Beveled miter on door casing - Page 3 - Woodworking Talk - Woodworkers Forum
Reply
 
Thread Tools Display Modes
post #41 of 50 Old 09-05-2013, 09:25 PM
Senior Member
 
Join Date: Aug 2012
Location: British Columbia, Canada
Posts: 5,666
View FrankC's Photo Album My Photos
Quote:
Originally Posted by woodnthings View Post
It's the length of the bevel on a constant width piece that seems to be the issue here. If you don't mind trying that OR if you already know please inform us. This is a mind bender!
When you swing your miter saw to 45 degrees and bring the blade down it passes through the slot in the table, now tilt the blade off perpendicular, it still passes through the slot in the table the same as when perpendicular only at an angle.

A compound miter at 45 degrees will still have four corners that form a square or rectangle, they just don't sit flat when joined.

Wise men speak because they have something to say; fools because they have to say something -Plato

FrankC
http://sawdustmaking.com
http://woodworkerglossary.com
FrankC is offline  
Sponsored Links
Advertisement
 
post #42 of 50 Old 09-05-2013, 09:36 PM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 27,623
View woodnthings's Photo Album My Photos
Thanks, but not what I had in mind ...

I'm seeing the bevel as a pivot of the saw and motor on some shaft
that's horizontal with the table. Where the center of rotation is located "may" affect the length of the leg on a miter...I donno? I would not think at least on the saws I'm familiar with, that the blade plane is the center on which it rotates, rather offset from the blade by some amount. This I believe, is what causes a bevel miter to change it's leg length over a straight down 90 degree miter....again, I donno? My degree is in ART/Design not engineering. My trigonometry expertise is very faded after all these years.

Any engineers listening to all this? WillemJM ?

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is offline  
post #43 of 50 Old 09-05-2013, 10:08 PM
Senior Member
 
chopnhack's Avatar
 
Join Date: Dec 2007
Location: Somewhere sunny
Posts: 155
View chopnhack's Photo Album My Photos
Sigh..

Geometry is complicated without pictures! I will give it a go



Ok, so what we see above is a 45 degree cut across the width of the piece of wood, as it lies flat on the bed of the cms. The first vertical line with the square attached is a perpendicular cut to the width, i.e. saw set at no bevel, 45 degree miter. This is your typical miter setting on baseboard, casing etc.

The next vertical line with the attached arc shows a 10 degree from vertical pitch. This would create a void on the back side of the molding, similar to what the OP stated. Notice how the lengths on top do not change . On crown, the lengths would change, but that is because they are held in position. This means you are working with a compound miter being cut on an angled piece of wood and that is what changes the lengths of crown miters as the angle settings change.

Clear as mud?

Last edited by chopnhack; 09-05-2013 at 10:10 PM.
chopnhack is offline  
The Following User Says Thank You to chopnhack For This Useful Post:
FrankC (09-05-2013)
Sponsored Links
Advertisement
 
post #44 of 50 Old 09-05-2013, 10:17 PM
where's my table saw?
 
woodnthings's Avatar
 
Join Date: Jan 2009
Location: SE, Michigan
Posts: 27,623
View woodnthings's Photo Album My Photos
OK, now we're getting closer..

But this is a theoretical explanation. I would like to see the same thing in real wood using a real saw. I see what you are saying that the bevel angles don't change and we knew that way back in the thread.
But there must be a reason the legs are different lengths in the photo.
My explanation is also theoretical, since I can't prove it ...yet....



Maybe I'll have to do it myself to show me if my theory is correct or all wet.

The answer to your question will only be as detailed and specific as the question is detailed and specific. Good questions also include a sketch or a photo that illustrates your issue. (:< D)
woodnthings is offline  
post #45 of 50 Old 09-05-2013, 10:25 PM
Senior Member
 
Join Date: Aug 2012
Location: British Columbia, Canada
Posts: 5,666
View FrankC's Photo Album My Photos
It is possible for the board to move during a compound miter cut, which could be a reason for the long cuts that are not at 45 degrees, I usually use the hold down on my saw when doing them.

