I just ran through a back-of-the-envelope calculation of the raw material processing cost of an anticipated project- $1600 in electricity, $3120 in plastic- and all that before heading to the mill. Got me wondering how much power I’ll be cooking through running a 3 kW spindle and air for 8 hours a day. What do you reckon your work-day of power consumption amounts to?
Just for the spindle I’m guessing 19.360kwh
( Big Boy toys have Big appetites) 
How much are you paying for electricity?
My worst case power is around $0.25/KwHr (middle of the afternoon in the summer), and the rest of the time it’s arount 8 cents a KwH
So my 3kW spindle (which is worst case, you won’t typically pull that much), two HP dust collector, and add another 1kw for the rest of the electronics is 5.5kW, which is $1.38 per hour on my worst case power. So a $1600 project would be almost 1200 hours of runtime, or roughly 7 months. Thats a big project, I’m surprised its only $3k in materials.
But if that really is how many hours you are going to run, measure your real power draw for the machine with a cutting load that is similar. I think you’ll find that the real load is going to be less then half of the worst case on average.
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The power company tries to shame me. They send me these little graphs showing my power consumption compared to my neighbors.
Definitely take your power bill and stick in your cost worksheet or you will go broke really quick.
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Last winter I got an email from the power company, letting me know that my bill was unusually high and something might be wrong, just letting you know rather than wait for a big surprise in your bill, etc…
No, it was working properly.
I had been testing some 10Gb network gear the same month the geothermal had to keep up with record low temperatures. $1150 electric bill for January.
My machine is going to need about 50 Amps of breakers to run everything at full power. Doing the math, that’s about $1700 per month at most, if I run it 100% of the time at 100% power. I’d also be 100% told to never do that again if my wife finds out…
“Normal” operation uses WAY less than 100% power though.
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$1600 is just the material prep cost- melting HDPE and annealing in the press will run about 48 hours per 75lb block.
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