Results 1 to 14 of 14

Thread: Birdsmouth joinery

  1. #1
    Join Date
    Sep 2008
    Location
    Spokane WA
    Posts
    248

    Birdsmouth joinery

    Thinking about doing a 8 sided box using Birdsmouth joinery. Lee Valley has the bits for a router but I want to build mine with hand tools. Anyone know how to do this??

  2. #2
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,347
    Blog Entries
    1
    If you do edge grain to edge grain it shouldn't be too difficult to do it like this > https://sawmillcreek.org/showthread.php?157217

    This became a birdhouse and has been out in the weather a few years.

    Just looked up birdsmouth joinery. That joint could be cut with a rabbet plane. You might need to make a custom angle add on for the fence.

    A Stanley #55 has fences that can be angled for this kind of work. Kind of an expensive investment for one project.

    It likely wouldn't be difficult to use an wood body rabbet plane with a set up for the board to be moved over the plane instead of moving the plane over the board. That was one way coopers used planes when making barrels.

    jtk

    -Oops! Just realized you are not a contributor. You won't be able to see the images of my 22-1/2º shooting board for making an octagon.
    Last edited by Jim Koepke; 12-03-2021 at 12:37 AM. Reason: -Oops!
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  3. #3
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    1,566
    If you aren't tapering over the length, like the mast for a sail boat, just a box with a consistent width or profile, I agree with Jim you can do it with a rabbet plane. If you are going to taper over the length, say 10" wide at the base and 6" wide at the top with four inches of height you are going to need one keg of Guiness for design and layout, a second keg for execution and a third keg for glue up and clamping- because that math will hurt your head.

    Without a Stanley #55 in stock I would lean towards a modern rabbet plane with an angled fence attached to the factory square fence. If you are going to taper it from base to top, one option is to build it big and then plane off the excess from the exterior- it has been done that way many times for sail boats.

    If it is going to be same diameter top to bottom, do the math, use a square fence on your rabbet plane, and praise Jesus that you dodged a bullet.

  4. #4
    Join Date
    Sep 2008
    Location
    Spokane WA
    Posts
    248
    I was hoping to make a 8 sided box. Sounds like it’s going to be difficult to get consistent matching angles.

  5. #5
    Join Date
    Jun 2010
    Location
    twomiles from the "peak of Ohio
    Posts
    12,120
    On the older Mitre Boxes...the Quadrant Scale does not have degrees( a later invention)....the numbers stand for how many sides to a box that you want to make...0 being a square ...there are some boxes out there that count up to 24 sides....I think there is indeed an "8" mark on that scale...
    A Planer? I'm the Planer, and this is what I use

  6. #6
    Steven, when I was in early grade school I asked several adults what those numbers were. They didn’t know ,or possibly didn’t want to try
    to explain it to a kid. Now I know, Thanks Steven !

  7. #7
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,347
    Blog Entries
    1
    Quote Originally Posted by Bill Sutherland View Post
    I was hoping to make a 8 sided box. Sounds like it’s going to be difficult to get consistent matching angles.
    That is what a shooting board is for. A shooting board with an angled bed is often referred to as a 'donkey ear.' The link in my first post is to a post on how a 'donkey ear' shooting board was made to make an octagonal birdhouse, basically an 8 sided box.

    If you want to do it wit a birdsmouth joint you could make the cut in a long piece of wood (at least 8 times as long as you want to make the box tall).

    If taller than a foot you will have to use more than one piece.

    It might be easier using a fixed plane with a shop made fence to guide the work over the plane.

    This is all based on wanting an 8 sided box with all sides being equal. The birdsmouth would then be at 45º.

    If you want to do some fancy sizing, then more planning is needed.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  8. #8
    Join Date
    Aug 2012
    Location
    Missouri
    Posts
    2,151
    I guess I may be a little thick here. I saw articles a few years ago about this joinery. I thought about it a bit and never came to an answer of “why”. I could not and still can’t answer that. Could someone enlighten me or is it like the impossible dovetail? Just something to do, more glue surface, stronger than splines.?
    Jim

  9. #9
    If you did actual birdsmouth joints using narrow stock to make rings with a bit of overhang on each joint and made a stack of them in decreasing size alternating the orientation of each ring, the result would look a pine cone. In my head this looks really cool.

  10. #10
    Join Date
    Sep 2007
    Location
    Longview WA
    Posts
    27,347
    Blog Entries
    1
    Quote Originally Posted by James Pallas View Post
    I guess I may be a little thick here. I saw articles a few years ago about this joinery. I thought about it a bit and never came to an answer of “why”. I could not and still can’t answer that. Could someone enlighten me or is it like the impossible dovetail? Just something to do, more glue surface, stronger than splines.?
    Jim
    It is a router table joint, easy to make with a router table and a specific bit for the number of sides desired.

    It does have more glue surface compared to an angled edge joint.

    Only one edge has to be cut to for a birds mouth where coopered or angled edge joinery requires both edges to be cut.

    jtk
    "A pessimist sees the difficulty in every opportunity; an optimist sees the opportunity in every difficulty."
    - Sir Winston Churchill (1874-1965)

  11. #11
    Join Date
    Aug 2012
    Location
    Missouri
    Posts
    2,151
    Quote Originally Posted by Jim Koepke View Post
    It is a router table joint, easy to make with a router table and a specific bit for the number of sides desired.

    It does have more glue surface compared to an angled edge joint.

    Only one edge has to be cut to for a birds mouth where coopered or angled edge joinery requires both edges to be cut.

    jtk
    Thanks Jim. Kind of what I thought. Don’t have a router table and not interested in having one. Don’t find it too difficult to make coopered things with hand tools. I really think it could be set up and cut with a 78 if one wished to. Cant think of how I would use it. May find a use for it sometime. Keep it stored in the backlogs of memory for now.
    Jim

  12. #12
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    1,566
    My understanding of a birds mouth joint is having a step on each piece makes clamping it up correctly a bit easier while the glue is wet. Gluing edge grain to edge grain is good, cutting 22.5 degrees on all the end grain would be the weaker glue joint. On a smaller piece like in Jim’s link clamping during glue up might be challenging but should be manageable.

    On something like a 30 foot spar for a racing sail boat that is maybe six inches at the base and two and five eighths at the tip birdsmouth all the way.

    for a small piece like the OP described I think it could be done as a birdsmouth with a 45 degree fence on a rabbet plane. I would be obsessing over making sure my depth stop didn’t flinch, and would put the rabbets on the longest possible stock. Cut pieces to length after the rabbet is cut.

  13. #13
    Join Date
    Jan 2019
    Location
    Fairbanks AK
    Posts
    1,566
    I have noticed different trades don't always use the same name for a joint, and often there are multiple correct names for one joint. The birdsmouth joint I have been babbling about in this thread looks like this one:

    https://www.timbecon.com.au/torquata...h-jointing-bit

    A homebuilder of course thinks of a birdsmouth as a thing to cut in the underside of a rafter for a roof.

  14. #14
    Join Date
    Jun 2010
    Location
    twomiles from the "peak of Ohio
    Posts
    12,120
    Imagine doing 8 sides using this joint..
    Jewelry Box, first corner done.JPG
    when done...looks like you somply folded a board into a box shape, using a hinge at each corner...
    Jewelry Box, meeting miters.JPG

    Jewelry Box. spline pattern.JPG
    "Hinge"
    A Planer? I'm the Planer, and this is what I use

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •