Under extrusion after upgrade to bowden extruder

Hello All,

And many thanks in advance for any help you can provide on this topic as I'm fairly new at 3d printing.

So let me give you some details about the configuration of the printer I've assembled:

-Electronics: Ramps 1.4 + Arduino Mega 2560 running Marlin 1.0.2
-Motors: 5x 17HS840 stepper motors (they hold a max operating current of 1.8A)
-Motor drivers: DRV8825 configured at 1/32 micro stepping.
-Hotend: Single, E3D v6 1.75 mm (initially on direct extrusion and now bowden mount (yes there's the issue)
-Nozzle 0.4mm / for 1.75mm filament
-Not sure what other relevant information i can give you but if I'm missing something please let me know.

Now, at the beginning it was working like a charm, i was able to print on nice quality and didn't have any problems at all except for the speed i could print at. if i set the speed higher than 20 mm/s I had bad quality. Sometimes even steps loosing, which i fixed by measuring and calibrating all axis motors. nevertheless i noticed that sometimes if i raised the speed i had less quality and some times i had some clogging. which i fixed by dissasembing the whole hot end and cleaning part by part with lindustrial thinner (toluene+acetone+alchol...).

So.. after a few of those I decided to print the parts needed and go fo the bowden configuration, as many people says that gies you more precision and better prints by eliminating much of the inertia of the extruder (mainly because you remove the motor weight).

so as i was removing the old extruder i also printed parts for adding couple of cooling fans for PLA ( i had noticed that i strongly needed them) and a support for adding an autolevel sensor (yes now i know it's stupid to change so manuy variables at once, oh well).

So after mounting everything and calibrating the new extruder steps/mm (to 300) i found that i have several problems of under extrusion. i'm not sure if under extrusion or over extrusion it is, but the fact is that at some point the filament starts having problems to be extruded and the printings are all messed up. First the motor starts "clacking" (yes many of you know that sound) and looks like it was missing steps.

I've been trying with changing variables for a few days:
- Increasing/decreasing temperature (tried several, from 185 to 250°C)
- Slowing/speeding print speed,
- reviewed the calculations on my calibration many times
- increased the current to the motor to the point that it actually heats more than I wished (this actually helped a bit not not enough to fix, the problems just delays more in appearing)
- increased the pressure to the filament till it gets deeply marked (and damaged)
- reducing the flow(%) in Cura in steps of 5% from 100% to 85% (not fixed but when got to 85% the extrusion was not even enough for a good print.. still the same clacking and under extrusion eventually appeared)
-cleaning the nozzle with the so called atomic method (does not fix it)
- In cura printing at any speed 10 / 20 / 30 / 40 / 50 or 60 mm/s won't fix the issue.

I've noticed that the first layers are printer perfectly... it is when it start doing the infill (maybe cause it's going faster) that it blocks the nozzle

In fact if I stop the printing when it is blocked or jammed or whatever it is what happens, i have to remove the filament manually cut the tip and immediately reinsert pushing manually, I can make the filament melt and pass thru the nozzle with no effort.

Just some extra information attached, my Configuration.h and my Cura's profile are attachede. Here are some of my speed config settings on the Configuration.h file:

#define DEFAULT_AXIS_STEPS_PER_UNIT {200,200,8000,300} // default steps per unit for Ultimaker
#define DEFAULT_MAX_FEEDRATE {300, 300, 3, 45} // (mm/sec)
#define DEFAULT_MAX_ACCELERATION {3000,3000,100,10000}

#define DEFAULT_ACCELERATION 3000 // X, Y, Z and E acceleration in mm/s^2 for printing moves
#define DEFAULT_RETRACT_ACCELERATION 3000 // E acceleration in mm/s^2 for retracts
#define DEFAULT_TRAVEL_ACCELERATION 3000 // X, Y, Z acceleration in mm/s^2 for travel (non printing) moves

#define DEFAULT_XYJERK 20.0 // (mm/sec)
#define DEFAULT_ZJERK 0.4 // (mm/sec)
#define DEFAULT_EJERK 5.0 // (mm/sec)

Do you think i'm having too small torque because of the micro stepping? i really do not know what else to try

I apologize if I wrote too much information but I guess that could save time on the question/answer back and forth for details... Also apologize for the looooooong thread but please believe me.. i'm truly desperate now!

thanks a lot for your help and time!

Gabe

Here are a few suggestions:

1. Is it a genuine E3D or a cheap clone? There may be something wrong with the internal shape of the nozzle, or a missing PTFE liner.

2. Does the nozzle maintain temperature as the extrusion rate increases?

I use the same motors and I find 400mA current enough for the extruder, because if the nozzle is cold or obstructed then I want the extruder to skip steps before it starts chewing through the filament. You have lower steps/mm than I do (300 vs 460) so you will need proportionally more current.

