IMPORTANT: Upcoming Changes in 3D Fab (if you use our 3D printers, you will want to read this!)

3D Fabrication
#1

Due to a huge increase in clogged nozzles on the 3D printers, here are some changes we are going to implement in 3D Fab for the month of March, to help better isolate what the core of the issues may be.

We are going to designate the following:

  • One PolyPrinter 3D printer will be “in-house black ABS filament only”
  • One PolyPrinter 3D printer will be “in-house - any color EXCEPT black ABS filament only”
  • Two PolyPrinter 3D printers will remain the same as we have been doing (“in-house” or “bring your own” ABS filament)

We will ensure that all four PolyPrinters have brand new nozzles in them on March 1st; and, that any clogs will be carefully documented (and resolved by replacing the clogged nozzle with another new nozzle).

The reason we are separating the two that will be designated for “in-house” ABS only between “black filament” and “any color EXCEPT black” is because we have been advised that the majority of the clogs are from black filament; and, this will allow us to get better data on it - instead of just flat out banning the use of all black filament across the board.

Other Upcoming Changes

  • As soon as we can code it, is that we will be configuring Octoprint to use members’ Active Directory logins - to ensure that only active members are using the printers (and only using one at a time), etc…

  • 3D Fab will be providing 2 gallon plastic bags for members to store their own filament in (along with some basic tips and training on how to properly store their filament); and, John is working on getting the acrylic covers added to the shelves in the 3D Fab Room, so we can do a better job storing the ‘in-house’ filament better.

  • We are going to be adding a ‘test’ as part of the 3D Fab trainings - that will ensure that the most important information that members need to know about using the printers/resources is learned & acknowledged once they have attended the training. We will likely allow members previously trained to ‘test-out’ prior to implementing the Active Directory login system.

Continuing the discussion from Usage report for Poly Printers?:

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Usage report for Poly Printers?
Usage report for Poly Printers?
#3

Comments on your clogged nozzle issue:

You’re not experiencing a 3D printing issue, you have a general thermoplastics processing issue. The same thing happens at the nozzle of injection molding machines (extruders dont have nozzles, they have a die head with various geometry). Material in the nozzle is degrading into carbon. It happens to all thermoplastic resins when exposed to processing temps for extended periods. You’ll find that the color will make no difference. Notice the dark build-up on the nozzle and the crusty build-up on the fiberglass thermal blanket around the hot end. This could have been white ABS at one time.

The nozzle fills with material allowing only a small amount to be extruded. The material held back is experiencing the hot end temps and degrading into solid carbon, which is causing the nozzle blockage. Who ever is cleaning your nozzles can confirm this. How long is the material sitting in the nozzle before it gets extruded? Its hard to tell. The inner geometry of the nozzle is responsible for this. A gradual taper with no land provides the best flow. If the nozzle has an acceptable taper, the time the hot end is up to temp with out extruding is degrading the resin.

Some ideas:

Verify and or modify the existing nozzles if a better taper is needed.

Purge the hot end after each print. (dyna-purge?).

Instructions to keep the heats off until absolutely ready to begin printing.

Can the temps be reduced? The temp of the extruded material is what matters. Have calibrated pyrometers been used to verify the nozzle temp (not the aluminum block temp)? Extrude directly on a T/C to get the actual melt temp.

I’ve been told that cleaning the current nozzles is not easy. If the degradation cant be overcome, coating the nozzle with mold release may ease the process. Something like McLube 1700 (not a joke :slight_smile: ) or a Zyvax material.

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#4

I have a polyprinter at home that is over 2 years old (serial #8) and I have never once had to change the nozzle due to clogging. Mine doesn’t get near the level of use that the ones at the makerspace does but I make sure that I use quality filament. Crappy filament causes too many issues to make it worth saving a couple of bucks.

Also the polyprinter will not allow the filament to sit in the nozzle for long while hot at least while running a job. It is possible to override this with the manual controls and burn up the filament in the nozzle but I can’t see a point in doing that.

Alyssa

#5

I managed to clog one nozzle in my 3d printer (Reprap Wilson 2) by letting the hotend stay hot for too long with no extrusion. What I would do is preheat both the bed and hotend before printing, but the bed takes a good 20 minutes to get to temperature. The hotend on the other hand gets to temp in about a minute. So it would just sit there for another 19 minutes at 250C, basically just slowly burning the filament inside it.

