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  1. #1
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
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    714

    Default Equivilent RHS/SHS in U Beam?

    Hey Guys, I'm doing a pretty big job over at Aus Fish.com its rebuilding a 5.5 meter boat but the trailer i bought with it needs to be towed to the tip, just wondering what are my options of using U steel beam (not perlins) instead of the 100x50mm shs that its built from now? would 80x40x4mm U channel be a replacement? the old steel trailer looks to be 2-3mm material, the shop also sells 100x45x4.5mm U beam

  2. #2
    Join Date
    Jun 2010
    Location
    Wimmera
    Posts
    78

    Default

    I have built eight or nine boat trailers and would not use anything else but RHS.
    But be very aware of where to drills the holes for the galvanizing to get inside and then out when dipped, as well as for the water to get out after immersion at the boat ramp. Also that you have to allow for what ever angle they dip the frame.
    Hope this helps.

    John

  3. #3
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
    Posts
    714

    Default

    Hi Jack, I was thinking of using these ones pictured as the main rails than use more as cross members with U bolts holding them on, there would be 4 welds and the rest bolted on, these are already gal dipped so i'm thinking i only need to look after the welds with a spray of inox every use

    what's everyones opinion?
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  4. #4
    Join Date
    Jul 2011
    Location
    Adelaide
    Posts
    242

    Default

    I have designed a number of farm implements using both RHS and and various channel and beam sections. You will never get anywhere near the torsional rigidity out of an open section as you do from a closed section and this will show up in more places than you can imagine in the final product. This is a problem in an implement trying to cultivate the top 40mm of ground evenly but maybe not in a trailer.

  5. #5
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    875

    Default

    Quote Originally Posted by gazza2009au View Post
    instead of the 100x50mm shs that its built from now? would 80x40x4mm U channel be a replacement? the old steel trailer looks to be 2-3mm material, the shop also sells 100x45x4.5mm U beam
    In simple terms, 80x40x4 PFC is going to be significantly weaker than 100x50 SHS in all dimensions due to the narrower sections and the fact that it's open. 100x45x4.5 PFC would come a bit closer, as the vertical section is the same dimension as the SHS, but still doesn't have the same torsional strength. That said, depending on the design, potential twisting of the section may not be a major concern.

  6. #6
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
    Posts
    714

    Default

    Thanks Lama and Rusty, here isa pretty bad sketch of what i am thinking i wanted to make the design out of aluminium but no one will bend the T6 material 0-160 degrees so now i am going to build it from steel either professionally bent/rolled or i will cut and weld it

    the main outside rails sit with the open channel facing outwards the cross members sit under the outside channels with there open channel facing the road or down i plan on using U bolts to bolt it together just like the aluminium trailers

    hopefully the already galvanized C beams can withstand the salt water it will save the expensive galvanizing process
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  7. #7
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
    Posts
    714

    Default

    I actually just found out the steel is called C Beam or Channel Beam, Do u guys think my 50t hydraulic press could bend like in this video? https://www.youtube.com/watch?v=9pdplWosdSw&t=33s

  8. #8
    Join Date
    Jul 2013
    Location
    nsw
    Posts
    256

    Default

    c channel, pfc ( parallel flange channel), c beam or channel beam are usually used with the flange upright (ie. open section toward the sides) in trailers i've seen.

    flange stiffeners and /or gussets are often used to close the channel or reinforce it where forces may act in an undesirable way.

    i would encourage you to look at existing trailer design which used
    channel as the construction members.

    good luck with your project!

  9. #9
    Join Date
    Jun 2010
    Location
    Canberra
    Posts
    875

    Default

    Just to be clear, PFC is typically used with the *web* upright, and the parallel flanges horizontal - which I think is what you meant .

    That said, having the cross-members turned so the flanges are pointing down may not be too critical as each one isn't carrying the full load like the side rails.

  10. #10
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
    Posts
    714

    Default

    Yeah thanks Street and Rusty the C beam is the plan i can hopefully bend it using my 50T press, atm i am doing the transom on my boat but i will be building the trailer shortly i will make a jig out of my 6x3" beams i was using to make my home made press i will than place this in a shape of rectangular shape and use the press to bend the C beam to the right angles

    i am trying to do this with already galvanized C beams that way i only have to coat any holes i drill with inox it will save quiet a bit of money over getting the whole trailer galvanized at the finish, around here they charge $5 per kilo for gal

  11. #11
    Join Date
    Jul 2013
    Location
    nsw
    Posts
    256

    Default

    yes indeed Rusty web upright : ) sorry.

    Quote Originally Posted by RustyArc View Post
    Just to be clear, PFC is typically used with the *web* upright, and the parallel flanges horizontal - which I think is what you meant .

    That said, having the cross-members turned so the flanges are pointing down may not be too critical as each one isn't carrying the full load like the side rails.

  12. #12
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
    Posts
    714

    Default

    Do u guys think i could bend alloy i beam 160mm bend 20 or 30 degrees without the alloy cracking? The i beam is 6061 T6 if so i would prefer the alloy over steel but either one will work

  13. #13
    Join Date
    Oct 2015
    Location
    melbourne
    Posts
    190

    Default

    Over what radius?

    Russ

  14. #14
    Join Date
    Aug 2009
    Location
    Sydney, NSW, Australia
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    714

    Default

    Russ any size i dont have anything in particular as i will need to fanricate the die

    Do u think a 350mm die diy made would be sufficent to bend the alloy i beam say from 180 degrees to 160 degrees?

  15. #15
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
    Age
    66
    Posts
    3,371

    Default

    I think that IF you tried to bend it in a press, there will be problems, maybe not immediately, but further down the track. If it was me, I'd look at getting it rolled, it would be over a larger radii, hence less stresses built into it.
    A lot of trailers are done by rolling the drawbar/chassis section.
    When you enquired about rolling previously did you ask to bend it 160 degrees? As most would think 160 is back on itself almost, as about getting it rolled 20 degrees in a curve. Better still workout the width of the chassis rails, halve it and ask that it be bent to X from straight. Trying to get to degrees is harder on a roller, whereas asking for X from straight is relatively easy.
    Hope this helps,
    Kryn
    To grow old is mandatory, growing up is optional.

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