Cut hole, fill, mold to shape in ABS motorcycle fairing

Anything goes in the world of fiberglass and plastic



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PostPosted: Sat Mar 07, 2015 2:38 pm
I would like to try this stuff instead of epoxy over raw plastic
http://www.urethanesupply.com/Bumper-an ... k-Gray-Qt/
This one is interesting too
http://www.urethanesupply.com/Waterborn ... ck-Primer/

These are the repair sheets for big hole that can be welded in with there welding rods.
They are of different materials and not ABS though so it wouldn't have worked for you.
But ABS cut from a Bumper cover could have been welded in and I am not sure but I wonder if TPO could be welded to ABS? using there universal welding Rods?
http://www.urethanesupply.com/Polypropylene-Sheets-1/

http://www.urethanesupply.com/Polyethyl ... -1/5010-4/

You said you have more of these to do this may help in Identifying the different types of plastic and what type of materials are compatible for repairing them. There is a lot of info on there sight. I thought the stuff you used from them to fill those big holes was cool stuff! I will be trying some on ABS in future.

http://www.urethanesupply.com/identify.php


Also in that one picture of the area where the Primer is trying to lift what ever is under their if you hit that with Base coat wont the Base coat solvents eat through and lift more of what ever the primer is trying to lift?

download/file.php?id=5336&mode=view
Dennis B.
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PostPosted: Mon Mar 09, 2015 6:54 am
The base coat might get through to whatever is reacting and be a problem later. Not sure. That's one of the reasons I went ahead and put glazing putty over those spots and feathered it out before I put on the high build K36. My thought was that I'd encapsulate it enough that the base coat wouldn't penetrate that far.

Could be misguided...but that's what I figured I'd try. At that point, those spots had come back after two coats of the epoxy. Once I did the glazing and K36, they didn't show again. I'm probably past it now? My biggest fear is that that area might a weak link in the adhesion chain and fail over time.

As far as ABS pieces for welding in, I do have access to plastic suppliers in Houston, through my job, where I could get my hands on an ABS sheet to cut for that purpose. I might do that for the next fairing I do. It would certainly be cheaper than using this PlastiFix to fill the entire hole. But, I was fairly impressed with the PlastiFix. It was very easy to work with and seems to have worked very well.

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PostPosted: Mon May 11, 2015 7:21 am
It's been quite a while since I have had the opportunity to work on this project. Work finally slowed down, so I'm back at it. These are other parts off the same bike. I still have the saddlebag bottoms and lids, lower fairing pieces, and some chromed plastic parts to prime before I start into base coats. Oh....and the gas tank and both fenders - which are metal. I'm trying to just get the plastic done first.

I shot some of those "speed shapes" from the paintwithpearl site...my buddy wants this to be white with a blue pearl, so this will get interesting for a paint-virgin like myself.

I am finding that the PPG K36 is very easy to sand, but extremely difficult to lay down in any way other than pretty rough. I don' t yet know if this is just the way it sprays, or if I need a reducer...or if it's just my cheap gun. I suspect the reducer will help me some. But if it's the gun, I'm going have a really hard time with base colors and clear.
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PostPosted: Mon May 11, 2015 8:38 am
Yeah, you'd better get that figured out with the K36 first... stuff lays down like glass for me. Even if I use one of my turbine guns it only requires minor viscosity adjustment. Cheap gun is probably suspect....
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PostPosted: Mon May 11, 2015 8:59 am
Dang...like glass. I've got real problems then. It just spits out of my gun, and gets worse as I go.

So far, I've had an issue with trying to decide WHICH tip to use with the things I've been spraying. K36 spec is 1.4 - 1.6. I have a 1.3 and a 1.8. I tried the 1.3. Perhaps I should be trying the 1.8 before I buy reducer? Or an air pressure change...

There are a lot of variables....I have a lot of respect for the folks who've spent years understanding how to control these variables, and can troubleshoot these things on the fly. Trying to do just a couple of project like this during the learning curve is pretty tough.

