rust pinholes in sheetmetal + 1 rusted out section

More of an art than a science - discuss metalworking and welding here.



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PostPosted: Tue Dec 17, 2013 1:25 am
hey all

so i'm doing some work on some 1950s scooters and have a bit of arc welding experience as well as brazing experience. I have some rust pinholes in the bodywork of the scooter, maybe 1-2mm in diameter, and I was wondering what people think I should do to fix these.

If I ground out the rust and wire brushed the metal I imagine some high content silver braze (40-50% rods) would flow really well into these pinholes. do you guys think this is an acceptable method to repair the holes?

also there is a part of the panel that is rusted out completely, I have a donor panel I could cut the good panel out of.

My question about this is, would it be possible to braze the replacement panel in if I cut it out really accurately? or would that be a crummy way to do it?

I don't have a mig welder, but could consider purchasing a cheap gasless welder, with a thin gauge wire would that be more suitable ?

I will get some photos up when I can...

thanks for any ideas

basically the thing to consider is that I don't have any welding equipment (other than a big old arc welder), so I wanna see if I can do it with brazing equipment - I don't have any oxy/acetylene, just a propane torch which has served me well with thicker gauge metal so I am thinking sheet metal should be ok...

Ed



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PostPosted: Tue Dec 17, 2013 1:33 am
ok after doing some reading I think I may have found the answer - basically seems like brazing is a bad idea as paint doesn't stick to it.

looks like I better invest in a mig welder... :D thats ok with me! I just need to generate some funds for it lol

can you weld sheet metal with a cheap cheap cheap gasless welder and thin flux cored steel wire? say like 0.6mm

I have seen plenty of mig welding so I understand the principles of sheet metal welding... would definitely need to practice on some similar metal before going crazy on the actual scooter bodywork



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PostPosted: Tue Dec 17, 2013 7:17 am
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the hood has 2 sheet metal skins which I guess is the problem, moisture gets between the 2 layers and rusts it out?

could I just grind all the surface rust off, hit the holes with a wire cup on the angle grinder, then carefully drill / stone drill out the rusty margins (if flaky) from the outer skin and then mig weld these holes in?

have a number of holes that were drilled by past owners in the hood, - how big can you go when migging holes ?

also see the little metal fins have been cut away, I have a donor hood with worse rust I could possibly take these fins from...

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PostPosted: Wed Dec 18, 2013 1:46 am
if it were me I would send out that piece to be sandblasted and then see what kinda shape its in. more than likely you will find that the spots with the holes that you wanna mig weld up are too thin to weld to and youll just blow the hole bigger and bigger.



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PostPosted: Wed Dec 18, 2013 11:59 pm
so you think patch panel is the only way to go ?



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PostPosted: Wed Jan 01, 2014 6:05 am
im with tanner, I wuld blast it orwire wheel it really good to see how bad the rust is, I find that a drill bit slightly bigger than the rust hole works well, drill thru the hole and move it around the "bore" the hole out a little, you will feel the bit bite and get harder to move when you get to good metal, then assess your approach on the repair, if you have a patch panel and not keen on welding it, take it to a sheet metal place to weld in, they usually charge by the hr and would prob get it welded in less than a hr if its all ready to go!!
I use a tig for my panel welding, its just a cheap inverter with HF for easier starts, I try not to use filler rod as its hard to planish nicely, wit a mig it can harden the weld area and make it too brittle to plenish, plus the penetration on the underside of the panel also makes it hard to planish, don't underrate oxy welding panels either, its perfect for sheetmetal!!
krem

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