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Forum topic by CB_Cohick posted 07-15-2015 01:48 PM 530 views 0 times favorited 12 replies Add to Favorites Watch
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CB_Cohick

460 posts in 712 days


07-15-2015 01:48 PM

Topic tags/keywords: question miter saw geometry trim

I messed around with this long enough to find a compound bevel that works. My question is why does it work? I want to know the logic behind why 33.9 degrees allows these pieces to come together. I understand the 45 degree piece of this compound bevel, and in my head I imagined somewhere near 40 degrees was the magic for the second angle. Then I noticed a mark for 33.9 degrees on my compound miter saw and gave it a shot. Well, butter my buns and call me a biscuit it worked. I want to understand why. Here is the moment of success.

-- Chris - Would work, but I'm too busy reading about woodwork.


12 replies so far

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Yonak

979 posts in 982 days


#1 posted 07-15-2015 02:02 PM

Chris, you must understand the concept of compound angles because you figured an angle of about 40° would be about right for a good fitting joint. Clearly, 33.9° is the constant. Whether some wise person figured it out by trial and error or if they calculated it doesn’t matter .. What was your question again ?

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CB_Cohick

460 posts in 712 days


#2 posted 07-15-2015 02:09 PM



What was your question again ?

- Yonak

What is the mathematical equation that gives the answer 33.9? Something like 3(2x+2y)(magic)=33.9

-- Chris - Would work, but I'm too busy reading about woodwork.

View rwe2156's profile

rwe2156

2190 posts in 941 days


#3 posted 07-15-2015 04:00 PM

Compound angles just like cutting crown molding.

There is also a similar thing in chair making where the legs have two angles, the splay and the something else. Anyway, the combination is the “resultant” angle.

As far as the equation….

....Google it!!

-- Everything is a prototype thats why its one of a kind!!

View dhazelton's profile

dhazelton

2322 posts in 1757 days


#4 posted 07-15-2015 05:38 PM

That doesn’t look right – has an open birdsmouth.

I thought the 33.9 was for cutting standard crown when you tilt the blade. Spring angle and all that good stuff.

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CB_Cohick

460 posts in 712 days


#5 posted 07-15-2015 05:45 PM



That doesn t look right – has an open birdsmouth.

- dhazelton

Yeah, I need to clean up the cut a bit, and hold it better. But it really does fit if you jiggle it around just right. I also thought the 33.9 was just for crown molding. Maybe 33.9 is merely close.

-- Chris - Would work, but I'm too busy reading about woodwork.

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Yonak

979 posts in 982 days


#6 posted 07-15-2015 07:26 PM

3(2x+2y)(magic)=33.9

- Chris

I think you got it.

View JoeinGa's profile

JoeinGa

7479 posts in 1468 days


#7 posted 07-15-2015 07:26 PM


What is the mathematical equation that gives the answer 33.9? Something like 3(2x+2y)(magic)=33.9

- CB_Cohick

.

-- Perform A Random Act Of Kindness Today ... Pay It Forward

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dhazelton

2322 posts in 1757 days


#8 posted 07-15-2015 09:48 PM

How did you hold the corner bead to the fence? Needs more ‘splainin.

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Yonak

979 posts in 982 days


#9 posted 07-15-2015 10:08 PM

Clearly, 33.9° is the constant.

On the other hand, I don’t understand why each rail does not have two 45° cuts at right angles to each outside face.

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dhazelton

2322 posts in 1757 days


#10 posted 07-16-2015 12:25 PM

I believe we’re talking one cut. 33.9 bevel at 33.9 miter? He hasn’t explained….

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CB_Cohick

460 posts in 712 days


#11 posted 07-16-2015 12:34 PM



How did you hold the corner bead to the fence? Needs more splainin.

- dhazelton

Right you are. The corner bead is L shaped (90 degrees). I held one side of the L flat against the fence. The miter angle was set to 45 degrees, and the bevel angle was set to 33.9.

-- Chris - Would work, but I'm too busy reading about woodwork.

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Yonak

979 posts in 982 days


#12 posted 07-16-2015 12:51 PM



I believe we re talking one cut. 33.9 bevel at 33.9 miter? He hasn t explained….

- dhazelton

Wouldn’t one cut leave a void in the middle with no way to attach ?

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