The Magic Miter

[donnydoors]

A question in the set builders test is: "How do you cut crown molding?" Answer: upside down and backwards. One can always flip the molding and set the saw to the opposite 45 degree angle, then cut as deeply as possible. Having done that, lay the molding flat on the saw table and try and match the bevel and miter of the partial cut. Mess up a few boards doing that and you're in.

[buffdr]

Holly cow brother, I would rather mess up few boards rather than doing what your doing.

[artsroofing1]

I would have just bought a bigger saw

[DrRSPMD2010]

Thank you very much Sir, you're the only one who was able to explained it scientifically. I hope you will teach us more for acute, obtuse and reflex angles that Crown molders might encounter in the future. I am familiar with the tables but still don't know the math involved, but thanks to you - now I know a lot more about Crown moldings scientifically. More power to you and God bless!

[Garciamrcool]

Excellent. I wish my maths teacher was as clear as you.

[LiveFractal]

what if your wall isn't square?

[danny223009]

I fell asleep watching this.

[donnydoors]

@danny223009

Hopefully not while you were runnning the chop saw.

[BrushCountryJamboree]

If anyone using the same model of calculator that Donny is using and does not get the same answer, I have discovered on my calculator which might be a newer version of the same model.

On my calculator you have to press the DRG (degree button) after you input the 45 which is 1/2 of the corner angle in degrees

[donnydoors]

Well, you're right about the .625. My mistake. But somehow, the mitire worked out close enough.

Regarding the calculations, I redid my math on the same old Sharp calculator I used in the video, and the figures came out the same.

[BrushCountryJamboree]

Also 5/8" does not equal .645 it is .625

[BrushCountryJamboree]

i bought the same calculator your using and i am getting the following answers

.815916148 for the miter &

.692128898 for the bevel.

so whats the deal with this

you need to zoom out enough for everyone to see exactly the keys you are pressing & when your pressing them

[BrushCountryJamboree]

i bought the same calculator your using and i am getting the following answers

.815916148 for the miter &

.692128898 for the bevel.

so whats the deal with this

[donnydoors]

Efficient finish carpentry is not the point of the video. It's a study in applied math.

So how do YOU quickly cut your over-sized crown molding? Super-size saw? Butt cut and cope? Are you willing to share your expertize?

[sinclga]

I install crown molding all the time and if I used that system I would be thrown off the job for wasting time and taking too long to do the cuts.

[benny5825]

How would you do external corners,would the crown have to be placed upside down,so the flat is facing upwards?

[donnydoors]

@Harppoman: Didn't make this video as a How-To so much as an experiment to see what would happen if one followed the math. When it comes to the real thing. As explained in a a previous comment, in my own set building work, we would make a test cut, upside down and backwards, as deep as possible with the biggest chop saw available. Then we flip it over and match the cut with bevel and miter. Trial and error.

[nejdriny]

VERY HELPFU. PLUS I GOT SAME MITERSAW AT WORK. THANKS.

[nejdriny]

VERY HELPFU. PLUS I GOT SAME MITERSAW AT WORK. THANKS.

[cyganmarek]

Hi. Are you sure there is no easier way to cut it ? Because i want to do something like this but after your video i've started to feel little bit confused or maybe even stupid.

[nmele]

As a novice carpenter and veteran math teacher, I'd like to commend you on making one of the best educational videos I've ever seen. I hope you don't mind if I use this in my class next year! (2 5/8 = 2.625)

[donnydoors]

@nmele :

I'm flattered. Make use of it as you will. I can turn the file into a proper DVD should you need it. But I would request a modest compensation, being a retired carpenter struggling to hang in there.

Maybe you could interest the shop teacher at your school to take a look at my door fixing videos.

But to reiterate my original statement: It's the digital age. Download the file and use it as you will.

~ D.S.

[dauhuan]

@nmele

i think he meant square root of (4 square - 3 square), which is the square root of 7 and that would equal to 2.645.

[professorcookie]

Around the 1:30 mark I was thinking that this video was going to be less than helpful. But, the actual cutting part helped me enormously. I am not a master carpenter, however, I am now the go to guy since I can cut much better. Thanks for the info.

