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Compound Miter Saw miter cut - help please

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Forum topic by ghawell00 posted 10-22-2014 12:47 AM 1354 views 0 times favorited 10 replies Add to Favorites Watch
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ghawell00

7 posts in 779 days


10-22-2014 12:47 AM

Topic tags/keywords: compound miter saw cuts

Hello to all, I am a newbie woodworker:

This is a stupid question but I have to ask for help with compound miter cuts. I have been on the forum, YouTube and web searching for the answer for 3 days. I have given up totally. I am trying to learn to cut crown molding for building a door cross header, mantel and shelves. I “figured out” the 45 degree angles on left and right (“see picture 1”) to fit around a square box. I got that one down after 2 days. Beginner!

What I can’t figure out is that:

If I want to cut the crown molding wider say 50” miter (see picture 2) how do I calculate the miter and bevel so it will line up on sides and fit around a square box as picture 1. I can’t figure this out and I have tools if anyone has advice (see pictures 3). I just don’t get it.

I appreciate any help!!


10 replies so far

View jerryminer's profile

jerryminer

528 posts in 907 days


#1 posted 10-22-2014 02:07 AM

Cutting crown molding—- pretty big subject. I’ve cut miles of it. I like to cut crown “in position” on a miter saw. No compound-miter calculations needed. Just set the crown in the saw like the pic, and swing the saw to a “regular” miter and cut. any wall angle you want.

Compound miter calculations are available on the web. You will need to know the “spring angle” of your crown (38 deg. is common, but there are many variations). Google “compound miter” and you will find math formulas, usually involving a couple of trig functions.

View ghawell00's profile

ghawell00

7 posts in 779 days


#2 posted 10-22-2014 02:33 AM

Jerry, thanks for responding to my post. Thanks for the tip because I can build that jig with ease and it will make it much “easier” to cut and at different angles. I google the “spring angle and and compound miter” and wow I founded a wealth of information with those two words even on You Tube.

Thanks again for the help! Well appreciated


Cutting crown molding—- pretty big subject. I ve cut miles of it. I like to cut crown “in position” on a miter saw. No compound-miter calculations needed. Just set the crown in the saw like the pic, and swing the saw to a “regular” miter and cut. any wall angle you want.

Compound miter calculations are available on the web. You will need to know the “spring angle” of your crown (38 deg. is common, but there are many variations). Google “compound miter” and you will find math formulas, usually involving a couple of trig functions.

- jerryminer


Cutting crown molding—- pretty big subject. I ve cut miles of it. I like to cut crown “in position” on a miter saw. No compound-miter calculations needed. Just set the crown in the saw like the pic, and swing the saw to a “regular” miter and cut. any wall angle you want.

Compound miter calculations are available on the web. You will need to know the “spring angle” of your crown (38 deg. is common, but there are many variations). Google “compound miter” and you will find math formulas, usually involving a couple of trig functions.

- jerryminer


View ColonelTravis's profile

ColonelTravis

1192 posts in 1359 days


#3 posted 10-22-2014 02:56 AM

Haven’t cut miles like Jerry but I’ve done our house. Can be frustrating at first, but the key is making sure you keep every board in the same position. A tip that helped me – if you look at Jerry’s drawing, put a big strip of blue tape on the base of your saw in the general area where your board is going to rest, lay your board in the position it’s going on the wall, hold it there, mark with a pencil on the blue tape where the bottom of your board rests, and then when you go from board to board you just line up the bottom with that line and it will be consistent every time. Sorry, not boards, crown, I’m lazy and not gonna go back and change all that.

On my wife’s side of the family there are so many builders and they can cut this stuff blindfolded. Envious of that, but it just takes practice.

View Loren's profile

Loren

8313 posts in 3113 days


#4 posted 10-22-2014 02:59 AM

Here’s a useful video that explains the topic well:

Aside from the approach under discussion, these digital angle
finders like the one Bosch makes will do the trig for you.
I have one. It’s pretty slick for wide crown applications
(interior designers love that wide crown) where
the cutting has to be done on the flat.

View ghawell00's profile

ghawell00

7 posts in 779 days


#5 posted 10-22-2014 05:18 PM

Thanks for the video, this video is a good tutorial! I start building a jig last night to make it a little easier.

Could you take a look at the “picture” I attached?

The first one is a cut that is 45 degree miter “and” 45 degree bevel

I don’t want this exact cut, but if I was to cut this …..

See the next “picture” how would I calculate the side cut to fit around a mdf box. 90 Degree angle

Because the cut I making for the side cuts makes a V angle 180 degree and want wrap around a square box. (see picture)

Thank you for any help!!!

Here s a useful video that explains the topic well:

Aside from the approach under discussion, these digital angle
finders like the one Bosch makes will do the trig for you.
I have one. It s pretty slick for wide crown applications
(interior designers love that wide crown) where
the cutting has to be done on the flat.

- Loren


View ghawell00's profile

ghawell00

7 posts in 779 days


#6 posted 10-22-2014 05:20 PM


Jerry thanks for the tip, I am trying all! You guys are a wealth of information! I am already buidling the jig, start last night. I will try your tip tonight.

Haven t cut miles like Jerry but I ve done our house. Can be frustrating at first, but the key is making sure you keep every board in the same position. A tip that helped me – if you look at Jerry s drawing, put a big strip of blue tape on the base of your saw in the general area where your board is going to rest, lay your board in the position it s going on the wall, hold it there, mark with a pencil on the blue tape where the bottom of your board rests, and then when you go from board to board you just line up the bottom with that line and it will be consistent every time. Sorry, not boards, crown, I m lazy and not gonna go back and change all that.