Wise men speak because they have something to say; fools because they have to say something -Plato

FrankC
http://sawdustmaking.com
http://woodworkerglossary.com
FrankC is offline  
post #46 of 50 Old 09-05-2013, 10:47 PM
Senior Member
 
chopnhack's Avatar
 
Join Date: Dec 2007
Location: Somewhere sunny
Posts: 155
View chopnhack's Photo Album My Photos
I'm just clarifying because there seemed to be some discussion in previous posts to the contrary: <<A miter is made in a vertical plane 90 degrees to the table. When you add a bevel this changes the approach angle of the blade to other than vertical. I can see how this would change the length of the mitered angle as well.>>

But going back the OP mentioned that the reason for longer lengths was a 47 degree instead of a 45 degree miter.

I also noticed that there was some room behind the molding between the wall. You may be able to rock the molding forward for a better fit, shim and nail. Rock forward meaning rotate down and towards you, away from the wall.
chopnhack is offline  
post #47 of 50 Old 09-05-2013, 11:38 PM Thread Starter
Junior Member
 
Join Date: Sep 2013
Location: Long Island, New York
Posts: 17
View ejordan's Photo Album My Photos
Quote:
Originally Posted by chopnhack View Post
I'm just clarifying because there seemed to be some discussion in previous posts to the contrary: <<A miter is made in a vertical plane 90 degrees to the table. When you add a bevel this changes the approach angle of the blade to other than vertical. I can see how this would change the length of the mitered angle as well.>>

But going back the OP mentioned that the reason for longer lengths was a 47 degree instead of a 45 degree miter.

I also noticed that there was some room behind the molding between the wall. You may be able to rock the molding forward for a better fit, shim and nail. Rock forward meaning rotate down and towards you, away from the wall.
To clarify, I made the cuts from 45 degree positive stops, the effective cut is closer to 47 degrees, hence the longer edge and the basis for the original post.

You noted gaps between the wall. On the left side (near side in the pictures), what you actually are seeing is a small gap where the back band (glued, nailed, and painted) doesn't quite cover the casing profile, leaving a 3/16 gap which I will caulk later. On the right (far) side, you see a combination of that and a gap where the drywall is not flush to the door frame. The piece is supported by 1/8 - 3/16 strips and caulked, just not caulked at the joint yet.
ejordan is offline  
post #48 of 50 Old 09-05-2013, 11:43 PM
Senior Member
 
chopnhack's Avatar
 
Join Date: Dec 2007
Location: Somewhere sunny
Posts: 155
View chopnhack's Photo Album My Photos
Don't forget to post finished pics to see how this turned out
chopnhack is offline  
post #49 of 50 Old 09-06-2013, 07:30 AM Thread Starter
Junior Member
 
Join Date: Sep 2013
Location: Long Island, New York
Posts: 17
View ejordan's Photo Album My Photos
Quote:
Originally Posted by chopnhack View Post
Don't forget to post finished pics to see how this turned out
Will do - that will be Sunday's project.

Unless I am able to figure out the angle/bevel needed to complement what's already there, I likely will try Frank C's recommendation of re-cutting the boards. After looking closely, he is correct in the, since the effective cut is a steeper angle, the error was on the long side, leaving enough stock for a square 45 degree cut. See pic showing 45 degree cut. See pic with 45 degree cut shown.

Given how extreme this particular back cut is, there may not sufficient material on the back side, but the front should align and I will just fill the back with mud.

Beveled miter on door casing-new-cut.jpg

Last edited by ejordan; 09-06-2013 at 07:36 AM. Reason: add picture
ejordan is offline  
post #50 of 50 Old 09-06-2013, 08:37 AM
Senior Member
 
Join Date: Jan 2010
Location: NW Pa
Posts: 2,995
View TimPa's Photo Album My Photos
i believe that a complimentary angle does not exist, that will provide the profile matching and the same miter length (as your last pic clearly shows), when the original side angle is not close to 45 degrees. re-cut would be way to go.
TimPa is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Woodworking Talk - Woodworkers Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Similar Threads
Thread Thread Starter Forum Replies Last Post
Cutting Door Casing 45 degrees glg54 Trim Carpentry & Built-Ins 36 04-09-2013 08:36 PM
Best Joint for a Door Casing Herbwood Joinery 1 08-24-2011 11:44 PM
rotten 20" wide door casing CarlySmarts Trim Carpentry & Built-Ins 5 11-27-2010 06:35 AM
Mission style interior door casing chadchiro General Woodworking Discussion 3 11-17-2010 10:53 AM
Groove on back side of door casing davej77 Trim Carpentry & Built-Ins 4 08-29-2010 07:25 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome