Working with ABS Plastic Grills

Anything goes in the world of fiberglass and plastic

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PostPosted: Thu Apr 25, 2019 10:42 am
I'm in the process of retrofitting a '69 Camaro RS grill and I have a question about the ABS material... I need to "twist" or shave the lower DS corner maybe 1/4" so it aligns with the "nose" of the fender. My fenders are all original 1969 parts, and the grill is an aftermarket (repop) so like many others, I will have to adjust the fit. 1st Pix shows what the fit _should_ look like.

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Next image shows the current fit. I have elongated the four lower mounting holes so the grill shifted about 3/16" to the PS. The upper mounting holes look like I can get the screws in. The grill is injection-molded and the cross-section is probably .125" to 150" so I'm thinking that if I receive the back side 1/16" where it seats on the sheetmetal... that might bring that lower edge in just enough. Plus... I guess I could very carefully sand the knife edge off and fair it in if I need a little more. Messing with 50 year old sheetmetal that's already painted is out of the question.

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Opinions on what might work best, and could I use a heat gun to sort of push the sanded edge tighter if there's a gap? I'd hate to countersink a screw there to tag it to the fender "nose" because I'd have to repeat it on the opposite side and bottom line is it wouldn't be authentic. TIA for any/all advice.-Mike

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PostPosted: Fri Apr 26, 2019 12:06 am
I've always had good luck "moving" fiberglass over the years with kit cars so about 10 years ago I started branching out with other plastics, doing some welding, and "moving" of parts. I had an old sports car with a pretty nice aftermarket lower nose made out of ABS. The end wraps were becoming distorted with age and just didn't snug up where they should be. I did indeed use a heat gun and a zip lock bag of ice to heat/set/heat/set the ends back to shape. The stuff does literally melt at just 220 F. so you do have to watch yourself and get a feel for moving it. Here is an interesting article on using boiling water to shape parts off the car.....
https://thefrugalprofessor.wordpress.co ... tic-parts/
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!

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PostPosted: Fri Apr 26, 2019 4:17 pm
DarrelK wrote:I've always had good luck "moving" fiberglass over the years with kit cars so about 10 years ago I started branching out with other plastics, doing some welding, and "moving" of parts. I had an old sports car with a pretty nice aftermarket lower nose made out of ABS. The end wraps were becoming distorted with age and just didn't snug up where they should be. I did indeed use a heat gun and a zip lock bag of ice to heat/set/heat/set the ends back to shape. The stuff does literally melt at just 220 F. so you do have to watch yourself and get a feel for moving it. Here is an interesting article on using boiling water to shape parts off the car.....
https://thefrugalprofessor.wordpress.co ... tic-parts/


Hey Darrel...

Used the heat gun with a ice cold microfiber, did a little "persuading" with a rounded 1" dowel. Its much better.

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Messed up the surface a little bit, but I can probably use some bondo or whatever to bring it back smooth. Would you use surface putty, bondo or something like JB Weld? I just don't want it to peel or crack off after prime and paint.

Mike

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PostPosted: Fri Apr 26, 2019 5:29 pm
Mike.....nice.... yeah, I like to use a poly putty surfacer with most semi-rigid plastics. I use USC's Body Icing. It has the ability to grip tight and flex but is much easier to "finesse" with higher grit sandpapers.
Metal, wood, fiberglass, we work it all... www.furniturephysicians.com We can restore the irreplaceable!

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