Filament breaking in extruder if left overnight

For a long time I've had a problem that if I leave filament in the extruder overnight, when I try to print the next day the print fails, because the filament breaks in the extruder (or has already broken). My Mini Kossel does not suffer from this problem.

At first I thought that the filament was weakened by being pinched between the hobbed insert and the bearing for too long. I am using the modified extruders by masonstonehenge, so I thought that slackening the spring tension overnight would solve the problem. It didn't.

I'm now fairly sure that the problem is the tight radius that the filament is forced to go round to complete the 90 degree inlet turn. This would explain why the printer is able to extrude several cm of filament from the nozzle before the flow stops (because the break is several mm before the hobbed insert) and why it often breaks in several places over 1 or 2cm. The room that the printer is in gets quite cold overnight, and this may be making the filament more brittle.

There appears to me to be room to move the filament inlet to the extruder down by several mm, which would allow for a greater radius of turn and less stress on the filament. Perhaps this would solve the problem?

Another possibility might be to design the extruders to push filament horizontally in the +X direction, and make the Bowden tubes loop through 270 degree. Does anyone have any other ideas for avoiding the sharp turn?

Edited 3 time(s). Last edit at 02/27/2015 06:38PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

No ideas but I suffer the same issue, usually breaks just inside the entrance to the extruder block, sometimes in two or three places. It's never broken on the exit side to the Bowden though as I have always been able to wind it out, maybe it's being under slight tension that kills it - the Bowden side is generally und slight compression.

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Another RS Ormerod Mk1 meets the world

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CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

I have never had this happen to me, my ormerod is inside, at room temperature which doesn't usually drop below 18C and I pretty much always print with the cheapest Chinese filament I can get my hands on.

I have however noticed a big difference between opaque type and translucent type filaments, the success rate of jobs and quality is noticeable better with translucent filaments (of any color). Almost all opaque filaments I have tried seem more sensitive to temperature variances, don't seem to cool as quickly and give inferior quality results. One particular reel of pink opaque filament that to be fair was quite old and hadn't been kept sealed, was prone to breaking but this was not caused by the extruder body.

Did you have this problem with the original RRP extruder body aswell?

Matt

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I have the same issue as Dave (dc42) with exactly the same setup. Also my printer is in a pretty cold room (13-15C). Break happens not overnight, but after a couple of days of nonuse.
Haven't had time to modify the setup, but maybe one could drill a hole from below meeting the filament channel below the hobbed insert. Put a bowden in that hole and guard the filament with a slightly bigger bend radius, to at least get a idea what the minimum required is to have it not breaking. Later maybe the whole setup needs to be turned 45 degree so that part of the bend is before and after the insert...

Quote
iamburny
I have never had this happen to me, my ormerod is inside, at room temperature which doesn't usually drop below 18C....

Ditto never happened and at 15C, my filament feed is direct and from the bottom of the spool so it bend same way into the extruder as from the spool, I always leave the filament in the printer, sometimes for weeks and never had that problem

Erik

Quote
dc42
.. I am using the modified extruders by masonstonehenge..

The one with the PTFE insert? - might make a difference if not

Erik

Yes, the one with the PTFE insert.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I have G1 E-10.00000 in the ending g-code to snort the snot from nozzle and reverse any strain between extruder and spool

BTW, thank You much for your work with the firmware, the silly "pork chops" sound from the extruder is gone, everything runs very smooth and I can finish most prints without feeling hungry :-)

Erik

An idea for you with this problem . Set up several curves of filament with different radius (over night) to figure out at which radius it breaks. I would guess somewhere between extruder and spool radius.

I had this breaking issue as well - but only with a transparent PLA Filament. I figured out it is because of the bending angle. I did some tests with it on the table and figured out, that it happens because the bending angle of my feeding was too high for that filament. Never happend with others.

Quote
dc42
For a long time I've had a problem that if I leave filament in the extruder overnight, when I try to print the next day the print fails, because the filament breaks in the extruder (or has already broken). My Mini Kossel does not suffer from this problem.

At first I thought that the filament was weakened by being pinched between the hobbed insert and the bearing for too long. I am using the modified extruders by masonstonehenge, so I thought that slackening the spring tension overnight would solve the problem. It didn't.

