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Liquid mettle
Posted: Thu Dec 11, 2014 11:16 pm
by sydduckett
Just got my leg shields back from the blaster and theres a lot of rot and perforations where the floor runner channels sit. This was filled with filler previously and can be again but ideally I'd like to get some metal in there and was wondering what the options might be.
I was thinking of May be filling the dips with liquid metal and then gently grinding back, or maybe brazing which I don't really know much about although Ed had good result on a floor plan on wheeler dealers

Re: Liquid mettle
Posted: Fri Dec 12, 2014 1:38 am
by coaster
Loading the area with lead might be possible but brazing will need a lot of heat (cherry red) over a wide area which could cause distortion/buckling. Brass is also very hard and will take a lot of grinding. I'd be tempted to use JB weld, it is very liquid and could be brushed out.
Re: Liquid mettle
Posted: Fri Dec 12, 2014 1:42 am
by sydduckett
coaster wrote:Loading the area with lead might be possible but brazing will need a lot of heat (cherry red) over a wide area which could cause distortion/buckling. Brass is also very hard and will take a lot of grinding. I'd be tempted to use JB weld, it is very liquid and could be brushed out.
When you say brushed in do you mean brushed into the pitting?
Ta
Re: Liquid mettle
Posted: Fri Dec 12, 2014 2:07 am
by goldeneye
brass (brazing) isn't hard at all to dress with a flapper disc in a grinder. if your going to the hassle of brazing in a large area, you might as well cut out and Mig in a piece of steel to make a proper repair. if its had a skim of filler in (not git big chunks) I would just go with that , your gonna have to do that even if with some metal work repairs. I"m no bodywork expert though.
Re: Liquid mettle
Posted: Fri Dec 12, 2014 2:39 pm
by sunrisemac
Devcon also make liquid metal similar to JB Weld, but if you can lead load the panel IMHO that's the best solution
Re: Liquid mettle
Posted: Fri Dec 12, 2014 5:33 pm
by GLscoot
On a similar note, on last years project with the powder coat. Condensation has emerged under the powder coat coming from the seams on the Vespa and has started to rust, nothing major and should be ok for another year. My plan was to weld up the seams and get it powder coated again.
Does anyone have ideas on what to do as in welding the seams, Lead would be a nice option as would brazing, I like the fact that it would all be different, but I am worried about the heat distorting the frame.
Re: Liquid mettle
Posted: Fri Dec 12, 2014 6:37 pm
by ducksta
dont think you would get much distortion on the seams as it is probably the thickest part on a vespa, find a good gas welder looks great done right.
Re: Liquid mettle
Posted: Fri Dec 12, 2014 7:05 pm
by coaster
sydduckett wrote:coaster wrote:Loading the area with lead might be possible but brazing will need a lot of heat (cherry red) over a wide area which could cause distortion/buckling. Brass is also very hard and will take a lot of grinding. I'd be tempted to use JB weld, it is very liquid and could be brushed out.
When you say brushed in do you mean brushed into the pitting?
Yes, that's what I meant although it is slow to set unlike other epoxy mixes, several hours to 'stiffen up'. Therefore it will self level to an extent and will probably drip through any large holes so put some tape over the rear first
Lead loading would work if you can find someone to do it but sanding it smooth afterwards is likely to be VERY risky to yours and anyone else in the areas health.
I once tried brazing in a section on my LiS leggies, I was using a MAP gas torch which was capable of of getting the steel up to the temp required for the rod to melt and flow but the buckling was awful. I ended up cutting it out and mig welded another section in plus a fair bit of filler to compensate for the heat distortion

If the are you want to repair is thin enough to have pinholes, it's likely that it will burn well before it is hot enough to melt the brazing rod

Re: Liquid mettle
Posted: Fri Dec 12, 2014 9:36 pm
by mr series 2
GLscoot wrote:On a similar note, on last years project with the powder coat. Condensation has emerged under the powder coat coming from the seams on the Vespa and has started to rust, nothing major and should be ok for another year. My plan was to weld up the seams and get it powder coated again.
Does anyone have ideas on what to do as in welding the seams, Lead would be a nice option as would brazing, I like the fact that it would all be different, but I am worried about the heat distorting the frame.
I have de-seamed using lead with good results but only to paint over not sure if powder coat would take to lead
Re: Liquid mettle
Posted: Sun Dec 14, 2014 11:47 pm
by GBCS
Soft solder melts at 180 to 190 degrees C.
Powder coating cures at 170 to 180 degrees C.
Curing the powder could well melt the lead out.