I have some 1x2 project boards for making a frame. The frame will hold a painted sign on Masonite.

I am uncertain the best method for joining the miter cuts and was hoping for suggestions. Wood glue only? Some sort of joiner like biscuits? The 1x2 board are rabbeted with router and =mitered with table saw. It seems to fit alright but there are a few small gaps.

Pictures are below. And some links I read through.

Bonus question: I noticed the 1x2 board can lie flat or tall. Is there a name for these two angles?


7 Best Types of Wood Joints to Know - Bob Vila

Perfect Miters Every Time

Making the Perfect Frame | WOOD Magazine


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If you don't have access to a proper framing underpinner (friend's or neighbour's), then you could either ask a local picture framer to join them for you or if you do want to do it yourself, a pocket-hole jig might be suitable as this will join the corners from the inside where it won't show.

Always back up the join with a good wood glue too.

If you do go down the route of finding someone locally who make picture frames, their guillotine will also get rid of those gaps in the join.

Edit : details of how an underpinner works:

An underpinner is a framing tool that pushes small (maybe 5mm to a side, and ranging from 10mm-15mm deep), 'L'-shaped pieces of metal into the frame from the underside. This is the model I have :

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a picture of the pins in place :

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and here's a description of the process : http://blog.ukpictureframingsupplies.co.uk/picture-frame-joining/picture-frame-construction-corner-joining-with-an-underpinner/

  • 1
    "framing underpinner" is a term I'm unfamiliar with. Are you referring to some sort of finish nailer, or is this something else entirely? Including a picture or a link to one would be really helpful. – FreeMan Feb 26 at 17:49
  • I'm also unfamiliar with the term. – Graphus Feb 27 at 8:58
  • @Freeman I never heard of it either, but it turns out it is a thing. A machine designed for securing picture frames. you can get one at Grizzly.com for a mere $789. – Ashlar Mar 1 at 2:08
  • Sorry - details of the underpinning process added to answer. – Steve Ives Mar 1 at 9:21
  • You must make a lot of picture frames to make that investment worth it! Good on ya! – FreeMan Mar 1 at 11:46

I would recommend using a miter spline joint. There few 2 orientations to accomplish different looks. A quick Google image search will show you the final look.

For the gaps, they are not big thus wood filler and sanding will fix it. But if you really want perfect corners, I would recommend building a sled for your table saw. That is the most accurate way to cut a 45 angle.

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