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kerklein2 (Mechanical) (OP)
10 Nov 08 13:50
I'm designing an enclosure for a device that rear-mounts using those screw pocket features.  The ones where there is a large opening for the screw head, and then you slide the device down to lock it in.  This is good for mounting on a wall, but not so good for an installed application.  I was wondering if anyone has any clever ideas for how to pull this off.  I've already designed something, but I won't post it in hopes of getting some original ideas.
MadMango (Mechanical)
10 Nov 08 14:06
What are your concerns with the design and performance?  What makes it "not so good for an installed application"?  You are not giving us enough data to assist you with.
kerklein2 (Mechanical) (OP)
10 Nov 08 14:59
First of all, it doesn't fully lock down the device.  Its only constrained in 2 dimensions.  Also, there is difficulty in installing in this manner because the screws have to be protruding just the right amount.
dgowans (Mechanical)
10 Nov 08 15:14
Just like any project, good output depends on good input.  Can you list specific requirements?  Otherwise we're all shooting in the dark.
kerklein2 (Mechanical) (OP)
10 Nov 08 16:22
I'm just trying to find a good way to mount the device.  Is there confusion about the screw pocket method of mounting I am describing?  Are the questions about the inherent difficulty of this mounting method?
MadMango (Mechanical)
10 Nov 08 16:50
At question is The Device.  What are your restraints and requirements/standards?  How does it behave?  Does it vibrate or rotate in a manner that requires a more solid mechanical interface instead of keyholes?  How does the current mounting method fail?  What materials are involved (a plastic housing, or some standard rack mounted device)?  What environment is it used in (industrial, consumer, aerospace, etc)?  What scale of product are you working with (the size of a pen, car, building)?
kerklein2 (Mechanical) (OP)
10 Nov 08 16:54
The device is about the size of your hand or so and is plastic.  I am mounting it in an IP NEMA box.  The mounting holes on the device cannot change, I am only integrating the device into the enclosure.  The current method fails because it is only constrained in 2 dimensions and because it is intrinsically difficult to do repeatedly and quickly.
MadMango (Mechanical)
10 Nov 08 17:12
That's a little better.  If you read your prior postings you will see you were like a patient going into the doctor's office and saying that you didn't feel well, and wanted the doctor to make you feel better.  The doctor would ask for more information too.

I don't understand why you can't use blind holes?  Is there a weight issue involved?  Are you manually assembling this or using automated manufacturing that you are trying to overcome?  You could keep your keyholes, if you are worried about slippage, you can make the keyholes kidney shaped.  You could install threaded studs in The Device and pass them trough the box wall and attached with nuts.
dgowans (Mechanical)
10 Nov 08 17:32
If the current method doesn't work and the geometry of the enclosure can't be changed, you'll need to come up with some means of developing a force that clamps your device in place.

Backside nut like MadMango suggests?  This might have an impact on the NEMA rating of the enclosure.

VHB tape?

You could possibly make the assembly easier by using a shoulder bolt or something similar to repeatably set the depth of the heads that engage your existing keyholes.  PEM makes keyhole fasteners that would do just this, but they won't address the third degree of restraint that you require.

Do you have any opportunity to modify the enclosure to which you are mounting?

kerklein2 (Mechanical) (OP)
10 Nov 08 18:30
I cannot do any modification to the plastic part.  It is a seperate assembly and I am simply integrating it as is.  I just looked up PEM's keyhole fasteners and they are perfect.  Unfortunately, they do not seem to have multiple available sizes.  This device was designed for no. 10 screws.  I could address the 3rd degree of freedom with a simple locking bracket if I could find a captive keyhole faster like the PEM SKC-F for a no. 10 screw.
IRstuff (Aerospace)
10 Nov 08 23:16
Retaining brackets with screws


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