New Mini Not Extruding

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bnazario
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New Mini Not Extruding

Post by bnazario » Wed Dec 07, 2016 3:09 pm

Hi,

Our school recently bought a Lulzbot Mini for use in our classroom. The students are excited to begin 3d printing. The machine has the most current Cura software installed, which I assume comes with the most current profiles. We are using eSun black filament purchased off the Lulzbot site along with the printer.

We printed the initial rocktopus with the HIPS filament, and it worked great. I unloaded the remaining HIPS, loaded the eSun PLA and made the appropriate software changes for the new filament.

I printed out another test rocktopus with the eSun filament. It came out like spiderwebs, but successfully stuck to the bed and completed the print. It looked like this (low quality print selected):Image

When we moved onto student printing, every successive print failed. The filament would come out but then bunch up under the extruder. I only let each print go a few seconds before realizing it wasn't adhering and seemed too far off the bed.

Thinking maybe the z-offset was the problem, I attempted to find ways to minimize that. However, before I could change z-axis settings, the printer simply stopped extruding filament.

The head heats up appropriately, is connected and goes through the motions of printing, but nothing is coming out. I unloaded the filament many times, and I saw a perfect mold of the inside of the head, as asked in the documentation on fixing a clogged head. When I release the head clamps and push the filament through, it comes out beautifully. However, when it is clamped up and I click "extrude" in Cura, I hear a purring sound of a gear and nothing comes out. Successive clicks also yield nothing.

If you could point us in the direction of some documentation with images of things that might need adjusting, I would be very grateful. I have 20+ children breathing down my neck to start printing stuff they've made off TinkerCAD and I am VERY new to this.

I have a video of it "printing", but you can pretty much just visualize it going through the motions and nothing coming out. I emailed support and they emailed me back to check the print temperature, which is 205C according to the eSun documentation and profile.

​Thank you very much

ttabbal
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Re: New Mini Not Extruding

Post by ttabbal » Wed Dec 07, 2016 4:55 pm

When you changed filament, did you purge the old HIPS out? Try heating the extruder to HIPS temps, 250C should be plenty. Then pull the PLA and cut the end off to make sure it's not stripped. If you push the PLA in by hand, you should be able to push out a string of plastic easily. Now push the idler lever over and push the clip the holds it in place over it. Make sure you have about 5mm of space between the 2 washers on the screws. Adjust as needed. Now tell the printer to extrude 10mm of filament. You should get a little string of plastic again. Wait about 10 seconds and do it again, 4-5 times should do it. Now drop the temperature to normal PLA temps, about 210C, and let it stabilize there. Try the extruding 10mm again. If that works, retract about 2mm, wipe the nozzle with a scotchbrite if you have one, turn off the extruder heater.

Load the PLA profile in Cura and try the rocktopus again. Watch the beginning to make sure it cleans the nozzle on the pad in the back, and that the auto-level touches all 4 corner washers without pushing the bed down.

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DougZ
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Re: New Mini Not Extruding

Post by DougZ » Thu Dec 08, 2016 6:11 am

When I release the head clamps and push the filament through, it comes out beautifully. However, when it is clamped up and I click "extrude" in Cura, I hear a purring sound of a gear and nothing comes out. Successive clicks also yield nothing.
So when you push it through manually the filament comes out like soft serve ice cream? That's good. But then when you reattach the idler and latch it then request an extrude through the software nothing happens? That's bad.

A couple of things...You may have a cracked idler. No big deal unless you don't have another one on hand already, or the ability to print a new one. There's a thread in this forum on what wear parts a new Mini owner should print a copy of "Just in case" and since yours will be used in a school environment it isn't a bad idea to print some spares. The idler latch tension screws have a particular setting and if someone doesn't know that and screws them in too tight, well, it is like over torquing a bolt. Lulzbot has a service bulletin on a cracked idler (not related to the tension screws) and they'll even send you a new one if that is your only option. Take a close look at the idler to make sure there isn't a crack in it causing it to not apply pressure to the filament against the hobbed bolt.

Speaking of, is the hobbed bolt spinning? You mention hearing a motor but no movement. When you attemp the extrude, do so without filament, idler latch open and look straight down into the filament path into the extrude. You will see the small hobbed bolt with the notches on it that are meant to grab the filament and push it down into the extruder. Make sure it spins when the extrude is called for and also make sure the small groves aren't caked with filament from when it may have been grinding. Lulzbot supplied a few tools to easily clean the grooves (turn the printer off then move the big green gear as you clean the grooves in the hobbed bolt).

Since you state the manually extruded filament comes out nicely I don't think there's anything in the nozzle area. Old, burnt filament remnants would be indicated by the new filament coming out like a pig tail and almost immediately twirling around in a circle.

You should consider getting some of the eSUN cleaning filament that Lulzbot sells to run through the extruder every now and then. Especially with so many kids who will be printing with many different colors/materials,etc

Regarding the Rocktopus, do as @ttabbal suggests and always switch back to Quickprint to load the appropriate 'built-in' filament profile first, then switch over to expert settings if you want to tweak from there.

Anyway, let me know if this helped at all...
Last edited by DougZ on Thu Dec 08, 2016 1:06 pm, edited 4 times in total.
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bnazario
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Re: New Mini Not Extruding

Post by bnazario » Thu Dec 08, 2016 12:14 pm

Thank you for the helpful suggestions.

