Grinding Impeller Shafts

[dlh0024]

Has anyone ever grinded their impeller magnet shaft? Mine was making noise and I found sand that put grooves in the magnet. Ordered a new shaft which was over $30 with cost and shipping. Now it's quiet again. But I thought what if you could grind the magnet to remove the grooves and reuse it? Has anyone tried this? Thoughts or opinions?

 

[scsinet]

No way.
Those pumps rely on magnetic coupling to drive the impeller. Magnet strength decreases exponentially as the distance increases. I.E. doubling the distance between the two magnets might decrease the strength by 10 times.
Ergo, grinding down the magnet would probably lead to a decompling of the magnetic drive, where basically the magnet sits still and just shakes while the drive revolves around it.
Frankly, it would be best just to leave the grooves in place. I can't see how that would hurt anything, provided the pump still works.

 

[dlh0024]

I figured sanding or grinding it down would lessen it's effectiveness but I can't use it as is without buying ear muffs. The grooves in the shaft somehow make the unit very loud and the new shaft I'm guessing will suffer the same fate. Spending $30 plus dollars everytime disgusts me.
Thanks for your info. I think I will try to light sand it and give it a go just to see what happens.

 

[scsinet]

I wonder why it would make it loud.. unless what I am picturing is not what is actually happening.
How is sand getting into the pump in the first place?

 

[dlh0024]

I think some fish were stirring up sand near the intake of the pump and it sucked the sand up. Than the magnet on the impeller rotated in some of this sand and got grooves in it. Thus it makes noise. The new impeller I installed has now quieted the pump as if it was new. What I don't understand is that I don't think the magnet actually touches the chamber it sits in so even if the magnet is rough, why would it matter? Perhaps I should cut the intake tube so it's not so close to the bottom where the sand is so this does not happen again.

 

[scsinet]

I assume then that this is a closed loop?
I'd put a sponge filter or something on that intake. If it's just a bare pump intake, fish could get sucked in.