touchplate question

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touchplate question

Postby lawrence » Tue Feb 06, 2018 7:55 pm

Hi all-
I have a shark HD3 and today while using my touchplate the wire for the touchplate that has the magnet on it (the part you normally stick onto the collet) fell/was pulled off. Out of interest, I found that the bit still recognizes the touch plate even without this wire attached to the collet... the touch off seems to still work just fine :|

Could anyone explain how this is possible/what the purpose of the magnetic wire is except to complete the circuit?

HD3 - Porter Cable router

Thanks in advance
Lawrence
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Re: touchplate question

Postby Rando » Wed Feb 07, 2018 1:59 am

I'm going to say that yours works because you have a grounded router that is plugged into the controller.

Normally one side of the touch-plate circuit uses "case ground", which is connected to the ground pin of the router power jack. But, not all routers have three-wire cables (My DeWalt did not), and not all users power their router by the controller. Faced with that reality--that a significant fraction of the user base could be expected not to have a setup compatible with not getting a magnet-wire--the alternatives of leaving off the wire, or carrying two versions, were ruled out. Similarly, to avoid confusion, the instructions just tell you to use the magnet, even if there's the case you don't need to. Making more customers happy by making the mystical seem easy :twisted:

Unfortunately, a problem with that scheme came in when I tried to bleed the static electricity off the bed by grounding that to the spindle (where the other half of the electrostatic charge goes). Because I also use a metalworking vise and cut mostly aluminum, the touch-plate circuit won't work at ALL, because the entire system was all shorted together. I found a way, using a 470K Ohm resistor, and reversing the polarity of the touch-plate sensor circuit. It's not difficult, but it's not "factory direct", either ;-).

Anyway, hope that explains it.

Thom
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