Questions about my 3B1 case

[Mark Dapoz]

I got this via mail but it's probably of general interest so I'll post my
reply.

>From: uunet!mtgzx!dwex (David E Wexelblat +1 201 957 5871)

>1) What is it made of?

I had the case built by a machine shop out of 3/32" aluminum.  They cut
the four sheets of aluminum and then welded them together.  I then used
a file to smooth out the weld beads which were left on the edges (aluminum
welding has to be done on the outside of edges).  For a finish, I used 
Tremclad paint sprayed on top of a base of white aluminum primer.  Total 
cost for the case came to about $200 Canadian.

>2) Is this a replacement for the plastic case, or the entire case (i.e.
>   does the motherboard fit in there somehow, or does this just sit
>   on the metal pan)?

The case just sits on top of the existing metal subframe that the 3B1 has
once you remove the plastic top.  The measurements I took for the case
were a bit smaller than I would have wanted so the case fits VERY tight
on the subframe.  Although this is good from a studyness point of view, 
however it makes for more difficulty when removing it.  If I were to 
build the case again, I would make it a bit bigger than the plans (a few
extra millimeters is all that would be needed).

>3) In the left-side view, what is the small opening on the left of the
>   floppy-drive openings?

That's where I have the new connectors which allow me to plug in the keyboard
and monitor.  The actual connectors are mounted to the metal subframe, not
the case.

>4) What is the opening on the left side of the back face?

That's where the power cord/switch assembly goes.  This is the one from the
original plastic case, I just relocated it.

>5) What does the internal structure look like?

Ok, time for some ascii art :-)

The basic layout is something like this:

				Back
	+-------------------------------------------------------+
	| +-----------------+  +-----------------+  +---------+ |
	| |		    |  |		 |  |	      |	|
	| |		    |  |		 |  |	      |	|
	| |	Maxtor	    |  |     Maxtor	 |  |	3B1   |	|
	| |		    |  |		 |  |	      |	|
	| |	XT1140	    |  |     XT1140	 |  |  Power  |	|
	| |		    |  |		 |  |	      |	|
	| |		    |  |		 |  |  Supply |	|
	| |		    |  |		 |  |	      |	|
	| |		    |  |		 |  |	      |	|
	| +-----------------+  +-----------------+  +---------+ |
	| X - keyboard/			+--------------------+	|
	| X     video connectors	|		     |	|
	+---------------------------+	|     Additional     |	|
	|     5.25" Drive	    |	|		     |  |
	+--------------------+------+	|      200 Watt	     |	|
	|     3.5"  Drive    |		|		     |	|
	+--------------------+		|    Power Supply    |	|
	|				+--------------------+	|
	+-------------------------------------------------------+
				Front

The additional power supply is used to power the Maxtor drives and both
floppy drives.  The 3B1 power supply is left to power the motherboard
and any cards which you have installed.  DON'T try to run all this from
the 3B1 power supply alone, it can't handle it!

>6) What does your monitor sit on?  Did you remove it from the old plastic
>   shell, or do you just use that for the base?

I took the monitor right off of the entire case and mounted it on the bottom 
half of one of those swivel bases that you can buy to put monitors on.
Seems to work ok and I can still swivel the monitor.  I drilled a hole in
the bottom of the monitor to allow me to get the video cable out.

>Also, in your followup to my query about vertical floppies, you asked what
>I was going to put in the hole if I mounted both floppies externally.
>Actually, I hadn't been planning on mounting anything there.  Putting both
>floppies in the same cabinet makes wiring the head-select switch simpler,
>and taking the drive out will reduce (by some small amount) the strain
>on the built-in power supply.

The power drain from the floppies is so minimal compared to the rest of the
system (especially the Maxtors :-) that it probably won't make much of a 
difference.  It may make it more convenient for you though.
-- 
Managing a software development team 	|   Mark Dapoz  
is a lot like being on the psychiatric	|   mdapoz%hybrid at cs.toronto.edu
ward.  -Mitch Kapor, San Jose Mercury	|   ...uunet!mnetor!hybrid!mdapoz