Any Electrical Raason - More Router Spindle Questions

Is there any electrical reason not to put the bearings in a metal bushing instead of the nylon one?

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Bob La Londe wrote:

Ed H will probably give you an authoritative answer.
As long as the bearings don't heat up so much that they grow, bind, grow some more and fail, I don't see why not. With nylon, there would be some give, but not in metal.
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Bob La Londe wrote:

Not if the frame is grounded. Otherwise, it's an attempt to isolate the frame from the armature. that will prevent a shock while using the tool, but could kill you if you touch the motor shaft & a good ground when the insulation fails.
--
You can't have a sense of humor, if you have no sense.

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I was thinking something along those lines. There is an internal brush like contact that touches the metal nose/frame of the router when it is assembled properly. I suppose its time to get out my meter and see how good the ground is.
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That's the "double insulated" concept. Ground the thing so as not to become a conductor yourself.
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No reason at all for a bearing to be electrically isolated from a case. They utilized that nylon bushing for their convenience.. assembly method, loose bore dimension tolerances, potential production change in parts source, etc.
Nearly all motor types have bearings mounted in metal frames, there is no electrical reason to attempt to isolate the rotor from the case.
Most routers (and various power tools) with metal nose pieces have pressed-in or snug fitting bearings (some with retainers) fitted into a bore in the housing.
There are no perfect insulators (nor conductors), so all insulation types have a minute amount of leakage current. This miniscule leakage level won't be harmful to the operator or the bearings.
The high rate of fan-blown airflow over a high speed rotor would generate static (Van Der Graff type effect) likely moreso on a plastic housing.
There is a potential for bearing damage when elevated currents pass thru bearings in some applications such as a turntable used for welding.
--
WB
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