duckkisser Posted February 1, 2015 Report Share Posted February 1, 2015 i need to make a box with a 4 sided roof shaped kind of like a pyramid. does anyone know the angles for cutting the triangle pieces? or know of a web site that walks you through it? Quote Link to comment Share on other sites More sharing options...
tim0625 Posted February 1, 2015 Report Share Posted February 1, 2015 This is basically a hip roof on a square house. When one of the builders jumps in, you'll know. You'll probably need to give the length, width, and height of 'the roof'. Quote Link to comment Share on other sites More sharing options...
duckkisser Posted February 1, 2015 Author Report Share Posted February 1, 2015 any size i want only thing i have made is 4 sides ill measure those after i finish shoveling the drive.....for the third time Quote Link to comment Share on other sites More sharing options...
Arminius Posted February 1, 2015 Report Share Posted February 1, 2015 The pitch of the pyramid dictates the angles - for reference, the Great Pyramid of Giza is about 51 degrees, most box lids won't be anywhere near that. Quote Link to comment Share on other sites More sharing options...
wtnhighlander Posted February 1, 2015 Report Share Posted February 1, 2015 Duck, it should be basic geometry + pythagoras. Angle through the thickness = 360 / # of sides / 2. Angle across the width = square root of a squared + b squared, where a is the width of the board, b is the difference between the long point and short point of the angle. Does that sound correct? Maybe some of the builder guys have a simpler method. Quote Link to comment Share on other sites More sharing options...
Dave H Posted February 1, 2015 Report Share Posted February 1, 2015 If I was building a house the roof would be figured off of the rise to run or what is referred to as the pitch which is how much rise in a 12' run, you have heard the term the house has a 4/12 pitch the cuts are made with a framing square the hip cut of a 4/12 because of the angle of 2 pitches converging would 4/17. But if I was building a box I would cut some cardboard tape it together to form the pitch draw the line from the outside of the eave to the point on the ridge connect the dots there is your angle set your bevel gauge and, get busy. No math involved. Quote Link to comment Share on other sites More sharing options...
Rapid Roger Posted February 1, 2015 Report Share Posted February 1, 2015 Well, I made a box like that a llloooonnngggg time ago so (Dec 2007) I know that it can be done. I honestly don't know what angle that I cut the miters but, I think it is just a 45. The pitch is what ever you want it measured on the center line at the base to the point on the top. It hast to be GREATER than 1/2 of the base line to form the pitch. The base on this box lid is 8" and the pitch is (about) 1-1/2" and the slope measured on the center line is 4-1/2". Black mesquite. Just in case you wanted to know. Rog Quote Link to comment Share on other sites More sharing options...
duckkisser Posted February 1, 2015 Author Report Share Posted February 1, 2015 https://www.stoneforest.com/gardenstore/img/products/Craftsman_Lantern-1246570587-detail.jpg roger is closest basically this is what i want to make, my bottom boxes pieces are 3 1/4 by 3 1/4 but i dont think that will effect the roof except for the size of my sides. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted February 1, 2015 Report Share Posted February 1, 2015 Duck, half the width of the base and also the height give you two legs of a triangle. With two legs you can figure hypotenuse and interior angles. With those angles you can calculate the hip miter values. In order to get more specific, we need how tall and wide of a cap you want. Quote Link to comment Share on other sites More sharing options...
duckkisser Posted February 1, 2015 Author Report Share Posted February 1, 2015 im thinking 3 3/4 inches square so it over hangs a little of my box as for height it wont matter exactly i im thinking it would look better as a flatter roof so want to keep it shorter in the 3-4 inch range. what ever is easiest to measure and cut. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted February 1, 2015 Report Share Posted February 1, 2015 http://www.csgnetwork.com/righttricalc.html Great tool for this discussion and anyone following it. Three to four inches tall is as tall as you are wide. That will be a bit aggressive compared to the pictures here. I have time to play. Seems iOS is back to flipping pictures. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted February 1, 2015 Report Share Posted February 1, 2015 Ok, half the box width is 1.875". If you went 1.875" tall, then your side plane to base joint is 45°. Just scratching my head about the corner intersections. I should be able to remember how to figure that bevel angle but Sunday nap is making me foggy. Quote Link to comment Share on other sites More sharing options...
ColinF Posted February 1, 2015 Report Share Posted February 1, 2015 Screw doing math, eyeball on a piece of pine until you get it. Quote Link to comment Share on other sites More sharing options...
