Filament grinding

A forum dedicated to the stock LulzBot TAZ 3D Printer
JRAlvarez
Posts: 22
Joined: Fri Sep 08, 2017 8:14 pm

Re: Filament grinding

Post by JRAlvarez » Mon Aug 06, 2018 8:17 pm

Cleaned the hobbed bolt with a brush and then a dental pick (gently) to make sure there wasn't anything stuck in there.

I had the same thought about settings, So I reverted to default, had a worry that it wasn't properly resetting to default, then discovered that there was a newer version of LB cura available and have been using that.

Filiment oilers? Yeah I had read about those, I actually printed one but I don't have any mineral oil. Keep meaning to order/go buy some. But I think we've decided that isn't the issue.

kcchen_00
Posts: 1589
Joined: Thu Feb 19, 2015 12:42 am

Re: Filament grinding

Post by kcchen_00 » Mon Aug 06, 2018 11:24 pm

Canola oil seems to be popular also...

JoeBowler300
Posts: 40
Joined: Thu Apr 28, 2016 12:20 am

Re: Filament grinding

Post by JoeBowler300 » Fri Aug 10, 2018 12:17 am

Yeah I’m just saying that there’s been sooooo much discussion here on these forums about failed prints with PLA filament. Let’s understand that PLA has one of the lowest melting points of the most common filaments and is one of the cheapest filaments price wise. Unfortunately it’s melting point is just low enough for all the heat sources to cause it to fail. Ambient heat, heat rise from the print bed, extrusion speed, extraction and retraction moving the filament up and down as it softens, all contribute to the perfect storm.

I actually purchased a 11cfm fan to replace the stock fan but before I was able to swap it out I eased up the tension on my idler screw on the hob bolt and started making it through the prints. However most my prints were under 2 hours, And now my prints are fully printing. Back and forth between various print heads, height of summer now and again experiencing failed PLA prints,,, EXCEPT with the new aerostruder print head. So I theorize that the stock print head and the dual v3 printhead is just not designed well enough to prevent heat creep for PLA. There needs to be a better design to keep the PLA filament cool. The aerostruder print head may have been designed to cool the filament quicker to make longer and straighter bridges across gaps but the design also seems to not cause heat creep on PLA.

I’ve thought about running the PLA filament through some ice gel tunnel somewhere between the print head feeder and spool of filament. I suspect the room temperature still isn’t cool enough at 76 degrees.

JRAlvarez
Posts: 22
Joined: Fri Sep 08, 2017 8:14 pm

Re: Filament grinding

Post by JRAlvarez » Fri Aug 10, 2018 9:31 pm

JoeBowler300 wrote:
Fri Aug 10, 2018 12:17 am
Yeah I’m just saying that there’s been sooooo much discussion here on these forums about failed prints with PLA filament. Let’s understand that PLA has one of the lowest melting points of the most common filaments and is one of the cheapest filaments price wise. Unfortunately it’s melting point is just low enough for all the heat sources to cause it to fail. Ambient heat, heat rise from the print bed, extrusion speed, extraction and retraction moving the filament up and down as it softens, all contribute to the perfect storm.

I actually purchased a 11cfm fan to replace the stock fan but before I was able to swap it out I eased up the tension on my idler screw on the hob bolt and started making it through the prints. However most my prints were under 2 hours, And now my prints are fully printing. Back and forth between various print heads, height of summer now and again experiencing failed PLA prints,,, EXCEPT with the new aerostruder print head. So I theorize that the stock print head and the dual v3 printhead is just not designed well enough to prevent heat creep for PLA. There needs to be a better design to keep the PLA filament cool. The aerostruder print head may have been designed to cool the filament quicker to make longer and straighter bridges across gaps but the design also seems to not cause heat creep on PLA.

I’ve thought about running the PLA filament through some ice gel tunnel somewhere between the print head feeder and spool of filament. I suspect the room temperature still isn’t cool enough at 76 degrees.
Oh I see what you mean. That just might be it, but wouldn't I also have run into this problem last summer? I got my Taz 6 in May 2017, and printed like a fiend for the first few months without issue.

And remember when I said prints were succeeding with the fan pointed at the printer? I just tested that again, and had a failure at about an hour in. Same story, the filament gets ground...

I just had a thought. I have a box of PETG and T-glase. I know these both require signifigantly higher temperatures, wouldn't trying one of these be a good test of my issue(s)?

JoeBowler300
Posts: 40
Joined: Thu Apr 28, 2016 12:20 am

Re: Filament grinding

Post by JoeBowler300 » Sat Aug 11, 2018 12:53 am

Why don’t you just chalk it up as heat creep is a problem with PLA and move on? No sense on mentioning that you should print with PetG or T-glase and all your problems will be solved cause you know damn well your problem will be solved only not with one type of filament, PLA. Have you read the this thread on the subject? viewtopic.php?f=36&t=7649&p=42012#p41998. He did some thoroughough research and testing. Please compare notes and see what you’ve tried and what you’ve missed. Build up a database so we can all benefit from it. Get the temperature stats of the days it was printing correctly, including humidity and atmospheric pressure. Also, get the quality control reports from the manufacturers of the filaments, both successful prints and failed ones, I hope you have the batch lot numbers as that will greatly assist the manufacturer in getting this critical information you’ll need. Maybe you’ll uncover that they’re not mixing in enough hardner when they’re making a spool, a cutback that save the company thousands of dollars but unknowingly compromised the quality of the filament. Also, record the co-efficient of friction on all the moving parts of your printer, I can’t imagine a fan slowing down a bit from particles of dust landing on it over time. Let us know when you figured it out Sherlock cause many of have tried to help but we don’t have all the answers to cause and effect of things. Have you even tried changing out the print head cooling fan as many have mentioned? A desktop fan blowing in the direction doesn’t work. 3D printing utilizes very precise and efficient methods, the cooling fan can be one of them. We tried! Ask Alexa, Siri, Cortona or Google Assistant for the answer. Good Luck in this journey Pal!

kcchen_00
Posts: 1589
Joined: Thu Feb 19, 2015 12:42 am

Re: Filament grinding

Post by kcchen_00 » Sun Aug 12, 2018 1:18 pm

The difference between last summer and current, it could be material build-up inside the hotend. Filament moving through the hotend could leave remnants of PLA along the sidewalls. Jams or failed prints where the hotend is at temp for lengthy periods can carbonize the PLA and potentially reduce the travel path.

I've always thought that the heat creep is mostly from the heater block. The suspect component could be the thin walled heat break which insulates the cold side of the hotend. Reducing / minimizing retraction during prints will help keep the tube cool. Ideally retraction should create just enough of a vacuum to reduce filament ooze during travel. To pass possible constrictions, increasing pressure from the idler should help the hobbed bolt/gear grip and push filament through. Lubrication could also help.

Of course there is a point where too much pressure from the idler can impede the hobbed gear/bolt from functioning efficiently. LB has a picture somewhere of "optimal" teeth marks on the filament... but the teeth marks and printing is really the only way to tell if you've got good pressure on the idler.

iguanaman
Posts: 36
Joined: Tue Feb 20, 2018 6:09 pm

Re: Filament grinding

Post by iguanaman » Sun Aug 12, 2018 5:52 pm

I had the same issue very recently. I switched to PETG and the issue stopped completely. My room (very small garage) would routinely get to 90F and I didn't really notice the issue with PLA until it got that hot and started failing. I tested yesterday (three hour print) very early morning before the outside temps got above 80 and the PLA did fine. Might not be your issue but the heat certainly seemed to cause my issues.

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