Many questions may be answered by reviewing the information on the Tech Details page.
How big is it?
7.5 inches wide, 12.5 inches tall (9.5 inches without the stack), and 13 to 16 inches long depending on where the legs are in their stride.
How does it work?
Solid fuel pellets heat the water inside the boiler turning it to steam. The increased pressure inside the boiler is piped through valves controlled by the eccentric and pushes a single piston back and forth. The piston rotates a flywheel which drives the sprocket and chain. This drives a series of gears and shafts which increases the torque to cycle the linkage allowing the steam spider to walk. Everything is connected to the leg bone...
Steam Spider History
The steam spider started in January 2006 when Crabfu contacted me regarding designing a steam-powered walking machine using the linkage he found on the mechanicalspider website.
The first one was built out of polycarbonate and designed using components that he had salvaged from an RC tank and a steam engine. It worked but we thought we could improve on it.
The second version was designed around readily available components and kept as simple as possible. A single prototype was constructed and tested. It is slow and does not turn, similar to a steam locomotive, but is interesting to see with the details of the mechanics exposed.
The runtime on my small bench-top mill for the custom pieces is about 48 hours which made doing the work for even a small number of spiders unrealistic. Quotes were received from multiple shops for fabricating the custom metal components but the cost was high and the project was shelved.