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QUESTION:I have a nice little power pack set up now... The pump and switch, connected by a 2x8 conducting plate, sit underneath a rack of 5 air
tanks ganged together in series and now I have the air power to do whatever I want!! (well, not like Moz and Andrew with their 25,000
cylinder behemoths, but I can feel a set of powered enginehouse doors coming on!)
ANSWER: Well, I haven't actually built a compressor yet, and in fact I'm tending
towards motors again because they give finer control. Pneumatics are great
for high power/direct control applications like Andrews cool excavator, but
for stuff like the forklift I want to be able to remote control it, which
means solenoid valves (someone else's problem) or electric motors. With any
luck I'll be able to use the Lego radio control for this baby :-), I'll
just have to put my own nicad in and run it on 10.8V rather than the
nominal 9V that the 6AA batteries supply. I assume it's 6AA's in the RC
cars? They haven't arrived here yet. Grr. Oh, 10.8 because that's one and a
half 7.2V Tamiya RC car cell packs (which I "happen" to have lying around
from an RC boat I scratch built last year).
I currently have 13 motors (4 more ordered), but ran into a minor problem
last night - the power supply I'm using tripped at 5 amps (its nominal
limit per side), with only 8 motors running. I'm a little worried, since
the new geared down motors usually only draw about 350mA when stalled
(5-200mA under normal loads) and I had four of those plus four of the older
non-geared 9V motors, which usually take 50-500mA or 600mA stalled. But,
none of them were stalled. I admit that I was trying to lift a book while
running everything (movement, steering, raising the arm, extending the arm)
but that beeping overload alarm has me worried. Does anyone out there have
any ideas on powering large collections of motors? I can use both sides of
the supply for 10A/9V regulated, or go unregulated to about 15A, but I want
to know how 4x0.4 + 4x0.6 = 4.0 can trip a 5A alarm. And those older motors
sure make a lot of noise compared to the new ones, presumably because
they've got faster moving parts closer to the surface. Who knows.
Anyway, I'm using the older-style rack and arm lifting mechanism, as in the
Crane 855? that is featured in the instructions for 854 that I have.
Basically a rack and pinion move horizontally, with a couple of axles under
compression pushing the crane boom up. Only I've used Technic beams and
some cunning tricks because I'm lifting rather more Lego than they are
Oh, and that model has interesting dual-steer - one rack driving it, with
the second steering set attached to it via an 8x2 plate.
Really must get back into LDraw and sketch some more of the model. Tempted
to buy myself a digital camera now I've had to return the one I borrowed.
Looks like my price point is about $US200-300 so a Panasonic KXL-600A
might do. 640x480, PCMCIA card, no battery-eating LCD. Available off the
shelf here.
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