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  1. #1
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    Question Crown molding coping question

    I learned how to cope a inside corner by a simple hand coping saw on Internet --- have a 45 degree angle cut, then cope. I did some practice yesterday, the result was frustrating. I don't know where I did wrong. Is 45 degree angle cut just for the molding with 45 degree spring angle, or for both 45 and 38 degree spring angles.
    My molding is 38 degree spring angle. Should I have 38 degree angle cut then coping?

  2. #2
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    Default Re: Crown molding coping question

    A 90* corner, divided by 2 is 45*, regardless of the spring angle of the crown. You will cut the molding at 45*. Where you are probably running into trouble is proper placement of the molding in the saw when you're making the initial cut. If it is not oriented properly, then it's not going to mate up properly when installed.

    I recommend adjusting the placement of your trim in the saw until you're getting the correct cut, then either draw a scribe line or install stop blocks on the saw to line up the trim perfectly every time.

    Once you've got the cut right, then you cope the end with a 5* back bevel, this will give you tight face joints that stay tight.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  3. #3
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    Default Re: Crown molding coping question

    For a right inside corner coping, I remember I lay the trim flatly under miter saw, with up side touching the fence, then had a 45* cut. Now you convinced 45* initial cut is correct, I'll have more practice. Thanks.

  4. #4
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    Default Re: Crown molding coping question

    Quote Originally Posted by qhwang View Post
    For a right inside corner coping, I remember I lay the trim flatly under miter saw, with up side touching the fence, then had a 45* cut. Now you convinced 45* initial cut is correct, I'll have more practice. Thanks.
    No, you place the molding in the saw upside down, with the bottom against the fence and the top out from the fence at the spring angle. Watch this video http://www.youtube.com/watch?v=pvRpm...eature=related

    If you want to cut the crown flat you need to set up a precise angle and bevel angle. For 38 degree spring, If I remember correctly, you need a 31.6 degree andgle and a 33.9 degree bevel. I personally prefer the first method.

    Jack

    Jack
    Last edited by JLMCDANIEL; 03-12-2012 at 05:16 PM.
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  5. #5
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    Default Re: Crown molding coping question

    Quote Originally Posted by JLMCDANIEL View Post
    No, you place the molding in the saw upside down, with the bottom against the fence and the top out from the fence at the spring angle. Watch this video http://www.youtube.com/watch?v=pvRpm...eature=related

    If you want to cut the crown flat you need to set up a precise angle and bevel angle. For 38 degree spring, If I remember correctly, you need a 31.6 degree andgle and a 33.9 degree bevel. I personally prefer the first method.

    Jack

    Jack
    See this video at around 2:18. http://www.thisoldhouse.com/toh/vide...056482,00.html
    And this article http://www.homedepot.com/webapp/cata..._Crown_Molding

    They don't say should put trim upside down. Maybe they miss details. I'll try as you suggested.

  6. #6
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    Default Re: Crown molding coping question

    Quote Originally Posted by qhwang View Post
    For a right inside corner coping, I remember I lay the trim flatly under miter saw, with up side touching the fence, then had a 45* cut. Now you convinced 45* initial cut is correct, I'll have more practice. Thanks.
    Laying the molding flat on the saw is not accounting for the spring angle, which is why you're not getting the pieces to mate properly.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  7. #7
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    Default Re: Crown molding coping question

    Quote Originally Posted by qhwang View Post
    See this video at around 2:18. http://www.thisoldhouse.com/toh/vide...056482,00.html
    And this article http://www.homedepot.com/webapp/cata..._Crown_Molding

    They don't say should put trim upside down. Maybe they miss details. I'll try as you suggested.
    It is easy to forget an "obvious" step when you know what you're doing, so as a novice DIY'r, you can't take a single how-to process or video as gospel. It will take trial and error on your part to ferret out the process that works for you.

    What I would recommend is that you forget about those videos for a second and just miter cut yourself some template pieces of trim so that you understand how to orient the material in the saw to get the cuts you need.

    Set the saw at 45*. How you place the material into the saw will depend on whether you're cutting an inside or an outside corner. Cut yourself a set of inside corner and outside corner template pieces. Now, you can simply place your template piece into the saw to set it up before you start whacking away at your lengths of molding.

    If memory serves, holding the material upside down at the correct spring angle against the saw fence will produce an inside corner. Holding the material right side up and facing the fence at the correct spring angle will produce an outside corner. Once you have your template pieces you'll never question saw orientation again.
    I suffer from CDO ... Its like OCD, but in alphabetical order, LIKE IT SHOULD BE!!!

  8. #8
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    Default Re: Crown molding coping question

    ghwang, you might consider a $30 investment in http://www.kregtool.com/CrownPro-Prodview.html

    Jack
    Be sure you live your life, because you are a long time dead.-Scottish Proverb

  9. #9
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    Default Re: Crown molding coping question

    More suggestions:

    Until you learn to cope accurately with a saw, don't cut to the edge- stay just a tiny bit shy of it, then use sandpaper, rasp, or file to get that last little bit. It's easier to control wood removed with these than with a coping saw. To find the edge you're cutting to easier, run a pencil held flat across it to make it more easily seen. When undercutting, think about how the corresponding part will fit so you can angle your saw correctly as you undercut too.

    Once you understand the basics, one piece crown molding is really pretty easy till you get to corners that aren't ostensibly 90 degrees or when you're running 2+ piece crown- that stuff can drive a perfectionist to drink in a decent home and drive you nuts in a bad one!

    Phil

  10. #10
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    Default Re: Crown molding coping question

    Quote Originally Posted by JLMCDANIEL View Post
    ghwang, you might consider a $30 investment in http://www.kregtool.com/CrownPro-Prodview.html

    Jack
    That saw looks very helpful and price is also very good. The saw I'm using is a compound milter saw borrowed from my friend. I have a good friend. We invest different tools then share. We also share diy knowledges. My inside corner is not tight enough, so I want to try coping.

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