How do I calculate length of tubing needed for making a handle with two 90 bends?
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  1. #1
    Join Date
    Mar 2006
    Posts
    33

    How do I calculate length of tubing needed for making a handle with two 90 bends?

    Okay so how do I work out how to bend this.

    I will use rounded up figures to make it easy, and it is in metric.

    Making a handle out of 20NB pipe that has a 90 degree bend at either end. Lets say that from outside to outside it needs to be 1000mm long. How do I know where to make the bends in the pipe. How far apart should the two starting lines be from each other?

    I do not know the radius of the bender right now, but I can try to measure it. Then what do you do?

    If the radius is say 100mm of the bender do you just go 100+100 for the two bends then that would mean make the marks 800mm apart. So 100+800+100 =1000mm. Oh, you would have to subtract 2 x the diameter of the pipe as well.

    So then 100-27mmOD pipe (I think it is 27)=73mm

    So 1000-73-73= 854 distance to have the two bend marks apart.

    That sounds about right to me, it that right?
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  2. #2
    Join Date
    Sep 2005
    Location
    Cave Creek AZ
    Posts
    1,386

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    Read this link over on the Pirate board, it explains using a bender pretty well.

    http://www.pirate4x4.com/articles2/tech/bendin_tube

  3. #3
    Join Date
    Jun 2010
    Posts
    1,062

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    I take a sample piece of the pipe, mark it in 1" increments while it is straight. After bending it, you can use it as a layout template on a welding table (or floor) to accurately know where to start bends on the real project. It is more accurate than math for me because of the stretch and shrinkage of the pipe.

  4. #4

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    2 90 = 180 or half a circle so you need ˝ pi D your diameter is to center line of pipe so diameter of jig + that of the pipe will give you D each 90 is = to R on the center line if you need out side measurement subtract pipe diameter from the middle of the handle. How you mark the starting point depends on the bender. Clear as mud let us know when you have some real numbers.

  5. #5
    Join Date
    Mar 2007
    Location
    west central OHIO
    Posts
    23

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    Measure from one end a known distance close to what you want as a finished height. Use this bend as the centerline of your first bend. After making your first bend, measure from the outside of the pipe to the end you measured from. The difference in these two dimensions will tell you what you "gained" in your bend. Now just measure your width from the outside of your first bend, minus the amount "gained", use this as the centerline of your second bend. It should be the exact OD you were looking for. I do this every time I bend pipe because different batches of the same size pipe will bend differently. Does this make sense?

  6. #6
    Join Date
    Feb 2008
    Location
    NH no mo - MA now.
    Posts
    1,595

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    Interesting reading about bending tube:

    http://www.bendtooling.com/bending_formulas.htm

    http://www.rorty-design.com/content/tube_work.htm

    Simple table used for bending pipe:

    http://www.informationdestination.ce...in%20Bends.pdf

    A problem with the last reference for bending pipe is minimum bend radius for standard nominal pipe sizes is not given. We would still need to research that separately to use that chart properly.

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  7. #7
    Join Date
    May 2010
    Location
    mine sites mostly and workshops of varying notoriety
    Posts
    15

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    get to know your bender...... get a sample piece 1000 long, mark a centre line around it and witness mark it with centre pops..... mark a reference line 300 from one end to be your bend line, set it in the bender, do a 90 degree bend, then measure from your centre line to the outside of the bend and see what you gained or lost ( from the centre line you've gained or lost from 200mm to your bend line....from the bend end you've gained or lost from 300mm.....if the pipe is seamed, be sure the seam is on the "mean line" of the bend...)

  8. #8

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    this is very easy !!!! just take a scrap piece of pipe, put it in your bender and mark on the pipe a line around the pipe . i use the edge of the die before it starts bending . any were befor it starts bending will work. bend a 90 degree or more bend. draw on the ground or a piece of cardboard what you want to bend . you dont have to draw in the radius ,just the width of the 2 bends and put a center line on your drawing. it is best to go from the inside out on both bends. the bends usually look a little different on the side were you start bending and the side that is at the end of the bend. after you draw what you want take your sample bend , put it on your drawing and line up the side with the mark on the pipe with the inside of the bend then just move the sample bend down till it lines up with the outside of your bend . if you bent mor than 90 just line it up were the pipe lines up at the outer part of the radius. mark the bend line on your template. i bend roll cages for drag cars all the time and they have to fit real tight so i make cardboard templates and put them in the cars first!!! so i dont waste any expensive chrome moly tubing.
    to get the measurement of how long to cut i just measure all the sides on your drawing. dont worry about the radiuses just measure the strait points ,add them up and cut it . it will be a little long . then trim after you bend. mark the centerline of the piece of pipe you just cut ,lay it on your template and line up your center line. mark the bendline on your pipe and bend it. than put your part back on your template to mark the other side. youll never waste anymore pipe besides the sample bend ever again.

  9. #9
    Join Date
    Sep 2005
    Location
    Cave Creek AZ
    Posts
    1,386

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    What he said.

  10. #10

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    sorry, did that sound confusing? it really is easy

  11. #11

    Re: How do I calculate length of tubing needed for making a handle with two 90 bends?

    probbably easier to show it than type it

  12. #12
    Join Date
    Apr 2008
    Location
    In my mind, everywhere!
    Posts
    399
    Make a video then

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