Why prime tower instead of poop?

Comments

• daannii@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  My experience in manually changing filament on my old printer. : There was often tiny gaps between color layers that ultimately made the model weak. Sometimes blobs instead.

  (I would pause and change filament at a specific layer to get a multicolor print without a multicolor printer).

  To solve this I would add a cylinder object to the plate so that the first place the head went after a color change was to the cylinder to get the filament back up to the right flow rate.

  The pressure changes from changing filament is why the printer usually does a quick line at the start of a print. And why it’s necessary for multicolor changes.

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• definitemaybe@lemmy.ca ⁨2⁩ ⁨weeks⁩ ago

  I don’t see the full reason anywhere in the thread; the prime tower is essential to quality multicolour prints. Purging quickly shoots out a high volume of filament to quickly clear as much of the previous colour as possible, but then when it goes to start printing, the temperature and pressure are all out of whack and you get inconsistent flow.

  So, if you skip the prime tower, you’ll get globby over extrusions and gaps from under extrusion on the first thing printed in that colour each layer, which looks terrible.

  That said, the prime tower can be much smaller than default. I set mine to 3mm³ of priming and it comes out 95-100% perfect, with only very occasional blobs on the edge, which pop right off with a fingernail flick (or a deburring tool, if you’re fancy.)

  Don’t skip the prime tower. I did for a few weeks before cluing in to why I was getting 1 bad print on every plate.

  I suppose if you’re changing filament by layer, then you could maybe skip it, but then definitely don’t print outer wall first or you won’t get a clean print. But even then, a 3mm³ prime tower is tiny, so why risk it?

  Hell, even the Snapmaker U1 uses a prime tower, and it has 4 hot ends; it’s needed to normalize the flow after a temperature/flow change (being idle). I don’t have one to test, but I expect it would greatly benefit from a bigger prime tower, since it hasn’t just been extruding filament as purge to get things flowing. But that’s just speculation, as I sadly don’t have one to test with.

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  • Blue_Morpho@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Hell, even the Snapmaker U1 uses a prime tower,

    I have a U1 which is what prompted this post. But Snapmaker doesn’t “use” a Prime tower. They took Orca and kept all the defaults. I was thinking that they might have intentionally kept the prime tower default because they don’t have a real poop chute but only a poop bin which would quickly overflow if they primed into it.

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    • definitemaybe@lemmy.ca ⁨2⁩ ⁨weeks⁩ ago

      I don’t have one, but I expect they kept that default setting for the reasons outlined above, but because of a lack of poop chute.

      I have a Creality Hi, and a 3D-printed poop chute off the side of the printer holds plenty of poop for typically-sized 4-colour full-purge prints.

      For really huge prints, I empty once mid print, but those prints last for days anyway, so it’s no big deal.

      With no need for colour/material purging, I would expect a purge tray to be plenty for a multi-toolhead printer. I can’t imagine it purges much?

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• TootSweet@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  Poop where?

  If it just makes spaghetti randomly somewhere not on the build plate, a) it’ll leave quite a mess that would need cleaned up and b) it can end up where it shouldn’t be. In a belt gear or incorporated into the print in a way that sticks out and looks bad or stuck to the hot end in a big gob that causes it to not extrude right and blob up in the print or some such.

  I suppose, depending on the other print settings, it might make sense use purged plastic to make up infill. That said, I don’t have any direct experience with multiple extrusion, so maybe that is a thing. Maybe slicers already do that to some extent but infill doesn’t typically take enough filament to fully purge and the tower is still necessary.

  All that said, I don’t think just making spaghetti would work out very well.

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  • Blue_Morpho@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    Poop where?

    That’s why I’m thinking it’s a legacy setting in slicers. All printers made in the past 5 years have a purge chute and wiper. So purge goes out the back and the nozzle is wiped before it starts.

    Well except the new FlashForge multi head printer that purges off the edge of the build plate.

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    • ExcessShiv@lemmy.dbzer0.com ⁨2⁩ ⁨weeks⁩ ago

      All printers made in the past 5 years have a purge chute and wiper.

      Uuh…no, not even close to being true. There are still plenty of printers without purge chutes available on the market today.

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• sbeak@sopuli.xyz ⁨2⁩ ⁨weeks⁩ ago

  In a nutshell, the prime tower lets the printer print a basic shape, and if it doesn’t look right, either you or the printer (depending on the model) can stop the print. It also it ensures that filament is flowing right between each layer change.

  edit: Fixed. The first point seems to be incorrect, but the second one is okay

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  • Blue_Morpho@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    The prime tower has nothing to do with “looking right”. It builds as the print goes and often looks bad while the print is fine because that is it’s purpose: to build pressure getting the filament moving in the nozzle before the head moves into place.

    In the case of mixing filaments like PETG and PLA for support it looks really horrible because it’s laying down lines of plastic that dont stick to each other. But the part looks fantastic because the slicer creates actual support interface layers for supports.

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    • sbeak@sopuli.xyz ⁨2⁩ ⁨weeks⁩ ago

      Oops, I think I misremembered. I fixed the comment now. I typed it when I was very tired.

      Now that I see your actual question, the main reason it’s a tower and not “poop” is because simply creating poop would mean the little wiper that pushes out excess filament to the poop chute needs to be used, increasing the time as there is a brief pause.

      If it was poop, the printer is like “poop poop clean - wait a bit - now I print” between each layer

      If it was a prime tower, the printer is like “tower tower >> actual print immediately after” between each layer

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• roofuskit@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

  Wiping to avoid dripping from the travel.

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  • Blue_Morpho@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

    The purge area always has a wiper. I don’t see why you can’t prime into the purge chute - wipe, then move to plate.

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    • BakedCatboy@lemmy.ml ⁨2⁩ ⁨weeks⁩ ago

      Purging into the chute doesn’t leave the nozzle with the same pressure as priming onto a surface because there’s no resistance. So even if you retract the same after both, you’ll get a different line start. Priming onto a surface is the best way to guarantee that the next line start is identical to one that comes after a print move and not differently due to coming from the poop chute.

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    • papalonian@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      If you have a printer that has these features, try it out and see the differences for yourself. There’s probably a reason why it’s set up the way it is, but sometimes the differences are so minute that you don’t notice or care. If you run a few prints and the color swaps look like garbage, you’ll have a better understanding of why the printer and firmware are set up that way. If it turns out fine, congratulations, you’ve made a personal improvement to your machine!

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    • roofuskit@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

      Because of gravity and time.

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  • neidu3@sh.itjust.works ⁨2⁩ ⁨weeks⁩ ago

    Sound advice outside of 3dprinting too

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