HI
I have a wall where the inside angle is approx. 134-degrees. I have a mitre-saw such that I can set to cut 45s or whatever I want I presume. In this case I do not know how to set the saw so that I accomplish this angle. It is probably basic geometry, and I need some help to make this a measure-twice cut once job rather than by trial and error.
Thank-you for reading.
Wouldn’t you just cut two at 23-degrees?
134 - 90/2
That’s exactly what I needed…thanks very much.
Oh wait a sec…
how do you get 23?
134 - 45 = 89.
I asked a similar question a while back, but the thread is too old to search.
Anyway, cut one piece to fit square to the wall. On the other piece cut a 45 as if you were fitting an outside corner (the face extends further than the back side)
Then take a scrap of the material and put it against the face and trace the outline. Cut along the outline with a coping saw. Check the fit. You may have to touch it up with some sandpaper.
Anyway you will get a perfect joint this way, and it does not matter what the angle of the intersection is.
I think it was Crafter man that suggested this in my thread, so thank him.
(134-90)/2 = 22
Yup, inside corners shouldn’t be miter joints they should be coped.
CMC +fnord!
Don’t bother tracing. Just use a miter saw to cut a 45-degree angle on the piece that you are going to cope. Look at the line where the angled face meets the front of the molding: it’s a perfect rendition of the profile of the molding – now just cut with your coping saw following that line.
You may want to then use a utility knife to trim some relief in the back side of the coped piece a little. A Dremel tool with a sanding drum can also be used here.
I’m having a little bit of difficulty explaining this in words, but as soon as you experiment with some scrap molding you will see what I’m trying to describe.
I personally wouldn’t cope chair rail and especially not on a wall with an odd angle.
I am still having trouble with this even though in the first example I was successful. That wall was oriented in a different position, so I must have lucked out. That wall is oriented east-west and the adjoining wall is projected outwards towards the north-east. 2 cuts at 23 worked perfectly.
Now I am on a different wall and I am messing it up.
For this other wall it is situated north-south, and the adjoining wall projects to the south-west. It looks like a very wonky, large open-mouthed “greater-than” symbol on the keyboard.
I used this nice little protractor to measure this “inside” angle, and it is a 150-deg angle.
So following Enipla’s reply I (150 - 90) /2 = 30. I tried cutting my chair rail such that one cut the saw was set to the right at the 30-degree mark, and then the other cut I moved the saw to the left 30-degree mark, but when I put the chair rail against the wall flush I get this “gap”…it’s got to be something rather simple but I am mucking it up horribly.
Why not? My chair rail came out looking perfect.
Was it on a 23 degree angle?
Coping inside corners works great if the corner is 90 degrees and the second cut is at 45 degrees. if the corner is greater than 90 degrees, you have to remove an unwieldy amount of stock from the back of the second piece to get it to fit over the first one. Much easier to make two equal miters.
On running trim in an over-90 inside corner: Rather than goof with the math, I use an angle finder (a handle with a blade that tightens down to it with a wing nut) I press it into the corner, tighten it down, and transfer the angle to a scrap. I then use a compass to bisect the angle and then read it with a protractor. Both of these tools can be purchased in any School Supplies section for about 89 cents each.
In any case, it’s always a good idea to cut your angles on two pieces of scrap first, trial fit, and re-cut until you get them right. Then cut those angles on the long pieces.
No, and I seriously doubt that anyone on this message board has two walls that join at a 23 degree angle. :dubious:
The OP was talking about a 134 degree angle. You can cope this just fine.
In my house I did not measure the angles, but I can guarantee you none of them are exactly 90 degrees.* That is the beauty of coping, the angle doesn’t matter.
*My laundry room is 8’ X 8’6". It is almost 4" out of square. :eek: I think my house was framed on a Friday afternoon at beer:30.
Two words, Dremel tool
I am such a dumass…I was reading my little tool wrong. The angle was actually 60-degrees, and not 150 (this is the second wall that I was dealing with).
Using the forumlua provided (60-30)/2 I was able to just made 2 cuts at 30 degrees and I got it done.
Thanks all for the help. Turned out to be “operator error”.
:dubious:
Maybe (150-90)/2 = 30?
:smack:
Sorry my original calcs where off by a degree. But it seems as though you have a handle on it.
Sorry, I guess I’ve used too many angle finders which tell you what to cut. The wall is a 23 degree angle to a good angle finder. Or a bad one. 
I’ve never seen anyone cope an obtuse angle, or any chair rail for that matter, but it’s just my personal preference that I wouldn’t cope it. You can always look at the lines on the top and tell when one has been coped to ‘overlap’ the first, but equal miters are always neater, more symmetrical. It’s ok for base, but chair rail is at the perfect height for it to be noticeable. But I come from the “measure twice, cut once” school, some people may rather cut extra to avoid measuring the angle.
AHHHHH I screwed up AGAIN!
:smack:
I ended up making 2 cuts at 15 degree angles and that’s when I got it done.