Does SCALE matter?

[A Guy In Town]

Hi from Kentucky!

I have a project I have been pondering for several years now.  I have a HUGE workshop building.  I want to (eventually) wrap the entire building with a connected mechanism of gears, chains, levers, and any manner of mechanical devices that will withstand the weather and provide "eye candy" to customers who stop by my home hobby shop. 

The building is 32x60, and 20 feet tall, so the gears and such must be LARGE in order to prevent the project from becoming a billion gear contraption.

If I design the various components using Gearotic (and other programs ?) does SCALE matter at all with respect to functionality?  I realize that the WEIGHT of the larger gears is a factor, and they must be made as light as possible while still maintaining structural integrity.  For example, offset elliptical gears cannot weight a lot due to the leverage issues.

I would be using CNC plasma and router tables, and I am looking at a laser table too, but that is a $174,000.00 "toy" that may need to wait a little while.  (It is calling my name!) ::)

The mechanism would be driven by one or more electric motors, perhaps with some assist motors here and there to overcome pure resistance of SIZE.  The entire mechanism would just be a collection of connected moving parts that make the building's exterior come alive when running.  I may incorporate a large clock and some other things as the imagination wanders.  Parts would be added to existing gears, etc. as the design morphs.

Christmas bonus!  The gears and mechanisms will have LED Christmas lights incorporated into them, on a separate circuit that will light up the entire display during the holidays.  A bit tricky to wire up, but not overly difficult.  It involves building the lights into each component, and setting up two separate and independent metal paths for power and ground, on each gear, each SET of drive chains, etc.  No extra wires. Just careful planning.  :-\

I am going on a short trip.  Then I need to learn this program so I can begin the project!  It is too late for THIS Christmas, but next year, I am hoping to have something really fantastic to show!

[steve323]

It sounds like a really cool project.  Please post pictures when you get it completed.

As a general rule, scale does not matter.  A 10 dot pitch gear can be scaled up by 10X to become a 1DP gear.  The proportions stay the same. 

You have additional flexibility to scale thicknesses, spokes, shafts, and hubs when the gears get to be crazy large sizes.  For example, a 2" diameter clock gear might be 0.1" thick.  Scaling it up to 100" diameter at the same proportions would result in a 5" thick gear, but it might be perfectly fine if it was 1" thick. 

Other random thoughts:
Limiting the contraption to one primary wall will have almost the same effect as the entire building, but is only 1/4 as complex.
Spokes can be made from I beams or hollow tubing to reduce weight.
Add extra backlash to prevent gears from binding.
Consider a few kinetic spinners to really add some visual movement.

Steve

[BobL]

Love to see this barn of gear also, please post if you ever get around to doing it. Agree with Steve, general rule scale doesn't matter.

Cheers
Bob
;)