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  1. #1
    Join Date
    Apr 2008
    Posts
    74

    Angry Connecting Picture Frames / Mitred Corners

    Hi, All:

    I have had problems in the past with getting a strong corner on a 45 degree cut, such as you would use in a picture frame or mirror surround. I just can't seem to get the corners to glue up correctly.

    Here's what I've tried in the past: (1) Simply gluing the corners and using a strap clamp to hold until dry. (2) Using glue and those squiggly corner inserts you tap in to hold. (3) a combination of 1 & 2 above. (4) Glue and finish/brad nailing the corners together.

    Here's the usual outcome of the above: (1) Corners slide all over the place when trying to attach the strap clamp, typically ending up with me throwing the whole works in the trash and grabbing another beer. (2) "Squiggly" corner tap-ins split the corners out, typically ending up with me throwing the whole works in the trash and grabbing another beer. (3) See 1 & 2. (4) Corners split out and/or nails/brads don't set correctly.

    I have many feet of great mouldings I've saved over the years with the thought of making some nice frames, but I'm getting frustrated! Can anyone PLEASE offer some advice on how to get better results? I have no problems with cutting and getting nice tight, square corners, I just can't get them assembled! Also, because most of my efforts are "one-offs", building a bench-top template to hold them while drying doesn't seem like the best approach.

    Thanks in advance for anything you can offer.

    Frustrated Tim!

  2. #2
    Join Date
    Mar 2009
    Location
    OKC
    Posts
    247

    Default Re: Connecting Picture Frames / Mitred Corners

    i have had good luck using a 45 degree clamp similar to a vise you put glue on both pieces them insert them into the clamp let them dry in the clamp, then you can take them out and screw the 45 brackets to them.

  3. #3
    Join Date
    Aug 2007
    Posts
    6,617

    Default Re: Connecting Picture Frames / Mitred Corners

    First you pull out your cordless jigsaw ...

    While you need to use glue to keep the joint stable, glue in and of itself won't work because trying to glue end grain of wood is like trying to glue the ends of straws together. All the glue gets absorbed down the grain fibers and the tips of those fibers have very little surface area for good bonding. If you look at the end of a bunch of drinking straws you'll see what I mean, that is essentially what end grain is.

    The reason that the squiggly corner thingies and nails are splitting and giving you fits is because it is very difficult to put a fastener through the tip of a board without it splitting. The squiggly thingie in particular is quite large and the displacement of the wood fiber forces the grain to split (think splitting wedge in firewood ). The fact that you're using old trim means that there is very little moisture or pliancy in the wood, compounding the splitting factor.

    The cure: Predrill the corners before installing the nail (hand driven ). The easiest method is to cut the head off a nail and chuck it into your drill and use it as a drillbit. Then take a fresh nail and gently tap it in. The predrilled hole does not have to be the full depth of the fastener, it primarily has to pierce the tip of one stick and create a guide hole in the end grain of the other. If you double nail the corner (one nail from each side ), be sure to offset the nails so that they don't meet in the middle and glance out.

    Other methods for excellent corners with even less hassles is to use a biscuit joiner, though obviously the trim needs to be of a substantial size to do that (larger than 2" ). On large moldings you could also use pocket screws.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  4. #4
    Join Date
    Apr 2008
    Posts
    74

    Default Re: Connecting Picture Frames / Mitred Corners

    Thanks for the responses.

    I tried the cordless jigsaw, but couldn't quite figure out how to plunge cut a mortise on a 45 to make it all lock together! I'm going to research "jigsaws and hidden dovetail joints" next. . . maybe that's the way to go? :-)

    And speaking of jigsaw plunge cuts, how on earth would this be done (seriously?)?

    Really, thanks for the advice. I have a few "coolies" chilling in the garage fridge for yet another attempt at frame-making tomorrow evening. Hopefully I'll be able to enjoy a cold one while looking over a sucessful attempt instead of a burn pile full of rejects!

    Tim

  5. #5
    Join Date
    Aug 2007
    Posts
    6,617

    Default Re: Connecting Picture Frames / Mitred Corners

    Quote Originally Posted by TRLambert View Post
    I have a few "coolies" chilling in the garage fridge for yet another attempt at frame-making tomorrow evening.
    Uh, I think I'm beginning to see the problem here ...

    Quote Originally Posted by TRLambert View Post
    And speaking of jigsaw plunge cuts, how on earth would this be done (seriously?)?
    Depends on the material, but generally you angle the saw so that the teeth rasp their way through, then upright the saw and cut normally. The safest and best way is to drill a hole the size of the blade or larger as a starting point. This method is much easier on the tool and blade.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

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