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Thread: whatís wrong with Domino joinery

  1. #46
    You may be right, Jim. I may have made them wrong. I own that. If people read my post as anything more than one person's opinion then let me disabuse them of that. It's just my personal conclusion. I'm no pro.

    But right or wrong, if feasible, I do trust an integral tenon on chairs more than a Domino. It's because I trust the integral side a little more than if both sides were floating.

    I hope the reader sees my post as nothing more than a personal, prejudiced opinion.

  2. #47
    Prashun,

    Thanks for your reply. I think I said this in a previous post but I do think that having two mortises to apply glue to is an additional source of error in a floating tenon joint that an integral does not have. But the floating tenon joint does not have the shoulder cutting source of potential error. Tight fitting shoulders help resist loading in chairs. So I do not see the risks of my mistakes as higher with the floating tenons. But I have no problem at all with somebody going the other way. It's nice we have choices.

    But if I wanted to use integral tenons I would still make the mortises with my domino. I just do not see a reason to spend more time doing them any other way.

    Jim

  3. #48
    Jim and Prashun,
    One more interjection that may help clarify the angle I'm seeing this at. I am in agreement to provide chairs/bar stools of the most economical yet strong variety to a local upholstery shop for them to ultimately add some upholstery to, then sell the complete units to their clients, = no time for integrated tenons and Maloof-style joinery. This is why I sing so highly the praises of the Domino. An erosion of pride I guess, given I'm more of a traditionalist, but hey - gotta make a living, and the occasional calls for a batch here and there is a welcome addition to round out the schedule each year. These chairs are considered heavy duty in every way, yet priced to actually be marketable. Heck of a tall order, pinched between Vietnamese imports and heirloom grade, bespoke furnishings.
    Really would like to dissect one of the $1200-$1400 Amish chairs to see if they're using dowels, mortise and integrated tenon, or (gasp) dominos...? wouldn't be terribly surprised.
    Anyhow- it's been an interesting, good spirited debate!

    Jeff

  4. #49
    Join Date
    Dec 2005
    Location
    Texas
    Posts
    207
    I found this on a Festool group:

    Here's the link if it's allowed: https://festoolownersgroup.com/index...int-strength.0

    Fine Woodworking published the results of joint strength tests in their January 2009 issue (#203). They tested eighteen joints: half laps, bridle, mortise and tenon, floating tenon, miter, splined miters, dowel max, bead lock, domino, biscuits etc. They attached a rail to a stile with various joints and tested them in a lab under controlled conditions for lever strength. The range of the results ran from 1660 pounds of breaking strength for the half lap joints to a meager 200 pounds for the stub tenon. Traditional mortise and tenon rated near the top with a breaking strength of 1444 pounds followed very closely by floating tenon at 1396 pounds The bad news is that the domino placed #14 out of 18 at a lowly 597 pounds, just above biscuits at 545 pounds.
    I replicated these tests for half lap, mortise and tenon, floating tenon, biscuit, and of course domino. I used used 1x2 1/2" stock and a simple vise and my arm. I performed the tests twice for each joint, once in red oak and once in white pine. I used Tightbond's original glue and allowed each joint to dry for three days. Obviously I can't give a psi specification for breaking strengths, but I can tell you that my results paralleled those published. The half lap was incredibly strong , The mortise and tenon and floating tenon were also very very strong. The biscuit sheared off easily, but this was no surprise. Sadly the domino (#8 50 floating) joint broke with sickening ease. The domino (#8 50 tight) joint was a bit tougher, but was not very impressive. Using two dominos if you can work them in substantially improved the joint, but fell well short of a mortise and tenon or floating tenon. The shortcomings of the domino surprised and saddened me. The questions for Festool Domino owners is why so weak and what do?
    In my opinion, the weakness results from the relatively slim glue surface of the domino. This shortcoming has in my opinion been exacerbated by
    the impressed pattern on the Festool dominos. Initially, I assumed that the beech domino was meant to swell like a biscuit and the impressed pattern on the domino would swell up and disappear. But this was not the case. On the joints I tested these impressed patterns did not swell out from immersion in water based glue, but remained impressed. I do not know what Festool hoped to achieve by adding these impressions, But they result in a further reduction of glue surface. They reduce the wood to wood contact by creating a series of gaps along the whole glue surface thus weakening the joint.
    So what to do? The answer is simple; increase the glue surface by widening the glue surface and getting rid of the impressions. You do this by using the domino joiner to make traditional floating tenon joints and making up wide smooth floating tenons. I recently made up red oak floating tenons 1 3/4" wide x 2" long for the #6 domino bit. Making up yards and yards of tenon stock is simplicity itself with a band saw and a planer. I cut matching mortises in rails and stiles by lining up 2 Domino machine cuts to make a 2" mortise including the corners which provides a 1 3/4" flat surface. I then glued up the joints using the smooth, wide, oak tenons. The resulting joints are enormously strong: far, far stronger than using the dominos. This method was quick and easy and produced true chair-strength joints. So the Domino machine is a great addition to my shop, but without the dominos!

  5. #50
    Join Date
    Dec 2005
    Location
    Texas
    Posts
    207
    Then there is this: dowelmax vs domino

    https://www.youtube.com/watch?v=_vgAeGCATgM

  6. #51
    Carl,

    I've seen that test in FWW. It proves that if you compare a bigger mortise and tenon joint to a smaller one, the smaller one will be weaker. Not sure it proves anything else. It looks like you agree.

    I have not purchased a Festool tenon or a Festool cutter for my Domino. I use CMT or Amana cutters. I ruined the 12mm Festool cutter mine came with and had to get an Amana replacement. I see no difference. Except the price is half as much. I make my own tenons for the reason you cite - I can make them the right size for my project - and also because I am cheap and I don't like wasting time. I normally can make all the tenons I need in less time than it takes me to go to the store and buy some. If I am hard pressed for time I may buy some someday but only if the size is right for what I am trying to do.

    It seems like we agree even if we don't say things exactly the same. Use the domino to make the mortises you need easily and quickly. Then make tenons to match (or cut integral ones if you prefer).

    Jim

  7. #52
    Join Date
    Nov 2015
    Location
    Philadelphia, PA
    Posts
    68
    Quote Originally Posted by Bryan Cramer View Post
    Iíll throw my opinion in as well. This has been a very good discussion and some good points have been made. I have a DF500 and honestly use it more for cabinetry and even solid wood carcasses. Itís just as fast a a biscuit joiner but makes a stronger joint. Itís great for traditional face frames as well. I still think itís comparable to glued mortise and tenon joinery however if you draw-bore the joint it far exceedes only glue for strength and longevity. Therefore Iíll be sticking with traditional joinery for critical joints table leg to apron, doors, etc. A well executed drawbored joint closes up without clamps once the pin(s) are driven home.
    You can always pin a domino tenon...

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