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Discussion Starter · #1 ·
Hi,
I'm new to the forum (just browsed in the past), and am hoping someone can help me out of the jam I've created.

I am installing door casing and am using a dual bevel compound miter saw. Based upon the passing recommendation of a friend, I decided to try beveling the miter cut on the legs to get a stealthier join. I had the saw set as follows:

Miter Angle: 45 degrees
Bevel: -10 degrees from 90
Kerf: 0.110

I set the bevel angle with a magnetic digital angle gauge.

Now, as I attempt to cut the head casing, I cannot match the angles. I have tried the complementary cut at 45 degree miter with +10 degree bevel and the fit isn't close. The finished edge of the head casing is far too "short" to match against the finished/facing edge of the leg.

Normally, I would scrap the materials and start from scratch, but these pieces are built-up, glued, and pre-finished, so I'd hate to lose the time (and money) I already have invested in them. I would be very grateful for any help you can provide. Thanks in advance.

Eric
 

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10 degrees is too much bevel

If you are going to deviate from a true 90, I would only go 2 degrees or so, maybe less. Both lengths of miter should be equal if your saw is set properly. Make some samples before you chop 'n hack the good stuff to get the fit just right. :yes:
 

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A slight undercut (think a few strokes of a handplane) can help in some cases when there is drywall that is proud of the frame, but why would you cut this at a compound miter when the pieces are all in the same plane? You may have very few options to work with here...
You may have to recut the top of the miter at a flat 45 and install a plinth at the bottom..
 

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10 degrees is way to drastic, 1 or 2 degrees is enough to give some relief to the bottom so the face fits tight. Rather tag tilting the saw, which can get you into trouble if you forget it was tilted for the other side, just lay a flat carpenters pencil on the table next to where the cut will be and rest your board on it.
 

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A slight undercut (think a few strokes of a handplane) can help in some cases when there is drywall that is proud of the frame, but why would you cut this at a compound miter when the pieces are all in the same plane?
+1. :yes: Cutting a bevel on the miter will leave a void either on the inside or outside corner or both depending on the profile. If the joint needs to be closed up, a handplane or rasp would be sufficient.




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Discussion Starter · #7 ·
Thanks guys, I appreciate the feedback. Going forward, I will revert to my historical approach of square cuts.

Concerning the problem at hand (as I wish to avoid scrapping the materials and plinth blocks will clash with my other molding), can anyone suggest either a saw setting for the complementary cuts (at least to line up the front-facing profile, I don't mind filling the edges) or at least point me in the right direction?

Thanks again,
Eric
 

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lessee now

You want to cut it twice and not have it too short? It will take better advice than I have..... :yes:
 

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Thanks guys, I appreciate the feedback. Going forward, I will revert to my historical approach of square cuts.

Concerning the problem at hand (as I wish to avoid scrapping the materials and plinth blocks will clash with my other molding), can anyone suggest either a saw setting for the complementary cuts (at least to line up the front-facing profile, I don't mind filling the edges) or at least point me in the right direction?

Thanks again,
Eric
Are you looking for a completely different answer? You have been given good advice.






.
 

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Discussion Starter · #10 ·
I haven't cut the head piece yet; it has about 8" extra length for now. I've been practicing on a scrap.
 

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Discussion Starter · #11 ·
Are you looking for a completely different answer? You have been given good advice.










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Not to be ungrateful, but yes. My question relates to finding the complementary angle/saw configuration to cut the head board to match the legs, which I already have cut and fastened to the wall.

Most of the advice given is great and will help me make better cuts in the future, but don't address the specific problem of cutting this head board to match the already installed pieces. Clearly the approach I took is suboptimal, but I'd like try and make it work.
 

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I don't think that you will be able to cut a complimentary angle to fill in the rest. If this is paint grade, get some 15 minute mud, an old credit card and pack the joint with mud, use the card as a scraper and follow the profile of the molding. Getting a little old world like raking plaster cornices :thumbsup: I have had to do it before on a larger molding that was a three piece corner around a round corner... lasted for years before wood movement finally cracked it, after you pack it with mud, prime it two or three times, this will help some with the cracking. The old timers used to embed lathe in their moldings, if the joint is big enough, consider some fiber of some sort. GL
 

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I'd like to see a photo of what you have

If the side legs are mitered and the bevel is negative then the head piece must slide down from the top to fit behind the bevels ...unless I don't understand this whole dilemma ..... possibly.... more than likely.... definitely? :blink:
 

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Discussion Starter · #14 ·
If the side legs are mitered and the bevel is negative then the head piece must slide down from the top to fit behind the bevels ...unless I don't understand this whole dilemma ..... possibly.... more than likely.... definitely? :blink:

You've got it exactly right. The cut shown is the one described in the original post (+10 degree bevel, intended to complement the original -10 degree cut on the right side leg). You'll see that the length of the cut is too short to match that of the leg.

