Wednesday, December 9, 2015

Panel support structure

It's been awhile since the last post, but I'm still working feverishly on this project - I'm simply behind in posting.

First, a few details on finishing up the individual panels...

I tried gluing the transparency to the cutting board for the status lamps.  This turned out terribly.  The glue discolored and the cutting board warped significantly.  So I decided to simply sandwich the transparency and cutting board up against the clear transparency I had printed for covering the painted wood on that panel - I hadn't cut out the center section, and it holds the cutting board and the printed transparency neatly with the LED holder box behind it.  A little hot glue around the edge of the LED box on the backside (NOT up against the transparency, just between the plastic and the masonite) once it is installed secures it all in place.

Similarly, I left the transparencies over the LED bargraphs and seven segment displays intact, simply pushing the electronic component in from behind and hot-glue tacking it into place.   Note on this procedure - make sure that your components are going in oriented properly.  This is easy with the seven segment LEDs as they have decimal points that will point you to the bottom.  This is not as simple with the bargraphs.  The ones I purchased have a small miter on one corner - that will point you to the side which has pin #1 on it (there are 14 pins overall, 7 on each side).  If you want to double check, apply a 5v load to the two pins closest to that miter, with the positive (anode) attached to the side with the miter (pin #1) and the cathode attached to the side without (pin #14).  The LED closest to the miter should light up red on the components I used.  If it doesn't light up, that would imply you either have your voltage reversed (remember, LEDs are one-way only!), in which case try swapping your leads to the pins  - or you've got pins 7 and 8, which are both cathodes on this particular component.  It is critical that you put the component into the panel the right way so that it is wired properly and so that it does what you want when the arduino tries to control it later.  For bargraphs mounted vertically, I put the miter corner at the bottom of the panel - this will match the LED behavior that Jeff used.  For the cryogenics panel, I put the mitered corner to the left as you're looking at the front of the panel (to the right as you're inserting it from behind).

That should cover most of the population details.

Oh, and use your voltmeter on a resistance (continuity) setting to check that all your SPST switches are aligned properly so that they are open (infinite resistance or no continuity) when the switch is in its "off" position.

From there, it was off to building the support structure.  This will be mostly hidden from view, so all we care about is something that will tie things together affordably.  I used 1"x2"x8' furring strips from the local home improvement store.  3 pieces at about 80 cents each is all it takes.  I cut 4 3' sections out to run the width of the panel - one at the  very top, one at the bottom, and one along the panes at the top of the center panel and one at the bottom.  I cut 2 1' sections to serve as horizontal runs for the panels at the middle of the overall structure (Jeff didn't have a cutout for a monitor in the center, so he could continue that run all the way across the structure, whereas I had to stop it at the center).  I then cut 4 2' sections for vertical runs - one at each end and one for each side of the center panel where the monitor goes, so those 1' sections had something to rest on.  Using the panels as guides to mark the points where their individual edges would go, I essentially dadoed a slot where each wood strip would overlap so that they would fit together nicely with just wood glue to bind them.  This was not precision work - I simply notched it all out on a sliding miter saw.

First, a simple dry fit to test

Then check for square....

Then it was a matter of simply gluing the pieces together and clamping them until dry.  Luckily I have a lot of clamps.  Again, don't worry about this being precision work - my overall structure was a hair too wide, so I simply belt-sanded it down to be flush with the edges of the panels.  And you'll likely need to notch out some bits for panels to fit on.  I did.  Better planning might have alleviated this, but it was fairly straightforward and the structure is still strong enough.