Smarter-than-wood Saw Blade Makes Perfect Foldable Joints

[Andrew Klein] knows the pain of building drawers from plywood. It can be a pain to get all of the pieces measured and cut just right. Then you have to line them up, glue them together, and clamp them perfectly. It’s time-consuming and frustrating. Then one day it hit him that he might be able to make the whole process much easier using a custom saw blade.

The the video below, [Andrew] does a great job explaining how the concept works using a piece of paper. The trick is that the plywood must be cut in a very specific shape. This shape results in the plywood just barely being held together, almost as if it’s hinged. The resulting groove can then be filled with wood glue, and the plywood is folded over on itself. This folding process leaves no gaps in the wood and results in a strong joint. Luckily this special shape can be cut with a specialized saw blade.

This new process removes the requirement of having five separate pieces for a drawer. Instead, only four cuts are needed on a single piece of square plywood. The corners are then removed with a razor blade and all four sides are folded up and into place. [Andrew] shows that his prototype blade needs a little bit of work, but he’s so hopeful that this new invention will be useful to others.

51 thoughts on “Smarter-than-wood Saw Blade Makes Perfect Foldable Joints

    1. This is exactly how cheap flat-pack furniture drawers are made, except from particle board.

      They take a long sliver of board with pre-made slots for the bottom and the rails, coated with a vinyl. Then they cut two grooves at the corners right up to the vinyl coating and drill a couple holes for the screws. When you assemble it, you fold the corners, slot the bottom in and screw in the face board and handle.

  1. Seems well thought out.
    The only drawback I see is it’s a $30 (assuming mid range mass produced saw blade) purchase on top of an already $100 dado stack investment.

      1. I was trying to give it a competative price. Even the most expensive 10″ blades tend to be under $75 (there are a few $100 blades). And that’s with fancy coatings on top of specialty tooth geometry. This blade’s teeth seem pretty coarsely spaced aside from the angled carbide profile not terribly difficult to make. So a more realistic price is probably around $60 without the dado stack.

        It is a specialty blade but there are plenty of people out there who would rather buy tools than build skills. Wood working isn’t their hobby it’s just a step that needs to get done.

        1. Not one blade I run on my table saw or mitre saw is less than a $100. Hell some of my 7 and a quarter blades are close to $50. Think about the thickness of the blade and the amount of carbide needed. Then think about the machineing process. The tolerance for the carbide would have to be within .0025 to make it work and last more than a couple cuts. This blade would have to cost close in comparison to a Forrest dado stack.

  2. Nice idea but I dont see how this is patentable. This is just a new shape for a saw blade or router bit. And I am sure this has been done before, maybe by hand

    1. That joint is old new (done with a router), but doing it on a saw in one pass is novel.

      V-groove boxes are old as well – http://www.youtube.com/watch?v=OiETlYskTrY

      V-groove blades are also common, adding that to the dado stack would seem to be the obvious choice, though I can see why he went for the custom blade. A separate V-groove blade would need to be custom, so eh, just make the full profile.

      Of course a CNC with a toolchanger can do that in two passes easily enough.

    2. Kudos to Mr. Klien for an elegant idea

      Re “don’t see how this is patentable”

      I would suggest taking a closer look at the US patent system. For example, Apple has patented what is essentially a rectangle with rounded corners, see https://www.google.com/patents/USD670286 A simple search for “patent troll” will provide hours of fun or rage filled web browsing,

      1. Well, to file a patent your idea must be “novel”, which includes not disclosing your idea before applying…
        “Novelty is a patentability requirement. An invention is not new and therefore not patentable if it was known to the public before the date of filing of the patent application,” (wikipedia)
        About Apple’s patent, it’s surely too broad to be usable, even if they somehow managed to file it.

        1. Except Apple did successfully use it against Samsung. America’s patent system is a joke, you’re all living in a democracy where are your and your public’s balls, hmm?

      2. quit with the rounded corners crap. Re-read that patent. It was just one of many items. But some headline said it was just rounded corners and now here we are.

        1. Apple has been riding on rounded corners for a long time. Windows versions before 3.0 has buttons with rounded corners and a solid highlight line to indicate which one would be triggered by hitting Enter.

          After the lawsuit was settled, Windows had no rounded corners anywhere, and the solid highlight line was replaced with a thinner, dotted line. Windows still uses the dotted line but started using rounded corners again, but not as rounded as Apple, in Windows 95.

          Design patents are only good for 14 years. Why does Apple still get any deference on round corners as a design feature on anything?

          Patents and trademarks are full of BS. Look up this one US6368227 B1 It’s been invalidated, but due to non-payment of maintenance fees, not for being something that never should have been granted a patent.

          For a WTH?! trademark case, look up the WWF vs WWF case. World Wildlife Fund VS World Wrestling Federation over the right to use the letters WWF. They claimed the wrestling companies use of those letters was “confusing” and “forced” the World Wildlife Fund to have to spell out their full name and use their panda bear logo. BS! Trademark laws *require the use* of trademarked logos, phrases and company names.