I have also included a side shots.
 

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Discussion Starter · #15 · (Edited)
I don't think that you will be able to cut a complimentary angle to fill in the rest. If this is paint grade, get some 15 minute mud, an old credit card and pack the joint with mud, use the card as a scraper and follow the profile of the molding. Getting a little old world like raking plaster cornices :thumbsup: I have had to do it before on a larger molding that was a three piece corner around a round corner... lasted for years before wood movement finally cracked it, after you pack it with mud, prime it two or three times, this will help some with the cracking. The old timers used to embed lathe in their moldings, if the joint is big enough, consider some fiber of some sort. GL

Thanks for the tip. Unless someone presents a better way, I'll first look way back to my high school geometry days to see if I can calculate the volume of the void and work my way into the correct cut (or close to it). If that doesn't prove successful, mud it is. I'm not familiar, however, with what you mean by lathe..??
 

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how's this?

Just cut the head piece at a true 90 degree as see if the length matches up better. If so, just mud in behind the negative bevel and let it squeeze out as you press down, clean it up and go home... just sayin'.

metal lath is expanded metal screen used in wet plaster wall and such.

I also wonder if the head piece is from the same stock as the sides...? Is it a cut off?
 

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Discussion Starter · #17 ·
Just cut the head piece at a true 90 degree as see if the length matches up better. If so, just mud in behind the negative bevel and let it squeeze out as you press down, clean it up and go home... just sayin'.

metal lath is expanded metal screen used in wet plaster wall and such.

I also wonder if the head piece is from the same stock as the sides...? Is it a cut off?

Thanks. The head piece is identical stock. Unfortunately, the true 90 degree cut at 45 degree miter is much worse. It seems that the beveling resulted in an effective miter angle of 47-48 degrees on the leg, hence the longer cut (hypotenuse, I guess?). I'll play with it some more, perhaps experimenting with 90 degree cuts at 42-43 degree miter will help (I'll try that tomorrow...too late for that kind of noise). If no luck, mudding it shall be.
 

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Best fix is to start with new pieces of molding, if available. When you cut compound angles the miter changes significantly. I am installing crown molding cutting it flat on the miter saw and cutting compound angles. My Starrett digital protractor gives me proper bevel and miter angle for installing crown molding. I know you are not installing crown molding, I am just using this as an example of how the angle changes when you go to compound angle cuts.

Example with 45 degree spring angle crown molding in a perfect 90 degree corner the miter angle is 35.3 degrees and the bevel angle is 30.0 degrees. This makes a perfectly fitting mitered corner joint with this crown molding in a perfect 90 degree corner.

George G
 

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You've got it exactly right. The cut shown is the one described in the original post (+10 degree bevel, intended to complement the original -10 degree cut on the right side leg). You'll see that the length of the cut is too short to match that of the leg.

I have also included a side shots.
Looking at second photo it appears you have extra length in the upright to make another proper 45 degree cut if you remove it.
 

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Thanks. The head piece is identical stock. Unfortunately, the true 90 degree cut at 45 degree miter is much worse. It seems that the beveling resulted in an effective miter angle of 47-48 degrees on the leg, hence the longer cut (hypotenuse, I guess?). I'll play with it some more, perhaps experimenting with 90 degree cuts at 42-43 degree miter will help (I'll try that tomorrow...too late for that kind of noise). If no luck, mudding it shall be.
I am a little confused. if the miter angle is set to 45 degrees, and a bevel is added to "tilt" the blade, why isn't the miter still at 45 degrees? I can't visualize why it will alter the miter angle. guess i'll have to go look at my saw.

fyi i always take away 1/2 degree on the back side of my miters for casings to close up the front, walls and jambs are seldom on the same plane.
 
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