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Mechanical battery switch-ATTN BN III

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echristley(at)nc.rr.com
Guest

Posted: Mon Feb 02, 2009 5:50 am Post subject: Mechanical battery switch-ATTN BN III

Fergus Kyle wrote:

 	  Quote: 	
		   Bob, 



                 I may have sent a message to your private address, and it's

 not monitored. However you sent me the subject diagram and I've begun to

 fabricate a form of it. I couldn't find any useful acetal version of Delrin

 nearby so opted for a slab of Phenolic which is several layers deep. Also I

 can't find any brass 5/16-24 stock so am going with 5/16 toilet stock which

 is coarser but hopefully usable.

   

The use of the delrin is for isolation, for the most part.  There is 
	


also going to be some mechanical gymnastics involved in isolating the 

cable.  Is all that really necessary?  We tend to get caught up on the 

idea that the positive lead of the battery has to have the switch;  

however, for isolation purposes it is just as valid to interrupt the 

negative lead.  Isolation in the reference design could be simplified to 

two vinyl shoulder washers for one of the 5/16 brass all-thread leads 

(the one attached to the battery).  Everything else could be safely 

grounded to a metal airplane.  In fact, it could safely BE the ground in 

an all metal airplane, and only have one piece of all-thread and one 

plunger, cutting the smaller area connections in half .



I don't have the time to do a CAD drawing, but  I now think I will be 

using a design composed of a piece of hat section aluminum about 

1"x1"x1" with 3/8" flanges, riveted to a steel gusset (I'm building a 

steel tube frame aircraft).  The allthread mounts in a hole in the top 

of the hat, the plunger through a threaded hole in the gusset.  The 

slider is just a brass plug that grounds the allthread to everything 

else, until it is pulled.

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echristley(at)nc.rr.com
Guest

Posted: Mon Feb 02, 2009 6:03 am Post subject: Mechanical battery switch-ATTN BN III

Fergus Kyle wrote:

 	  Quote: 	
		   Bob, 



                 I may have sent a message to your private address, and it's

 not monitored. However you sent me the subject diagram and I've begun to

 fabricate a form of it. I couldn't find any useful acetal version of Delrin

 nearby so opted for a slab of Phenolic which is several layers deep. Also I

 can't find any brass 5/16-24 stock so am going with 5/16 toilet stock which

 is coarser but hopefully usable.

   

As a followup to my last post, I left out one point.  The plunger could 
	


be replaced with a short piece of stainless flat spring shaped like a 

bow, riveted at the entrance and exit of the hat to leave a hump in the 

middle.  A slight depression filed into the center of the brass bar that 

the spring settled into would provide for positive retention.

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nuckolls.bob(at)aeroelect
Guest

Posted: Mon Feb 02, 2009 11:48 am Post subject: Mechanical battery switch-ATTN BN III

At 03:53 PM 2/1/2009, you wrote:

 	  Quote: 	
		  Bob,

                 I may have sent a message to 

 your private address, and it’s not monitored. 

 However you sent me the subject diagram and 

 I’ve begun to fabricate a form of it. I 

 couldn’t find any useful acetal version of 

 Delrin nearby so opted for a slab of Phenolic 

 which is several layers deep. Also I can’t find 

 any brass 5/16-24 stock so am going with 5/16 

 toilet stock which is coarser but hopefully usable.

                 I hope this is satisfactory 

 from a practical point of view – I note the 

 toilet kits are now yellow-coated steel as a 

 partial scam. If it works I’ll fire off a 

 message describing it. At present my Main 

 battery switch is a racing-car cut-off switch, 

 so this will constitute a second battery switch 

 thus saving me about 2+ amperes forever.

Cheers, Ferg


	


   Ferg, if you're ordering spring-loaded ball plungers

   from McMaster, they also stock 5/16-24 brass rod

   stock. They also stock Delrin but I have some scraps

   of 1 x 1 inch Delrin I can send you. The plated steel

   parts are NOT suited to this task.



   Bob . . .

        Bob . . .



        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

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