Outrunner Underwater??

Anything to do with Propulsion.
rehoward
Posts: 49
Joined: Dec 15th, 2015, 5:41 am
Location: Everett, WA

Re: Outrunner Underwater??

Post by rehoward »

olegodo wrote:Last update on the printed bushings.

Done testing for now. Perhaps 15h total run time in water with no sign of wear or degradation.
I believe they will hold up well in water.
Now I also tested them bone dry 100% throttle and they lasted maybe 30-40 seconds before one of them melted.
This bushing was quite tight on the shaft so I guess the excessive friction caused a rapid heat buildup.
I will do another test with a pair that is slightly loose fitting and see how that goes.
3D printing materials are limited in choice. I am no 3D printing expert, but working from memory the most inherently friction free is probably Nylon, and that is not all that common for printing. If when running dry you experience bearing failure I would guess the material is not really suitable as a bearing. Some plastics are even abrasive and make for terrible bearings. I think that finding a suitable material in rod stock and machining to size would be a better approach. Bushing type bearings are very simple to make using any sort of metal lathe. Just my $.02.

Randy
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olegodo
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Joined: Aug 30th, 2013, 9:47 am
Location: Bergen, Norway

Re: Outrunner Underwater??

Post by olegodo »

You are absolutely correct. Finding a good material and using a lathe to machine it down to the correct sizes is better. However, I don't have access to a lathe, but I have a printer and nylon filament for it. :)
I still think this will be usable though. I will keep using printed bushings as I go forward. If in the end they don't hold up I will switch to igus bushings.
johzac
Posts: 7
Joined: Aug 16th, 2015, 6:57 am

Re: Outrunner Underwater??

Post by johzac »

My printer isn't set up for nylon at the moment (working with PETG now) but the fact that nylon is said to absorb water got me thinking. Could it also absorb oil? Soaking a nylon bearing in oil for a while and make it self lubricating?
rehoward
Posts: 49
Joined: Dec 15th, 2015, 5:41 am
Location: Everett, WA

Re: Outrunner Underwater??

Post by rehoward »

johzac wrote:My printer isn't set up for nylon at the moment (working with PETG now) but the fact that nylon is said to absorb water got me thinking. Could it also absorb oil? Soaking a nylon bearing in oil for a while and make it self lubricating?
Don't think it works that way. Nylon is not a porous "sponge" but rather a material that has an affinity toward water. If you want an oil filled Nylon you won't find it, or as I suspect, make it either. Closest would be a graphite filled Nylon, such as Nylatron. I recommend that you buy a piece and machine it to your bearing diameter/needs remembering to allow for dimensional change due to water absorption.
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