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  1. #1
    Join Date
    Jul 2019
    Location
    London
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    7

    Default Bending and welding sheet steel?

    Hi,

    I have an upcoming project which will require some bending or "large" mild steel sheets which will be welded to a tubular frame. I will be attempting to create a set of dining chairs with a curved back from 1-2mm sheet mild steel and im wondering what the best process would be to bend this accurately by hand?

    The radius would be around 20-25cm.
    What thickness of sheet steel is actually possible to bend by hand. We have some 2mm plate at the moment and i cant budge it.

    My second question is about welding the sheet to the frame. Previous attempts of welding sheet steel have resulted in melting holes in the work instead of actually welding. This was with 1.5 and 2mm steel and i assume i will have to go to a thinner sheet to actually create this dining chair.

    I also only have access to an arc welder, How can i weld thin sheet steel without it melting?

    Thanks,
    Matt

  2. #2
    Join Date
    Dec 2005
    Location
    South Australia
    Posts
    1,656

    Default

    Bending 2 mm steel sheet will be a task but not impossible,some type of home made device will be needed, I would need to think about what you could build
    hopefully some one more experienced than myself will chime in or you could cut the sheet to size and have them bent at a local fabricator.
    I have welded 2 mm sheet many many times with stick type arc welder, secret is short welds low amps, if you need to make long welds, just work your way along making a series of joined tack welds
    and pause if necessary to allow the work to cool down

  3. #3
    Join Date
    Jul 2019
    Location
    London
    Posts
    7

    Default

    Thanks for the reply, do you think i would be able to weld anything thinner? 1 - 1.5mm?

  4. #4
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    71
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    5,942

    Default

    Can't see why not, mind you it would help to know how much experience you had welding.
    Any chance of a pic or sketch of what you're trying to make, please? It would help in determining how to go about bending your sheet and fixing the sheet to the frame.
    Depending on where you are wanting to bend the sheet, some pipe of various diameters and a sand bag along with a heavy hammer to do the persuading will probably be all that is required. To give you an idea, have a look on You Tube, this one is an example, there are possibly hundreds of different one on there, https://www.youtube.com/watch?v=V-dzvdeYGsg
    HTH
    Kryn
    To grow old is mandatory, growing up is optional.

  5. #5
    Join Date
    Jul 2019
    Location
    London
    Posts
    7

    Default

    Quote Originally Posted by KBs PensNmore View Post
    Can't see why not, mind you it would help to know how much experience you had welding.
    Any chance of a pic or sketch of what you're trying to make, please? It would help in determining how to go about bending your sheet and fixing the sheet to the frame.
    Depending on where you are wanting to bend the sheet, some pipe of various diameters and a sand bag along with a heavy hammer to do the persuading will probably be all that is required. To give you an idea, have a look on You Tube, this one is an example, there are possibly hundreds of different one on there, https://www.youtube.com/watch?v=V-dzvdeYGsg
    HTH
    Kryn
    I have had some experience with welding, not a lot mind you but i can put 2 pieces together. The quality of the welding isn't really a problem for the sake of this project, i am trying to achieve something very rough and raw, I just cant have the whole thing to melt.

    I have attached a quick sketch of what im trying to achieve, its very simple with a large curved radius. IMG_20190717_165200.jpg

  6. #6
    Join Date
    Feb 2012
    Location
    Tamworth, NSW
    Posts
    202

    Default

    As well as low amps for welding thin sheet, get the smallest diameter welding rods you can buy.

  7. #7
    Join Date
    Oct 2011
    Location
    Norwood-ish, Adelaide
    Age
    59
    Posts
    6,540

    Default

    If it is a proper radius that you are trying to achieve, it may be worth going to a local sheet metal fabricator and seeing if they would let you use (or do the job for you) a set of sheet metal rolls. Here in Australia, a carton of beer helps lubricate things. Not sure what the appropriate thing in the UK is.

    This may sound obvious, but the reason you are melting through is too much heat, so as has been said, short welds, low amps. The other thing that may help is a block of Al or copper on the back of the weld that can help suck some of the heat out.

    Michael

  8. #8
    Join Date
    Jul 2011
    Location
    Adelaide
    Posts
    837

    Default

    Matt,

    From your sketch it looks like you are going to try to weld to round tube. This further complicates the welding because of the awkward gap you need to fill. Have you considered pop rivets as a means of fixing the sheetmetal?

    Eric

  9. #9
    Join Date
    May 2011
    Location
    Murray Bridge S Aust.
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    71
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    Default

    Thanks for the sketch Matt, puts a whole new light on the matter. To bend your sheet, it could be bent around something as simple as a drum of a suitable size, I'd put an edge around the panel, to prevent injury from the sharp edges, this would be as simple as putting the edge over a piece of timber and tapping it to a right angle all the way around then going further as in the link that was attached earlier.
    Kryn
    To grow old is mandatory, growing up is optional.

