Hi finish dudes. As most of you know I’m a framer…. so bear with me. I recently built a dormer that called out for crown under the rake serving as a frieze of sorts. The roof was an 4 pitch so that created an obtuse true angle of around 144 degrees or so. I can’t really recall the exact number right now, but I threw the Bosch miter finder on it at the time.
Keep in mind that when crown runs up the inside of a rake it creates a weird situation. The wall of the dormer is still the wall the crown projects up and out from and the soffit of the rake is the ‘ceiling’. But the inside of the corner at the peak is where it gets tricky because the ‘long point’ of the miter actually need to be on the top of the crown. Whereas if you were mitering this inside corner in a usual situation the long points would obviously be on the bottom of the crown.
But I don’t like to miter crown on inside corners and especially not in an exterior situation where movement will be an issue for sure.
So here’s how my line of thinking went……. with that 144 degree corner, I was thinking I could just take 180 minus the 144 and end up with 36 degrees in ‘miter saw angle language’. So I first tried cutting the crown in position with the saw table swung to 18 degrees. I don’t remember exactly what I did, but I recall getting confused and flipping the stock right-side up against the fence (IIRC) to get the ‘long point’ to be on the apppropriate edge of the crown. Then I hogged out the back with my coping saw as usual and got a horrible fit. 🙂
So I then just tried using the bevel and miter settings that the Bosch angle finder gave me and cut it on the flat. This was a nicer fit. But I had to hog out an insane amount of the back side of the crown to get the joint to close up tightly. And I’m thinking I may have actually had to reverse the miter/bevel angles. Not sure on that one though. I was starting to get frustrated and just wanted to get the gable up so I was trying just about everything.
In the end, it looks great. But I’d really like to know the correct way to go about this in the future to save some frustration, time……. and crown! 🙂
This particular crown had a 45 degree spring angle BTW.
Any help? (Go easy) 🙂
Edited 4/15/2007 6:37 pm ET by dieselpig
Replies
what you describe reminds me of the situation that occurs when you are cutting the miter's for fascia on square cut rafters. the angle changes in relation to the pitch, and is less than 45. will holliday reprints with permission in his book roof cutters secrets the formula for that one.
the "hogging out" with the coping saw indicates a compound bevel for which i am certain there is a formula, but i certainly don't know it.
i would do as you did, make an educated guess, and remove material to fit. most of the supposed math genius's do not have the added degree of difficulty we framers deal with, exhausted, hot, sweaty, time pressure from schedule, etc.
I have not a set answer in cases like these and probably what you did was your answer. Usually I think in terms of a transitional block of some sort that is acceptable which both sides can butt to.
I have never run into that exact situation - don't do a lot of crown, and its seldom used in exterior situations, like you describe, here in Central Calif. But I do have some crown molding experience, and some roof-cutting experience, and I enjoy a math puzzle.
It sounds to me like your solution was more complex than it needed to be.
It seems to me that if your miter saw was set to cut at 56.3 degrees (which I guess would be 33.7 degrees on the miter angle marker, since a 90 degree cut is marked as 0), the angle of the plumb cut on a 8:12 roof (you can double-check me on that), and the crown molding was set in the miter box "upside down and backwards" as Tom Law used to say (i.e., the cutoff on the right side of the blade would be the crown that goes down the left side of the gable), with the spring angle sprung (at 45 degrees), then one fell swoop would yield the proper angle for the crown to miter tight at the ridge. No?
Maybe that's too easy, because of the size of the crown it wouldn't fit in the miter box in the "sprung" position, and had to be laid flat and cut with a compound angle? If that was the case, I'd do exactly as described above, with a smaller piece that has the identical spring angle. Then you could use that to set your angles on the compound miter saw.
"...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Edited 4/15/2007 2:57 pm by Huck
Lost me. But anyway, remember that most crown moulding stops on a saw are for a 38 degree spring angle.
I probabaly would have done the same as you wound up doing.
Parolee # 40835
Yeah, didn't use any of the stops on the saw because on my LS1013 they're just for 90 degree corners cut on the flat, IIRC.
I probabaly would have done the same as you wound up doing.
Good. Now I don't feel like such a butcher. ;)View Image
Brian:
Can you post a photo? I want to understand this one.
here's what I envision (sorry about the size)View Image"...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
I cut a section away so you can see the profile of the 45 degree crown molding a little better"...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
I'm having a hard time understanding what Huck's diagram is representing. Here's a photo of a similar job. This is not the job in question, but we ran crown in a similar manner here on this one so it'll work as a reference. On this one, I boogered a miter and the joint opened up again by the time I was done framing the house.... hence the burning desire to cope these joints from here on out. Pre-primed crown woulda helped, I'm sure, but I don't get to choose the materials... just install 'em.
