I want some input from the community, especially those with knowledge on the subject, concerning the possibility of utilizing alternative means to achieve movement of the Z axis.
Specifically I’ve mulled over the idea of using an inflatable device to achieve said movement.
The device would be inflated to maximum capacity at the beginning of a print and would deflate gradually via an electronically controlled valve.
The printer would have to be encased, I surmise, and the temperature within regulated carefully to achieve uniform air pressure.
However, I believe it could be significantly cheaper and more durable/reliable; and could be improved upon more rapidly via software development than current motorized methods.
I would also like this to be an open door to discuss alternative methods of operation for 3D printers in general.
You wouldn’t want to use air as it is compressible, you would not have very good control of distance. I also don’t thint it will be cheaper, quality pneumatic/hydrolic controls are more expenisve that $10 steppers.
Indeed, but I believe that the heat generated by the hot bed might give the air better properties for the application, and I believe that the compression could be compensated for with calculation.
I imagine the control of distance could also be achieved with experimentation and calculation, which is one of the specific reasons I thought of it, because the math is free if you know how to do it. Whereas hardware constraints are more of a concern with current methods I believe.
When you figure in all the costs I believe the difference wouldn’t be so great, and especially in terms of long term reliability I think you’d save quite a bit.
But I’m not familiar enough with pneumatic/hydrolic systems.
Does any one know of a valve that could possibly be utilized for the operation?
Vibration is a big issue, and air pneumatic systems would shake around a lot. You’d have to add significant damping to your z axis, or as said use hydraulics. McMaster-Carr have hydraulic valves, but hoo boy are they expensive – because generally they’re intended to run at tens of atmospheres of pressure. I don’t know of any low-cost low-pressure hydraulic systems, although they may well exist.
I’d have to agree with @Misha_Tikh - air is not a suitable medium for precise movements, especially when there’s a load involved, since air gets quite springy when there’s a dynamic load involved. This circumstance improves as pressure improves, since air compresses absolutely nonlinearly.
Air is only usable for precise positioning when you have some kind of closed-loop control in place (with normal layer heights, we need Z accuracy to be better than around 10µm). Usually glass scales provide that feedback for high-precision applications, but the cylinders and feedback system easily cost more than the whole rest of the printer.