I'm now fairly sure that the problem is the tight radius that the filament is forced to go round to complete the 90 degree inlet turn. This would explain why the printer is able to extrude several cm of filament from the nozzle before the flow stops (because the break is several mm before the hobbed insert) and why it often breaks in several places over 1 or 2cm. The room that the printer is in gets quite cold overnight, and this may be making the filament more brittle.

There appears to me to be room to move the filament inlet to the extruder down by several mm, which would allow for a greater radius of turn and less stress on the filament. Perhaps this would solve the problem?

Another possibility might be to design the extruders to push filament horizontally in the +X direction, and make the Bowden tubes loop through 270 degree. Does anyone have any other ideas for avoiding the sharp turn?

Hey dc42 - give this a bash - let's see if it's the radius..
[forums.reprap.org]

Hi Guys

Used to have a similar issue on my side.. Had the filament spool setup behind the printer, feeding from the bottom over the X-axis motor then down into the extruder..

Silly thing, on one of my refills, I changed it to feed from the top of the spool, over the X-axis motor down into the extruder. But havent had any issues after this thou.

Must say in the original setup, the filament had a mind of its own, unspoolling when ever I looked away... This also seems to have gone.

Might be the different directions the filament is being bend in, causing stresses in the material...

Maybe...

Madmob

My Printer gets allot of vibration when I'm as work and it's sat on the cabin desk onboard ship, but I think I only ever had the filament break once (where ever the printers been used), and that was at the entrance of the PTFE flexi tube (before the feeder). I think it got knocked to be honest, so can't really count it.

Sometimes the filament is left in the machine for a week or more without being used, and it's still ok.

I used to reverse the filament out sometimes when re-locating the printer (it travels around the country with me), but now I don't even do that.
I deliberately break the filament leaving about 2" before the feeder. When Printing the first print afterwards, I just manually feed the filament in untill it's reached the hobbed
nut and the prints never fail. In fact since upgrading the firmware a few months ago, the printer has been remarkably reliable, with only the occasional loose screw or a blocked
nozzle to mar a 100% success rate.

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I have had this but the printer is in our office and it only occurs when we don't leave the room heater on low over night. I have come to the decision that PLA doesn't like how cold our office can get.

Edited 1 time(s). Last edit at 03/04/2015 04:02AM by jy_oc_hx.

Interestingly enough I have just started using another filament, made by a manufacturer in UK (Bought from RS). This filament breaks if left unattended overnight, but breaks in all sorts of different places - when straight, inside the outside feed tube, at the reel itself.
The filament itself is great and the prints wonderful, but the breakage is very annoying! I'm not convinced that the larger radius on the extruder will solve that problem.
Funny that the cheap knock-off chinese filament just keeps working!

My 2 cents... air conditioners dry out the air. If you use cable ties you will find that they break easily in winter when air is dryer ptfe or nylon types.... so I would say the breaking is as a result of dry air.
ABS specifically says on the pack, use between certain temperatures and after opening shelf life is 30 days... so you can always use a temp/humidity logger to check conditions and verify the above for pla. Also check the uv if your printer is close to a window and the sun shines in on it when you are not there and out of office..

tx Ben

Edited 1 time(s). Last edit at 03/16/2015 03:53PM by BenBB.

Interesting but the PLA comes shipped with a bag of silica gel in the wrapper - surely that would make it worse??

I've got stuff from three suppliers and they all do it

---

Another RS Ormerod Mk1 meets the world

Retired now but I used to make....
CNC Machined Mk1 aluminium bed support plates for the Ormerod
CNC machined X-plates and ribs for Mk1 & Mk2 Ormerods
CNC machined bed support arms for the Mk2 Ormerod.
Dual Hot-End heatsink blocks.

with the white filament that came with the printer i didnt have any problem at all, bought a 1kg black Verbatim PLA and it could brake in five places over the night. Now i have a white 1kg spool from a Swedish web-store www.kjell.com and i havent had any problem at all.

Do the color pigment have any role in this?

About wet / dry filament, stumbled over this on youtube All shouts about silica and sealed bags and then this dude throws a spool in hot water
[www.youtube.com]

Quote
Davek0974
Interesting but the PLA comes shipped with a bag of silica gel in the wrapper - surely that would make it worse??

