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I'm in the middle of a "living room acceptable" project, and I'm looking to capture the spirit of a 1970s preamplifier (Quad 34, see below). My design has 6 LEDs, 4 push buttons, a latching mains button, and a rotary encoder. The rotary encoder has a threaded attachment, but this would only provide attachment at one side of the board. My original plan was to make a PCB with the front panel controls, and then use adhesive standoffs, but I don't think that the adhesive will sustain button presses over time.

Quad 34 preamplifier

My question is how to attach the front panel controls securely, but without visible screw mounts on the front panel itself. I'm using a Hifi2000 case (picture below), which is not drilled on the bottom panel. The front panel is 4mm thick aluminium, and comes blank (aside from the countersunk corner holes). I don't have the tools to blind tap holes just, although this might a good time to pick them up if that's the accepted view.

enter image description here

Thanks in advance!

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    \$\begingroup\$ definetly pick them up, its not expensive and gives you a whole new set of possibilities, regardless of the current project; though you might want to have a bit more meat than 4mm to screw into. In a real world product you might have a custom aluminum piece with spots to screw into. \$\endgroup\$
    – PlasmaHH
    Apr 11 '18 at 15:07
  • \$\begingroup\$ @PlasmaHH Thanks. Probably a one off project, but good excuse to get some useful tools :) \$\endgroup\$
    – awjlogan
    Apr 11 '18 at 15:18
  • \$\begingroup\$ Relevant: electronics.stackexchange.com/questions/356151/…. \$\endgroup\$
    – Transistor
    Apr 11 '18 at 21:34
  • \$\begingroup\$ Thanks for the link @Transistor. It's more the mechanical side, rather than the printing that's causing issue. Still looks nice! \$\endgroup\$
    – awjlogan
    Apr 11 '18 at 22:15
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I suggest considering PEM-style blind fasteners. Eg. CSS-series

enter image description here

They are clinched into a blind hole. You will need a suitable diameter end mill to make the blind hole. A milling machine is best but a good drill press may work okay since you have a lot of thickness to play with.

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  • \$\begingroup\$ Thanks for the part, no milling machine but might get away with the press... \$\endgroup\$
    – awjlogan
    Apr 11 '18 at 20:31
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I have seen plenty of equipment where there is an additional metal panel slightly behind the decorative front panel. If you take that approach, it doesn't matter how ugly the controls' fixings are - all the user sees are the buttons poking out through holes in the front panel.

Where appropriate, you can also attach small PCBs to the extra panel, for small switches that solder to a PCB, and for lamps and the like.

The control fixing panel doesn't need to be attached to the front panel directly. Mounting it to the base of the box should be strong enough.

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  • \$\begingroup\$ Definitely an option I'd considered - I was a little unsure about the tolerances to be expected, but will investigate further :) \$\endgroup\$
    – awjlogan
    Apr 11 '18 at 20:36
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Simon and Spehro have posted solid ways to solve this problem, but here's a slightly more ghetto option you could consider.

If you put 2 rotary encoders on your front panel, and not right next to each other, then the PCB will be held securely just by the nuts on the encoders.

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  • \$\begingroup\$ Agreed - although I'd have to change my design, or make it properly analog and forgo the rotary encoder for a couple of pots :) \$\endgroup\$
    – awjlogan
    Apr 11 '18 at 22:16

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