          Total complete bullshite case, yet the World Wildlife Fund won and forced World Wrestling Federation to change their name to World Wrestling Entertainment and change their “claw scratch” WWF logo to WWE. The only use they can make of WWF and World Wrestling Federation is in copies of old videos where the name and logo are part of the original program.

          There are some other organizations with three word names that have the initials WWF but the World Wildlife Fund has not sued them. That should be grounds for dismissal of the suit because if you want *exclusive* use of three particular letters you ought to have to send cease and desist letters or sue *every other organization* that’s using them.

          What would make a fun TV show is one that digs out crazy old patents for insane gizmos that were never actually built, then builds functioning versions of them. US3216423 A would be an interesting build, though I wouldn’t expect anyone to actually use it for its intended purpose. Name of the show? “Patently Crazy!”

    3. Since there has been a public disclosure before a patent application it no longer is patentable. Simple as that. Any company that wants to use this is now free to do so. Very unfortunate for mister Klein, but that is the way this works. Because there has been disclosure a patent for this is no longer defensible and thus useless.

      Think before you make a public disclosure of anything innovative people!

      1. That’s not the case. It’s not about disclosure, it’s about novelty and prior art. Assuming this is the first time this method has been done it would be patentable regardless of when he announced it. The US also operates on ‘first to file’ so if somone saw this and got their application in before him it would be harder for him to prove.
        Enforcing that patent however, takes more money than most hobbyists have.

        1. Oh right, in the US it seems you can disclose the idea even before filing the patent (and if he has it pending, then that might be good, I guess).
          “The United States, Russia, and a few other countries have a one-year disclosure window, allowing a one-year period after initial disclosure before you need to file a patent application.”
          Then, as Leithoa says, it’s all about the money to actually enforce it, the patent itself doesn’t do much more than disuade.

  3. Agreed, A very nice take on manufacturing an old joint. The North-West American Indians used to do it. Admittedly they had to use a plank of real wood rather than this new-fangled plywood. The advantage they had was this could then be steamed to shape. For example look up Kwakuitl indian food tray & water boxes (ref woodworker magazine p418).

  4. Wow….this is soooo good. Yes, I would buy a set if came available. I would say max that I would be willing to spend for the set up is ~$150 to $200. [just to give a ballpark price for an ave garage hack builder, not a cabinet maker]. Nicely done. I’m super impressed.

  5. No doubt a truly new new profile for truly new saw tooth profile is patentable. I don’t see how the possibility that this process could have been done by hand at some place back in time should or would affect patent grant prospects. Progress would grind to a stand still if such stringent guidelines where part of the patent process. Yes patents have been granted where they shouldn’t have been, but there should be caution as to not allow the pendulum swinging too far in the other direction. The target customer is those who find making drawer as tedious as Andy does, not those who aren’t going to be swayed from doing the joinery they enjoy doing. Established wood workers most likely already have the dado cutters, those entering wood working will need the dado cutter in the future. Cost is more of a issue for the newcomer than it’s going to be for the established wood worker. The beginner should make some saw dust building drawers using other joinery before considering purchasing(assuming it comes to market) this blade, even if the have the dado cutter are considering purchasing one. They may discover they don’t find those methods as tedious as Any does

  6. Firstly, comment to Rick: Nice job! Cleaver idea! Appreciate the nice video. Nice skill set and nice set of tools in yer shop.

    Secondly, Dan & Wes, yes, Rick’s joint would be quite strong but I too wonder if a simple “V” joint would be strong enough. After all, the needs would be different if the drawer was full of nuts and bolts or if the drawer was filled with sheets of sandpaper…

    1. Thinking about it this morning, the surface area isn’t all that much higher than a V groove, but it does mean that some stresses are now perpendicular to the glued surface, which should be a lot stronger. Clever design if that’s what he’s thinking.
      Still, it’d be interesting to see a direct comparison of them. I’m sure in many cases the additional strength wouldn’t be needed. I think his design of blade would need to be changed for each thickness of wood, whereas a V would just need the blade height adjusted.

  7. a few problems

    1) As soon as it gets dull, it’ll rip out plywood like nobodeies business
    2) yes, it can probably be sharpened a bit, but damn that won’t be cheap, it’s a custom tip/shaped blade
    3) the amount of measuring involved seems like a pain! Don’t forget, gotta flip it so you cut to get your red and blue sides to be opposites!
    4) there’s already a plethora of router bits that essentially do the same end product. Sure, you have to route out the sides for a drawer bottom, but he’s just not going to get the buyout that he’s seeking from some big tooling/blade companies.
    5) you still need to supply your own dado stack. It’s not the wonder tool people are making it out to be if you still have to supply a secondary portion of tool!

  8. I have seen a similar joint cutter in my grandfathers old wood workshop like 20 years ago. Maybe have been one of those one off tools that gets reinvented multiple times over the years, but never catch on.

  9. Well, the main problem is that the vertical cut must be in sync with the dado width – they must be kept equal. No problem adjusting the rise and fall wheel but how do you make the dado infinitely adjustable. ? Even the Freud variable dado stack is adjusted in ‘clicks’ . If he cracks that one he deserves to be a millionaire.

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