It's not a great pic, but it's the best I've got showing the situation. Notice that as the crown runs up the belly of the gable rake.... it hits the peak.... and the inside miter is actually an upside-down miter if you think about it enough. It's an inside corner, but the "long point" of the miter (if you were to miter it) is on the top of the molding where as in a "normal" situation and inside corner would have the long point of the miter on the bottom of the molding.
If it helps any.... I did the same detail on some smaller dormers on the same job. But these dormers were a 12 pitch..... 45 degree inside corner. And I was able to cut the crown in position with the miter saw simply set at 45 and cope as normal with a great fit.
But when you add in the fact that the roof in question is a 4 pitch (typo in the original post of mine) that creates a very obtuse angle... and then the whole upside down corner thing.... it gets complicated fairly quickly. To me, anyway.
View ImageView Image
Or another way to think about that corner.....
Picture the gable laying flat on the deck. The crown actually goes from the "floor to the wall" rather than from the "wall to the ceiling". And this is what creates the 'upside-down' inside corner joint. So imagine if you had a client who had an octagon shaped room... and wanted you to install crown as the base molding! :)
Any help here dudes?View Image
dieselpig
I couldn't say I'm a bona fide finisher but the rules I use when coping interior trim are
The coped piece must be first cut at the angle as if it were to be mitered to generate the proper profile
The farther from 90 you get, the more you must hog out to get the face to be tight
In this case I guess you'd need to take out quite a pile of the back.
And you certainly are no hack from what I read here at BT.
Regards
Ian
I work through strange crown situations following a rather intuitive approach. Simply cope from the line where two planes of the molding meet.
It's rather easy to cut a mitered joint for the crown at the peak of the gable soffit, even if it's using scraps and a trial and error. These mitered cuts show the exact line the planes of the two sections of crown meet regardless of the type of joint. All we're doing with a cope is allowing one section to run by uncut and coping away excess wood on the piece that butts into the joint.
If you can figure out the miter, you've done 90% of the work to get an oddball cope.
A very simple cope such as base follows the same rule of thumb--cutting one piece at 45 degrees as we'd do for a mitered joint simply provides the profile to cope. It isn't 45 degrees that's worth remembering, it's the fact that this cut represents the exact intersection of the two planes.
Coping around the interior of an octagon would simply be a matter of finding the angle for a miter joint and use that to cope the profile.
Cheers
Beer was created so carpenters wouldn't rule the world.
I missed the part that he wanted a coped, rather than a mitered joint. I would probably use a mitered joint in this application, but since this detail is rare here, I'm sure I'm not aware of the shrinkage factor lengthwise in a piece of exterior trim like this.
But as you point out, a coped joint is begun with a miter cut, then scarfed back from the miter line. The opposite piece needs no miter cut, it is simply cut to fit in the corner that its going to. Then a miter is cut for the overlapping piece, and the back of the cut scarfed out to make room for the lap. A disc grinder makes quick work of the coping.
My figures were given for an 8:12 pitch, but the same principles would apply in a 4:12 pitch, the angles would just have to be adjusted accordingly."...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
f you can figure out the miter, you've done 90% of the work to get an oddball cope.
LOL.... yeah that's the point brother. :) The problem I'm having is determining the correct angles given the fact that unless I'm working on a 12/12 pitch, I'm dealing with angles other than 90 degrees... and then as M2akita pointed out when the gable runs up the rake it's actually installed upside down in relation to a normal scenario. And this wreaks havoc on using some traditional methods for determing the miter/bevel angles.
But from what I'm reading here, it sounds like I'm on the right track anyway. What I'll try to do in the future is just cut it in position and hopefully no longer be confused by having to flip the crown right side up on the saw instead of upside-down as you would normally cut if cutting in position.
What I find frustrating though is that even though I know of a way to do it properly, I still really don't have my head around 'why' it works. And I'd still be in a jam if I run into crown that's too large to be cut in position on my saw which pokes holes in my "solution".
I just thought somebody might be able to explain the math behind it.View Image
if you can figure out the miter, you've done 90% of the work to get an oddball cope.
LOL.... yeah that's the point brother. :) The problem I'm having is determining the correct angles given the fact that unless I'm working on a 12/12 pitch, I'm dealing with angles other than 90 degrees... and then as M2akita pointed out when the gable runs up the rake it's actually installed upside down in relation to a normal scenario. And this wreaks havoc on using some traditional methods for determing the miter/bevel angles.
