bead on the front side would close them off. If the gap of your plywood tenon bothers you much, just add a piece of veneer to the plywood tenon to make it tight enough to close off the gap in mortise—although it’s not necessary, I think.

  2. Hey Paul and Co.

    I would really like to see how you sharpen your router blade. I have gotten fairly good a free hand sharpening thanks to your videos but the router isn’t so straight forward. Thanks in advance for any help you may have.

    1. Tom, I was thinking the same thing. I’m curious to see how the construction evolves and learning Paul’s design considerations. The ply tenons seem purely decorative, so I wonder about using decorative inlays that give the appearance of a through tenon and then keeping the ply panel rectangular.

    2. Seems to be a good alternative, particularly since these tenons and mortises supposedly do not add to structural integrity: an assumption I make based on a comment by Mr. P. Sellers

      ‘Personally I would not (ever) use plywood joint areas like dovetails or mortise and tenons but I would and have used a housing dadoes fine.’ (from 7th Oct 2017, 4:35 PM: Blog post “Why Ply Wood”)


    3. You certainly could make it without the plywood tenons. Paul did feel that they add structural integrity. Sven-Olaf, I think that comment is more for ply on ply mortise and tenons, whereas this has ply mortises into solid wood corners where there is also a groove to position the ply.

      1. Thank you Phil for the clarification on structural integrity!

        With European (and US, I believe) tolerances on thickness for sanded Baltic Birch Plywood being ±0.4 mm (±1/64″), could there be a risk for the tenons to be too thin for the use of a chisel with the same width as the groove (1/4″); thus requiring the mortice to be fitted to the tenon, which given the groove to me seems a challenge, particularly if the mortice is to be centred within the groove?


      2. Hi Sven-Olaf
        I think that is certainly worth keeping an eye on and could be a challenge. Grinding a plough plane iron and chisel to width can be an option, but as you mention there may still be variation. I think it is more of an aesthetics issue than a structural one, so up to the individual.
        Best, Phil

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