Measuring Two 30 Degree Angles

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Forum topic by JackInGalway posted 10-26-2010 11:05 PM 1337 views 0 times favorited 10 replies Add to Favorites Watch
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31 posts in 2735 days

10-26-2010 11:05 PM

Hi Ya`

I been trying to figure a way to measure accurately the size of the 3×2 support in consideration of the two 30 degree angles. I cut the one in the pic but it wasn’t meant for the leg I used it for, just happened to fit.
Picnic Table Upside Down


Just bought a sliding miter saw, lots of pencils and an inch/mm combo tape measure. Im getting to the point (with my belated interest in woodworking) that I know what I don’t know.

So, I thank you all in advance….Jack

10 replies so far

View MrsN's profile


985 posts in 3492 days

#1 posted 10-26-2010 11:08 PM

Can you use the one you have as a guide and cut more to match?

View supervato's profile


153 posts in 2895 days

#2 posted 10-27-2010 03:25 AM

if it were me I would cut a piece long enough to overlap both intersections at a certain length and height and scribe the angles. Then repeat the cuts on the rest. It doesn’t look compound. Wht ever the angle is on one it’s opposite on the other. Remember length is the key here it has to stay the same. If it changes so does the degree of angle.

View supervato's profile


153 posts in 2895 days

#3 posted 10-27-2010 03:29 AM

Mrs. N is correct use the one you have as a template. But if it’s not the fit you want then try the way I explained. Trust me it’s hard to say in words. But pick a height mark it and and do the scribe trick.

View JackInGalway's profile


31 posts in 2735 days

#4 posted 10-27-2010 11:35 AM

Hey thanks for your replies, I gonna go out now and and work off the one length that does fit.
I may be making this too difficult for myself.


“It doesn’t look compound” do you mean to different angles on the same length of wood?

Thanks again, I will post the outcome in a bit…Jack

View rance's profile


4255 posts in 3126 days

#5 posted 10-27-2010 12:23 PM

I agree, doesn’t look compound, that should fit all 4 legs. If it doesn’t, then the leg is warped. You can calculate it with math, but sometimes it is a lot easier to just sneak up on the fit. Sounds like you already know the angle, just not the length.

-- Backer boards, stop blocks, build oversized, and never buy a hand plane--

View BTKS's profile


1986 posts in 3430 days

#6 posted 10-28-2010 08:38 AM

I think supervato is right. Nothing wrong with MrsN’s way. Copies only work if the center block is exactly centered on the seat. Even a 1/4 inch off center will really show up. Over-length and scribe then sneak up on the best fit. Good luck.

-- "Man's ingenuity has outrun his intelligence" (Joseph Wood Krutch)

View swirt's profile


2646 posts in 2938 days

#7 posted 10-28-2010 05:09 PM

Take a 2×4 that is ~5” shorter than you need. Rip it so you have 2 2×2. Cut the end of one at the angle you need. Cut the end of the other at the angle you need for the other end. Now hold the two against each other so that it resembles the original 2×4 but slide the pieces length wise to make it longer, fit it into place, when it is perfectly in place, make a pencil mark across the two pieces so that it records the length. You now have the perfect length with the angles in tact to mark and cut the actual piece.

Erase the mark you made, and re-use the sticks to measure the remaining ones.

-- Galootish log blog,

View RickMathison's profile


3 posts in 2733 days

#8 posted 10-28-2010 11:34 PM

You are basically working with a 90 degree corner (rise and run). The math formula that you are looking for is.
A squared, plus B squared, equals C squared.
Example: Rise = 12”. Run = 24” 12×12=144, 24×24=576 144+576=720 The square root of 720= 26.833 or 26 and 13/16


View JackInGalway's profile


31 posts in 2735 days

#9 posted 10-29-2010 02:03 AM

Thank you all for your replies.
I hate to say it but I kinda messed up 3 of the 4 supports. I just don’t know how.
I cut each piece long and scribed it and measured twice but I was off by quite a bit.

Considering that I now have lots of 3×2 lengths cut to different sizes I will make a mock up on the bench top and practice cutting and fitting the angle and length. I will figure out where I went astray.

I very happy will the rest of the table and will go on this week to make a gate for the driveway.

rance / BTKS
Neither center blocks are centered and one pair of legs are a little offset to the opposite side pair of legs. I sure this complicated things abit.

swirt / RickMathison
Next time I tackle something like this I gonna “Split n Slide” the wood into place and proof the cut with the rise and run calculation. I definitely will do better next time.

Thank you all again for your help… Jack

View JackInGalway's profile


31 posts in 2735 days

#10 posted 10-30-2010 03:55 PM

I gonna sand and paint the table today.
Wife liked it, thanks again….. Jack



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