OK, I see what you're saying. You have to put the crown in the miter saw rightside up, with the top of the crown on the fence, and the bottom of the crown on the base, and with the 45 degree spring. But then you would set your cutting angle the same as if you were cutting a simple 1x4 trim to miter at the top of the gable.
If the blade is angled to the right, then the piece to the right of the blade will be the piece on the right of the gable peak.
Once you make that cut, you can back-bevel, or cope, the joint. In this case, it will be a severe angle, as shown in the attached sketchup drawing of the joint on a 4:12 roof."...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
Oh, I see. Must have misunderstood what you were getting at.
The easiest way for me to whip those cuts out is to visualize it on the miter saw right side up, but set at the spring angle with the top portion projecting away from the fence. In this position the cut angle on the saw is a bevel equal to the plumb cut of your rafters.
Turn the crown upside down so now it's sprung against the back and bottom of the saw and change the bevel to the other direction and there you are.
Upside down and backwards still works, but it's a bevel cut, not an angle as with normal crown.
As for the math I'm not smart enough for anything other than plumb cut angle = bevel.
Beer was created so carpenters wouldn't rule the world.
I dont know if I would try and cope an angle that obtuse, never had good luck. End up hogging out so much. I think you where on the right track though. I came up with an obtuse angle of 143, so about the same as your 144. Taking that angle, for cutting on the flat, you could look at one of the charts that Joe Fusco ( http://www.josephfusco.org/Articles/Crown_Moulding/CrownChart.html) has. So for a 45 spring you would set your miter at 13.31 and your bevel at 12.97.
When you tried cutting it in place, I think you did right by flipping it opposite the way one normally would ( the soffit is akin to the wall and your gable wall is akin to what normally would be the ceiling, your just installing the crown upside down). Your 18 degrees, or 18.5 for my 143 obtuse angle, should have worked.
But what do I know. Very very little. Glad it worked out in the end.
You're coming up with the same number I did. Your 13/13 miter/bevel set off a bell and I recall that that's what I ended using.
Thanks for thinking about this a bit for me. Let's me know I was on the right track after all. View Image
You need to ask Gary Katz what he would do. I can imagine the smile on his face while concocting a solution for your problem...
I'll pass along a link to him and see if we can lure him aboard...Justin Fink - FHB Editorial
Your Friendly Neighborhood Remodelerator
Diesel, I just found this thread and "speed read" through it so bear with me ...
Your problem is the same as cutting purlins meeting a Hip-Valley created by two intersecting 12/12 slopes at a 143.13010° plan angle (the angle at the peak being the "plan angle": 2 × arctan (12/4) = 143.13010°).
If we were to make the cut from the face of a purlin set in the surface of such a roof, the angle on the stick would be the sheathing or plywood angle. The miter angle for the saw would be the complementary jack rafter side cut angle of 13.26268°. The saw blade bevel would be 12.92097°, the same as the backing angle to cut a purlin.Comparison of Crown Molding and Purlin Miter and Bevel Angles
Joe Bartok
Huck is right. Cutting crown up a gable end is like cutting baseboard going down a stair. The base would have to be laying flat on your miter saw in order to cut the proper miters. You don't really cut the crown 'right side up' but right side up and lying back against the fence. But as Huck says, the right side is the right side, the left side is the left side.
As for coping obtuse angles, it's not that difficult. You should put the crown in a jig though, so that you can look straight down the joint, plumb down through the joint, and that way you'll 'see' exactly how much you have to back cut. When I use a cc foot for those copes, I have to use a very long Progressor blade to get all the way through the cope. It's not that hard to cut, just a little bit of extra patience....like most things.
Gary
You happen to recall the blade # you use..... the longer one.... for the coping foot? IIRC, Dave recommends a coarse blade, no?View Image
No, I don't remember the number. I just bought the longest blade I could find, with the coarsest teeth.
Gary
try this link
http://www.altereagle.com/5_How_to_insta.html
once you have the angle
you can cope
Gord
Edited 4/15/2007 11:56 pm by gordsco
Upside down and backwards--
Your saw table represents the rake overhang.
Your saw fence represents the wall.
The miter angle is 0°
The bevel angle is 90-(144/2) or 90-72 or 18°
That will give you the miter cut. I wouldn't try to cope a joint like that--just too long to get a good fit. You'll end up with loooong long point that will want to curl away. I would miter and use a liberal amount of PL Premium.
Upside down and backwards--
I made that mistake also - that works when the miter is forward or back - but not when its up or down"...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
It'll work if you use the bevel, not the miter like you normally would.
