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http://en.wikipedia.org/wiki/Special_right_triangles

There's no computation required at all = if one side is '3' and the other side is '4', then the diagonal must be '5'. = done.

Got a freezer in the basement? Draw lines at 90 degrees on that nice white top for an assembly surface. At least, it gets you close and a clamp of some sort does the rest.

More than a century ago, as the Haida were perfecting the techniques to make kerf bent boxes (at least 10 known different corner geometries), they made pairs of sticks of equal lengths to span the diagonals as the wood cooled. Beautifully square box corners. Go into the University of British Columbia Museum of Anthropology and study them for your self. Failing that, search the UBC MOA on line collection.

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The diagonals trick works to ensure the corners are 90 degrees, but that does not ensure that you have a square.

What kind of joinery are you using?

If you want a square (as opposed to a rectangle) then you need to factor in the way the sides are joined at the corners and adjust the lengths if necessary.

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Why not just use a combination square or other known accurate square? They are not expensive, readily available AND will save lots of time, whether making/sawing/cutting by hand or machine. The process will be much more enjoyable. :yes:

Look here at Harbor Freight:

http://www.harborfreight.com/catalogsearch/result?q=square

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Agreed....you should a have a selection of squares anyway.Why not just use a combination square or other known accurate square? They are not expensive, readily available AND will save lots of time, whether making/sawing/cutting by hand or machine. The process will be much more enjoyable. :yes:

Big and little for all sized projects.

What is the real purpose of this question?I want to know about making square or rectangular boxes. is there a way to make them without using combination square (tool) ? Is it an indispensable tool? I still believe there is a way to do it.

There could be different answers depending upon what you are really looking forl

George

Robson,Robson Valley said:

There's no computation required at all = if one side is '3' and the other side is '4', then the diagonal must be '5'. = done.

Got a freezer in the basement? Draw lines at 90 degrees on that nice white top for an assembly surface. At least, it gets you close and a clamp of some sort does the rest.

More than a century ago, as the Haida were perfecting the techniques to make kerf bent boxes (at least 10 known different corner geometries), they made pairs of sticks of equal lengths to span the diagonals as the wood cooled. Beautifully square box corners. Go into the University of British Columbia Museum of Anthropology and study them for your self. Failing that, search the UBC MOA on line collection.

I see now. Then I can make four 3-4-5 corners. No or little computation. Then decide what I want square or rectangle for wooden boxes. Wooden boxes can represent tables, beds. Rectangles' length is just longer.

Without combination square I ask myself how I can make accurate corners? The replies are 3-4-5 method and diagonals. Good answers.GeorgeC said:What is the real purpose of this question?

There could be different answers depending upon what you are really looking forl

George

To answer your question, Now I know that the factories make combination square through 3-4-5 trick. No computation needed.

Now I can go to Harbor Freight buying angles with peace of mind because I can make one myself.

Pardon me, rectangle. Now I have the concept how to make accurate corners. Then decide what kind of joinery I need. I believe very basic.Chris Curl said:

The diagonals trick works to ensure the corners are 90 degrees, but that does not ensure that you have a square.

What kind of joinery are you using?

If you want a square (as opposed to a rectangle) then you need to factor in the way the sides are joined at the corners and adjust the lengths if necessary.

Now I can go to Harbor Freight buying different angles with peace of mind.alanskil said:Wrong posting... I was not able to delete it.

Without combination square I ask myself how I can make accurate corners? The replies are 3-4-5 method and diagonals. Good answers.

To answer your question, Now I know that the factories make combination square through 3-4-5 trick. No computation needed.

Now I can go to Harbor Freight buying angles with peace of mind because now I can make one myself.alanskil said:Without combination square I ask myself how I can make accurate corners? The replies are 3-4-5 method and diagonals. Good answers.

To answer your question, Now I know that the factories make combination square through 3-4-5 trick. No computation needed.

This is wrong posting, answering to my reply. but am not able to delete it.

alanskil said:Wrong posting..cannot delete.

George C, Now I can go to Harbor Freight buying different angles with peace of mind because I can make one myself.

I understand you and Frank about the diagonals are the same for square.. Also diagonals for rectangle has to be same, but for comparison's sake measurement for square diagonals are different from rectangles'; shorter.Dave66 said:What Frank said above. Square or rectangle, if the opposite sides are EXACTLY the same length, just assemble your box and make the diagonal measurements the same.

If you're mitering the corners, your miters need to be EXACTLY 45*.

I agree with you and Frank about 45 degree mitering. It has to be the same regardless square or rectangle. 45 degree has nothing to do with diagonals.

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