can you spot weld 3 pieces of metal together?

  1. richyrs New Member

    Posts: 6
    uk
    hi i am a bit unsure and need a bit of help, as title says is it possible to spot weld 3 pieces of metal together in 1 go, doing some repairs to car and have never used a spot welder before, can i weld floor lip, inner sill, outer sill together using a spot welder.
    all metal is clean as its new the metal at a guess is 1mm each also need to know what setting to put spot wellder on?
    the welder is a clarke csw 13t
    the settings are
    0.6+.06
    0.8+0.8
    1+1
    1.2+1.2
    1.5+1.5
    2.2

    now seeing as the total thickness is approx 3mm do i put it on 1.5+1.5 or do i put it on 1+1 as the metal is 1mm thick each?
    any help would be great as i should be getting on with this tomorrow, will obviously be having some practice on some off cuts 1st to get the hang of it.
    cheers for any help Richy
    Last edited: Feb 6, 2011
  2. awemawson Member

    You can, and I have.

    I suggest you do trials on offcuts of similar material so that you can adjust your settings and inspect the results. That way you can be fairly sure you get a weld to your satsfaction.
  3. Chickenjohn

    Chickenjohn Morris Minor and Porsche 944 fan

    Posts: 1,264
    East Kent
    Yes, I agree on the usefulness of trials. I've used a spot welder loads on time at college and the key to success is trialling the settings with the thickness of metal you want to spot weld. Then using the pilers, vice an peel test to break the pieces apart. If the metal breaks around the weld and the weld itself is still firmly stick to the lower piece then you know the settings were right.

    Don't forget to use weld thru primer between each overlap!
  4. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    Twisting a spot weld is not the correct way to test, as it does not replicate a real world failure.

    The two pieces need to be pulled apart/torn. If the weld is successful one sheet will have a hole or part of, with the remainder left on the other sheet.
  5. TIG Paul

    TIG Paul Moderator Staff Member

    Posts: 3,520
    Northampton. UK
    Whilst is possible to weld more than 2 thicknesses with a spot welder, its unlikely that a hand held diy spot welder will have the power or mechanical force required to produce reliable welds, modern and industrial spot welders have pulsing features, water cooling, and clamping force is pneumatic or hydraulically applied.
    Testing of spot welds should be carried out by using a peel test, a satisfactory weld will pull a hole in one plate.
    • Peel test.JPG
  6. steve202

    steve202 ǝlʇıʇ ɹǝsn ɯoʇsnɔ

    Posts: 422
    Wales.UK
    Punch a hole in each outer piece in different places and spot through them?
  7. Chickenjohn

    Chickenjohn Morris Minor and Porsche 944 fan

    Posts: 1,264
    East Kent
    Yes, I meant pull it apart with pliers, not twist, sorry, typo!

    As said above, spot weld should remain on the lower piece.
  8. Shox Dr

    Shox Dr Chief Engineer to Carlos Fandango

    cheers Paul, better than my explanation
  9. Robotstar5

    Robotstar5 Casanunda

    Posts: 7,963
    Birmingham UK
    Known in the trade as "pulling a slug"!
  10. richyrs New Member

    Posts: 6
    uk
    cheers for the help, will give it a go on the scrap and see what happens if it cant spot the 3 together will do as steve202 suggests and try that
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