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knobtwiddler · 1st Jun 2020, 2:23 pm

Hi,

I need to open an enclosure. However, one of the screws on the base plate (flat, sheet steel) is cross-threaded into a brass stand-off underneath (which goes into a PCB, with nyloc nut on top). When I try and unscrew the M3 Hex-head screw, the stand-off simply spins around inside the PCB, along with the nyloc on top. This means that the plate is effectively bolted to the PCB, thus preventing access to the enclosure as the PCB can only be removed (and the nyloc accessed) once the base plate is off...

My options (as far as I can see) are:

i) Get a Dremel and try and slice off the cap of the M3 screw. This will risk damaging the base plate, so not ideal - but I'm not exactly spoilt for options. I'm not sure I'll be able to get the Dremel cutter in-between the screw and base plate.

ii) Try and drill off the head of the screw. Start with an extremely sharp 0.5mm bit and go up, in the smallest increments possible. The drawbacks to this method are: firstly, it'll need clamping in a pillar drill (a whole chunk of delicate electronics). Secondly, the head will need gripping with fine nippers to prevent it spinning.

If anyone here has a tip, I'd be extremely grateful. The screw is stainless, which is an added complication.

Thanks in advance!

1st Jun 2020, 2:23 pm	#1
knobtwiddler Octode Join Date: Mar 2016 Location: London, UK. Posts: 1,051	Removing Awkward Screw... Hi, I need to open an enclosure. However, one of the screws on the base plate (flat, sheet steel) is cross-threaded into a brass stand-off underneath (which goes into a PCB, with nyloc nut on top). When I try and unscrew the M3 Hex-head screw, the stand-off simply spins around inside the PCB, along with the nyloc on top. This means that the plate is effectively bolted to the PCB, thus preventing access to the enclosure as the PCB can only be removed (and the nyloc accessed) once the base plate is off... My options (as far as I can see) are: i) Get a Dremel and try and slice off the cap of the M3 screw. This will risk damaging the base plate, so not ideal - but I'm not exactly spoilt for options. I'm not sure I'll be able to get the Dremel cutter in-between the screw and base plate. ii) Try and drill off the head of the screw. Start with an extremely sharp 0.5mm bit and go up, in the smallest increments possible. The drawbacks to this method are: firstly, it'll need clamping in a pillar drill (a whole chunk of delicate electronics). Secondly, the head will need gripping with fine nippers to prevent it spinning. If anyone here has a tip, I'd be extremely grateful. The screw is stainless, which is an added complication. Thanks in advance!