Thursday, August 9, 2012

Morrow Progress #2

It's a box with knobs on it.  (Okay, two boxes, but that's just duplication.)

The knobs have to turn.  This is a hard-learned lesson from the props builders; don't cast a solid trigger.  Because no matter how many people you warn, someone will pick it up and try to pull it and snap it off.

Making it light up is a stretch goal.  Which of course I'm going to try to do anyhow, but since it will probably be admired for a few minutes then stuck away in a box, I'm only budgeting a limited amount on bells and whistles.  Well, lights and whistles.

The most complex part of the electronics would be making a functional display.  Which I may not be able to do within the time and budget.  Anything else is just throwing some LEDs behind the indicators and wiring them to one or two poles of the rotary switches.

Which makes it, electronically speaking, a box with knobs on it.

This means the project is dominated -- the construction, the costs, the planning sequence -- by the knobs.  What are they, where are they sourced, what are their dimensions.  The look of the box is a period military radio.  The box itself will have some grooves, divots, curves, but the look of the thing is, basically, the look of the knobs.

Knobs and lights, that is.

I'm still, after almost two weeks of work, still in selection hell.  I've been purchasing potential switches and indicator lights, researching and drawing out to scale various display modules, and looking at far too many pictures of knobs.

What I haven't been able to do, just yet, is nail down much of anything beyond basic dimensions.

To progress, you have to start making commits.  According to my hand-drawn Gannt Chart (I have some nice freeware software but I haven't had a chance to learn it yet), the lead time for the 3d printer is the most important dependency.  I have to have the 3d model completed in enough time to get the print back in enough time to do the final assembly and painting.

Every commit you make is flexibility you are removing.  Each decision risks being found poor in hindsight -- but hindsight only happens when you've been able to collect information from the ongoing build.  You can't plan everything in advance, not even the plan itself; you have to start making assumptions based on inadequate information, and develop them until you learn if they are going to pan out.

The vacuum fluorescent display I really want to use is currently wending it's way from Dnepropetrovsk.  It will not arrive in time to be able to alter the 3d model.  It may not even arrive in time to breadboard then to package it up!  The only commit I've been able to make so far is to leave room for that display -- but I suspect I will need to develop a backup display and test the electronics package on that.

I am not firm on it yet, but I believe the knobs are going to be custom printed as well.  Plus button caps, if I chose to have multiple buttons (which adds a whole new layer of complexity but anyhow!)  I've been looking at military surplus knobs but the space is limited and I like the potential of a very specific (yet familiar) look.  Plus the nicer knobs are simultaneously quite expensive and in shoddy condition.

I believe the basic labeling will be raised letters on the print itself.  I won't know until I get into the 3d model if this is possible within the detail level of the 3d print but my experience with previous 3d prints says it is.

However, it would be nice to have one vernier dial.  That would almost certainly exceed what 3d printing can do.  I spent a day looking at options to laser-etch a dial surround, and I've been looking at existing surplus knobs, but my feeling is this is going to end up being a water-slide decal.  I do want to look at acid-etch -- I saw a nice Instructable on that -- but I don't like the idea of doing an acid etch in my apartment!

 I'm toying now with the idea of a slip-ring for dose/time calculations; some way of integrating the radiation detector sensitivity dial (the vernier dial) with an "actual reading" ring that would then read off the "maximum safe time in contaminated zone" on an outer ring.  Which maybe makes a lot more sense mechanically integrated, but you build what you can.

Lastly, I'm fairly firm on the Dialight I found at the local electronics store.  On the minus side, it is so big it is difficult to cram two of them on the faceplate, and it stands pretty high as well (I may have to sink them in, or raise the display -- either of which uses up more plastic.)  On the plus side, it looks very military (the Dialight is very common on aircraft displays), and the actual dial function (dim/not so dim) involves physically shuttering off a trefoil pattern behind the lens.  So it looks something like a radiation symbol when lit!

What I haven't quite integrated is how to work other indicators in conjunction with the Dialight.  I don't know if they are absolutely needed, but it would be cool to have one red LED for "antidote ready." 

I think I'm about to make a firm commit on having the CBR kit have two Dialights.  That at least will allow me to move forward.


Whew.  Created a new scale drawing using the revised measurements of an actual Stoner magazine (the CBR kit has to fit in the same kind of pouch.)  Two Dialights fit, plus the Ukranian VFD (at least, as close as I can get from the only photograph I have of it).  Two knobs, one of which is probably custom-printed, and two decal dial surrounds.  It has some of that compact, efficient, yet oddly hap-hazard look of military radio gear.  And enough detail in the plastic that it should make an interesting print.

Now to start on the 3d model!

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