Saturday, 12 September 2009

Raising the dead

I've had to abandon my plan for skeleton raising as detailed in my last post. The forces required are just too high. The problem is that with the lift bar flat, the force required to get it moving is considerable. My piston can just about supply this, but once the lift bar starts to move, the force required to elevate it decreases as it rises from the horizontal. As I cannot reduce the cylinder pressure once the bar is moving then this extra force results in acceleration, the outcome of which is I've made a siege engine.

Here's my test rig with the full length lifting bar installed:


I've only dared to run it once, which resulted in plan B. This involves having the pneumatic cyclinder at 45 degrees ish to the lift bar. This means that the skeleton coffin will have to be on a plinth to accommodate the cylinder. Not a problem.

Here's a video of plan B with the recently arrived 'Albert'

Note the slightly bemused Matthew in the background.



video

I was pleased with the damping effect as the system returns to the start position. I have some 'connectors' that limit airflow in one direction only. The system returns to the start position under gravity and the damping effect is caused by a build up of pressure within the cylinder as the piston compresses the air within it.

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