Any reason to close the vent cap?


#1

I was wandering why the Priming routine has a step to check that the vent cap of the cartridge is open.
Is there any reason whatsoever to close the cap, like ever, while inserted in the printer?


#2

Great question. I generally leave mine open. I guess there’s potential for itsy bitsy contaminants like dust or a bit of reflected light to get in.

Try and remember to close it before removing the cartridge, especially if you’re pulling it out to shake it up (not that I’ve ever made that mistake before -cough-).


#3

Oh yes… of course I close it before pulling it out… it’s next to the handle, so it’s difficult to miss.

Your guesses are indeed plausible causes why someone would want to do it. I guess for multiuser environments it makes sense to add that check to the protocol.

But if there was no real harm, Formlabs could put some text on the cartridge like “never close cap while in the printer”, and remove that step…

Just an idea


#4

The new caps on new cartridges are actually solving the dust issue. it is a twist mechanism instead of the push one with the vent


#5

@Randy_Cohen Prime Remotely?

Hi Randy, if I understand correctly you say the vent cap needs to be closed because the cartridge empties itself otherwise due to the resins weight?
I’d say after the end of the print, the air pressure inside the cartridge above resin is equal to ambient, so if you close it the resin wouldn’t the valve drip until the air reaches enough under pressure to stop the dripping?

Really never happened to me
Did it to anyone?

It gets me thinking though about the creep in the valves rubber material. I haven’t cut a vent cap yet but if your cartridge stays upright it might become more relaxed overtime and be more prone to leaking.


#6

That’s a good point I missed. Closing the cap when you’re not using the printer could help mitigate against a leaky bite valve.

if I understand correctly you say the vent cap needs to be closed because the cartridge empties itself otherwise due to the resins weight

Really never happened to me
Did it to anyone?

The bite valves were slightly notorious for problems. I recall seeing some reports of leaks (e.g. 1, 2). Lots more reports where the scoring was too shallow and customers were instructed to use a knife to finish the cut through the material. I’m guessing the manufacturer had trouble achieving the desired control over tolerance and Formlabs may have shifted the spec slightly to the conservative side for a while. It’s also been proposed the rubbery material is sometimes self-healing.

I expect things have improved since then, as I haven’t seen chatter about this lately.


#7

Interesting links, thanks!