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Magnetic drive through waterproof bulkhead

R/C Submarine modelers

Postby Seasub88 » Thu Aug 28, 2003 5:21 pm

Has anyone tried the magnetic drives put out by MMC ? They have a size that might work on our sub main drive shaft. :cool: listening out.. seasub88
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Postby Scott T » Fri Aug 29, 2003 9:51 am

Thats a question I had. See the MMC site.
They give the torque specifications the magnetic drive handles. How much torque capability do you think a motor+propeller coupling would need? ??? Do any torque savy people have an opinion?
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Postby JeffG » Fri Aug 29, 2003 1:41 pm

We frequently use magnetic coupling to stir chemistry experiments in a beaker. Very prone to loosing sync. They must be excelerated slowly and when they get out of sync you let everything come to a complete stop before restarting. When they loose sink the driven end goes bobbing all over. Containd to a motor / prop shaft this would result in lots o vibration.

On the plus side we do run subs slowly and smoothly not like a ski boat. New magnets are also getting more powerful. A additional source might be found in chemistry supply sources like VWR and Cole_Parmer.

I would definatly experimnet with this setup, real speed controller, coupler, driven shaft into a propeller in water before I built it into a boat.

JG ??? :cool:
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Postby dietzer » Fri Aug 29, 2003 3:20 pm

I don't think the vibration will be that much of a problem. A drive shaft application is not like stirring a beaker, where the stirring rod can also act like a free-swinging pendulum.

In this case, if you have bearings on the drive shafts by the magnets, and another bearing on the prop shaft by the prop (in addition to a strong motor mount), the vibration should be kept to a minimum because the prop shaft can't move (except for rotation).

I agree, though, that once you lose sync you have to stop the shafts and start slowly from zero. And if your sub is negatively buoyant, you might just sink your sub before you can get the prop(s) restarted...

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