I looked at the idler and found that it is in two pieces. This is not correct? Here is where the crack is:

Image

Perhaps this is my issue. If I ask for another one I assume there are instructions online on how to take apart the printer and put the new idler on? Again, we are very new to this.

Thanks again.

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DougZ
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Re: New Mini Not Extruding

Post by DougZ » Thu Dec 08, 2016 12:31 pm

Nope, the idler should be one piece. No worries though, it is a very easy process to swap it out and does not require dismantling the printer. As I recall it is just the one small bolt right in the front at the idler hinge area. All you need is an allen key to fit.

Below is the Service Bulletin from Lulzbot about it. The crack in yours may or may not have been directly related to this particular issue but it is a simple fix. There is a new "beefy" idler and latch upgrade by Lulzbot that I have printed for mine and have been using for quite some time. It will be shipped on the next generation of Minis as I understand. It is a direct replacement for the one you have and will work like a charm.

If you have access to another printer you can print the one in the Service Bulletin, or the newer beefy idler and accompanying latch that I have attached. Either one you choose use ABS @ 70% ~ 80% infill. If you don't then the service bulleting contains the info necessary to contact Lulzbot Support for a replacement. Their support is top notch.

https://www.lulzbot.com/sites/default/f ... etin_0.pdf

BTW, if you're anywhere near Southeast Florida I can get you a new one very quickly... ;)
Attachments
beefy_idler_latch_v2.2.stl
(148.52 KiB) Downloaded 130 times
beefy_extruder_idler_v0.4.stl
(222.15 KiB) Downloaded 114 times
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bnazario
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Re: New Mini Not Extruding

Post by bnazario » Thu Dec 08, 2016 3:23 pm

Thank you so much. I am in Michigan:). However, I contacted support and they shipped out a new one (not sure if beefy or not). I was a bit worried because they asked for a receipt and I bought it from MakerShed during a huge sale, but they honored that and I should have a new idler fairly soon. Hopefully we can be printing for the class after winter break.

I received a grant for 1000 for another 3d printer because of the sheer number of kids wanting to take the class. I admit my first Lulzbot experience isn't all that great, but the forum and service support has been top notch. So maybe I will buy another mini. The sub-1000 printers seem kind of shady. We have an XYZ printer that I got on Black Friday that I'd like to take out back and beat Office Space style. The other schools in the area have Afinitys.

Thanks for all your help! I'm sure once I put the parts on, I'll still have issues with the z-axis:).

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DougZ
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Re: New Mini Not Extruding

Post by DougZ » Thu Dec 08, 2016 4:23 pm

The Mini was my first printer and I haven't looked back. Glad to have helped with this issue. Went through it myself and recognized the symptoms.

I'll be more than happy to help you out with whatever z-axis issue you're having, don't get discouraged. You will constantly see the Mini and the big brother the TAZ 6 (or the TAZ 5 depending on the review date) in almost every "Top X Printers" review - and for good reason. I have both the Mini and the 6 and use each one daily (they're both printing as I type this). Sometimes they take a bit of dialing in but once they're there...they're workhorses.

Again, don't hesitate to reach out.
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Biolumo
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Re: New Mini Not Extruding

Post by Biolumo » Fri Dec 09, 2016 2:41 pm

Sounds like hopefully you've already found the problem and hopefully will be back up and printing soon. I'm still new to 3d printing myself, but i will offer a few tips and/or things to check just in case that i've learned from my mini.

1.I haven't always had the best luck going back and forth between HIPS/ABS and PLA since they both run at vastly different temps its easy to get one or the other clogged in the nozzle and it's a pain to clean out. My advice is to have dedicated Print heads that are for each type of filament that you can switch out and/or have each printer dedicated for a specific filament. Just my experience, maybe others have had better luck.

2.Check that the hobbed bolt grooves didn't get clogged when your printer wasn't extruding well. Sometimes when a issue comes up these grooves spin around and just grind off plastic and fill up. I like to use one of those "ACID BRUSHES" clipped short to clean mine. You can get them at your local hardware store or online at sciplus.com.

3. double check the screw on your small herringbone gear. Sometimes they come loose.

ttabbal
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Re: New Mini Not Extruding

Post by ttabbal » Fri Dec 09, 2016 5:10 pm

When switching from a higher melt plastic to a lower one, do a cold pull on the old plastic, then use the higher temp to extrude 50mm or so of the lower temp plastic before dropping the temp. That works pretty well for me, and is a lot cheaper than a second print head, faster to do than swapping them as well. :D

bnazario
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Re: New Mini Not Extruding

Post by bnazario » Tue Dec 20, 2016 1:43 pm

I wish I had a better update!

So the beefy idler came today and I installed it. I actually pushed through about 50mm of the cleaning filament, and then loaded a brand new filament (3mm Verbatim). I locked up the idler with the retainer.

Nothing upon a test print. When I hit 10mm extrude on Cura a tiny bead came out. I took some pictures.

I don't see the silver notched gear trying to take the filament down into the extruder.
Image

But when I push the filament down, it comes out nicely
Image

When I turn the Mini around and press extrude 10, the small gear, which I assume is the gear that is supposed to push the filament down into the idler, doesn't spin, but it vibrates a touch.
Image

Help! The students are getting super anxious and I'm losing their interest! I'm also freaking out because we spent good money on this and I can't get it to work except the ONE time I used the HIPS that it came with.

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