How To Do Butt Joints in Stainless Steel
- The secret is to control the heat. Controlling the heat prevents distortion.
• Cool frequently and quickly
• Jump around – keep the heat spread out
- Do the side welds before the edge welds.
• If you do the edge welds first, when the side is welded and heat expands, it will have no way to relieve the pressure other than to buckle
- SS distorts more easily than bronze or aluminum because it traps the heat. Bronze and aluminum conduct the heat away from the weld. SS keeps the heat right where it is applied and warps it right there.
- Good fit up is essential. It is essential to use the pattern to cut the metal exactly. Then…… check fit up, trim as necessary, bend & shape
• Big gaps must be filled with MIG – go in hot and fast for a short time duration – 5 seconds max - then immediately apply the wet paper towel – cool, do a little more
• Never use TIG to fill a gap
- Consider using thick copper as the seam backer ipo SS
- Mig – this is ideal to close the seam – only do manual pulse. Manual pulse means on for 0.3 seconds, then full off. Use the proper WFS and Volts for good penetration. Do not run a bead! JUMP AROUND – do one inch, then immediately apply a wet paper towel
- MIG - Stop frequently and check for distortion. Use the necessary wfs and volts for good penetration – JUMP AROUND – do not do a complete bead. Do one inch, then put on a wet paper towel
- Use copper shields on each side of the join to block the splatter and to absorb some heat
- Heat control – wet paper towel – apply to the welded area – let it stick there and proceed to another area while that spot cools
- Never grind below the plane. You can’t grind a hole away.
- Mig welds should be ground with the 3M cubitron disc until almost flat. You will then be able to see where the repairs need to be made. Leave that extra metal to help with the tig welding repairs
- Tig welds – only do manual pulse. Do full pedal on, slow pedal to completely off. Count one-thousand between each puddle. Make sure the red has died away from the metal. Back off on the pedal slowly – rapid cooling leaves a tiny hole in the top of the weld
- TIG – do not melt the wire before the base metal. This technique has poor penetration. The rod metal does not get blown into the base metal, it simply bridges over the top of the join. When you grind smooth, you will see the joint and have to redo the weld.
- Don’t try to create a fluid puddle and control the puddle – that is a stick welding technique and will put much too much heat into the join – that will guarantee the metal will warp
- Tig welds must be ground with the Roloc pad – this will allow you to focus precisely and to grind only the weldment and not the rest of the metal. 5” pads are too large – too hard to aim precisely
- It is very easy to grind too much metal – even 16 gauge SS can be ground paper thin
- Grinding makes the metal hot also – cool immediately by applying a wet paper towl
- Note – edge seams are not so prone to heat distortion. You generally don’t need to cool these or jump around while welding.
- Note – repairs – do not reweld an entire edge – this is a waste of time. Only tig weld repair divots
- Do not try to grind away divots after the edge has been blunted to 1/16” – fill these with Tig
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