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Post by oldgeek on Dec 13, 2018 19:57:05 GMT -5
It is extremely important to use equal parts of the epoxy, and that you mix them thoroughly. Even when using the original slow set epoxy, which is all I use, it can be difficult to get it mixed and put into place before it "kicks" over and begins hardening. There is also the issue of a limited shelf life, possibly you got some older stock.
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Post by harleyracer59 on Dec 13, 2018 21:05:55 GMT -5
I used the OG jb weld. I know most anything that is quick setting isn't as strong as the regular setting counterpart. ive always just eyed it. but I have a little digital scale that I use to weigh rollers and stuff. what I wonder though is did I put a little extra hardener in the good side or not enough in the problem side? I almost think im gonna have to mix up 3 test batches one with a bit less hardener, 1 weighed exactly 50-50, and 1 with a little extra hardener and set them in a jar of this blend gas for a week and see what happens to them. I over think stuff sometimes. im sure the strong side wasn't with less hardener, but I want to know if I just didn't mix enough into my problem case half...
I never even though of shelf life. good call. ill have to check for a born on date
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Post by oldgeek on Dec 13, 2018 21:54:36 GMT -5
I squeeze an equal length line out of each tube next to each other and eyeball it like you say. I dont know if weighing equal parts of the JB weld will work properly, it is fortified with steel and I dont know if the steel is in just one part or both. Like Pitobread said, if you could find the proper ratio for weighing it out, that would be the best.
For what its worth I always overthink stuff too, better than under thinking it Lol!
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Post by aeroxbud on Dec 14, 2018 1:57:43 GMT -5
Will be interesting to see the results of you do this test. People have been putting JB weld in two strokes for years without problem. I have not done any serious tuning since I sold my Aerox. Ethanol was not really a problem then. If I decided to do another project it would be good to know the outcome. We don't have that much ethanol in our fuel, typically less than 5%. But it's still enough to expand plastic motorcycle tanks, and swell fuel fittings.
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Post by benji on Dec 14, 2018 10:57:32 GMT -5
Has anybody tried using brass as a filler? Or maybe welding some beads in the thin areas to grind down? That's usually how one adds metal to a thin area. Maybe we're just using the wrong material as filler.
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Post by benji on Dec 14, 2018 11:03:06 GMT -5
Also, I think there is a "professional grade" jb weld that you would need to use an exact amount of hardener with. I'm sure there is some industrial grade version epoxy, but I'm not sure how solvent-resistant it would be. I used to use fiberglass alot, and when you mix resin and mekp your suppose to weigh it so you get EXACTLY 2% mekp and 98% resin, then mix it with a drill with mixer attachment on low speed, making sure to get all of it mixed.
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Post by benji on Dec 14, 2018 11:08:07 GMT -5
Cr250 casework
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Post by 90GTVert on Dec 14, 2018 14:55:52 GMT -5
I think they just make a professional size JB Weld... a bunch of it for people that use it a lot. Could be wrong though.
Welding is great, but I've heard many times over the years about unknown or poor quality metals, especially in Chinese engines. I know people do it though. Some here have welded engines for various reasons. I believe there are people here that have welded engines for Frankenmonster builds, but I think even the ones I recall there used epoxy for the flow work. For the average Joe, a successful weld would be tough. Not just the metal quality, but I'd think risk of any sort of distortion could be bad. Most of us that just screw around with scoots in our garages don't even touch aluminum, so $5-10 worth of JB Weld looks pretty darn good.
I'm on the fence with this issue. Part of me thinks maybe the mix has to be real close, but realistically I have used JB in street 2Ts for years and hardly had any issues, and I'm not weighing it out and even have seen that the color is different at times from different ratios. I've even had one of mine sit with fuel in the crankcase for a while (long enough to find a totally corroded crank when I opened it up) and the JB was OK. Then again, most of mine don't involve tight tolerances where any epoxy is present so maybe it swells and it just doesn't matter as long as it doesn't cause it to break loose from the case. I've had JB sealing my crappy welds on my fuel tank for at least a couple of years now without issue with constant exposure to whatever is in the 10% ethanol mix here. Again, swelling may not matter there either and it's not under the same stress. We also have the variable of who knows what is in which gas in what area at what time of the year. There's also always the risk that some of the good stuff is substituted in products that have worked forever because of environmental or whatever concerns. Don't think that's prob the case here, but don't know.
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Post by harleyracer59 on Dec 14, 2018 15:17:24 GMT -5
so I talked to katie at jb weld today. she gave me her email to send the pics to pass on to their chemists. they will try to help figure this all out. she also said they just mix it 1 to 1. no weights. but shell try to see if there is a difference in A and B weights
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Post by pitobread on Dec 14, 2018 17:58:33 GMT -5
Welding is great. But when you weld you move the metal around due to heating. Bearing pockets can go a bit egg shaped, gasket surfaces can pull and warp. This along with simple poor casting having to be built up and ground down continually to get enough filler in the base material to make a "clean" weld. It's very tricky.
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Post by harleyracer59 on Dec 14, 2018 18:50:52 GMT -5
^^^^^^^^^^^
also the constant oil saturation. ive seen what looked to be supper clean 50's Harley engine cases that when welded show signs oil in and around the welded. that's happened where welded metal turns a brownish or blueish tint. I've seen a lot of this with Harley k model ALUMINUM cases, and on steel crankshafts or transmission parts.
plus the dipping of hot parts in oil is part of heat treating so when welding you create different hardness's in 1 part of metal. and ive seen this lead to failure or breaks
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Post by benji on Dec 14, 2018 20:23:28 GMT -5
I know welding isn't very easy, and maybe not a good idea on a used motor with oil in the pores. But maybe brass? Use a torch and map gas to melt some brass in there, and sand it down. Then you wouldn't have to get the case that hot.
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Post by harleyracer59 on Dec 23, 2018 22:19:45 GMT -5
howdy yall, I been playing in my dungeon all week and might have found a viable solution or replacement for jb weld. its called quicksteel* its a 2 part stick that you cut a piece off and mash it together. I like that its more of a putty and doesn't run like the jb weld. also has a stronger strength and shear rating. final selling point was it actually conducts electricity so it has some kind of metal in it, which I figured might help with multiple hot/ cold cycles my situation calls for. once cured, it was harder to grind on than the jb weld side and more equal to the hardness of the case metal. while I still like jb weld, it has its uses, and great if you need to pour it in some places. the quicksteel left a far cleaner finished product. with out having to grind. when I figure out how to get my pictures out of that damn cloud, ill post them. stupid technology!!
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Post by aeroxbud on Dec 24, 2018 0:37:48 GMT -5
I have used quick steel before. Seemed to take quite a while to go really hard. Might of been because the packet was about 10 years old though. Once it did, it was solid. I used it to patch a split seam on the Yaris. Worked a treat. Was exposed to all weather's for two years but never budged from the joint.
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Post by SMALL CC TEK on Dec 24, 2018 2:26:06 GMT -5
I built a lot of GO-Ped 25cc 32cc and 62cc using LPS Strong Steel . I probably built 15 motors using it and only one failed my fault.. I am thinking i will try some 2000 Degrees F Putty high Temp loctite , it's a bit expensive and cure time is 7 hours for a full cure . It's a D 80 on the hardness scale so it's hard and that is the middle of the scale so it looks good ..
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