filament stops feeding partway through the print (bondtech dual)

Topics around mechanical design, controller and electronics. Mods & hacks welcome.
Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Tue Feb 13, 2018 2:13 pm

So, I was having this problem before I upgraded to the bondtech extruder, but I was really hoping that the upgrade would fix the issue. I am printing Hydrofill support material in the left extruder at 230 degrees with a 90 degree bed, as you can see in the following picture,
it starts printing just fine but then at some arbitrary point in the print it suddenly stops extruding properly,
the material isn't burning, and I don't think it is clogging
IMG_20180213_155951111.jpg

this occurs every single print. additionally, and this is a new development since I started using the bondtech extruder, after these events there is a sort of corkscrew pattern near the end of the filament, as can be seen in the following picture
IMG_20180213_160102583_DEPTH.jpg

I think I might try swapping the filaments in the left and right nozzles to see if anything changes, but I don't think it will.

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 3:20 pm

#1 Which exact model of Bondtech extruder are you using? There are a few options and there are different details and instructions specific to each one.
#2 Validate the motor temp at the time of failure. Since you are printing high temp material likely lid left on you may be experiencing an issue where the motor is rising in temp and that in turn conducts and softens the filament in the feed path. Here is a combination of properly adjusting the stepper driver current and also controlling rising temp with the Raise3D lid.
#3 Ensure you Bondtech drive gear and it's setscrew are using threadlocker and is tight on the shaft. This does not just apply to the BMG but is an example video https://www.youtube.com/watch?v=CDC8qogG0QY
#4 ensure that your gear on the shaft and it's "groove" is perfectly aligned to the feedpath. This is related to the above where you either installed the gear on the motor shaft or it was loose and could have moved back and forth on the shaft. I do this by inserting filament in the feed path while tightening the gear to the shaft.

What we know form your first post:
I was having this problem before I upgraded to the bondtech extruder

This indicates that for some reason, this filament likely is hard to extrude and for some reason may be jamming in the hotend. Yes, the stock extrude feeder can be improved upon, but the feeder is only 1 part of the extruder.
I was really hoping that the upgrade would fix the issue

Agreed, but again, just as said, the feeder is but one part of the extruder, you still have the feed path through the central crossing block and ultimately into the hotends. There are diameter restrictions here and oversized filament can and will jam. This problem exists in poorly produced filament with diameter bulges along the length from errors during the filament manufacturing process. In addition, water absorbing filaments (ABS, Nylon, HIPS, definiteley PVA based, and anything water soluble. Even PLA in extreme cases can swell from moisture.

So in no certain order specific to this filament:
#1 Does your current setup work well with other filaments and this is the exception?
#2 measure and inspect filament diameter in the jammed section when you remove it and also measure multiple times down the spool of filament the diameter. In my experience, much over about 1.85mm gets to be the limit and may be less depending on some details of your hotend and path from the extruder feeder to it.
#3 have you dried this water soluble filament before usage?
#4 Again, have you checked stepper motor temps, chamber temp if you have the lid closed? These temps would indicate closed chamber printing for ABS and other high temp materials "extruder at 230 degrees with a 90 degree bed".

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Tue Feb 13, 2018 3:29 pm

I haven't tried printing other materials on the left extruder, but I have prited ABS on the right extruder successfully, the filament is actually under diameter by a bit (last time i measured it it came in at about 1.68). The filament was sitting in a container full of silica gel before trying to print it. I haven't checked the temperature of the motor itself since there is no probe on it, but it is warm to the touch (but not uncomfortably so immediately after the failure)

I swapped the filaments (so the support is on the right and the ABS is on the left) and it has gotten much further, so I am unsure what the issue is, I will update when the print finishes or fails again.

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 3:39 pm

As to a filament diameter issue. I too have run into this frustrating issue. I too have bondtech extruders now installed on every printer and have seen a bondtech wedge a bulged filament into the feedpath so tight I had to take apart the hotend, take the heatsink off, heat the entire throat tube top normally cold section to melt this filament and remove it. This happened to be MakerGeek's Raptor PLA and was a confirmed defect in the spool.