It'll work if you use the bevel, not the miter like you normally would.
yup"...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
I haven't read the whole thread, but i'll tell you what my old master told me.
"Cut it like you see it"
Divide your angle, whatever it is, set the saw at said angle, lay the crown on the saw with the top of the crown agianst the fence, and cut it. Do the complimentry cut and nail the sucker up.
I can't tell you how many feet of crown I screwed up overthinking that cut. I was so frustrated after a day of buggering it up that I went by "Sir Wllliam's" house on the way home that night, with my miter box and a stick of crown on my truck. It took him all of 30 seconds to cut it for me. Made me feel like I was back in his shop, looking and feeling stupid everytime I picked up a tool.
Try it, it works.
Dave
Edited 4/16/2007 6:47 am ET by DaveRicheson
Divide your angle, whatever it is, set the saw at said angle, lay the crown on the saw with the top of the crown agianst the fence, and cut it. Do the complimentry cut and nail the sucker up.
That's how I would do it, too. But he wants a coped joint, because of shifting/shrinkage. Which is figured just like a miter, then coped along the miter line. The angle of the resulting coped piece is acute."...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
OK, I see what you're saying. You have to put the crown in the miter saw rightside up, with the top of the crown on the fence, and the bottom of the crown on the base, and with the 45 degree spring. But then you would set your cutting angle the same as if you were cutting a simple 1x4 trim to miter at the top of the gable.
Yes.... this is the whole magilla in a nut-shell right there. In all the confusion, I somehow lost track of the fact that the miter setting on the saw is simply the roof pitch represented in degrees when cutting in position. And the crown must be held right-side-up against the fence since it will essentially be installed upside down. That's the part that I couldn't get my head around.
So now as long as the crown I'm using will fit "in position" on my saw I'll be good to go.
Now, let me ask you this.... say it wouldn't fit in my saw against the fence. I could use the Bosch miterfinder and set the spring angle, the corner angle (represented on the BMF as 180 minus 2X the roof pitch in degrees) and it would give me the correct bevel and miter angles for my saw to cut on the flat. Would I now have to do anything special with those mtr/bvl angles since the crown is essentially installed upside down? I guess what I'm asking is, does the upside down joint effect the angles in any way? I'm thinking it wouldn't on 45/45 crown but would be effected on 38/52 crown.View Image
On stuff like that, I usually cut a small piece with the same spring angle, and check the angles - because they'll be the same for the larger piece."...never charged nothing for his preaching, and it was worth it, too" - Mark Twain
In addition,
So here's how my line of thinking went....... with that 144 degree corner, I was thinking I could just take 180 minus the 144 and end up with 36 degrees in 'miter saw angle language'. So I first tried cutting the crown in position with the saw table swung to 18 degrees. I don't remember exactly what I did, but I recall getting confused and flipping the stock right-side up against the fence (IIRC) to get the 'long point' to be on the apppropriate edge of the crown. Then I hogged out the back with my coping saw as usual and got a horrible fit. :)
This "should" have worked for me. I think I had it right the first time. I must have just not been holding the crown in position properly or made some other bone-headed mistake. But I think the theory was correct. My only problem was over thinking the miter saw setting which actually should have been the easiest part.View Image
hey Huck,
"But he wants a coped joint, because of shifting/shrinkage. Which is figured just like a miter, then coped along the miter line. The angle of the resulting coped piece is acute."
I know what you mean , but, I'm not sure that is correct. The 90*/45* relationship is unique.
Think about a 30* inside corner that you are putting baseboard in, coped.
The first piece is put in cut at a 30* miter(this would be the 0* piece in a 90* corner. The second piece(the coped piece)would get mitered at 60*(not 15* or even 30* as with the 45*/90*).
I think the confusion comes about by designating 90*as 0* and the reciprocal angles thing. That and the unique relationship of 90*/45*.
My rule of thumb is that :any inside angle other than 90*(+or- a* or three), gets mitered. It's just too hard to get your head wrapped around how to do it or understand what you did to get it to work.
And then if you add the 3rd. Dimension of Crown Molding......well you just end up in The Twilight Zone. Maybe to never return!DAVEJust wondering if PIFFIN got washed out to sea
I don't think I can offer much help, but I was faced with this problem a few years ago and what we ended up doing was to mitre and glue the joint. To find the angles we went trail and error, 2pieces of scrap, 1 guy inside, me outside, " little off the bevel, touch more on the mitre" 4 or 5 cuts later, we had it.
What kinda through us off was the corner was on the "cieling" (soffit) not on the wall. That made it difficult to visualize.
Anyway, don't feel so bad, I'm reading this thread and I still don't get it.