Since I did the repair on the inside of the fairing only, I was going to call the thread "Backside Crack Repair", but come on, I can't make it that easy for you guys.
I wanted to do a basic, slightly hidden mechanical repair on my cracked fairings so I could put them back on and ride while I read up on doing an outer cosmetic repair and painting. It's going to be a while before I'm ready to try painting all my fairing at once, so I wanted a quick and dirty repair that would prevent further cracking, would be strong enough that I wouldn't have to go back and redo it before painting, and made the fairings looks reasonable from the outside.
Feel free to post comments or suggestions on how to do this better. I know there is a lot of info out there on doing repairs, but sometimes it's hard to find. I did this as practice on a totally destroyed part to see how it went first. The hardest part was keeping my gluey, resin covered hands from getting gunk all over the outside of the fairing while handling it. Some masking tape on the good side would fix this.
I also think using a pyramid layup of progressively smaller plys would be good to prevent edge cracking around the fiberglass repair. When done, the repair area is significantly stiffer than the surrounding plastic, so any in-use flexing may create a stress riser on the edge of the fiberglass patch. I haven't seen this happen yet, but a pyramid stacked patch would decrease the stress at the edge of the repair.
Materials used:
CA glue (generic superglue from walmart)
Baking powder
Fiberglass mat
Fiberglass resin kit (from walmart)
Spreader
Dremel with teardrop shaped sanding wheel
Rubber gloves
Degreaser
Sandpaper
Synopsis of the steps:
1: Using a 1/16" drill, I found the very end of the crack (sometimes in multiple places) and drilled out the end to prevent further cracking while I worked.
2. Using a teardrop shaped sanding wheel on a dremel, I removed plastic in a trough shape from the length of the crack. Why I did this, I'm not sure, but it seemed like a good idea at the time.
3. Gently spreading the crack open a tiny bit (insert jokes here), I applied CA glue to the length of the crack. I wanted the CA to run into the crack, but not all over the outside of the fairing. I then pinched the fairing tightly together.
4. I sprinkled baking powder on the glue and worked it in a bit while keeping the crack pinched together. I tried applying the baking powder first then wetting out the powder with CA, but the CA just beaded up and rolled off the powder. This method may work with different CA glues?
5. After the glue dried (20 minutes or so), I hand sanded all the paint off the repair area and cleared away the dust. The bond was strong enough at this point to hold up to sanding.
6. I degreased the repair area with my favorite desgreaser (West Penetone Pensolv).
7. Followed the instructions on the fiberglass repair kit - cut three plys of fiberglass mat to fit, mixed the resin and hardener, wet out the repair area with a paint brush, applied the first ply of fabric and layed it on using a spreader tool, wet out that first layer thoroughly, layed on the second layer and repeated.
8. After drying over night, it was very strong. I flexed it quite a bit to try and break it, and all I did was pop the superglue bond.
Conclusion: It's a very strong repair. My only concern is the inducing edge cracking around the patch while in use, as I mentioned before. I'm not too concerned with the superglue bond popping, because when I finish the repair later (once I figure out how to paint) I'm going to grind out the crack from the outside, fill it in with plastifix or something similar, then sand and finish the outside. That way, it won't really matter if the superglue bond pops, the fiberglass will hold it together and later the plastifix will really bond it.
Let me know what you think!
1. Crack in the ABS:
2. Drilled out the crack to prevent spreading
3. Ground a trough in the plastic (hmmm not sure why...)
4. Superglue and baking soda (this might not have been done right and didn't do as much as I'd like)
5. Superglue bond and sanded/degreased repair area:
6. Finished repair:
7. From the outside, with all the resin gunk I got on it from handling!
Just thought I'd share!
Since I did the repair on the inside of the fairing only, I was going to call the thread "Backside Crack Repair", but come on, I can't make it that easy for you guys. I wanted to do a basic, slightly hidden mechanical repair on my cracked fairings so I could put them back on and ride while I read up on doing an outer cosmetic repair and painting. It's going to be a while before I'm ready to try painting all my fairing at once, so I wanted a quick and dirty repair that would prevent further cracking, would be strong enough that I wouldn't have to go back and redo it before painting, and made the fairings looks reasonable from the outside. Feel free to post comments or suggestions on how to do this better. I know there is a lot of info out there on doing repairs, but sometimes it's hard to find. I did this as practice on a totally destroyed part to see how it went first. The hardest part was keeping my gluey, resin covered hands from getting gunk all over the outside of the fairing while handling it. Some masking tape on the good side would fix this. I also think using a pyramid layup of progressively smaller plys would be good to prevent edge cracking around the fiberglass repair. When done, the repair area is significantly stiffer than the surrounding plastic, so any in-use flexing may create a stress riser on the edge of the fiberglass patch. I haven't seen this happen yet, but a pyramid stacked patch would decrease the stress at the edge of the repair. Materials used: CA glue (generic superglue from walmart) Baking powder Fiberglass mat Fiberglass resin kit (from walmart) Spreader Dremel with teardrop shaped sanding wheel Rubber gloves Degreaser Sandpaper Synopsis of the steps: 1: Using a 1/16" drill, I found the very end of the crack (sometimes in multiple places) and drilled out the end to prevent further cracking while I worked. 2. Using a teardrop shaped sanding wheel on a dremel, I removed plastic in a trough shape from the length of the crack. Why I did this, I'm not sure, but it seemed like a good idea at the time. 3. Gently spreading the crack open a tiny bit (insert jokes here), I applied CA glue to the length of the crack. I wanted the CA to run into the crack, but not all over the outside of the fairing. I then pinched the fairing tightly together. 4. I sprinkled baking powder on the glue and worked it in a bit while keeping the crack pinched together. I tried applying the baking powder first then wetting out the powder with CA, but the CA just beaded up and rolled off the powder. This method may work with different CA glues? 5. After the glue dried (20 minutes or so), I hand sanded all the paint off the repair area and cleared away the dust. The bond was strong enough at this point to hold up to sanding. 6. I degreased the repair area with my favorite desgreaser (West Penetone Pensolv). 7. Followed the instructions on the fiberglass repair kit - cut three plys of fiberglass mat to fit, mixed the resin and hardener, wet out the repair area with a paint brush, applied the first ply of fabric and layed it on using a spreader tool, wet out that first layer thoroughly, layed on the second layer and repeated. 8. After drying over night, it was very strong. I flexed it quite a bit to try and break it, and all I did was pop the superglue bond. Conclusion: It's a very strong repair. My only concern is the inducing edge cracking around the patch while in use, as I mentioned before. I'm not too concerned with the superglue bond popping, because when I finish the repair later (once I figure out how to paint) I'm going to grind out the crack from the outside, fill it in with plastifix or something similar, then sand and finish the outside. That way, it won't really matter if the superglue bond pops, the fiberglass will hold it together and later the plastifix will really bond it. Let me know what you think! 1. Crack in the ABS: 2. Drilled out the crack to prevent spreading 3. Ground a trough in the plastic (hmmm not sure why...) 4. Superglue and baking soda (this might not have been done right and didn't do as much as I'd like) 5. Superglue bond and sanded/degreased repair area: 6. Finished repair: 7. From the outside, with all the resin gunk I got on it from handling! Just thought I'd share!