all about welding

[Cameron Reed]

Hi Mike, welding of the outer fender should be reasonably straight forward, as long as where you are trying to put the patch in, is tying in with good sound metal. It has to be super clean both inside and out as when you weld it tends to draw any impurities from the backside through. If you have a mig and wish to try it you have to use pure argon as sheilding gas(as stated) buying wire shouldn't be to bad .035" (.9mm) 4043 is available in small spools (I've got some if you wish to try). Make sure that you keep the gun lead as straight as possible, give the liner a good blow out(generally best if you take the liner out of the cable and blow compressed air through whilst trying to rap it lightly on the ground). I would generally go for the next size up tip to help the wire to feed freely (all helps to avoid birdsnests when you get burnback). Probably another thing to check is that the feed rolls line up with each other in the vee, if they are offset a little they tend to shave the wire which then builds up in the liner and then makes nice birdsnests. The feed roll pressure should only be enough to feed the wire smoothly(my simple test is to pinch the wire between your thumb and finger and adjust feed roll pressure until you can't stop the wire with reasonable pressure) When you buy material to make patch ask for 5052 grade if available it is a marine grade 5% magnesium, it is a little stronger than 5005 so it will help hold it's shape a little better. Not sure where in Vic you are but if your sorta close to s/e burbs I could do it with the Tig (dynasty 200). please feel free to sing out if you have any questions or want any help just pm me, or from anyone for that matter
regards

[ozm29c]

Further to the constructive comments by other forum members. Here are some other thoughts to consider.
1. Always check what lies behind your proposed patch panel ie will it burn!!!!! Is there a fuel line or electrical wiring looms.
2. Prepare the joints to ensure that you are welding clean metal, Any contaminants in the weld pool will either weaken the join or blow out while you are welding like a mini volcano!
3. Keep the joint width between 0.5 to 1mm to allow for expansion of the donor patch and to ensure good joint penetration.
4. Use 0.6/0.8mm dia wire with your smaller Mig welders. Having said that my thoughts on MIG welders are the bigger the better. Small MIG welders are fine but the bigger welders have more OOMPH! In Australia 0.9mm welding wire for the bigger welders is cheaper to purchase as it is made locally where as 0.8mm wire is imported.
5. If possible try to avoid using flux cored wire.
6. With patch panels don't try and weld in continuous seams, spot here then move away and place a spot there. Continue staggering your spotting until the join is filled-This takes more time but will help dissipate the heat and minimise your patch panel and parent metal from heat distortion. Remember HEAT is your enemy. A good cup of Tea or Coffee can be enjoyed many times
7. Use heavier gauge metal ie 1.2mm or at a pinch 1.6mm (than your parent metal)to make your patch from. This will help you to start and maintain your weld without blowing a hole in the joint. Looks no different on the outside.
8. Use sunscreen on exposed parts of your skin as MIG welders have a tendency to burn your skin with excellent results. Better still try to cover all exposed parts of your body.
9. I know it is hard but try to weld with elbow length gauntlets (Leather gloves). I am sure experienced welders at some time in the past have grabbed a hot bit of metal with their bare hands by mistake. OUCH!
10. If you can borrow or purchase an auto darkening helmet, do so. Good for tak welding.
11. Buy yourself a cheap Chinese angle grinder but always use good quality cutting and grinding discs. Use the very thin section cutting discs. As always use PPE ('FULL' Eye protection and hearing defenders)
12. When grinding off the finished welds try not to use excessive force to speed up the removal of excess weld. All you will do is create heat with the end result being metal distortion. Once you have levelled the ground surface, get hold of a flapper disc to further smooth the surface. After all due care to minimise distortion you still might have to delve into the lost art of heat shrinking metal. The technique is for another post.
13. Paint/prime the exposed metal as soon as possible to prevent corrosion.
14. BTW The point of a screw driver is a very good tool for probing around the affected area to try and determine the extent of rust damage. Once you have cut the rust out of a particular area, then and only then is when you will know where to start your repairs.
Anyway I hope this will give you something to work with.
Don't rush the job
Good luck
Cheers
John Wilson