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  • compound mitter joints

    OK I've posted this Question under ask an expert but had no replys. So I'll ask again does any one know of a formula for figuring out the proper angles for cutting compound mitters. I'm not doing crown molding. I'm make picture frames on my RIDGID MS1250. My knowage of Geometry is not very strong. So please make this as semple as possible. Maybe someone know's of a good book that will help me. Any takes on this one. If anyone would like to E-mail me derect sent it to danomal@home.com Thanks
    Regards Daniel J. Maloney

  • #2
    Figuring compound miter angles can get very complicated very fast. Its not hard if the material you are cutting, say CM, will sit at a 45 degree angle Then you just take the angle, divide by two if you are doing a straight cut miter, divide by two again for a compound miter.
    Example: 45 degree CM 90 degree corner; Miter angle:22.5
    Bevel angle:22.5
    Now if the angle of the material is not right at 45 then the calculations get very complicated. 38 degree CM is very common. It requires a miter angle of 33.6 degrees and a bevel angle 31.9 degrees.

    I have some charts I can send you for CM miter and bevel angles, now for a way to calculate other angles, it requires a lot of trig. I can see if I can dig that info up if you want it, but you will need a scientific calculator to figure the correct angles.

    E-mail me if you want more info.

    Jake

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    • #3
      THANKS FOR YOUR HELP JAKE. I'M GREATFUL
      DAN

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      • #4
        Originally posted by JSchnarre:
        Figuring compound miter angles can get very complicated very fast. Its not hard if the material you are cutting, say CM, will sit at a 45 degree angle Then you just take the angle, divide by two if you are doing a straight cut miter, divide by two again for a compound miter.
        Example: 45 degree CM 90 degree corner; Miter angle:22.5
        Bevel angle:22.5
        Now if the angle of the material is not right at 45 then the calculations get very complicated. 38 degree CM is very common. It requires a miter angle of 33.6 degrees and a bevel angle 31.9 degrees.

        I have some charts I can send you for CM miter and bevel angles, now for a way to calculate other angles, it requires a lot of trig. I can see if I can dig that info up if you want it, but you will need a scientific calculator to figure the correct angles.

        E-mail me if you want more info.

        Jake

        Comment


        • #5
          I just bought a Compound Saw (MS1250) I tried making Crown Molding cuts..but the walls aren't true and the angle was off...is there a book that I could read that would show me what adjustment to make...Thanks in advance..

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          • #6
            There is a program available on the Badger Pond website which calculates compound angles, I have used it and it is simple and accurate, called Polycut.

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            • #7
              Jake:

              This question comes up often enough that wouldn't it make sense to put either a copy of the article, or better yet some sort of interactive calculation program, a permanent item on this site? I just spent several minues looking for a prior post to answer Dan's question.

              Dan and others:

              The trouble with doing a lot of math to figure out the precise answers is that in the real world our projects may not be perfect, and trying to cut a compound miter on a flat table doesn't give you an easy way to "cheat" or "sneak" as needed. In my experience, it is worth the effort to build a jig that will hold the stock in the same angle relative to the table that it will eventually take with respect to the ceiling, and then cut a straight miter.

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              • #8
                Originally posted by WaMan:
                There is a program available on the Badger Pond website which calculates compound angles, I have used it and it is simple and accurate, called Polycut.
                I'd appreciate it if you could give me the websitewhere I could see the angle cuts for Crown Molding....thanks

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                • #9
                  Try http://www.hobbywoods.com/free_woodworking_software.htm

                  Part way down the page is a link for polycut

                  Also see the calculator at www.issi1.com/crown.html

                  Also see the article with calculator and chart
                  http://www.josephfusco.com/GoLive5//...ngcrownpg1.htm

                  I haven't checked the links today, but have in the past.

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                  • #10
                    Here's the link to the crown molding chart:

                    http://www.ridgidwoodworking.com/new..._02.html#clean

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                    • #11
                      hi

                      best way i have found to set the saw for compound miter cuts is with a bevel gague. Even if something is supposed to be a perfect 90, 45, etc you may end up with a half of degree or so difference in cuts which depending on the size of the project can be very noticable. the bevel gague allows you to set it to the exact angle and every cut will be a perfect fit.

                      as far as doing crown molding, trim work etc, a crusty old carpenter friend of mine introduced me to the technique referred to as "back cutting". essentially you run two pieces of your trim parallel to each other on opposite walls. run them the full length of the wall. then go ahead and cut your miters on the other two sides of the room "using your bevel gague to measure the exact angle of the wall. once cut take a coping saw and "back cut" the "meat" behind this cut. what this does is eliminate where the trim would stop and allow those pieces of trim to make full contact with the face of the other side. this gives the appearance of a perfect miter joint without the aggrivation and fuss of matching up miters perfectly.

                      hope this helps

                      ed
                      \"A SHIP OF WAR IS THE BEST AMBASSADOR\"<br /><br />OLIVER CROMWELL

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                      • #12
                        This site may be able to help you;
                        http://www.woodworking.org/WC/mitercalc.html
                        Teach your kids about taxes..........eat 30 percent of their ice cream.

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