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Help finding correct angle to miter...

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Forum topic by fsutim posted 05-23-2016 01:49 AM 621 views 0 times favorited 15 replies Add to Favorites Watch
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fsutim

17 posts in 573 days


05-23-2016 01:49 AM

I am working on putting cross braces on a table and am having trouble finding the correct angle. I have been trying 45 degree angles and I am left with a gap at the connecting points top and bottom (see picture of cross brace). How do I find the correct angle rather than continually guessing and re-cutting which so far has been doomed for failure. I appreciate any insight…


15 replies so far

View jbay's profile

jbay

820 posts in 367 days


#1 posted 05-23-2016 01:54 AM

Cut your board long and place it against the sides of your top and bottom stretchers at the angle you want it.
Draw a line on the new board, under the top stretcher, and on top of the bottom stretcher. Now simply cut on the lines and it should fit perfect.

-- My “MO” involves Judging others, playing God, acting as LJs law enforcement, and never admitting any of my ideas could possibly be wrong or anyone else's idea could possibly be correct -- (A1Jim)

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fsutim

17 posts in 573 days


#2 posted 05-23-2016 02:14 AM

Thanks Jbay, that sounds simple enough. I knew I had to be overlooking something…

View fatman51's profile

fatman51

335 posts in 1305 days


#3 posted 05-23-2016 03:43 AM

Just a thought….Jbay has given you the simplest solution for a common problem. However, it is good practice to check to be sure that your table legs are square to the top. Keep in mind that braces form a triangle where the brace forms the hypotenuse, which is equal to the square root of the sum of the length of each leg squared. if the distance of each leg of the triangle formed by your brace is the same and the 45 degree angle of your brace does not fit, you need to square your legs to your top and the 45 degree braces should fit. Where the length of each leg differs, all you need to do is temporarily brace your legs square to the top, hold the braces in place, and mark them as jbay suggested.

-- The Constitution only gives people the right to pursue happiness. You have to catch it yourself. Benjamin Franklin

View TheFridge's profile

TheFridge

5765 posts in 954 days


#4 posted 05-23-2016 04:32 AM

-or-

The distance between the top and bottom stretchers times 1.414 will give you the length between points

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

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realcowtown_eric

565 posts in 1405 days


#5 posted 05-23-2016 05:31 AM

if yer top and bottom pieces are parallel,and straight and your cuts are at 45%.(ckeck em) it should all fork out…

just like you thought and wished for.The top pieces have to be square as well,

If on the other hand, your 90 degree angles aint quite 90. or your 45’s aint exactly 45 this is precisely the problem that one might expect And it’s not unheard of to have a dull saw blade on a chop saw pull as it cuts, so even a perfenctly set 45 angle on the chop saw may end up at a lesser (or more) angle.

It looks to me that that might be the insight into solving your problem.

My first try would be to back off those screws on the upper and lower beams, then attach your 45’s and see if they tighten up the joints. often times the angled screws will twist and tilt members. thry that..that may be an underlying problem in your assemblyAnd be sure you assemble it on a flat surface

Maybe that helps

remember it’s all about precision.

Eric

-- Real_cowtown_eric

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fsutim

17 posts in 573 days


#6 posted 05-24-2016 02:01 AM

Great insight, thank you guys!

View firefighterontheside's profile

firefighterontheside

13529 posts in 1324 days


#7 posted 05-24-2016 02:15 AM

If your table parts are parallel and you cut the same angle at either end of your brace the only thing that will make it not fit is the length of the brace. Too long and the short points will be making contact. Too short and the long points will be making contact.

-- Bill M. "People change, walnut doesn't" by Gene.

View devann's profile

devann

2202 posts in 2160 days


#8 posted 05-24-2016 04:42 AM

Another easy method to learn what length to make a board for a project like you’re building is to make a full scale drawing of the area in question on a piece of plywood using the factory cut edges. If you don’t have a factory edge corner to work from use the right angle triangle formula to establish your lines. Your accuracy when making the drawing is a must. Take you time.

It’ll also give you options on the direction of the brace, etc. before you make a cut. You’ll also know what the right size is to achieve a square, properly aligned project without the need to temporarily square and brace your project.
Establish the proper lengths for fitting the part where it needs to be. And then use proven techniques to reproduce exact copies of all parts needed to complete the task.

btw, when making braces in similar situations like yours above, I prefer to cuts the ends of the brace twice, making it a square end, instead of a miter end, coming to a point. It doesn’t have to be symmetrical, just square. It will give you load bearing in two directions taking some of the stress off of the mechanical fasteners. It makes for a stronger connection.

-- Darrell, making more sawdust than I know what to do with

View dhazelton's profile

dhazelton

2326 posts in 1764 days


#9 posted 05-24-2016 10:46 AM

What firefighter said – there’s nothing wrong with your angle, you just made your board too short.

View tomsteve's profile

tomsteve

394 posts in 687 days


#10 posted 05-24-2016 02:12 PM

my wixey gage makes finding angles real simple.

View tchara's profile

tchara

33 posts in 211 days


#11 posted 05-29-2016 10:30 AM



What firefighter said – there s nothing wrong with your angle, you just made your board too short.

- dhazelton


View tchara's profile

tchara

33 posts in 211 days


#12 posted 05-29-2016 10:38 AM


What firefighter said – there s nothing wrong with your angle, you just made your board too short.

- dhazelton

OK, I’m lost. What difference does the length of the brace make? If you have a straight 90 and two straight 45 degrees, to get to the 180, why would the length of the board effect the fit. I can feel for fsutim. I too have made braces in the past that I could have sworn were cut correctly, only to get the same results.

- tchara


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firefighterontheside

13529 posts in 1324 days


#13 posted 05-29-2016 11:55 AM

Look at the picture of what he’s building. He’s cutting a brace to go between the bottom and top stretchers. Let’s say those stretchers are 24” apart. If he’s cutting 45’s on each end those angles will create parallel cuts to each other and those lines have to be 24” apart for the piece to fit right. Too long and the short points of the angles will be touching, too short and the long points will be touching.

-- Bill M. "People change, walnut doesn't" by Gene.

View BobAnderton's profile

BobAnderton

219 posts in 2258 days


#14 posted 05-29-2016 03:44 PM

The tangent of angle theta is a/b in the diagram below. If you want to know theta it would be arctan(a/b).
On most calculators you’d calculate a/b then hit shift then hit tan and it’ll spit out the angle theta.
If you’re using a mitersaw you’d set it to (90-theta) because it calls cutting something off at 90 degrees to the fence zero.

-- Bob Anderton - Austin, TX - Nova 3000 lathe, Alaskan Mark III mill, Husqavarna Saw

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firefighterontheside

13529 posts in 1324 days


#15 posted 05-30-2016 02:02 AM



The tangent of angle theta is a/b in the diagram below. If you want to know theta it would be arctan(a/b).
On most calculators you d calculate a/b then hit shift then hit tan and it ll spit out the angle theta.
If you re using a mitersaw you d set it to (90-theta) because it calls cutting something off at 90 degrees to the fence zero.

- BobAnderton

True, but that’s not what he’s cutting. He’s making a brace that goes between two parallel parts and not between two perpendicular parts.

-- Bill M. "People change, walnut doesn't" by Gene.

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