There are some details about the Raise 3D V2 hotend that could be slightly improved in light of more long term experience using them.
#1 the cone shaped entrance where the PTFE guide going through the central cross mates leaves room for flexible filament and even in extreme cases, normal more rigid filament to either wedge or buckle. I know why the cone entrance is there- to make minor alignment between the 2 parts compatible, but at the same time, this compromise does affect the ability of the feeder up top to push on filament into the hotend. Seen in this topic here viewtopic.php?f=4&t=2276&p=16789&hilit=cone+shaped#p16789
#2 The throat tube is a nice tight tolerance compared to typical Raise 3D supplied filament right at 1.75mm diameter. As such, oversized filament by even a little bit, that other extruder hotend systems handles fine, may jam in the Raise3D V2. This is just some of the dynamics of this hotend.

So in saying all that, we recently DO have an alternative.
Thanks to this adapter viewtopic.php?f=4&t=4841&hilit=e3d, you can now use E3D V 6 style components to include the V6 style thermal barrier (AKA throat tube), the smaller heater block and matching silicone sock, E3D K style thermocouple and heater cartridge.
In fact, E3D even has a titanium thermal barrier tube for less conduction of heat up the tube to the heatsink. https://www.filastruder.com/collections ... ccessories
They also have an all copper heater block as a premium option https://www.filastruder.com/collections ... r-block-v6

I cannot lie to you, this is yet another upgrade and it's not cheap as a total system. Yes, the stock V2 is $80, so buying the custom parts, you can build a "standard" E3D V6 for about the same money (normal stainless thermal barrier, aluminum heater block, silicone sock). The copper block is $25 and the titanium thermal barrier is $45, the required heatsink adapter (either buy direct back in that thread or also i saw them on Amazon https://www.amazon.com/Raise3D-E3D-v6-H ... B077RXJNPR)

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Tue Feb 13, 2018 3:51 pm

ok, it failed again, but it got much further this time, and it failed in a different way on the left extruder than the right one (it shredded more at the gear point but didn't form the spiral at the end of the filament) As I said before, the filament is actually undersized (1.68 mm average) so it isn't an issue with it being too large. The motor was actually pretty warm. I was hoping that the motors on the bondtech extruder would run cooler. I doubt I will be able to talk my adviser into purchasing any more upgrades for this printer, I am using it for my research and it has already been way more expensive than expected. I do have video with the sound that it was making at failure but it is still rendering, and I will post it when it completes.
Attachments
IMG_20180213_174714889.jpg

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 4:06 pm

Jab136 wrote: As I said before, the filament is actually undersized (1.68 mm average) so it isn't an issue with it being too large. The motor was actually pretty warm. I was hoping that the motors on the bondtech extruder would run cooler.


Undersized is bad too! Too small and even the Bondtech has a minimum distance the 2 gears can pinch minus the hobbed groove, same with the stock feeder, undersized filament requires an adjustment to the motor and thus gear position VS the v-groove idler and the V groove idler forms the minimum filament diameter limit on that extruder too.

Stepper driver current adjustment and ambient air temp controls the temp rise of the motor. Again, I'm pointing you at no more than a fine tuning adjustment from the recommended starting point from the Bondtech install directions. http://shop.bondtech.se/shop/ws71/47371 ... t.docx.pdf
Lower Vref is lower motor current, less heat, but also less force before skipping a step. You have to strike a balance between motor heat and force to not skip steps, but not heat up the motor.
Attempt lowering from the suggested 0.50V to first 0.48 and then even further to 0.45V.
Peform a force test by using the load filament after adjusting and attempt to stop the filament going into the top of the extruder while it's trying to extrude. Get it to the point the motor stops and skips steps. As you lower the current, that point becomes weaker pull before skipping steps.
Last edited by Jetguy on Tue Feb 13, 2018 4:13 pm, edited 1 time in total.

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 4:08 pm

Again, if 1.68mm is the average on that spool of filament, how bad is worst case thin spot?
You should be complaining to the filament manufacturer and getting resolution there for poorly sized filament.

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Tue Feb 13, 2018 5:17 pm

the variance is actually pretty non-existent, it is .68 for the entire length, I cannot upload the video since even zipped it is too large, but basically there is just a rapid clicking after it stopped feeding. Additionally, when I tried to unload it, the gears no longer had enough of a grip and I had to pull on the filament as well to get it to start unloading. I will see what I can do about varying the other parameters tomorrow.

