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Wood X legs angle help please!!!

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Forum topic by jscore08 posted 05-09-2014 06:46 PM 579 views 0 times favorited 6 replies Add to Favorites Watch
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jscore08

4 posts in 132 days


05-09-2014 06:46 PM

Topic tags/keywords: cedar milling joining modern tip question miter saw bandsaw clamp tablesaw

I am having trouble determining the angles of to make x legs for a wooden table base. I am using 4×4 cedar pieces and need to make x legs that are 37.5 inches tall and the top can be a maximum of 24 inches wide from edge to edge. I wondered if anyone has a formula or a way to determine what the top and bottom angles are so that the wood legs lock in to be those specs previously stated. My friend made these legs previously (in the picture) but the height and width were different. Any help or direction would be greatly appreciated.


6 replies so far

View dhazelton's profile

dhazelton

1185 posts in 950 days


#1 posted 05-09-2014 07:36 PM

I would draw out a box 24 inches wide by 37.5 tall. Then take your 4×4 and lay it in there with the outsides of the stick touching opposing corners of the box and trace the stick of wood. Now use a protractor or just put tick marks on the 4×4 where it runs past the out side of the box and cut that angle. Probably a way more scientific to do it but whatever works.

View Yonak's profile

Yonak

276 posts in 174 days


#2 posted 05-10-2014 04:41 AM

Like dhazleton says, you can draw it out on paper then measure the angle. You could even draw it exactly 1/4 scale on a sheet of copy paper. The angle will remain the same. Cutting 1” wide paper strips to represent the legs for layout purposes would likely help, similar to what dhazleton suggests,

If you don’t trust measuring the angle, you could take your drawing to the cedar pieces and transfer the angle directly to the wood.

View Tedster's profile

Tedster

2271 posts in 865 days


#3 posted 05-10-2014 06:24 AM

One thing I’ve learned in my many years of doing carpentry work is to always chose direct measurements over calculating, if possible. Ditto what dhazelton and Yonak say… lay it out on paper and measure your angles from that.

-- I support the 28th Amendment. http://www.wolf-pac.com/28th

View CaptainKlutz's profile

CaptainKlutz

53 posts in 148 days


#4 posted 05-10-2014 11:53 AM

I agree with the others, using direct measurements is always best.

But if you really, really want to do this the hard way, Wikipedia has the geometry and math equations
http://en.wikipedia.org/wiki/Right_triangle or
http://en.wikipedia.org/wiki/Isoceles_triangle

I’m half asleep and I probably did this wrong, but I come up with these numbers -

Since each leg half forms a right triangle to the floor:.
hypotenuse = square root of the sum of A squared plus b squared
Leg length = square root (24 squared plus 37.5 squared) = 44.523

Since an X is two triangles that form a rectangle you also can use isosceles triangle math:
angle = arc tangent of (2X height divided by base length)
With a 24” base and half of 37.5 as the triangle height, you get a floor to leg or table to leg angle of 57.38.

Since you are trying to create a 57.38 degree angle to the floor, the wood will have to be cut as the complementary angle of 90 – 57.38 = 32.62 degrees.

Note it’s not quite that easy. :)
These angle calculations are wood centerline dimensions, ignoring wood thickness. The actual angles need to have the final wood thickness added/subtracted in the calculations to get the real cut angle. I leave that math to you.

When it comes to making the notches for cross over lap joints, you need the exact wood width, and more math to find the beginning and end points. But this is another case where it will be much easier to just lay the pieces on top of each other in the prescribed rectangle on paper and physically mark it.

Even if I wanted to make this piece, and had the proper angle numbers; I would still make a paper or cardboard rectangle template and use it to verify the calculated angle values. Even putting caulk lines the concrete floor will work if you don’t have paper.

Always measure twice and cut once.

Best of luck.

-- I'm not a woodworker, but sometimes I do occasionally find useful tools and furniture inside a pile of lumber!

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jscore08

4 posts in 132 days


#5 posted 05-12-2014 05:04 PM

Thanks everyone for the help. I will try it out today and hopefully I can figure it out. Much appreciated!!

View junebug's profile

junebug

82 posts in 1058 days


#6 posted 05-12-2014 05:17 PM

I’ve never been a fan of math..

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