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Discussion Starter #1
As I posted earlier in my Alaska thread, the front mount on my left mirror broke during the trip. I finally got time today to start the repair. I did a somewhat similar repair on the right mirror several years ago and it seems to be holding, but I did not take any pictures of that repair as I quit frankly did not expect it to last long.

Here is what I did today. I Dremeled out the broken surfaces to true them up a little and cut a piece of ABS sheet stock to fit. The sheet stock is a little thinner than the piece that broke out, but I plan to add a second layer over the glass so that should help. It looks like I have enough clearance on the bike around the ball mount to tolerate the extra thickness.

I added a piece to roughly replace what broke out. I then added a second piece on the end perpendicular to the first to serve as an additional gusset. It was a bugger to get in place with the ABS cement on it, but a pair of curved forceps helped get it roughly in place. I then lathered the outside well with ABS cement (standard plumber’s cement and primer was used) and pressed one layer of glass cloth into it. I will let that harden for 24 hours and then add another layer of ABS sheet over it to make a sandwich. Hopefully, this will hold as well as the other side has.
 

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I decided to just drill, tap and screw mine on, at least for now. Looks like a good repair though. I hope it holds up like the other side has.
 

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Discussion Starter #3
I decided to just drill, tap and screw mine on, at least for now. Looks like a good repair though. I hope it holds up like the other side has.
That is my backup plan. Where did you drill? The flat metal strap that the ball mounts to? It felt like the was something behind that strap and I am hesitant to drill into something I can’t see behind.
 

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That is my backup plan. Where did you drill? The flat metal strap that the ball mounts to? It felt like the was something behind that strap and I am hesitant to drill into something I can’t see behind.
Will take a picture but yes, there is a metal strap/plate behind the plastic in certain places.
 

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Wrencher Extraordinaire
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I have done what you have done except I weld the plastic as I don't like using glue. I have gotten pretty good at it with a couple of dedicated welding tips for my Weller Temp controlled soldering station. Have not had a weld break yet and I have done body panels as well.
 

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Discussion Starter #6
I have done what you have done except I weld the plastic as I don't like using glue. I have gotten pretty good at it with a couple of dedicated welding tips for my Weller Temp controlled soldering station. Have not had a weld break yet and I have done body panels as well.
Well, ABS cement is not technically a glue. Is performs a solvent welding operation and is every bit as strong as a thermal weld, often stronger as you have more surface area. I am not a big fan of glues either which is why I use solvent cement rather than epoxy or cyanoacrylate.
 
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Wrencher Extraordinaire
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Well, ABS cement is not technically a glue. Is performs a solvent welding operation and is every bit as strong as a thermal weld, often stronger as you have more surface area. I am not a big fan of glues either which is why I use solvent cement rather than epoxy or cyanoacrylate.
True but I feel I have better control on the thickness of the "weld" and can build a better bond over a larger area with more strength over just where the solvent touches. Especially on the small area for the mirror clips and it allows me to "shape" the area better.
Plus I just never seem to have ABS solvent around, lots of PVC and CPVC though.
 

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Discussion Starter #8
True but I feel I have better control on the thickness of the "weld" and can build a better bond over a larger area with more strength over just where the solvent touches. Especially on the small area for the mirror clips and it allows me to "shape" the area better.
Plus I just never seem to have ABS solvent around, lots of PVC and CPVC though.
I have only bought the all purpose cement since it was first available. That way I always have the right kind. :grin:

Much depends on what type of joint you have. If you are butting two sheets together, then thermal welding might be a little stronger as you can build up a bead. However, if you are joining a pipe into a fitting, then welding around the external joint would give you very little surface area compared to solvent welding the pipe into the fitting where you can get the full surface between the pipe and the fitting welded together. That gives probably 6-10 times the surface area and is far, far stronger.

https://www.lowes.com/pd/Oatey-8-fl-oz-All-Purpose-Cement/4750817
 
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