Rapid Roger Posted February 1, 2015 Report Share Posted February 1, 2015 OK, I got out my "Smoley's Four Combined Tables" book to give you some dimensions. If you want to use 30 degrees for a pitch and your base is 4", that would mean that half of that is 2" and at 30 degrees your rise would be 1-5/32" and your slope would be 2-5/16". So you make a triangle with a 4" total base and a distance @ CL of 2-5/16 and when you square up the four sides, you will get a 30 degree slope on your roof. If you have another pitch in mind, please post it and I will look it up. If you have a different size for the four sides of the roof, please post it and I will give you exact (within 1/32") dimensions for the four triangles. Always happy to help. Rog Quote Link to comment Share on other sites More sharing options...
ResidentEvil Posted February 1, 2015 Report Share Posted February 1, 2015 This is a timely topic. My wife has been on me to make a light fixture to go above our dining table. We decided on something that looks similar to a pool table light, or one of those vent hoods that go over a range in a kitchen island. I've been putting it off because I hadn't had the first clue on how to determine the angles and cuts on the angled "roof" like pieces. Quote Link to comment Share on other sites More sharing options...
Coop Posted February 2, 2015 Report Share Posted February 2, 2015 Duck, if the height is not critical, make all three sides the same length and all three angles 60 deg. Quote Link to comment Share on other sites More sharing options...
krtwood Posted February 2, 2015 Report Share Posted February 2, 2015 If at all possible the easiest way to deal with a compound miter is to cut it at the angle it is going to be, the same as it's easier to cut crown molding with it standing up in the miter saw than it is lying flat. Then all you have to do is cut 45 degree miters. So if you want a 12 degree slope, make a 12 degree wedge to put under your stock and whatever the heck that compound miter angle is supposed to be is magically done for you. Quote Link to comment Share on other sites More sharing options...
Byrdie Posted February 8, 2015 Report Share Posted February 8, 2015 Mathias has a table on his website that's intended for figuring the bevel angle to cut when making laminated bowls. I think it would have an application here. Basically you have to figure the number of sides (4 in this case) the pitch and the rise and the table will tell you what angle to set your miter gauge and blade to. I have a copy of it somewhere. Used it to make a six sided top for something. I think it's in PDF format. Quote Link to comment Share on other sites More sharing options...
Plays in Woods Posted August 28, 2017 Report Share Posted August 28, 2017 The one I just did was at an 8/12 pitch...so 33.70 degrees. Pain to do a tar paper cap for it...you have to cut four sides and gorilla tape inside and outside seams. Other than that, piece of cake. Much easier if not lifesize I am sure. Quote Link to comment Share on other sites More sharing options...
Tom King Posted August 28, 2017 Report Share Posted August 28, 2017 When framing a hip roof, change the 12, in the roof pitch, to 17 on your framing square, and it works out just right. I don't see why it couldn't be scaled down. As an example, if you're framing an 8 in 12 hip roof, step off the rafter lengths with the square set for 8 in 12, and step off the same number of steps for the hip rafter with the square set at 8 in 17. Even us simple minded carpenters can do it. Quote Link to comment Share on other sites More sharing options...
wdwerker Posted August 28, 2017 Report Share Posted August 28, 2017 2015 thread, I'm pretty sure the original project is done. Quote Link to comment Share on other sites More sharing options...
Popular Post Tom King Posted August 28, 2017 Popular Post Report Share Posted August 28, 2017 I have a long list of projects older than that that aren't. Ask my Wife. 3 2 Quote Link to comment Share on other sites More sharing options...
Conley Posted December 27, 2017 Report Share Posted December 27, 2017 This is the Power of the internet. Info at your fingertips when needed. This is so so valuable for me right now. Been looking for it for "2 hours" Good advise like this never gets old. Please keep this thread for future woodworking amateurs like me 10 or 100 years down the line... Thank you for everything who chipped in! Quote Link to comment Share on other sites More sharing options...
Conley Posted December 27, 2017 Report Share Posted December 27, 2017 On 2/2/2015 at 4:26 AM, wtnhighlander said: Duck, it should be basic geometry + pythagoras. Angle through the thickness = 360 / # of sides / 2. Angle across the width = square root of A squared + B squared, where;A is the width of the board,B is the difference between the long point and short point of the angle. 1 SQR (A^2 + B ^2) Thank You, I think this would work just thinking back many years too long forgotten maths classes. Going to test it in a short while ========================================= Nope - Did not work. But found another article. and went with that. Basically just Make the 3 Sides all equal in length (can be any length as long as all three sides are the same), Then cut the 3 sides of each triangle at 35.5 deg. (Don't ask me why), but hey, it works Quote Link to comment Share on other sites More sharing options...
wdwerker Posted December 27, 2017 Report Share Posted December 27, 2017 I stole my high school geometry textbook for just this reason. I knew by the time I needed a formula I would want instructions on how to use it. 1 Quote Link to comment Share on other sites More sharing options...
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