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How to join long angle cuts.

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Forum topic by Split posted 321 days ago 1918 views 0 times favorited 17 replies Add to Favorites Watch
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Split

33 posts in 322 days


321 days ago

I am making a corner cabinet and I am having to rip two 45 angles And put one behind the other to make a 135 degree angle. Or if I am thinking correct I can use a 90 and a 45 degree cut to make the 135 degree angle. Either way I am unsure of how to join them as clamping would be near impossible. Biscuits will not be strong enough I don’t believe. Dowels will be too long. The material is 6 ft long and the angle has to go the long way so spline would be really odd. Any ideas?

Thanks


17 replies so far

View pintodeluxe's profile

pintodeluxe

3201 posts in 1396 days


#1 posted 321 days ago

The joint on the right is a long 135 degree miter joint with biscuits. It went together great, and has held up perfectly over the past couple years. Is this the type of joint you are making?

Here is the project page…
http://lumberjocks.com/projects/51723

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View yrob's profile

yrob

338 posts in 2235 days


#2 posted 321 days ago

Traditional corner cabinets with angles like that were assembled with splines. A groove would be made in each board and a hardwood spline inserted. It will hold together great. The racking forces on a cabinet are not that big.

-- Yves

View Split's profile

Split

33 posts in 322 days


#3 posted 321 days ago

Pintodelux how did you get the biscuit cutter to long up with the angled corresponding pieces when making the slot?

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pintodeluxe

3201 posts in 1396 days


#4 posted 321 days ago

I held the long miters together, and marked the biscuit locations. Then I used the fence on my biscuit cutter to stabilize the tool while cutting the slots.

Good luck

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

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Split

33 posts in 322 days


#5 posted 321 days ago

Ok I will have to try it on some scrap pine before I try the proposed red oak. Thanks again. Oooo I was also thinking of using pocket holes but I don’t think they will reach to both materials without going through?

View Split's profile

Split

33 posts in 322 days


#6 posted 321 days ago

As far as the 45 degree angles go do you cut them opposite and but them together so they don’t make a 90?

View pintodeluxe's profile

pintodeluxe

3201 posts in 1396 days


#7 posted 321 days ago

You always want to cut the same angle on both mating pieces. So you can rip the boards on the tablesaw at a 22.5 degree angle, and it will yield a 45 degree (135 degree) angle.

I agree with you, I don’t think pocket holes would work in that situation.

-- Willie, Washington "If You Choose Not To Decide, You Still Have Made a Choice" - Rush

View Split's profile

Split

33 posts in 322 days


#8 posted 321 days ago

Yes it is exactly what I am trying to do. But I was not sure if I had to leave one as a 90 and one as a 40 to get the 135. Or if I needed to cut the 22.5 on both and put them backwards to each other to get the 45 which is the 135. Does that make sense?

View Earlextech's profile

Earlextech

887 posts in 1273 days


#9 posted 321 days ago

Glue and masking tape as a clamp. Really alot easier than you think. And, pintodeluxe is right, use the same angle on both and you’ll be gluing long grain to long grain.

-- Sam Hamory - The project is never finished until its "finished"!

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Split

33 posts in 322 days


#10 posted 321 days ago

So it would be better to do cut two 22.5 angles and glue than to try a 90 and 45? It is still playing with my head that two 22.5 degree angles makes a 45 and yet is not the same as one 45 degree cut or angle.

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Split

33 posts in 322 days


#11 posted 320 days ago

I got close but I used a stalled drawing and for some reason my middle piece is too big when it should be perfect. Any ideas why?

View Bogeyguy's profile

Bogeyguy

454 posts in 651 days


#12 posted 320 days ago

Hey Split, these guys are the best, huh? :)

-- Art, Pittsburgh.

View Split's profile

Split

33 posts in 322 days


#13 posted 320 days ago

They certainly are I am very appreciative for all the assistance I have received.

View Split's profile

Split

33 posts in 322 days


#14 posted 320 days ago

How did you find the measurements is there a way in sketchup to measure or is there a formula I should use? Thanks

View yrob's profile

yrob

338 posts in 2235 days


#15 posted 319 days ago

You can find it by simple trigonometry. Observing that the triangle that has its hypothenuse (the long diagonal) equal to 17 also has the other 2 sides exactly same length since the angles are 45 degrees, Calling this side a, you get:

a^2+a^2=18^2 using pythagorus theorem. This gives you a=18/sqrt(2) . The side remaining is therefore 24-18/sqrt(2) which is 11 4.35 /16 or as james rounded it, to 11 5/16.. With the diagonal side at 17” you would have needed 24-17/sqrt(2) wihich is very close to 12” (11.98 or 11 63/64”) again, like James previous drawing.

So to sum up, if you build it like that and want a specific diagonal, you can compute the other two dimensions by doing: longside- diagonal/sqrt(2) where longside is 24” in your case (but you can plug in another number there) and diagonal is that diagonal length (17 or 18 in your case). This formula will work as long as you do 135 degrees like in your drawings.

-- Yves

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