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  1. #1
    Join Date
    Jul 2008
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    near Warragul, Victoria
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    3,718

    Default bending Gal. pipe - how to

    Hi I have this project . I am making a canvas frame for my little 1940 chevy military truck. I restored this truck many years ago, and never got around to making the frame for it . The frame is 3/4"gal pipe with a OD of just over 1" . A fellow Chevy owner sent me these pics of the frame . Does anyone have any ideas, tips on how to bend the corners to a 6"radius ? Maybe I need to make a jig . there are 3 bows to make . The folding legs on the side are for removing the frame and setting it up on the ground as a shelter . Thanks Mike. PS the chap who has this frame lives in Canada ..hence the white stuff
    Attached Images Attached Images

  2. #2
    Join Date
    Apr 2008
    Location
    Perth
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    269

    Default Galv Pipe

    Um, a pipe bender.

    DD

  3. #3
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    Jul 2008
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    near Warragul, Victoria
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    Default tricky

    Quote Originally Posted by Dingo Dog View Post
    Um, a pipe bender.

    DD
    The pipe bender tends to kink the smaller diam. pipes . I have one and its pain of a thing .

  4. #4
    Join Date
    Aug 2008
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    near Rockhampton
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    6,216

    Default

    Quote Originally Posted by morrisman View Post
    The pipe bender tends to kink the smaller diam. pipes . I have one and its pain of a thing .
    That is caused by at least two things.... A mandrel that does not support the sides of the pipe very well, and/or using thin pipe... In my experience with convention benders usually anything thinner then blue band (medium) is generally prone to kinking...

    I think the best way to proceed would be to find a pipe bending place, get them to bend up a heap of bends, to which you weld the straight sections...

    Bending pipe and ending up with the right dimensions can be difficult and create a lot of scrap.. As when you make a bend the pipe grows, and how much it grows depends on a lot of variables...
    Gold, the colour of choice for the discerning person.

  5. #5
    Join Date
    Dec 2010
    Location
    Mornington Peninsula
    Posts
    97

    Default

    Quote Originally Posted by morrisman View Post
    The pipe bender tends to kink the smaller diam. pipes . I have one and its pain of a thing .
    Would filling the pipe with dry sand prior to bending help?

  6. #6
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    71
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    5,945

    Default

    Quote Originally Posted by morrisman View Post
    The pipe bender tends to kink the smaller diam. pipes . I have one and its pain of a thing .
    I used to bend a lot of pipe by hand in that bender, arms like bowling pins, make sure to give the other arm a turn. Used to make a lot of side rails and other types of bar work.
    The way I used to measure for a 90 degree bend, was to measure overall distance required, find the centre measurement of the pipe, halve the distance minus the pipe diameter and that mark is the centre of the die.
    The problem lies in the dies being made for pipe in imperial sizes. The way I got around it was to make a shim half the difference between the pipe and the die. For example 23.3 - 20 = 3.2 /2 = 1.6., 3/4 pipe OD 20 mm, pipe die 23.2 mm. use a piece of 1.6 thick steel sheet approx 50 mm wide and the length of dies outside radius. Insert between the pipe and die, pump away, it may take several pipes on the die spacer to get it right. If you have an oxy set, heating the spacer helps too. Have found that warming/annealing black pipe, till the outside COATING turns white helps also.
    The correct size dies can be purchased from places like H&F, for pipe dies to fit the BULLDOZER, a bar/pipe bending machine made in NZ, pretty sure their dies are for metric pipes, I had one about 12 years ago.

    Order Code: P508
    BZ-P20 - Round Pipe Former
    20mm
    Suits Bulldozer


    ex GST
    inc GST

    $79.00
    $86.90
    Hope this is of some help, to those that suffer the same problem. They have other sizes available also.
    Kryn







    Last edited by KBs PensNmore; 31st Jul 2015 at 03:16 PM. Reason: More detail

  7. #7
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    Jul 2008
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    near Warragul, Victoria
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    Default Ok

    ok SOME GOOD IDEAS THERE.

    Seems that having the correct mandrel is the secret to achieving good quality bends

    Thanks

  8. #8
    Join Date
    Oct 2007
    Location
    Alexandra Vic
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    69
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    654

    Default

    The correct mandrels are absolutely essential. You can hire hydraulic benders from some of the hire places, similar to this one which handle pipe from 12 to 50mm. I also strongly agree with the notion of making bends and then doing a cut and weld to form accurate frames. However you can determine bend gain empirically by cutting a sample of pipe that is big enough to bend and measuring its length, bend it , and measure the projected length of each arm after bending. The difference between cut length and the sum of the projected length is the gain, which is then factored in for each bend. We used to be able to bend tube into a rectangular loop to an accuraccy of 0.5mm for furniture frames using this technique.
    I used to be an engineer, I'm not an engineer any more, but on the really good days I can remember when I was.