I've got stuff from three suppliers and they all do it

If moisture gets absorbed by the filament it'll vaporize in the extruder, which will totally muck up the print (this is a big issue with nylon, I've read about people having to dry nylon in an oven before extrusion to get good performance). I'm not sure if moisture will make it more brittle or not. But you should always try to keep filament dry, I personally keep open rolls in Ziploc bags with the silica gel it came with.

Quote
RoSt
with the white filament that came with the printer i didnt have any problem at all, bought a 1kg black Verbatim PLA and it could brake in five places over the night. Now i have a white 1kg spool from a Swedish web-store www.kjell.com and i havent had any problem at all.

Do the color pigment have any role in this?

I would think the pigments are to blame for the variance. In reality pigments are basically contaminants we have added to the polymer because we think it looks pretty. They can actually interfere with the polymers properties.

I also think the differences in dye are why some people have clogged nozzles after 'cooking' filament and others don't.

Is there a non-pigment PLA and what is its natural colour?

Also what is the effect of the pigment on the final printed product, is anyone seeing adverse affects?

Edited 1 time(s). Last edit at 03/19/2015 09:39AM by Treth.

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Ormerod #007 (shaken but not stirred!)

Quote
Treth
Is there a non-pigment PLA and what is its natural colour?

Also what is the effect of the pigment on the final printed product, is anyone seeing adverse affects?

I believe that natural PLA is transparent (which is available as a filament). I've not so far noticed any differences in the physical properties of different colours of finished parts, but I suspect it would take formal strength & bending tests etc. to find any such differences, and then you could never be sure whether it is a direct difference due to the pigment in the final product or a difference caused indirectly by the pigment affecting the optimum print parameters needed. Obviously dark coloured parts will absorb & radiate heat more than light colours, and I should think some colours will fade over time more than other colours.

I did find that conductive ABS filament produces parts that are more brittle and the layer bonding is weaker than other ABS filaments I have used, and I would expect other fillers that are designed to be more than mere colourants would similarly have a more pronounced effect on the physical properties of the finished part (indeed in many cases they are used for the very purpose of affecting the physical properties).

Dave

Today I unloaded filament that I had left in the extruder for several days. There was either a break in the extruder inlet already, or one occurred as I unloaded the filament. But the filament also broke at or above the hobbed bolt, because some filament was left in the Bowden tube.

I examined the broken pieces of filament, and I found them unusually brittle. Taking a piece of filament fresh from the spool (which sits on the floor), if I try to break it then it just bends. But the pieces of filament that have been sitting in the machine or leading up to the extruder inlet snap instead.

So I think that something is making the filament brittle, and this in combination with the small radius of the extruder inlet causes it to break. I have finally got round to printing VortZA's modified feeder part with the larger radius today, so I am hopeful that this will solve the problem. As for what is making the filament brittle, I guess it could be UV light, because the room the printer is in has a south-facing window.

Edited 1 time(s). Last edit at 03/19/2015 02:27PM by dc42.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
dc42
Today I unloaded filament that I had left in the extruder for several days. There was either a break in the extruder inlet already, or one occurred as I unloaded the filament. But the filament also broke at or above the hobbed bolt, because some filament was left in the Bowden tube.

I examined the broken pieces of filament, and I found them unusually brittle. Taking a piece of filament fresh from the spool (which sits on the floor), if I try to break it then it just bends. But the pieces of filament that have been sitting in the machine or leading up to the extruder inlet snap instead.

So I think that something is making the filament brittle, and this in combination with the small radius of the extruder inlet causes it to break. I have finally got round to printing VortZA's modified feeder part with the larger radius today, so I am hopeful that this will solve the problem. As for what is making the filament brittle, I guess it could be UV light, because the room the printer is in has a south-facing window.

That filament from FilamentPrint that I had breakage on has done it to me a few times now - always after a long 'rest' - like over a weekend.
I find it has broken sometimes several places at once, but normally wherever the filament is under strain, so too tight a corner or too straight or when it has a rotational twist to the bend. In the extruder there is a gentle bend followed by a straight section (past the hobbed insert) and then an angle change or twist going into the Bowden tube.
So to me the most obvious place for it to break would be at the hobbed insert itself because it's both being straightened against it's natural curve from the reel, AND being twisted into a different angled curve. Another place would be at the entrance to the extruder because most people still have the filament being fed from around the back of the printer, so there's another angle change.

