Re: Anti-ooze valve for extruder February 19, 2018 08:53AM |
Registered: 10 years ago Posts: 564 |
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MKSA
And what pressure do you think it will have to act upon ? If there is no leak, a 1 bar in the "air chamber" at room T° will become how much at let say 200° ?
Re: Anti-ooze valve for extruder February 19, 2018 10:18AM |
Registered: 6 years ago Posts: 1,007 |
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LoboCNC
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MKSA
And what pressure do you think it will have to act upon ? If there is no leak, a 1 bar in the "air chamber" at room T° will become how much at let say 200° ?
If the temp (in Kelvin) is increased by 2/3rd (300K to 500k), then the pressure in the air chamber should also increase from 1 bar to 1.66 bar..
An alternative to this that I'm pondering is replacing the silicone o-ring and air chamber with a pad of closed-cell silicone foam and have the piston press on that. That eliminates the problem of leaking seals. The amount of motion required is less than 1mm, so it should be doable with, say, a 3mm thick piece of foam.
Re: Anti-ooze valve for extruder February 19, 2018 12:51PM |
Registered: 7 years ago Posts: 270 |
Re: Anti-ooze valve for extruder February 19, 2018 04:05PM |
Registered: 6 years ago Posts: 1,007 |
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newbob
I have no idea what amount of pressure would be needed - that would not be my biggest concern. More troublesome would be assuring that exactly the same amount of pressure over time would move the needle. If amount of pressure or time varied from retraction to retraction, system would never 'know' if plastic have been extruded through the nozzle or used to move the plunger.
Re: Anti-ooze valve for extruder February 19, 2018 07:26PM |
Registered: 10 years ago Posts: 564 |
Re: Anti-ooze valve for extruder April 03, 2018 09:37AM |
Registered: 7 years ago Posts: 4 |
Re: Anti-ooze valve for extruder April 03, 2018 12:32PM |
Registered: 10 years ago Posts: 564 |
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Quenta
Hello, this is just a note so that you won't need to reinvent wheels.
I've successfully machined out an all-metal, anti-ooze nozzle with a passive mechanical valve.
Its working perfectly fine with the E3D ecosystem(namely chimera or kraken).
It's currently in small lots production, available from here.
documentation can be found here.
I haven't decided on going for commercial production with this or not.
Re: Anti-ooze valve for extruder April 04, 2018 12:30AM |
Registered: 7 years ago Posts: 4 |
Re: Anti-ooze valve for extruder April 04, 2018 01:51AM |
Registered: 6 years ago Posts: 207 |
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Quenta
1. I wish not to write this because it is key in manufacturing
2. You are right about your concerns. To keep it all metal there is no seal. A certain level of precision in the machining of the pin / barrel is necessary to block molten plastic to enter the air chamber.
3. Your intuitions are somewhat right, but given the acorn-nut shape nozzle with a thin orifice, the plastic is rather likely to flow down than up.
Nevertheless in very long extrusion(like over 10 minutes, depending on the tolerance of the seal) sometimes a jam occurs. The fix for this is
a. more precision(smaller tolerance) between pin / barrel
b. retraction. Best if retraction forced between layers.
I can't directly observe the phenomenon, but the motion of the valve opening & closing seems to purge the plastic in the chamber like a pump. So it means you'll be fine if you have certain precision in its manufacturing & retract once in a while. The former is a little difficult, that is where your manufacturing competence is required.
Re: Anti-ooze valve for extruder April 04, 2018 11:39AM |
Registered: 7 years ago Posts: 4 |
Re: Anti-ooze valve for extruder April 04, 2018 12:21PM |
Registered: 6 years ago Posts: 207 |
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Quenta
I have no intention of promoting the nozzle here. This thing is yet experimental. By the way I haven't sold any yet.
Re: Anti-ooze valve for extruder April 11, 2018 07:18AM |
Registered: 7 years ago Posts: 4 |
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klcjr89
What I'm saying is that I would've been your first customer, if you supported PayPal on your site.
Re: Anti-ooze valve for extruder April 11, 2018 12:13PM |
Registered: 6 years ago Posts: 207 |
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Quenta
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klcjr89
What I'm saying is that I would've been your first customer, if you supported PayPal on your site.
Issue resolved for 0.4mm. @klcjr89 Thanks anyways for pointing out the shortcoming in the payment system, I didn't realize it's so crappy from a customer view. I'll soon be back with paypal & some stocks.