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 5:53 pm

Also understand how filament diameter VS fixed bore diameter works inside the hotend. The idea is that as you push solid cold filament into the extruder it slides down in and at the hotend and "melt zone" where the very walls are melting temp, it begins to form liquid. As you push more filament there is a gap of bore size VS actual hard filament diameter being pushed in. This liquid wants to push back up between the filament and side wall. That said, it's also viscous and then remember there is a defined melt zone of which above that is cooler internal walls in the heatsink area of the hotend. This molten plastic is creating friction or shearing. The idea is the fresh incoming filament tries to push this back down and depending on nozzle backpressure and actual filament diameter determines where this liquid filament gets to height wise.
This is again, why different diameter not only affects the feeder, but changes the entire dynamic of pressure and flow inside the hotend.

When you get to a retract segment where the cold filament and some of this hot molten filament is pulled up into the cold section of the extruder during a not extruding travel move, if you have small diameter filament and 230C extrusion temp, you definitely pull up more melted filament with the retract into the non-heated part of the hotend. That in turn solidifies and can jam or stick to the walls. Then you cannot feed and since it's in a non melting zone, your extruder appears clogged and is, but it's NOT a nozzle clog.

Just trying to get you to think about the system and how one variable (filament diameter) affects many aspects of the entire operation of extrusion.

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 6:14 pm

To give you some suggestions:
#1 I'd be contacting the filament manufacturer for undersized filament and replacement
#2 Printing with this filament is obviously difficult and may be causing jams. As pointed out, that can be from retraction. I would ensure I was using no more than 1 to maybe 2mm retraction for all move including often overlooked toolchange retraction. Again, the idea being that if retraction can pull up melted filament and cause a jam, then reducing the distance of retraction, we reduce the risk of a jam.
#3 Knowing this is a water soluble filament I would go to extremes and ensure I dried the filament before any print job.
https://www.matterhackers.com/news/filament-and-water
Even Airwolf 3D is eluding to this in the filament details:
Storage Instructions

Keep filament sealed in protective wrap until ready to use.
Once HydroFill has been opened, keep the spool in a closed bag to protect against exposure to moisture.
Remove HydroFill from the printer when not in use.
Store HydroFill at 45°F-86°F and in low humidity for optimal shelf life.


Even though this is not PVA, it's still water soluble filament. Ignore the temps in this article which are different for PVA, but I imagine much of the general rules and printing are not that far off https://www.matterhackers.com/news/how- ... t-material

Retraction distance is in multiple places in the profile.
general retraction length.jpg

Toolhead retraction length.jpg

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Tue Feb 13, 2018 6:24 pm

the problem is that this filament is also extremely prone to oozing, and also, I am using s3d for slicing not ideamaker, but again, I will look into all of this tomorrow. thanks for the suggestions.

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 6:49 pm

This could further explain because of a 12.0mm default retract on toolchange and dual extrusion support material would definitely invoke that distance.
Toolhead retraction lengthS3D.jpg

general retraction lengthS3D.jpg

Jetguy
Posts: 2346
Joined: Tue Mar 22, 2016 1:40 am
Location: In a van, down by the river

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jetguy » Tue Feb 13, 2018 6:51 pm

I would lower toolchange retract distance to half or quarter of what it is now minimum. So 6mm, then 3mm, then 1.5mm as tests to prevent jamming.

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Tue Feb 13, 2018 6:57 pm

there is no toolchange during the period that it has been failing on, I have been trying to print the raft in the support material and then switch to ABS, but it isn't getting through the raft.

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Wed Feb 14, 2018 12:31 pm

ok, so I checked and there were several retractions (but they were nowhere near 12 mm) so I just removed retractions on that filament and instead put in a coast and wipe in S3D.

Jab136
Posts: 152
Joined: Sun Jul 16, 2017 12:00 pm

Re: filament stops feeding partway through the print (bondtech dual)

Postby Jab136 » Wed Feb 14, 2018 2:11 pm

the tool change retraction still caused a jam, and this time it was a true jam, I had to remove the extruder from the print head to clear it... I think this material is un-printable on the N2 plus no matter the extruder


Return to “Hardware”

Who is online

Users browsing this forum: No registered users and 4 guests