[Beowulf] Re: case (de)construction question

David Mathog mathog at caltech.edu
Mon Feb 22 16:25:15 PST 2010

The support staff at PennEngineering said that it would only take a
couple of hundred pounds of force to push out a standoff, and to try
tapping it with a hammer.  There is no hammer in the machine room, but
there is some unistrut, so...

1.  On top of a rubber wheeled cart (to cut down on the shock to
everything else) put the case flat on 3 parallel pieces of unistrut,
with the hexagonal back of the standoff centered on one of the slot
holes in one piece of unistrut.  

2.  Dropped a closed ended 3 ft. piece of unistrut on the standoff side
a few times from a height of about 6 inches.

3. When the standoff was punched down flush with the inside pulled it
out from the back with a pair of pliers. (I had put a screw in the
standoff first, the blows alone would have shoved the standoff all the
way through.)

The case did warp out slightly (2mm?) on the bottom around where the
fastener had been.  To fix that, flipped it over, stood the standoff up
over the hole (hex nut side down), taped it in this vertical position
with some masking tape, and once again employed the 3ft unistrut as a
hammer.  A couple of quick taps and it was flat enough so that it would
slide into the rack.

Drilling the standoff out wouldn't have deformed the case, but at least
this way there were no little metal shavings to worry about.  Using a
couple of fender washers instead of the unistrut might have reduced the
size of the deformation.  Or maybe not, as the dimple was round and
about 2 times wider than the unistrut slot.

The standoff seems little the worse for wear.  The nut part was chewed
up slightly by the pliers, but the cylinder part and the groove appear
to be undamaged.


David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech

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