Not sure what the final solution would be apart from different filament or unloading at night. Fortunately zombiepantslol's web interface has that lovely unload feature which makes it very easy to do!

Quote
VortyZA
Not sure what the final solution would be apart from different filament or unloading at night. Fortunately zombiepantslol's web interface has that lovely unload feature which makes it very easy to do!

IMO it is good practice to unload the filament and store in a sealed bag out of sunlight whenever you are not printing for reasons apart from breakage - (1) it protects against moisture absorption (2) it protects against UV effects (3) it stops the reel gathering dust which could block the nozzle.

My method for unloading is to turn off the motors and gently try turning the extruder gear by hand to remove the filament as I switch on the hotend heater. As soon as the filament starts to melt the gear will turn, pulling the filament out of the nozzle while it is not yet too molten and so does not "string". I then switch off the heater and remove the filament completely by turning the gear by hand, which I find is faster than using the motor to do so. I also feed in filament by hand, which is not only faster but also allows you to feel if the filament catches on something or is otherwise not feeding smoothly.

Dave

Quote
dc42
So I think that something is making the filament brittle, and this in combination with the small radius of the extruder inlet causes it to break. I have finally got round to printing VortZA's modified feeder part with the larger radius today, so I am hopeful that this will solve the problem. As for what is making the filament brittle, I guess it could be UV light, because the room the printer is in has a south-facing window.

I doubt that it is UV because IME the breakage most commonly occurs inside the extruder where it has been shielded from light. Perhaps it is moisture absorption? I should think the filament on the outside of an open reel and the unwound filament would absorb more moisture from atmospheric humidity than filament in the inside layers of the reel.

I have also noticed that a freshly printed part (ABS) is less brittle than a similar part that was printed some time ago. It seems, for example, that it is easier to snap off extensive support material from parts that have been left a few days than to remove it immediately after printing, though I have not done any proper study to confirm and it may just be my imagination, coincidence or due to a different factor. I've just completed printing a chess set which have all the pieces completely surrounded by a scaffold of support. The (quite large) pieces were printed over a period of a couple of weeks, and I would sometimes do the finishing work almost immediately after printing, and sometimes would leave the finishing operations (including support removal) for a few days, which is how I formed that impression.

Dave

I've not had this issue at all with ABS or PLA
And I leave my filament in for days sometimes.
My extruder is a PLA type and one I printed months ago. So probably quite slack.
Maybe it's to do with the filament contracting. i.e tightly held in the extruder as the hot end cools?
Just a guess.

Quote
Jon Steward
Maybe it's to do with the filament contracting. i.e tightly held in the extruder as the hot end cools?

That's something I hadn't thought of. I retract the filament by 5mm at the end of a print, so the filament will be under tension in the Bowden tube. However, the filament generally breaks in the extruder drive inlet, and only occasionally in the tube.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Quote
Jon Steward
..Maybe it's to do with the filament contracting. i.e tightly held in the extruder as the hot end cools?
Just a guess.

Yes it shrinks back to the nozzle, the warm side of the hotend, I usually find that I can pull out the filament without any resistance and that the end of the filament is pointed, so obviously the filament is broken while contracting from liquid to solid, sometime a small force is needed to pull back the filament but not much and always very thin at the point of the breakage, so the point just above the nozzle is the weakest link and I doubt it has the strength to stress the filament to the breaking point at the extruder end

Erik

Yesterday I fitted VortZA's modified extruder with the larger radius. After doing a test print I left the filament in overnight... and it didn't break! Since it usually does break, I am hopeful that this is at least a partial solution to the problem.

The pneumatic connector is also working well. It does allow a slight movement of the Bowden tube, which is evident during retraction/un-retraction cycles, so I may add another 0.5mm or 1mm or retraction in my slic3r config to allow for that.

VortyZA, thanks very much for doing those modifications to your design! I have printed out a second one, and I am just waiting for more pneumatic connectors to arrive in order to use it.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I've now left a filament in the new extruder for 3 nights, and it hasn't broken. But it's a new roll of filament, so I've changed back to a roll that I know has caused problems in the past.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].