Once it clogged, I figured out my mistake, and I now preheat the bed first, then the hotend, then immediately start the print.

I know it’s possible in octoprint to do something similar - preheat both at the same time, which will result in the hotend sitting at 250C for 10 minutes or so while the bed heats up. Perhaps it should be mentioned in the training class that this isn’t a good idea, and that the hotend shouldn’t be preheated unless the bed is already up to temp.

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#6

Once you press print, Octoprint itself will set the hot end to 180 until the bed gets up to temp. But users may be heating the hot end to 250 to load fillament, then waiting for the bed to heat before they press print.

I agree it would be good for the class to instruct people to set the hot end back to 180 while waiting, and for people to understand why octoprint backs off to 180 when they press print.

Actually, the drop down that has 250 abs next to set hot end temperature probably should have an option added for 180 standby.

#7

I’ve noticed this heating behavior and have tried to heat the bed first on my last couple prints as the hotend seems to heat to temp really fast. Almost to the point that the Hotend doesn’t need any pre-heat, just heat the bed and then click print as it comes up to temp in just a minute or so anyway.

#8

Thanks for all the input so far, y’all ~ it’s much appreciated! :slight_smile:

#9

Thanks Matt! We were discussing the space under the tables after the meeting the other day (and a bit since then, too…). I’ve been wanting to get the PLA tubs over closer to the PrintrBot, too… Others are offering to help with various things in the room as well… This coming weekend is going to be pretty busy for me; but, maybe the following we can all get together for some brainstorming? Are there days/times that work best for you?

Oh and speaking of needs for the room… Frank (@frank_lima) ~ what are the chances that we might be able to sweet-talk you into helping us design (and cut out using the CNC router) a “frank table style cart”? Lemme know when would be the best time to catch you at the 'Space if you might be willing… (We are wanting a sturdy cart that stands about the same height as the tables in there, that will fit one PolyPrinter on top and a shelf on the bottom to store a computer/laptop to be able to easily move the printer into another room during training… more details when you have a bit of time to chat about it ~ if you have time 'n all…)

Thanks again to Everyone who helps make 3D Fab so Awesome! :slight_smile: :slight_smile:

#10

This is an excellent idea, having storage under the printers would help isolate which filaments are available for each printer as well.

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#11

The hot end takes about 60 seconds to heat up to 250. The bed takes about 6-8 mins.

If it is hot when the print is started and the bed isn’t, it will drop the temp on the hot end to 180 - wait for the bed to get to 110 and then start.

Warming it to just 180 would make it hard to manually extrude plastic to color flush, 250 is fine as long as the head itsnt homed against the bed the entire time. This allows it to “drool” instead of letting the heat just build up.

@mike the reason black filament is being singled out is because we have noticed a significant increase in clogs being reported while using it, not the burnt color filament around the nozzle may have.

#12

This will not stop clogs. User error causes clogs, from what I’ve seen and heard. Disclaimer: I do not own a printer, I’m just a user.

I have run of the mill “CTC” brand black ABS which I’ve run in nearly all the printers we have. I minimize the time the head sits baking away the ABS by heating up the bed first, mounting my filament when that is happening, then heading up the extruder and extruding a bit to clear the old stuff out. I then immediately hit “print”. Never a clog.

We’ve got people running 6 hour jobs on these machines, and I’m betting they aren’t the ones who use committee-purchased filament. That locks me out of printing, basically.

I think this policy is a really bad idea.

Then again, I’m looking to build my own printer to eliminate having to wait on a free printer. This policy will just bump up the priority of that project.

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#13

If this doesn’t improve the rate of clogged nozzles we can reevaluate the policy.

If the byof printers are constantly in use, we could look into scheduling the prints. We just need to try something to stop the problem

#14

Every single roll of Inland brand black filament I’ve ever bought has clogged like mad. Their red is pretty awful too. I have two PolyPrinter 229 at work which are pretty heavily utilized. I suspect banning member supplied black filament will resolve most of the clogging issues.

#15

Quite the heavy-handed approach to the problem, assuming that is the cause in the first place.

#16

Cheap black filament is unambiguously the cause of most clogs which you can see first hand if you use 3D printers day in and day out for a year. I don’t know if it’s right for us to enact that policy but it would likely end most of the clogging problems.