Metal Bending and calculating length

  1. Diveboy New Member

    Messages:
    2
    Location:
    Newcastle
    Normally I search, but I apparently don't even know what I'm asking...

    I'm drawing up plans for a pizza oven, similar to the UUNI one and need to put two bends in the top to add 100mm of height, but that will make the overall width shorter how to I work out how much to add to compensate for the bends (height).

    Hope you make it through that description in one piece...
     
  2. Mee Banned

    Messages:
    1,509
    Location:
    Here and There
    For someone inexperienced I would suggest marking datum lines across, and either side of the bend, then do a test bend, and you then have the original lines to measure against to get accurate measurements for the amount of material you need to compensate for.

    As long as all your bends are consistent all your marking out is consistent.
     
  3. carbon

    carbon Member

    Messages:
    587
    Location:
    S. Glos. U.K
    I think what you are looking for is 'bend allowance' just had a quick look not at pc now and have found this

    reference

    Scroll down to the bend allowance section
     
  4. Hitch

    Hitch Moderator Staff Member

    Messages:
    11,106
    Somerset
    Draw it out to scale, inside and outside faces of the material thickness you will use, and measure the inside sizes, add them up and that should sort you...it will be accurate enough for a pizza oven.
     
  5. Normsthename

    Normsthename Member

    Messages:
    490
    Leicester, UK
    The quick and dirty method is to take a thickness off of the overall.
    So, if you had an angle that measured 100 x 75 in 2mm Mild Steel, the true length would be 171mm long (98mm inside and 73 inside)
    That is assuming they are 90 degree bends.
    That method will work for Mild steel upto and including 3mm thick.
    Above that you need to do a bit of calculation using the mean line and also take into account the bigger bend radius.
    If you use 2D cad you can draw the profile with an internal radius of the material thickness.
    Then you draw a dividing line down the centre of the profile and measure the lengths and radii

    Andy
     
  6. Hitch

    Hitch Moderator Staff Member

    Messages:
    11,106
    Somerset
    Exactly, when you get inside to outside measurements or folds not up to 90degs people seem to get a bit befuddled, then i suggest forgetting outside measurements and just working to the inside ones.
     
    Welderpaul likes this.
  7. bricol Member

    Messages:
    268
    N.Yorks, UK
    That's how I'd dimension a drawing - don't tend to go much above 3mm so it's worked for the last 20 odd years ;-)
     
  8. Diveboy New Member

    Messages:
    2
    Location:
    Newcastle
    Thanks Guys, So if the base is 500mm and I want a 100mm rise in the top using 2mm mild steel the total width would need to be 650mm?
    I've uploaded my plans with the extra for height still missing for reference.
     
  9. Blackolive Member

    Messages:
    54
    uk lancs
    Hi, wondering what you are planning to use for the burner arrangement ( assuming you are planning using wood pellets ) and are you insulating the top of the unit with ceramic fibre ? will be watching this one with interest, Ive fancied a wood fired oven for years but the brick ones are too big for our garden
     
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