# Help Calculating a compound angle

 Forum topic by Heinlein0311 posted 01-10-2019 03:56 PM 3553 views 0 times favorited 22 replies
 Heinlein031113 posts in 1234 days 01-10-2019 03:56 PM Hey folks, I have a range hood project I’m trying to build for my house. I’ve built 2 frames that I need to attach with 4 legs that will be angled. The legs are what’s throwing me off. The shape is essentially a rectangular truncated pyramid or I think the technical term is rectangular frustum. I know they will be compound cuts and I’ve used the calculator on www.jansson.us but I’m not making much heads or tails Of it. I believe the calculator is giving me the miter and bevels I need to join the edges together. That I’m not worried about at this point. I need help finding out what the compound cut is that I need on the 4 corner legs so that the 2 frames join up centered on each other. These I circled in red on the last picture. I’ve included pics with measurements and a pic of a range hood that I’m trying to replicate in shape, most times I can tell a better story with pictures rather than words. Any help is appreciated

## 22 replies so far

 AlaskaGuy6876 posts in 3771 days #1 posted 01-10-2019 04:14 PM I believe if you Google ”compound angle calculator” you will find several. -- Alaskan's for Global warming! jonah2283 posts in 4760 days #2 posted 01-10-2019 04:24 PM If I’m remembering my trigonometry, you’d need to find the inverse tangent (arctan) of the bottom angle. I can’t read your writing in the front view there, but based on the side view, you’d have a right triangle with the bottom side being 5.25” and the opposite side being 24”. Based on that geometry, the angle there is 77.66 degrees. If the front view of the top box is 16.5” (I can’t tell for sure), then the geometry there is an adjacent side of 8 inches, an opposite side of 24”, and thus an angle of 71.57 degrees. I used this calculator, FYI. BroncoBrian899 posts in 3420 days #3 posted 01-10-2019 04:25 PM I like the design you are going for. Are you set on a range hood? I’d prefer not having that monster in my face and going with a downdraft at the range (they are pretty effective) or nothing at all. I cook a lot and when I remodeled I did away with it. It was a good decision. -- A severed foot is the ultimate stocking stuffer. jonah2283 posts in 4760 days #4 posted 01-10-2019 04:25 PM I believe that means tipping your saw to ~12.3 degrees and rotating it to ~18.4 degrees should get you the right compound angle. jerkylips495 posts in 4032 days #5 posted 01-10-2019 04:30 PM I like the design you are going for. Are you set on a range hood? I d prefer not having that monster in my face and going with a downdraft at the range (they are pretty effective) or nothing at all. I cook a lot and when I remodeled I did away with it. It was a good decision. - BroncoBrian Off topic, but I’ve heard people complain that the downdraft sucks too much heat from the burners & it takes longer for things to cook than it would with a traditional hood. Have you experienced that? BroncoBrian899 posts in 3420 days #6 posted 01-10-2019 04:36 PM I like the design you are going for. Are you set on a range hood? I d prefer not having that monster in my face and going with a downdraft at the range (they are pretty effective) or nothing at all. I cook a lot and when I remodeled I did away with it. It was a good decision. - BroncoBrian Off topic, but I ve heard people complain that the downdraft sucks too much heat from the burners & it takes longer for things to cook than it would with a traditional hood. Have you experienced that? - jerkylips Not really with gas, most of them have 3 speeds. But I would imagine that is a problem with electric ranges. But I do not even use one anymore. Unless you burn something badly, there add little value. Plus if you are crushing it in the kitchen, you want the smell to stick around! -- A severed foot is the ultimate stocking stuffer. GR8HUNTER9623 posts in 2174 days #7 posted 01-10-2019 04:53 PM THIS is GREAT :<)) -- Tony---- Reinholds,Pa.------ REMEMBER TO ALWAYS HAVE FUN :<)) Robert4989 posts in 2942 days #8 posted 01-10-2019 05:43 PM I would build a v-shaped jig to hold the piece and just cut one angle. -- Everything is a prototype thats why its one of a kind!! Heinlein031113 posts in 1234 days #9 posted 01-10-2019 06:30 PM I believe that means tipping your saw to ~12.3 degrees and rotating it to ~18.4 degrees should get you the right compound angle. - jonah Thanks Jonah, that’s exactly what I’m looking for. Took me a Few minutes to understand what you were talking about but I absolutely see how you arrived at those answers. My main concern was at what degree to bevel and mitre but you answered that too and now I understand how you arrived with those figures. Now to get home and put it in action. Thanks again! Heinlein031113 posts in 1234 days #10 posted 01-10-2019 06:58 PM I like the design you are going for. Are you set on a range hood? I d prefer not having that monster in my face and going with a downdraft at the range (they are pretty effective) or nothing at all. I cook a lot and when I remodeled I did away with it. It was a good decision. - BroncoBrian Well if I was to be completely honest, although I will make it functional and to code, it will mostly be for visual effect. I like big range hoods. I’ve got some sheets of copper I want to age and make some panels with it and trim it out in hickory to match the kitchen sinks and cabinets. I do have a venting feature now but my jackass kitchen designer and builder ( ahem cough cough, me) made a mistake and it was to late in the process to fix. So the story goes, I found a great deal on a pop up vent that goes behind the oven. So I bought it and than I bought the freestanding oven not realizing the pop up vent was meant for a cooktop. It was to late to return any of these appliances so I rolled with it. This mistake created about a 6” gap between the back of the oven and the vent rendering the vent fairly useless but guests love to push the button and watch it pop up….I covered my mistake with a nice piece of stainless.My cooktop is electric and I’ve heard before that hoods can steal heat. We have some pendant lighting over the island where the oven is located and when we did a deep cleaning for Christmas some of the lights had a good amount of grease on them. jonah2283 posts in 4760 days #11 posted 01-10-2019 07:39 PM Not sure what you’re building the frame out of, but if it’s not construction lumber I’d try it on scrap first. BroncoBrian899 posts in 3420 days #12 posted 01-10-2019 08:05 PM Greasy lights mean you are using the right amount of oil and butter! Yep – for electric, the popup will take some heat. I prefer gas because I can see it and the adjustment is immediate. Done right, the wood/copper vent hoods are statement pieces – I am with you on that. -- A severed foot is the ultimate stocking stuffer. BlueRidgeDog918 posts in 1241 days #13 posted 01-10-2019 08:15 PM I typically draw the item in SketchUp and can the measure the resulting compound angle…control the two angles and measure the resulting one, just as for a chair leg. Heinlein031113 posts in 1234 days #14 posted 01-14-2019 01:36 PM Ok so a complete stranger (hell of a guy) from another forum drew me up a 3D model of the range hood with my dimensions and calculated the angles for me. I believe they are pretty close to what was mentioned earlier. The second picture is a cross section view of the legs that will join the 2 frames. So to get this to work do I still tilt my blade on my CMS to 11.72 degrees and rotate it 18.04 degrees? Heinlein031113 posts in 1234 days #15 posted 01-14-2019 01:36 PM

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