  10. #10
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Matt, Guys,

    I've seen a similar type of construction where the edges of a metal sheet was wrapped around a tube. Epoxy resin was used to secure the tube in the roll formed sheet edge. No welding, no pins or screws used to fasten the two together.
    Best Regards:
    Baron J.

  11. #11
    Join Date
    Sep 2012
    Location
    York, North Yorkshire UK
    Posts
    6,439

    Default

    Hi Matt, Guys,

    Double post ! Deleted !
    Last edited by BaronJ; 18th Jul 2019 at 05:45 PM. Reason: Double post
    Best Regards:
    Baron J.

  12. #12
    Join Date
    Oct 2008
    Location
    N.W.Tasmania
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    1,407

    Default

    Hi Matt, I don't want to be negative about your quest, but it seems to me, judging by the questions that you have asked, that with your present skill and experience level, you may find this a difficult task to achieve successfully. That is not meant as a criticism of yourself, after all we all have to learn somewhere, but welding thin sections of any material, is much more difficult than welding some heavy structural steel sections like 50 x 50 x 6mm angle for example, and made even more so if you only have very basic equipment and facilities at your disposal. You haven't said what sort of arc welder you have, and I'm assuming that it is not some sophisticated welding machine with lots of high end controls to make it easier to weld your thin sections, if my assumption is wrong, then that might change things a bit. Your questions on forming the metal to the shape you want also suggest a lack of experience, not to say that you couldn't possibly get the job done but my suggestion would be to look at some of the metal forming youtube videos, and one from this forum which may be of interest https://metalworkforums.com/f295/t20...t-screen-kombi and give you some ideas on how you might go about things. Google and YouTube will be your friends, and then perhaps you need to look for some place with the right equipment, maybe some schools after hours, vocational training places, even panel beaters or Mens Sheds if you have them nearby. Slip rolls if available, or if not a large anvil or some solid round bar would give you something to hammer the sheet metal to the shape required might be found in the right places as well as mig and tig welding gear which I think might work better for you than basic arc welder. I do hope that I haven'y put too much of a dampener on it for you, but good luck and I hope that you prove me wrong on my assumptions

  13. #13
    Join Date
    Jul 2019
    Location
    London
    Posts
    7

    Default

    Thank you to everyone who replied, I will take these into consideration for the project and hopefully learn some new techniques.

  14. #14
    Join Date
    Mar 2009
    Location
    Blue Mountains
    Posts
    195

    Default Chair Backs

    This project was completed last year but it is the same idea as Kryn posted in #9 above.
    In our house we have 5 of the office chairs shown in the first picture, they are all in good condition except for one problem, the plastic chair backs were breaking up badly. Picture 2 and 3 show the best back which I kept, the failure point is where the screwdriver point is. I don't like discarding anything which is possibly fixable and with 5 identical parts to make, some sort of attempt at repairing them was worthwhile. Using fiberglass to make up a part was one option but I have had limited experience with this and the exposed edge around the where the upholstery sits in the back would be an issue. The next thought was to try and make a part in aluminium (picture 4) by bending and bashing around a steel former. Picture 5 and 6. The former was made up using a set of bending rolls to get the desired curved shape. The parts were welded and the edges were rounded. The soft aluminium sheet was also curved with the same rolls and clamped to the former with soft face clamps-picture 7. The mounting holes were used for positive location and the corners of the sheet were trimmed. Using a soft face hammer the edges were bent over the former working progressively at opposite ends. I did not have high expectations but it worked well, the edges were cleaned up with a fine file and emery and the parts prime coated and painted. Picture 8 shows the finished part and picture 9 the bending rolls used.


    Mm.
    Attached Images Attached Images

  15. #15
    Join Date
    Mar 2009
    Location
    Blue Mountains
    Posts
    195

    Default

    Matt,
    i forgot to list the material thickness, it is 2 mm thick soft aluminium , I could have used thinner material as the part is very rigid when formed, however I wanted enough material thickness at the edges to be able to round off the shape similar to the plastic part. Interestingly after moving the chairs around with the plastic backs for nearly 20 years it still comes as a supprise to feel the cold metal when touching the new parts.
    If you are interested in chair design the pictured book might be of interest, it caters to the obsession that Industrial Designers seem to have with (often impractical) chairs. It would appear that you have not 'arrived ' as an Industrial Designer until you have designed a notable chair.
    Mm.

    Book cover.jpgBook rear cover.jpg

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