  9. #9
    Join Date
    Jun 2007
    Location
    Vic
    Age
    48
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    544

    Default

    Last time I took some bits to Glennsam for tig weld. He has quite a lot of benders in the shop and making handrails for living. Maybe give him a call to see if he could help? His name is Jeff.
    039768 2400 - 473 Hammond rd, Dandenong South

    ps: found his website http://www.glennsam.com.au/

  10. #10
    Join Date
    Feb 2010
    Location
    Duquesne, Pa. USA
    Posts
    4

    Smile Bending Galv. Pipe.

    Bending schedule 40 galvanized pipe is fairly easy if you have a pipe bender. To get a close radius of what your looking for. But, if you tried that method and it kinks then you have to fill the pipe with dry white sand that is packed down. Doing it that way, first get a rag & pack it into one end of the pipe so it don't come out. Then start filling the pipe up with dry sand, while packing it in at the same time. You do that by hitting the side of the pipe with a hammer. That will pack the sand in the pipe tightly. Do that until the whole pipe is filled then cap off the remaining end with a rag. Tamping the rag in firmly. Being though you have to make 2 bends, make sure the bends are plumb/level with each other or you will end up with a twist. If you do manage to twist it, it's easy to get out if you have the righ equipment. Anyways say everything does come out perfect. Take the sand out the same way you got it into it, take the rag out of one end, hit the side of the pipe with a hammer & the sand will come out, DON'T add water to it, your asking for trouble if you do that. You'll learn on the first hoop to what to do on the remaining ones. Now, a word of advise, if your going to weld galvanized pipe, make sure that you grind of the galvanized coating at the point of the weld, remove all the zinc coating at that point, or suffer the consenquences at approximately 3 in in the morning when you wake up coughing your lungs out. That's the hazards of welding zinc. What, we always use to do after we welded galvanize was to drink a carton of white milk, seemed like you didn't get the 3 am hack, then. I don't know why it worked but it worked. By the way, you can skip the bender if you have a large and strong vise. You can hand bend, but take the same precautions as I stated above. Keep the pipe level & pack with sand. Good luck on your project.

  11. #11
    Join Date
    Jan 2015
    Location
    Sydney
    Posts
    211

    Default

    Dawn pipe bending dies, blackwood sell them. I got a 40nb one recently from then. Cost about 150 but you wont look back. Beats using sand.

    Sent from my SM-G900I using Tapatalk

  12. #12
    Join Date
    Dec 2007
    Location
    Melbourne
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    1,628

    Default

    There has been a lot of mention of using pipe benders, and one photo the kennards hire unit but there are many designs and sizes of pipe benders in industry.
    …..Live a Quiet Life & Work with your Hands

  13. #13
    Join Date
    Dec 2010
    Location
    nsw
    Posts
    51

    Default

    Have a pipe bender similar to the Kennards Hire one shown, always made good smooth bends until the last two times that I have used it. Feel most of the
    problems come from the quality of the pipe we get these days. Metric pipe imperial dies as mentioned may also be a contributing factor.

  14. #14
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    Oct 2008
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    N.W.Tasmania
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    Default

    Malb has hit it on the head with his explanation of doing a bend on a scrap piece of the pipe that you will be using, and measuring the gain in length for the bends you are making. When you make this test bend, mark the pipe at a repeatable reference point, for example at a point level with the edge of the bender frame. When you have done the bend, measure the distance from your mark to the centre of your bend, or to the point where it would intersect the line of the perpendicular leg if making 90degree bends. You will then know where to place the pipe so that the bend is in the correct position.
    If you had to modify the die to suit the pipe that you are using, I guess that it may be possible to build up the surfaces of each edge of the die, and then mount the whole thing on a rotary table and mill it back to the right width using a ball ended end mill. More work than Kryns method of shimming, but possibly less hassle if you have a fair few bends to do. Good luck,
    Rob

  15. #15
    Join Date
    Jun 2004
    Location
    Kyabram. Vic
    Posts
    632

    Default

    I inherited an aussie made 'STEER' brand pipe bender. I haven't used it for quite a few years though. I have made farm gates with it out of gal water pipe. My method used to be make your first 90 deg bend; then measure from the outside of the 1st leg; the length you wish, minus the od of the pipe. Mark the pipe and use this mark on the centre of the mandrel. This used to give me repeatable results. Then again farm gates are not exactly precision items; but are a real nuisance if they are longer than the opening.

    This may give you something to start off with. As has been said it made things difficult with the move to metric size and lighter guage pipes on older imperial benders. Another thing is those benders depicted have a short radius mandrel which I found causes the kinking. The old Steer gave a more gentle radius and eliminated the kinks. I also found that the adjustable 'bending' pins appeared to be graduated for 1/2" pipe on the inner to 2" on the outer.

    Ken

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