On my wife s side of the family there are so many builders and they can cut this stuff blindfolded. Envious of that, but it just takes practice.

- ColonelTravis


View ghawell00's profile

ghawell00

7 posts in 779 days


#7 posted 10-22-2014 05:21 PM

Let me ask you also:

Thanks for the video, this video is a good tutorial! I start building a jig last night to make it a little easier.

Could you take a look at the “picture” I attached?

The first one is a cut that is 45 degree miter “and” 45 degree bevel

I don’t want this exact cut, but if I was to cut this …..

See the next “picture” how would I calculate the side cut to fit around a mdf box. 90 Degree angle

Because the cut I making for the side cuts makes a V angle 180 degree and want wrap around a square box. (see picture)


Jerry, thanks for responding to my post. Thanks for the tip because I can build that jig with ease and it will make it much “easier” to cut and at different angles. I google the “spring angle and and compound miter” and wow I founded a wealth of information with those two words even on You Tube.

Thanks again for the help! Well appreciated

Cutting crown molding—- pretty big subject. I ve cut miles of it. I like to cut crown “in position” on a miter saw. No compound-miter calculations needed. Just set the crown in the saw like the pic, and swing the saw to a “regular” miter and cut. any wall angle you want.

Compound miter calculations are available on the web. You will need to know the “spring angle” of your crown (38 deg. is common, but there are many variations). Google “compound miter” and you will find math formulas, usually involving a couple of trig functions.

- jerryminer

Cutting crown molding—- pretty big subject. I ve cut miles of it. I like to cut crown “in position” on a miter saw. No compound-miter calculations needed. Just set the crown in the saw like the pic, and swing the saw to a “regular” miter and cut. any wall angle you want.

Compound miter calculations are available on the web. You will need to know the “spring angle” of your crown (38 deg. is common, but there are many variations). Google “compound miter” and you will find math formulas, usually involving a couple of trig functions.

- jerryminer

- ghawell00


View jerryminer's profile

jerryminer

528 posts in 907 days


#8 posted 10-23-2014 03:06 AM

You are trying to cut something like this, right?:

If you are trying to cut “on the flat”——and trying to figure out the miter and bevel angles, you may want to look at this chart:

compound miters

With a 38 degree spring angle the settings are: Miter: 31.6 Bevel: 34

But if it fits in your saw, I still think it’s easier to cut “in position” :

View ghawell00's profile

ghawell00

7 posts in 779 days


#9 posted 10-23-2014 09:21 PM

Jerry, that’s exact what I am trying to build, its very similar!!! (attached a picture, making the crossheader as a shelve)

That picture is perfect and again exact what I am trying to do for the ends!! To add, those photos you added is awesome because I am a visual learner. (start making the jig hours after you sent me the first photo, finishing it up today – see pic)

Thanks for the link to the compound miter chart. I looked at the chart and study it for a minute. I had to Google to figure how to read it and practice on the saw, but I finally got it!!! Chart is awesome. Due to that, I found another article online after Googling how to read the chart but had a calculator to plug in the numbers. Talks about the spring, slop and run and etc. Stuff you outlined in the post! Crazy but I am taking one part at a time and practicing until I get the whole piece down.

Jerry there is a wealth of information on the web, but they show you the first and last steps! Never show the moulding on the saw and turn the compound miter saw to the miter or bevel cut or a picture. Left me turning to figure this all out….

“Thanks again, I appreciate all your wealth of information and help!”

You probably don’t need a calculator but I added for you see: http://www.pdxtex.com/canoe/compound.htm

If you are trying to cut “on the flat”——and trying to figure out the miter and bevel angles, you may want to look at this chart:

compound miters

With a 38 degree spring angle the settings are: Miter: 31.6 Bevel: 34

But if it fits in your saw, I still think it s easier to cut “in position” :

- jerryminer


View ghawell00's profile

ghawell00

7 posts in 779 days


#10 posted 10-23-2014 09:24 PM

Travis, thanks for your help and tip!

Haven t cut miles like Jerry but I ve done our house. Can be frustrating at first, but the key is making sure you keep every board in the same position. A tip that helped me – if you look at Jerry s drawing, put a big strip of blue tape on the base of your saw in the general area where your board is going to rest, lay your board in the position it s going on the wall, hold it there, mark with a pencil on the blue tape where the bottom of your board rests, and then when you go from board to board you just line up the bottom with that line and it will be consistent every time. Sorry, not boards, crown, I m lazy and not gonna go back and change all that.

On my wife s side of the family there are so many builders and they can cut this stuff blindfolded. Envious of that, but it just takes practice.

- ColonelTravis


Haven t cut miles like Jerry but I ve done our house. Can be frustrating at first, but the key is making sure you keep every board in the same position. A tip that helped me – if you look at Jerry s drawing, put a big strip of blue tape on the base of your saw in the general area where your board is going to rest, lay your board in the position it s going on the wall, hold it there, mark with a pencil on the blue tape where the bottom of your board rests, and then when you go from board to board you just line up the bottom with that line and it will be consistent every time. Sorry, not boards, crown, I m lazy and not gonna go back and change all that.

On my wife s side of the family there are so many builders and they can cut this stuff blindfolded. Envious of that, but it just takes practice.

- ColonelTravis


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