Sanding

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duracolors

Guest
I've got a rear fender to paint that came from the bike shop with some deep scratches . I da sanded with 80 , 120, 220 then wet sanded with 400 prior to primer. I am up to the 220 grit and was wondering if this is normal. My plan is to fill the remaining scratcheds with spot putty after primer. Is this the correct process?
Thanks
 

rex

New member
Were you sanding paint or factory primer?The best thing to do is sand out the scratches and prime and block it to smooth out the featheredges.If the scratches are deep through lots of paint it's better to strip and start fresh.
 

rex

New member
Hey Den,not too bad so far.It.s been 'a nice' 50's in the mornings and gotten mid to upper 70s the last few days,figures the scooter's in pieces and I can't enjoy it.I know this wont last long,but at least I'm not in your shoes
haha.gif


Duracolors,got ya.The wetsanding wasn't good though.After I go through the chore of removing all the friggin oil-if yours was-I beadblast the part then DP it(PPG's epoxy).If I can't I sand it with something course like 80-120 grit then DP it.Once the epoxy has set long enough I red Scotchbrite the area I need to fill and do it.A few gouges like you said will fill right in with some 2 part polyester putty.Look at it after it's primed though,I bet this thing is a nasty wavy mess that's hard to see in raw steel.All those little grooves on the sides left from shrinking the sides while forming are going to show up twice as bad.I won't be surprised if you need to skimcoat it with bondo.I'm doing a Custom Chrome brand-whatever their generic maker is-rear now for my buddies scoot and it needed almost as much work as the last one I got.I rework the rear edge and recut the folded flange on the sides on them automatically and radius all the edges.This crap usually takes me 45 minutes or so along with the normal prep.I like to weld a rod around the rear edge of aftermarket fenders but most people wont go for it,so I'll be making money later when it cracks on them and it needs replaced.Sorry,kind of rambling again.Just clean it really well with grease and wax remover through the metal prepping stage and keep to the 120 or sharp pieces of 220,120 scratches on steel are about the same as 240 on paint so they're nice and aggressive to hold the primer without worrying about having to fill them in with lots of primer and sanding.
 

rex

New member
I read my last post and need to clarify something.I don't grind and radius so it will fail if I dont weld a rod in,I do it to prolong it from happening.The cheaper aftermarket tin is usually thinner steel and crudely stamped.The ends that aren't flanged are usually beat up so after a little hammer and dolly work you want to grind the edge back slowly without heating it up until it's full thickness metal.Then debur all edges by knocking 150 over them,running your finger over them they should be radiused and not feel sharp.Where the flanges are cut them at a 45% angle or so and round it all out.Any square edges at the flanges or sharp edges will eventually crack on a Harley,especially rigid mount engines.
 

flamethrower

New member
Yep, listen to Rex.
Never wet sand bare steel. Your primer will fill any 220 scratches no problem. Don't introduce any avenue for rust to start.
 
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