The Magic Miter

How to cut crown molding on the flat using a small sliding chop saw and a math formula.

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25 Responses to The Magic Miter

  1. dado moj says:

    Reading the other comments left by the dougheads ,who would not take the time to learn explains what is wrong with us in the west, and why foreigners are mopping the floors with us in academics, if you showed this video 50years ago to most people would have gotten it.
    Just one suggestion if I may, you should show the same exercise but on a corner of a different angle say 89′ or 120′. then people will see how valuable your wisdom is :-)) good work can’t wait for more:-))

  2. eventualentrophy says:

    I believe the angle of the dangle is inversely proportional to the? hypotenues. If I have a complicated ceiling to crown I just charge 1.625 percent extra X tan plus 1.

  3. dewaltcarp says:

    Your FIRED!

  4. donnydoors says:

    Too late.? I’m retired.

  5. speezguy says:

    Great video. Nice to see? someone with brains.

  6. daniel feltimo says:

    intresting, but you know? most, if not all mitre saws have pro “notched” measurements on the angle gauge for both bevel and mitre….

  7. 315dave says:

    you’re a genius. but it was kind of fast, can you send a more detailed steps in calculating crown molding cuts using scientific calculator and can it?? be used for vaulted ceilings? thank you!

  8. learnerlearns says:

    This is a fascinating and superb example of how a little trig can increase capacity of tools while decreasing danger & mistakes.

    Hey Donny! You could sell a chart that includes the products of common formulas or invent a gadget! Act fast though!

    I bet someone in Japan or China will make a gadget that directly reads interior and exterior angles and does the math automatically.

    If Ryobi makes it, it will sell for $59.95.

    If? Festool makes it, it will cost $592.00. 😉

  9. MollariB5 says:

    Good video , thanks. I’m forever trying to balance similar shapes whilst trying to mitre them , it never works as accurately as this.
    Your tape measure seems to? be missing Centimetres though 😉

  10. MollariB5 says:

    *You’re . When trying to be? a smart ass at least spell it ‘write’ eh?

  11. dewaltcarp says:

    The only smart? ass on the page is you trying be the spell police and use eh! idiot

  12. MollariB5 says:


  13. donnydoors says:

    In the set building trade of years ago (I’ve mentioned this previously,) one of the journeyman questions was: “How do you cut crown molding?” The answer was”Upside down and backwards.” If one can find some material that extends the back of the saw table high enough to back up the crown, one can make a start cut. Then? lay the molding flat and match the saw blade to the cut groove. That makes a decent approach when calculations fail.

  14. donnydoors says:

    As regards those “Senty-meeters,” the trades people of southern California are yet to make the transition to metric. Materials, layouts, tape measures are still the old English system that the English themselves? don’t use anymore.

  15. briana straw says:

    im going to apply trimwork. i need to apply a horizonal peice that will connect to an angled facial board and? trim the facial board as well. how can i cut that miter? please respond as soon as possible!

  16. donnydoors says:

    To begin with, I made this video as an experiment, to see if the process actually worked. I never had time to fiddle around with it in my set-building work. I’m not an expert? finish carpenter. My simplest advice is: measure your angles. Divide them in half and either work out the flat formula or cut them in a miter saw, upside down and backwards. You might try a real expert: Rich Christopherson at his web site, waterfront-woods. Good luck!!

  17. L33tLady says:

    Finally! A youtube video that teaches something of use. My husband works in renovations so I’m trying to learn some of? the tricks and whathaveyou so when he talks to me about his day my eyes don’t start to glaze over…….I have no freaking idea what it all means, and my brain hurts, but I will study this and grasp its meaning and be super proud of myself. HUZZAH!

  18. donnydoors says:

    Happy to be of service. Check out my other videos. If your mate has to redo a fence, or fix a door. . . In facdt I’ve got a whole book on fixing doors. Check out the? site mentioned in videos. Oh, you might find the Handy Dandy Dust Pouch to be useful from the home cleaniless p.o.v. Enjoy!

  19. kayartist says:

    omg wtf are you going on? about grand dad?

  20. carpe1959 says:

    on a crown molding angle generator site alter eagle. there angles disagree with yours? there miter is 35.26 and bevel is 30 i would be interested to hear from you ps good video

  21. db33ful says:

    enjoyed the? video.. good math. although profiles change and wood moves.. there are basically 3 common spring angles on crown, depending on how high the ceiling is…. the crown you are displaying is a 38*52* common angle, which would be 31.62*angle “usually indicated on most saws” and a 33.9* bevel ” also usually inicated”… if cutting crown on the flat

  22. ehaughey says:

    nice Video, have to mention though that you sound exactly like Uncle Eddie from The Griswolds Christmas? Vacation. 🙂

  23. woodbine66 says:

    You? have just turned carpentry into rocket science.

  24. sonicqtip says:

    Very informative; however, your decimal? conversion of the “A” width is an error: the decimal equivalent of 2 5/8 is 2.625, not 2.645. Considering the small amount of difference 2/100’s of an inch makes, it is probably not much of a concern in practice, but I thought you might like to know.

  25. sonicqtip says:

    I watched it again, & I see that you were? using known dimensions printed on the sheet to derive the unknown decimal equivalent with your calculator, not your tape. Maybe you could add an edit or an epilogue? All things considered, it’s still very informative.

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