[Moe7133]

Old school teaching new school! :) Nothing like old schoolers! You da man!

[donnydoors]

I did this video just to see how it would work out, having taken home some big crown molding scrape from a TV set. I was lucky, especially since my little HItachi saw only tilts in one direction. I don't think the charts work out because crown moldings vary so much in size.

[donnydoors]

@donnydoors But on the job, carpenters rarely have the time to do the math. In my set builders union, the old phrase for cutting crown molding is: upside down and backwards. This dates back to the days when we'd make a special mitre box for big molding, free up the big back saw from a standard mitre box and cut away. Recently, I've had success starting such a cut on a piece of crown, then lay the mold on the chop saw table and match the position of the blade to the cut.

[Brandoskey]

i think it's a GREAT idea to know why you set the bevel and miter a certain way in order to cut crown on the flat, but doing all this math and possibly making a mistake can be costly.

my suggestion is to look at a crown chart to find your miter and bevel settings.

i still think it's a great idea to know why we use said angles, but it's not always the most practical solution.

either way good job on the video, very intelligent carpenter right here!

[vxAREKxv]

good job 5 stars you help me a lot !

[tree50va]

That reminds me, try going to any university to become a minister without taking math. I know for a fact these same formulas are taught in those same classes idiot.

[tree50va]

You are crazy. This man posted a video trying to help people with moulding and you insult him like this? Shame on you. Jesus was a carpenter and im sure he used math equations to help him with his work. We use equations all the time to help us with our work, even if we dont know we are doing it.  Shame on you!

[327h]

great video and great use of math BRAVO and GOD BLESS

[cocoaton]

this man is a satanist, and a freemason.this science was built in order to confuse the masses. There are many ritualistic phrases in these formulas. don't take my word. do your research. this man is really evil. this is a very old knowledge. going back to the scotish rite. I you read the details of carpentry and masonry there is a lot of occult rituals tied to it. These were supposed to be the builders of the world without god.he's not just talking shop he talking alot of language of the occult.

[donnydoors]

News to me. The closest I ever came to the occult was reading the ife story of Alistair Crowley. Math is math. Saw blades cut. And garbledy gook is just that.

[cocoaton]

well if your not involved in that, then I do apologize. Some know exactly what all of this stuff symbolizes. There are some that don't. Its a very interesting study. Don't take my world for it. do some research. I love wood working. I'm a woman with tools. Thats why I was drawn to your video. I saw something at the beginning like you were flashing that satanic hand sign. Many people are caught up into this stuff. They don't understand that the occult is at boil now. It dangerous

[rthomas003]

this is a great tutorial for cutting on the flat, i have always just cut crown up side down and up at an angle against the fence but it is not nearly as accurate as what you are doing here. i am not as enthusiastic about using the clamp to hold your piece though, why is that necessary? i have never needed to use a clamp to hold something i am cutting on a miter saw,does cutting on the flat create more opportunity for injury somehow? messin with that clamp would = major time loss on a big job.

[coolidge6666]

I think gdbomb5112 was comparing the results to published charts. EG 38/52 will tell you for 80 deg corner to use miter of 36.27 and bevel of 37.13 and this formula tells you the same PROPORTION but different fiqures eg 38/52 using this method= miter of 27.32 and bevel of 30.43, diffent results but should be the same angle. I guess the charts differ due to the stock being different in projection/width but they should yeild the same accurate miter, I havent tried it so cant be 100% sure.

[gdbom5112]

i have the formula you have given down pretty good, but is there another formula for cutting on the flat for walls that are not 90 degrees

[donnydoors]

The formula should work for any angle. That's what's meant by the "flat miter." In my example it's 45 degrees, half of 90. If you're molding around an octagon, then your corners are 45 degrees, so your flat miter is 22-1/2 degrees. Plug that in.

I did this video just to prove the formula works. I'm not a full-time molding installer. If you want another look at this formula, google Rick Christopherson to go to his site. Or send me your e-maill address so I can attach stuff to you.

[gdbom5112]

Uh huh now i got it. Thanks it works perfectly. But i must say for a person that isnt a full time molding installer you sure know what your talking about. Thanks for the help much appreciated