Software suggestions and requests

[DoulosDS]

Peristaltic Pump Amazon.JPG Found this pump on Amazon for $12, free shipping. I was thinking I would need to replace the motor with a stepper, but I don't think that's necessary. I can add an optical sensor to detect the rotor arms as they pass (looks like there are 3). The software can count them and run the motor forward and reverse as needed to adjust the resin level. If the flow rate and RPM specs are accurate, it should transfer 0.2 ml per 1/3 revolution. Conveniently, that is the same volume I calculated for Z-axis error due to tube pinch displacement in my previous post. So, if the print tank is approximately 3" in diameter or 75 mm, the area is 4418 mm2, and 1/3 rotation of the pump results in a Z-axis increment of 0.0456 mm. That's not great resolution, but it means the maximum resin level adjustment rate is only 13.5 mm/min or 0.228 mm/sec. I think that a second pump could run in parallel with this one, maybe with a higher flow rate. Both pumps could pump extra brine to overcome resin surface tension and viscosity issues, ensuring all the previous layer is covered with fresh, liquid resin. Then remove all but the increase for the current slice, within a few seconds.

[DoulosDS]

Peristaltic Pump Ebay.JPG Here is the best inexpensive peristaltic pump I could find with a relatively high flow rate: 500 ml/min for $30 and free shipping. It doesn't provide much info on specs, like rotor RPM, number of rollers (3? 4?), and tubing inner diameter. It does say the in/out hose barbs are for 1/4" tubing, so I expect the pump tube is 1/4" ID also. It may be possible to soup it up with thinner wall tubing, or speeding up the rotor. Regardless, at 500 ml/minute, it could speed up printing.

[CescoAiel]

So, if the print tank is approximately 3" in diameter or 75 mm, the area is 4418 mm2, and 1/3 rotation of the pump results in a Z-axis increment of 0.0456 mm. That's not great resolution, but it means the maximum resin level adjustment rate is only 13.5 mm/min or 0.228 mm/sec.

0.045mm is a good enough resolution for most prints (0.05 is considered typical layer thickness for laser based printing), and can be doubled (ie rise halved) to 0.0225mm by increasing the tank diameter to 8,5 cm, and almost tripled (approx 0.015mm) by going to 10cm.
Of course that also decreased the max rise speed, but then again, how many filament 3D printers complete a 0.2mm (standard thickness for those printers) layer in 1 sec?
Also faster pumps usually also mean less accuracy...