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PostPosted: Mon May 11, 2015 2:23 pm
Well, at least your smart enough to know there are a lot of variables.... Yeah, try your 1.8 tip and just see how the coating flows. If you notice any improvement at all that would probably point toward increasing pressure and/or reducing.... That 1.3 is smallish for that stuff in my opinion.
Trust me everything that's got to do with a car is a big learning curve.
I just spent 42 hours cutting and fitting a full mandrel bent 11 gauge rotary headers/ exhaust system going through 3 pounds of welding wire.... And hell, my minor in college was Welding Engineering and Heat Treating....
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PostPosted: Tue May 12, 2015 8:48 am
Thanks again. That makes sense. One step at a time in the troubleshooting process...so you stand a chance of understanding exactly what fixed the issue. Good advice.

Last night, I went to prime the saddlebags, but I realized that I never did hose them down after all the sanding. They were filthy in the little corners. And there are a lot of little nooks and crannies on the back side of these bags. That part never gets seen, and I couldn't really scuff all of it very well, but I figured it best to take care of it the right way and let them dry overnight before I try. I've only got about a 2 hour window to work on this stuff each day between the day job and the other things I have going on. So I hope to have something good to report tomorrow.

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PostPosted: Wed May 13, 2015 9:53 am
What a difference a day can make. Moved to the 1.8 tip. Better. Adjusted the air pressure up. Looked better, but thought it would flow better with a little reducer. So...I added about 1/2 of the allowed 1 part. Amazing difference! It looked so good that I actually shot another coat over the rough parts from Saturday's shot. It flowed and leveled it out quite a bit, reducing the amount of sanding I'll have to do on those. I feel good about it.
IMG_4063.JPG


Here's a shot of a piece of chromed metal from the back end of the bike. My buddy wants this and some other chrome pieces, both plastic and metal base material, painted. Having read a lot of different ways to pull this off, I went with the one that seemed the easiest to me....and used this piece as a test. I simply scuffed this with 220 grit, sprayed it with adhesion promoter, and hit it with the K36 primer. I figure this piece will be easy enough to strip if it doesn't work or if one of you happen to tell me that there's no way this works long term. I've read where folks say you have to use etching primer, and where folks say you don't. So I figured, what the heck, just try it.
IMG_4065.JPG


Now, all that being said. As far as air pressure goes, I really feel like I'm well above what I've read should be at the gun on a HVLP gun. I'm looking at near 40 psi at the inlet when the trigger is pulled. But I felt like the paint wasn't really atomizing well below that....was still spitting a lot. Maybe the cheap gun...maybe just me. Not sure. Of course, the problem here again is my lack of experience. Not knowing exactly what I should be seeing.

I also sort of feel like I should dial back the paint delivery and the spread. In retrospect, I felt like I was having to move VERY quickly with the gun, as it was putting out way more primer than ever.

Bottom line is - I can finally say I got primer to lay down "like glass" as Darrel said it would. I'm pretty excited about that.

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PostPosted: Mon May 18, 2015 9:09 am
I tell ya...this reaction to the metal flake in the OEM base coat is soooo frustrating. I just don't see any way around having to sand completely to the ABS in order to just get it out of the way.

Begs the question...when it comes to scuffing or sanding an OEM finish to prep for refinish, I'm operating under the assumption that I have to get rid of ALL shine. Which, on these Victory motorcycles, is pretty hard to do without sanding through the base coat due to the heavy orange peel of the OEM finish. Scuff or sand, there are always little divots that retain the shine until you really get after it.

If the purpose of scuffing an OEM finish is to give a primer a physical edge to grab, am I correct in thinking that any shiny spots left are a bad idea?
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PostPosted: Mon May 18, 2015 1:20 pm
Bummer, it's always a "sinking" feeling when coatings go reactive like that. Your thought process is correct about getting rid of "shine." If there is shine, well, at least in my mind, there is no "profile" for physical attachment and the good ol' days of coatings (lacquers mostly) "burning" in or melting in for grip are gone so..... yeah, if that coating is that sensitive down to ABS you go.... been there many times.....
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