spintend at 120k erpm
is it gonna blow up?
How much tolerance from the calculated center to center do you need for gears? @Boardnamics @MoeStooge imagine you guys would know this?
Mod 1.5 15:100 → 86.25mm
Mod 1.5 28:100 → 96mm
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How do y’all retension motors? I need to retension this one, but it is impossible for me to reach the two inner screws without deflating the tire all the way. The distance from tire to mount is also too short to use allen keys without deflating the tire either. So far I’ve sucked it up and deflated the tire so I can fully remove the screw and reapply loctite, but I’m curious if anyone has any easier ideas.
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maybe you could cut off the tip of the allen key so that it’s shorter? With belts I just take the wheel off, but I’m guessing that doesn’t work for chains. I can’t quite tell, but maybe a ball-end key could fit at an angle?
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Yeah belts you could stretch and slide over the side wall, but chains are kind of fixed onto the sprocket. A ball end might work, but once the screw starts backing out I think I’m going to run into clearance issues again.
Does this work for pelican cases?
Gotta move my cable glands and patch the old holes. But pelican/nanuk/etc cases are made from crazy low surface energy plastics. (google says it’s polypropylene).
Anyone have experience with adhesives for these style of cases?
I have not personally worked with them;
But if epoxy will stick to it, the technique should work. Worst case, I imagine, would be it not properly adhering and popping off later, and that’s not really so bad.
If you do a full coating on the inside, too, even if it doesn’t properly stick, it probably isn’t going anywhere, right?
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In my experience with polypropylene there is almost nothing that will stick to it well. With a little ingenuity you could probably plastic weld it though.
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You’ll either need a primer to effectively bond to polypropylene or you can flame treat the surface to help make it bond better (if done properly) to the adhesive: Flame Treatment of Plastic Substrates for Adhesive Bonding - The Epoxy Experts
Using an adhesive designed for low surface energy plastics will help too.
There was an acid treatment you could do too (chromic?) but that seems a bit risky considering the other options.
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PP flambé seems like an interesting experiment. I might.
The internet suggests:
- regular old super glue
-
JB Weld Plastic Bonder, 2 part urethane adhesive
-
Loctite Super Glue Plastics Bonding System
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Anyone know if it’s okay to use a 48V contactor on a 50.4V battery?
They look like good choices 
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Okay?
No, you’re at above its rating and that can never be without consequence.
Will it explode or instantly fail?
No, I don’t think so. It will probably work for a decent number of cycles, a bit less than whatever it is rated for.
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Good to know. If someone like you is saying it’s not okay I’ll just not even try in the first place. I was wondering about using a contactor instead of a loopkey or antispark switch. Might try a 72V version.
It should be noted that contactors with a high enough current rating to handle the full battery current will have a not-insignificant power draw from the electromagnet, and it will produce a noticeable amount of heat from that. Plus they’re pretty chunky.
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I’m definitely not any kind of contactor expert. I just know that operating any device at beyond its rating will affect its life span. 
@MysticalDork brings up some very good points!
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I have noticed the bulk factor. I kind of wanted to have it sticking up out of a pelican case, sort of like a hot rod, next to a big unnecessary heatsink, sort of like a hot rod
Can you put a loopkey on a big unnecessary heatsink, and add a bag of sand for weight, and then just skip the contactor?
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that would be the smart idea, but not hot rod enough. and if the contactor switch setup is rated appropriately and functions properly I see no reason why a loopkey would be superior besides size. also if you can do a button in an electrically sensible way, why not? it’s not like a contactor with appropriate ratings will burn out or anything if used within its spec.