Form3 Filling logic suggestion

The logic on filling seems to close bite valve when mixer arm moves, then wait about 20 seconds before opening again. This leads to dispense errors (3 in a row) so doesn’t seem particularly optimal.

On a brand new form3 install, noticed glacial filling of tank with clear resin - the bite valve slit looked fine, just a tiny drizzle, even after heating up the cartridge to around 25C, and yes the vent cap was open :slight_smile:

With next test with Tough 2000 I partly prefilled the tank (wasn’t sure what level exactly) which helped save about an hour off the fill time (after scoring the bite valve as it was completely shut and would not open with a squeeze!), but was still very slow as it continually stops filling!

It seems the mixer arm movement occurs around every 60 seconds, and the filling is stopped during this process for at least 20 seconds (it seems ages after the mixer arm stops moving before opening valve again), so we’re losing minutes of filling time (possibly up to 50% slower than it could be).

When the printer moves the mixing arm with resin in the tank, it will push the level sensor up so the printer will be able to know when there’s resin filling… but the stopping of filling closing the bite valve every time does not make sense at all.

I would suggest after two or three ‘dry mixer passes’ (where the level sensor doesn’t register), the printer should slow down the frequency of mixing AND not close the bite valve, to allow faster filling… This way the rate of fill can be crudely monitored and adjusted dynamically.

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Filling takes an extremely long time if you do not prefill. There are some drawbacks to prefilling though. Although the process may be slow, I think you would get more accurate cartridge resin level in preform. I don’t think there is a resin level sensor in the actual cartridge so preform just subtracts the amount of resin used from your print with the total amount of resin in the cartridge until it eventually gets to zero. There have been issues with it being inaccurate anyways soo. Secondly, You may run the risk of overfilling if you are not careful how much you are filling. I just prefill it right under the halfway mark of the wiper (when printer is at idle) and let it fill automatically from there which shouldn’t be much time. I keep track by feel on how much resin is in the cartridge so I do not rely on what preform says about resin level in the cartridge. Just prefill and keep tabs on how much resin you have in each cartridge and order new ones accordingly and you should be fine.

That’s why I make this observation on filling time that could be optimised somewhat by not pausing the fill process. I don’t think it makes any difference to cartridge level though - as you say it appears to only deduct the resin used from the print each time - I know around a 1/3 of the cartridge (or more) has gone into the tray and both the one I prefilled and the one that took about 2 hours with 3 dispense errors say roughly the same amount remaining (over 900ml so the cartridge remaining has to include the contents in the tank too).

I just loaded Draft V2 into a new tank - I compared the fill level of both existing tanks of Clear and Tough 2000 and roughly prefilled to the same level (the mixer arm parked on the left acts as a bit of a barrier so the actual level won’t be as much, leaving some filling for the printer to do itself). :slight_smile:

The issue is compounded by the fault in the dispensing valve actuator design.

After a couple of cycles it loses the ability to fully open the valve so the fill rate goes from a trickle to a few drops per cycle.

Possibly an undersized motor driver, chip thermally limiting?

If you don’t manually fill, it will add several hours to your print time.

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