Mounting sensitively placed PCB in wood enclosure

Discussion in 'The Projects Forum' started by stoopkid, Feb 20, 2012.

  1. stoopkid

    Thread Starter Member

    Mar 3, 2011
    136
    1
    I need to mount my PCB in a wood enclosure. The enclosure is made of 1/4" miter cut wood, with just enough room to fit the PCB. The PCB will have nixie tubes attached to it so it needs to be mounted this way, with some amount of distance between it and the top of the enclosure. The exact distance is variable because I haven't attached the tubes yet. There was only just enough room on the PCB to make room for screws at the very corners.

    Basically I figure it needs to hang from screws that are attached to the top (or blocks glued into the corners of the walls but this might be tricky when putting it together). My main concern is how to attach either screws hanging from the top, or nuts for the screws to screw in to. The only thing I could think of was to glue nuts right onto the bottom of the top piece, but that seems messy and unreliable. Also that large blank spot on one side may need to be cut out to make room for controls at the front of the enclosure.

    Is there a system specially suited for this?

    1st attachment is a drawing of the enclosure how the PCB will be mounted, second is how I see the screws being attached to the bottom of the lid (with red circles around where I am lost) and third is the PCB. The only thing not shown is that the Nixie tubes will be soldered to their own individual boards that will then be attached to the headers on this board. Also an inch or two down there will be another board in pretty much the same position, but once i figure out the first board I'm not worried about the second.

    Thanks
     
    Last edited: Feb 20, 2012
  2. MrChips

    Moderator

    Oct 2, 2009
    12,418
    3,355
    You can try something like this hex standoff. They come in various lenghts.


    [​IMG]
     
  3. luvv

    Member

    May 26, 2011
    186
    31
    All thread rod is in my mind perfect, you can adjust height of multiple boards as needed.

    And to mount to the container just epoxy 1 or 2 nuts per leg to the bottom of the box.
    It Can be used to tie earth grounds between boards and case,if the board needs to be very isolated from other boards or the case they do make nylon all thread also.

    -luvv-
     
  4. ErnieM

    AAC Fanatic!

    Apr 24, 2011
    7,386
    1,605
    Your connection substrate is wood, so you need things that work with wood.

    My personal feeling is 1/4" isn't much "meat" for holding a fastener, plus I would worry I'll eventually punch thru it and damage the outer surface which we want 100% perfect, right? So I would glue an additional piece to the enclosure. Adding just to the corners is fine, you need not double up the entire thickness.

    Good old Elmer's glue is incredibly tenacious, you will not pull two pieces of wood apart glued with it. The wood fails first.

    My choice for a fastener would be a sheet metal screw. They work nice in wood, have a uniform diameter over most of the length, and would fit into a hollow stand off.

    Do you have a number for the bottom of the Nixie? How far below the top of the enclosure can it go?
     
  5. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,793
    829
    I have glued wood blocks and used sheet metal or wood screws to mount a PCB into a wood enclosure. The local craft store had some 1/2" sq. wood strips, from which I cut small blocks.

    In your case, could you glue such blocks to the corners of your lid? Then, you would not have to worry about "punching through" the 1/4" lid and be able to use the same mounting method as the lower PCB board. This is similar to ErnieM's suggestion. The same wood strip could be used in the corners of the case for the bottom PCB board.
    [​IMG]

    [​IMG]
    (P.S. Make sure you pre-drill holes for the mounting screws into the blocks)
     
    Last edited: Feb 21, 2012
  6. studiot

    AAC Fanatic!

    Nov 9, 2007
    5,005
    513
    Why not simply cut two grooves in opposite sidewalls of your box to slide the board into?

    Remember also to provide some ventilation for your nixies.
     
  7. stoopkid

    Thread Starter Member

    Mar 3, 2011
    136
    1
    Ok I like the block idea, but I need the boards to be able to come off (for inevitable repairs and tube rotation) so the head of the bolt needs to not be blocking the boards from sliding on and off so I figure I make some block like what I have attached. The head of the bolt will fit inside the block, a nut will fasten it and some epoxy will keep the bolt from rotating. Then I glue it to the bottom of the lid (and when I glue the box together they will be further reinforced with glue to the sides).

    I have a drill press so I'm not too worried about the holes or anything. The blocks could be a bit longer, for more surface area to attach to the lid, that wouldn't get in anything's way. What do you guys think?
     
  8. djsfantasi

    AAC Fanatic!

    Apr 11, 2010
    2,793
    829
    Sounds good to this blockhead :)
     
Loading...