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The sprinkler arms fit into a Tee. That Tee then screws into a sleeve which drops into the gearbox. The worm gear is the bottom part of this sleeve, so as the arms turn (thrust), the worm gear turns, and the wheels turn. Another brass sleeve fits inside the (nylon?) sleeve and fastens the arms to the gearbox.
It's very easy to want to pick this sprinkler up by the Tee that holds the arms. DON'T DO IT! The sleeve broke, right at the top of the worm gear. I suspect that most of the reports about stripped gears on this unit can be traced back to a broken worm gear. Now the arms turn, but I'm watering the same spot all day long. The rest of my yard hates me for that and insists on pushing up dandelions.
As far as I can tell this sleeve and gear is made from some sort of nylon? I have tried a 2-part epoxy. It failed to hold. I have tried Red Hot Blue Glue (for PVC/ABS tubing). It failed to hold. I have tried Superglue. It holds, but only for a short while (days to weeks). What in the world can I use to weld this stuff back together. I promise, once it's repaired I will never pick the unit up by the arms again.
buy another sprinkler
don't break it this time
Is anyone familiar enough with manufacturing in general to know what this sleeve/gear might be made from? It looks like PCV, or plastic. Is nylon the material they most likely used? The manufacturer seems to be ignoring pleas to manufacture metal gears. I wonder why...?
From your description it is most likely a nylon based product, which is notoriously hard to repair with any type of adhesive.
I have had the same problem with car parts. Whenever possible I have machined a metal (aluminum/brass) replacement part....100% solution forever! (GM have a gearbox part made of nylon....guaranteed to fail within 7 years!) The bushels on many car manufacturer's steering columns are also nylon, they don't fail......but "squeak" like crazy!
When machining a replacement part for a nylon part isn't possible/practical the only real success I have had is with my soldering iron!
Now, fair warning folks......the fumes are toxic, the process is nasty, and I'm not suggesting you do as I do. But, melting the nylon with a soldering iron produces the only (welded) joint I would ever trust afterwards. It requires a steady hand and patience......but works the best!
Only try it under a strong blowing A/C duct, or outside with a fan in place. Choose a bit suitable for the joint size.....and practice first, you don't get to make many mistakes before the part becomes totally unusable/destroyed!
For gluing plastic in general, try plastic model cement. The non-toxic kind is worthless; get the toxic stuff. ;)
Black plastic is probably ABS. Much other plastic is probably PVC. Don't go heating these if you don't want to be breathing toxic #$%$ like phthalates etc. ABS or PVC cement and (important) primer can be bought in the plumbing department.
Clear polycarbonate is hard to fix and DONT heat it because it is made from bisphenol A. I would try model cement on it. I believe PC is "solvent-welded" (chemically melted together) but I don't know how, probably xylene or something.
JB weld works best on plastic when you can well-encapsulate the break area; flexing tends to break the bond.
Of course, replacing the part, even fabricating a new one, is always best, as repaired plastic is inevitably more brittle than it was before breaking in the first place.
Have fun and I share your plastic pain,
Meanwhile, I picked up some JB Weld this weekend. My superglue is still holding, but JB Weld gets the next attempt. I can build the joint up on the outside of the sleeve, but not on the inside. I'm thinking about the soldering iron method, but my past history with things like that isn't so hot (pun intended). Liquid Nails could be interesting.
It's a good thing for one of my neighbors that I'm an honest man, I spotted their traveler this weekend, and I know how to pull that gear out in about 30 seconds. I was looking at it, then I thought, it's probably broken too. Besides that, it's not worth explaining to a judge.
Only use formic acid under very good ventilation.