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  #1  
Old 03-10-2017, 09:44 AM
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DanH DanH is offline
 
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Default Circuit Board Mounting

A best practices question please...

I want to mount this circuit board in this box:



I can machine hard mounting points, or some other elaborate mounting solution. However, is it permissible to simply place four blobs of an "electronics safe" silicone RTV in the bottom of the box, then float the board on it?
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  #2  
Old 03-10-2017, 09:49 AM
Lars Lars is offline
 
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What loading will the device be subject to?

My default inclination is to say yes, just use the silicone...
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Last edited by Lars : 03-10-2017 at 09:52 AM.
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  #3  
Old 03-10-2017, 10:04 AM
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DaleB DaleB is offline
 
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RTV or hot melt, if it's an indoor thing. The fancy way would be to remove the existing mounting bosses, then drill and use nylon standoffs and screws. Depends on the environment in which it will live.
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  #4  
Old 03-10-2017, 10:07 AM
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wirejock wirejock is offline
 
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Default Stand off

Quote:
Originally Posted by DaleB View Post
RTV or hot melt, if it's an indoor thing. The fancy way would be to remove the existing mounting bosses, then drill and use nylon standoffs and screws. Depends on the environment in which it will live.
Agreed. Local hardware stores usually have Delrin or Nylon stand offs. Usually a star washer is installed on the top of the board before the nut.
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  #5  
Old 03-10-2017, 10:09 AM
Ralph Inkster Ralph Inkster is offline
 
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Don't know about 'best practices', but how about 5min epoxy (or JB Weld) 4 studs to the box? Insures ability to service later.
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  #6  
Old 03-10-2017, 10:22 AM
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Weasel Weasel is offline
 
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Default

Quote:
Originally Posted by DanH View Post
A best practices question please...

I want to mount this circuit board in this box:



I can machine hard mounting points, or some other elaborate mounting solution. However, is it permissible to simply place four blobs of an "electronics safe" silicone RTV in the bottom of the box, then float the board on it?
Not sure on your time frame. If you draw an adapter in cad shoot me the STL file and I will print the adapter for you or if you want draw up the entire box with mount points like you want and I will print it.

No charge. I already owe you for your many contributions
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  #7  
Old 03-10-2017, 10:30 AM
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az_gila az_gila is offline
 
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Thumbs up Normal practice

If it was mine, I would "Dremel off" the existing molded in attach points and drill holes in the base to match the mounting holes in the circuit board.

Countersunk screws and the previously mentioned nylon spacers from the Ace Hardware aircraft aisle finish the job off.

It probably would take less time than reading VAF for the day...

PS, is it a flap/cowl flap position indicator?
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Last edited by az_gila : 03-10-2017 at 10:33 AM.
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  #8  
Old 03-10-2017, 11:19 AM
Jordan1976 Jordan1976 is offline
 
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Silicone and other adhesives are used to mount and stabilize electronics all the time. Most cell phones today are stuck together with adhesives, not screwed together. One of the ways to make something as environmentally robust as possible is to just bury it in epoxy or silicone. Silicone is nice because it has a bit of give and vibration damping. The only real downsides to these options are maintenance.

Do whatever is fastest.
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  #9  
Old 03-10-2017, 11:19 AM
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DanH DanH is offline
 
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Thanks gents.

Quote:
Originally Posted by az_gila View Post
PS, is it a flap/cowl flap position indicator?
Voltage monitor, with a built in display and settable upper and lower limits in 0.1V increments. The blue relay can operate whatever, here a panel mounted LED under the #2 ignition switch. I'll set the low limit at 13V, so the LED will come on prior to start, just like an alternator light. The idea is to keep an eye on the diode-isolated #2 battery charging for the EI.

My 2010 vintage GRT Sport monitors its own power inputs, but doesn't have an available input to alarm an independent bus voltage. I suspect some EFIS units can do it. Seems like a useful feature as the world moves toward more EI and EFI usage.

Not too worried about maintenance. You're looking at a whopping $7.
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Last edited by DanH : 03-10-2017 at 11:22 AM.
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  #10  
Old 03-10-2017, 01:40 PM
rapid_ascent rapid_ascent is offline
 
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Location: Dublin, CA
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I would go with Gil's idea.

It looks like the mounting holes would interfere with the existing molded standoffs. Cut/grind those off with your dremel then use some 0.25" standoffs to mount the board. You'll probably have to use a nut on the top of the screw unless there is enough height in the box to use longer standoffs. If you can fit longer standoffs then I would use threaded standoffs and a screw through the back of the box and a screw through the circuit board mounting holes. Use locktite on the screws.
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