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Thread: Alan B's cabinet corner plywood joint

  1. #1
    Join Date
    Jun 2008
    GTA Ontario Canada

    Alan B's cabinet corner plywood joint

    I am about to cut a bunch of ply to make some more shop draw cabinets and plan on using Alan B's corner joint image Click image for larger version. 

Name:	Alans tonge and groove ply joint.jpg 
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    We learnt of this joint from him during his kitchen cab build. I have already privately asked Alan for the best practice method to cut this edge and the additional dimension needed to be added to the piece in question.

    I thought it would be an interest post to have on its own and raise some debate about how best to go about cutting this edge on ply.

    While waiting on Alans response is there anyone here that can venture a method for me to try.

    All I seem to be able to do as of right now is totally overthink the method and I aint even going to go there.

    Just some thoughts I have, it would seem to me the joint and depth is a full size blade kerf wide/long.

    If this is the case I might be pooched.

    But for the life of me I cannot get my mind around where and how to start cutting an edge like this efficiently. My emphasis is on the efficiently part. I can cut it but I would be here all day with one piece that don't make sense to me that a cabinet maker like Alan would then bother with a joint like this. So there has to be a simple clever well thought out way that I just cannot see right now.

    Thanks for any replies.

  2. #2
    Join Date
    Apr 2007
    No, not all of SoCal is Los Angeles!
    Disclaimer: the following is JMHO and worth just what you pay for it . . . . I might be persuaded to agree that you are over-thinking it ;-) Depending on how reliable your plywood is I would use a dado stack or a router table or a hand held router.

    Tablesaw / Router table - this relies on your ability to run the large reference surface across the flat table top consistently. This means your plywood is as flat as MDF or milled lumber; rarely happens but, for this joint I think you could be good enough.

    Hand held router - This method assures a more reliably consistent depth of cut as the smaller router baseplate will follow the contours of less-than-perfect- sheet goods surfaces.

    Click image for larger version. 

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    For long "tongues" I make sure to run one of the dados on all parts at one run/setting. I then test for proper depth on the opposite dado (which controls the tongue width) and run all the other sides. I am not very good at working with ply so factor that in. When I work with it I try not to have to "go back" as relying on the face of the ply as a reliable reference surface for duplicating an existing profile rarely works out for me. Accepting a bit looser tolerance for the fit can also brighten my day when working with ply ;-).
    Last edited by glenn bradley; 10-19-2013 at 01:27 PM.
    Any sufficiently advanced technology is indistinguishable from magic.
    - Arthur C. Clarke

  3. #3
    Join Date
    May 2011
    Cape Cod, Ma.
    its a simple modification of a tongue and groove joint Rob. figure 1/4" for your tongue and 9/32 for your groove depth so your tongue is 1/4x1/4 and your groove is 1/4x9/32.
    This little added depth is going to allow a tight fit at the edge where you want it. Also, space the tongue and groove accordingly.
    Although this is a good system, and I have used it on several occasions one has to be a bit more particular in the faceframe and box construction as there is less margin for error. Also, you cannot used this system if you are going to go with a prefinished cabinet interior which imo is far more labor intensive than the time savings on this joint. Typically with an 1-1/2" stile I dimension the box to be 1/32-1/16 wider than the opening dimension of the ff. Given that plywood runs about a 32nd undersize this allows for me to skin a piece of finish grade plywood that is species specific to the project and if its a little fat then I can belt sand the back. then edge glue to the ff and run some 1-1/4 screws from inside the box. also this is only needed on your finished ends all the rest, having that extra space between the outside of the box and the edge of the ff gives you more than enough fudging room for wall variances and allows for a tight joint when attaching cabs together. Another plus to dimensioning the box to the opening is in the installation of hardware such as euro hinges and drawer slides. There is no labor to having to pad out the sides. And when installing partitions run the face to one side so that only the other has to be padded.
    When you are doing several cabinets all this time savings adds up pretty substantially. And gives you more margin for error.
    He who laughs last, thinks slowest

