Use a scuba tank as an air compressor for 300+psi pressure

[tbone1004]

flow of 10cfm will only last you 7-10 minutes on any scuba tank if you are lucky, even the big industrial welding bottles will only last about 20 minutes at that flow rate. That is a BIG flow rate for a compressor at that pressure though and you are talking real money to get up there with continuous duty

 

[jbbaille]

Yes indeed, sorry I meant 0.00035 cfm (10cm3/min) - not used to talking with imperial units!

I basically push the clay through another scuba tank, and finish this scuba tank in about 12 hours. So it would take 12 hours to divide by 2 the pressure inside the scuba tank, if its water capacity is the same as the scuba tank full of clay

 

[BRT]

Is the video using compressed air to move the clay?

 

[jbbaille]

No they use an extrusion screw

 

[BRT]

No they use an extrusion screw

I have a fair amount of experience positioning things, and that is what you are doing. It is very hard to do with air. On a continuous basis it it close to impossible to do it accurately. It requires absolutely constant fluid consistency. Absolutely accurate valve "nozzle" consistency, perfect pressure control and so on. That is why they use an extrusion screw. You have to remember that the dynamic co-efficient of friction is always lower than the static. Once you get enough air pressure to move things they always speed up. You will not make it work like you think.

 

[jbbaille]

The air only pushes the clay at a very average/rough flow (it doesn't need to be precise) to feed the auger that precisely (by changing the revolution speed) feeds the clay through the nozzle.

Here is the system that I bought: http://www.vormvrij.nl/homepage-pictures/new-landing-index.jpg

Because cartridges are in plastic, they can't be used at more than 6 bars (and only 3 bars when temperature is over 21C, which is often the case in Sydney!). That's the reason why I started using scuba tanks instead of those plastic cartridges, to be able to print at up to 8 bars, the limit of my air compressor. Now I would like to push the limit even more by trying with greater input pressure.

The extrusion screw is a better system I think, but more expensive as well (and I have no idea how I could design that. So far, I just improve a system. Going with an extrusion screw would mean to re-design it completely...)

 

[BRT]

The air only pushes the clay with a very average flow (it doesn't need to be precise) to feed the auger that precisely (by changing the revolution speed) feeds the clay through the nozzle.

Here is the system that I bought: http://www.vormvrij.nl/homepage-pictures/new-landing-index.jpg

Because cartridges are in plastic, they can't be used more than 6 bars (and only 3 bars when temperature is over 21C, which is often the case in Sydney!). That's the reason why I started using scuba tanks instead of those plastic cartridges to use them up to 8 bars, the limit of my air compressor. Now I would like to push the limit even more by trying with greater input pressure.

The extrusion screw is a better system I think, but more expensive as well (and I have no idea how I could design that. So far, I just improve a system. Going with an extrusion screw would mean to re-design it completely...)

Got you! Obviously I didn't understand the process. The screw controls the flow. You may find that doubling the pressure does not do as much for the flow of the unwatered material as you think, but I could be wrong

 

[67macoshark]

I expect a refrigerator compressor would be a much cheaper alternative at your needed flow rate and pressure. There are some DIYers with some helpful tips online if you go that route.