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pipe miter

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Gerhard Olivier:
Hi ieezitin

Don is right here as it is round pipe there is only the angle between the two pieces that is important - it would only be a compound miter where there is a difined top ( as in a stair railing that is square or profiled) but as yours is round pipe anywhere on the circ of the pipe can be the top.  Hope this helps.

Gerhard

mklotz:

--- Quote ---I would have though (sic) Marv would chime in on this math problem.

--- End quote ---

No point.  The OP has already calculated the angle between the two pipes somehow.  Since two lines define a plane, that's all there really is to know.

I don't think anyone here really wants a mathematical solution but I'll outline the technique anyway.

Each pipe can be considered a vector.  Then calculating the dot product between the two vectors will yield the angle between them.

Define an xyz coordinate system with its origin at the point labeled "start point" in the diagram.

Determine the coordinates of the end of the first pipe, which is the point of intersection, and label them x1, y1 and z1.

Using the same coordinate system, determine the coordinates of the end of the second pipe and label them x2, y2, z2.

Define L1 to be the length of pipe #1

L1 = sqrt (x1^2 + y1^2 + z1^2)

Define L2 to be the length of pipe #2

L2 = sqrt ( (x2-x1)^2 + (y2-y1)^2 + (z2-z1)^2 )

Then:

cos(phi) = [-x1*(x2-x1)-y1*(y2-y1)-z1*(z2-z1)] / [L1*L2]

where phi is the angle between the two pipes.

Bernd:

--- Quote from: mklotz on July 23, 2010, 12:47:01 PM ---
--- Quote ---I would have though (sic) Marv would chime in on this math problem.

--- End quote ---

--- End quote ---

Ya I know. I have a spelling problem at times.

I'm now sorry I asked.  :lol:

Bernd

ieezitin:
Marv.

Thanks for the solution. And a good reference for people.

 Your right! You knew I did my math as I already had the length and angle.

Don. Gerhard.

My original question was “   What is the formula to making a swing joint off set miter joint. I really want to make a template out of card so I can wrap around the pipe and trace the line to make the cut on the pipe.”

I used the term (swing joint) (offset) this confused a lot of people, and then through discussion the term (compound miter) came into play which is the correct term.

I admit I was confusing, I have a tendency be like that just ask my wife!  HS93(peter) showed me a little trick and this was offered by a few people in various forms but all much the same and it works sufficiently to get a joint weld able.

I also was over thinking this problem.

I would like to thank everyone for there efforts in trying to help me, a lesson I have learned here is im nearly 50 now and I need to stop being so stubborn.

Do I hear something about dogs and tricks?    :scratch:

Anthony

dsquire:
Anthony

I'm glad that you have the results that you were looking for. I am sure that a few people learned something from this exercise, I know that I did. Sometimes I can complicate a simple problem just by thinking about it too much so you have to stand back and look at the bigger picture.  :D :D

Cheers  :beer:

Don

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