  4. #4
    Join Date
    May 2007
    Thomasville, GA
    I'm assuming that's a face frame type of assembly on the front of the cabinet. Regardless, seems to me a simple way to join the cabinet side to the front is with biscuits a few inches apart along the height. Been there, done that a lot! You don't have to worry about bows in your plywood, either.
    Bill Arnold
    Citizen of Texas residing in Georgia.
    NRA Life Member and Member of Mensa
    My Weather Underground station

  5. #5
    Join Date
    May 2011
    Cape Cod, Ma.
    gotta be fussier with biscuits but you are correct. set the biscuit joiner to #20 and use #10's

    Also, regarding the variance of plywood thickness, in this instance its irrelevant as one is indexing both parts from the same edge so variance will get eaten up on the waste side. true that the tongue may be slightly thicker or thinner in places but that is easily remedied again from the waste side.

    this joint is good for open cabinets such as an entertainment center or book shelves where one would not be using prefinished interiors as it does make for a consistent joint. The other and most important factor is the quality of the cutter used AND the quality of the plywood core. both will affect the joint.
    He who laughs last, thinks slowest

  6. #6
    Join Date
    Dec 2006
    RETIRED(!) in Austintown, Ohio
    An easier way would be to use a ¼" slot cutter in a router, and cut slots in both the plywood and the frame. Then, cut a spline from plywood or hardboard to join the pieces.

    Cutting both slots from the face side would ensure the mating surfaces would be flush, and the spline would provide the alignment.

    Note: I would NOT use solid wood for the spline, since it would be a long grain application that could eventually split - offering no structural strength.
    Jim D.
    Adapt, Improvise, Overcome!

  7. #7
    Join Date
    Mar 2008
    bethel springs TN, but was born and raised in north east PA
    Rob about the only thing I do different is to set my plywood in a 1/4 inch, from the edge of the faceframe. This way you have some wiggle room, if it's a tite fit, or things just ain't plumb. Also I think it just looks better. Of corse that's just me.

  8. #8
    Join Date
    Feb 2012
    St. Catharines, Ontario, Canada
    Nice useful joint, but probaby not what I would have used for shop drawers. I'll keep it in mind if I have to do any drawers.

    The other member of Mensa, but not the NRA

    Everyone is a self-made person.

    "The thing about quotes on the internet is that you cannot confirm their veracity" -Abraham Lincoln

  9. #9
    Join Date
    Dec 2006
    Quote Originally Posted by glenn bradley View Post
    ... I am not very good at working with ply so factor that in. ...
    I thought I was the only one. Part of the reason that I prefer to work with solid wood, as it allows you to easily tweek any joint. I respect commercial cabinet makers because they have worked out systems to make plywood joints a simple process for them. Me, I rather just work with solid wood.
    “When love and skill work together, expect a masterpiece.” - John Ruskin
    “Nowadays people know the price of everything and the value of nothing.” - Oscar Wilde

  10. #10
    Join Date
    Jun 2008
    GTA Ontario Canada
    My bad I am getting worse at explaining my needs every day. My apologies.

    I had to use this pic as I cannot find the one where he does it on a corner of ply on ply.

    Alan I know has a very simple easy way to do this joint on the table saw. I don't remember too many threads but I do remember a post where Larry actually asked him to explain how he does it, I wish I had bookmarked it. However even at the time I did not quiet get it, slow I am slow learner I guess.

    There is no way in my opinion Alan is having this take a whole lot of effort hence my request.

    I am not putting face frames on these boxes its a three side with top and bottom and this joint will work well to hold it all together.

    Alan has juts complete a job doing exactly this making tool draws and I am trying to copy it. The draws for this are going to run on wood runners. Cheap but they worked for my grandfather and the intention on these draws is no more than the height of one layer of tools.
    So think in terms of loads of draws but very shallow, ( I will discipline myself somehow ).

    The total length of a side in my case is only going to be 24 inch by 24 x24. So I don't see an issue as Glenn pointed out running it over table saw. I just want to get the pro manner of working efficiently. Otherwise these cabs will take me till next year to make.

    THis is the issue when one is a part time weekend dabbler, one can never get into a groove and retain and practice.

    Hope Alan chimes in.

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