Scale is a personal choice. It used to matter more if it was 1/2" or 1/4" because you had to
plot it to paper and maintain legibility for the text. The ubiquity of iPads and tablets has made it so fewer people
plot their drawings. I only ever PDF my drawings now and import them into
Fieldwire. I can pull the
plot up on my phone, my iPad, my desktop, my laptop, or share it with anyone with an iOS or Android device. I can
drop task markers into the plans for things that still need to be done and assign someone to do them. For annual events I can
mark up the lessons we learned this year as "as-built data" to keep in mind for next year. Everyone can
mark up the drawings as they need to adjust and it automatically updates on everyone's devices. No more last minute patch changes that one person scribbled onto a piece of paper, and then everyone had to go on a scavenger hunt to find the paper before they could patch the show.
The general rule of thumb is your text size should never be smaller than 1/8". The smallest you should go is 3/32". As far as your paper size goes and the scale of your geometry to fit the paper, that has more to do with how much text data and annotations you have to fit on your drawing. Again -- if you're plotting only to PDF and not paper, you could make it lifesize 1:1 if you wanted to and someone could
zoom in on it. In a digital workflow, the most important thing is that your text size is legible without being so large it gets in the way of your other text or symbols.
Devil's advocate for
conventional scaling is that 1/4" and 1/2" scales are easy math for someone to convert paper inches to decimal feet. But with an app like Fieldwire or Plangrid, you can also just as easily measure exactly directly off of the PDF.
Even on a paper
plot, my rule of thumb is that if someone has to reach for a scale rule to read the drawing, you've drafted your documents poorly. Dimensions that need to be exact should be shown. Dimensions that need to be +/- 6" should be discernible by approximation off of some reference
grid. For paper sizes I like 30"x42", because if I need to
plot, I can
plot it at full-size if I have a gun to my head, or I can
plot it half-size at 18"x24" with the text still legible and the scale is adjusted half of whatever is shown on the hard copy.
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I'd argue against the
conventional wisdom of using different symbols for fixtures like
USITT has laid out. I've seen too many "standards" on that with contradictions, and then you need to keep a legend on your plots for every type of
fixture in use. With all of the standard size ellipsoidals, all of the intermediary sizes, all of the extremes (10's, 5's, 70's, 90's), and zooms -- the symbol method breaks down. Especially if you do something like
LED's or
PAR's with interchangable lenses and so forth -- it's easier just to show the information in
clear text on the
plot than it is to come up with a 26-symbol legend everyone needs to reference against. Keeping in mind that everyone comes from different backgrounds and one designer's "X"
fixture could get screwed up by a
stagehand who just got off a show where that was the designer's "/" symbol. There's also something to be said for seeing visually on your drawing just how long the
lens tube is on 10° or a 15°/30°.
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You could
line a dozen designers up who would adamantly disagree with everything I've just said and I wouldn't lose a single night's rest over it. It works awesome for me -- my load-ins have never gone smoother because I stick my digital PDF's in anyone's hands in
clear text and they can readily discern every salient detail. For others, their
plot gets distributed to a bunch of union guys who have no idea how an iPad works and this whole process would break down for them. The most important thing is that your process works for you, highly enables your crews to install your plots at whatever skill
level they may be at, isn't overly drafted for something that's stupid simple, and isn't severely under-drafted for something that would've saved you 6 man-hours if you had taken the 20 minutes to put some dimensions and accessory information directly on your drawings.
By the way -- best part of a digital workflow is being able to have someone walk down an
electric and highlight fixtures in green if they're completed or red if they need some attention later. Then if your head electrician gets hit by a bus, catches the flu, or leaves for the day you can
pick up exactly where they left off without needing 20-minutes with them to have them talk you through how far they did or didn't get. Likewise, if they show up at the theater the next morning at 8AM and you're not in until 11AM, they can pick right back up wherever you left off. Added bonus is never having to pay for a blueprint shop to
plot your drawings or pay for your own plotter you have to keep
fed with pricey toner and bond paper.