Edited 1 time(s). Last edit at 05/14/2015 03:24PM 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].

Thanks for your answer dc42,
1. Yes it's genuine e3d V6. Bought it and received directly from e3d-online.com
2. The nozzle reads stable temperatures just like it did when i had it mounted in direct extruder.

Quick questions for you:

1. Are you using bowden configuration as well, and if so, using an MK8 gear too?
2. Do you have your DRV8825 an if so, configured for 1/32 microsteps on the extruder motor too?

If you have same config then it means i'm calculating somethign wrong cause i have less steps/mm than you after calibration.
what max feedrate and acceleration you have for your extruder?

agian than you very much for taking the time to respond.. really appreciated!

Gabe

Unfortunately the E3D V6 has acquired a bad reputation for jamming as it warms up during print (note that I have no idea whether this reputation is deserved or not, as I do not own a genuine E3D hotend, V5 or V6). Could you post a couple of pictures of your print head and extruder setup? Are you providing proper cooling for the E3D aluminum fins?
Have you tried another brand of filament (I have also faced the case where a certain brand of PLA filament would print perfectly fine and another brand would systematically jam in the hotend)?
Also note that you should properly set the current for the direct drive extruder to something like 70% of the maximum current your stepper is rated for.
And to prevent the filament from slipping against the MK8 gear, the spring forcing the idler against the filament should be tightened as much as possible.

Check this video for a similar Bowden setup to yours: [www.youtube.com]

Quote
gabrielcr78
1. Are you using bowden configuration as well, and if so, using an MK8 gear too?
2. Do you have your DRV8825 an if so, configured for 1/32 microsteps on the extruder motor too?

1. I am using a Bowden extruder, with the RepRap mini geared extruder that I received with my Mini Kossel kit from Think3DPrint3D. This is what it looks like:



The extruder works perfectly since I reduced the motor current.

2. I am not using DRV8825 drivers, I am using the A4982 drivers on my Duet electronics, with 1/16 microstepping.

Edited 1 time(s). Last edit at 05/14/2015 03:31PM 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

Quote
gabrielcr78
1. Are you using bowden configuration as well, and if so, using an MK8 gear too?
2. Do you have your DRV8825 an if so, configured for 1/32 microsteps on the extruder motor too?

1. I am using a Bowden extruder, with the RepRap mini geared extruder that I received with my Mini Kossel kit from Think3DPrint3D. This is what it looks like:
...

The extruder works perfectly since I reduced the motor current.

2. I am not using DRV8825 drivers, I am using the A4982 drivers on my Duet electronics, with 1/16 microstepping.

yeah i've been thinking in changing the microstepping from 1/32 to 1/16... maybe that coudl help.... maybe it would have more torque?
BTW that's a very ncie extruder! i tried to find it in thingiverse and couldn't.. is it open source? thanks!

Edited 2 time(s). Last edit at 05/14/2015 06:06PM by gabrielcr78.

Quote
AndrewBCN
Unfortunately the E3D V6 has acquired a bad reputation for jamming as it warms up during print (note that I have no idea whether this reputation is deserved or not, as I do not own a genuine E3D hotend, V5 or V6). Could you post a couple of pictures of your print head and extruder setup? Are you providing proper cooling for the E3D aluminum fins?
Have you tried another brand of filament (I have also faced the case where a certain brand of PLA filament would print perfectly fine and another brand would systematically jam in the hotend)?
Also note that you should properly set the current for the direct drive extruder to something like 70% of the maximum current your stepper is rated for.
And to prevent the filament from slipping against the MK8 gear, the spring forcing the idler against the filament should be tightened as much as possible.

Check this video for a similar Bowden setup to yours: [www.youtube.com]

Hello Andrew, lastnight after posting here I tried with XT co-polyester from colorfabb (some samples i had) and it has less friction than the PLA i have... the problem did not happen, however i still could hear the click of the gear a few times and it seems like I over extruded one or two times...
here are some pictures, the grey is the PLA, it's a bit rought so it presents a bit more friction in the bowden system than the black XT Copolyester. posting some pictues, as you can see in all of them at least a few layers were not propperly extruded, also, many of the tests won't even finish extruding (only put a couple of them in the picture).

also putting some pictures of the boden configuration / fans/ etc.

one observation is that when I use the FANs, the nozzle seems to block sooner because the layers are more stiff when the nozzle tries to deposit filament on top, while the soft layers (when not using FANs) offer some tolerance to allow the nozzle to push filament on top, so maybe it's an issue of Z axis calibration, but if i send the comand on pronterface to move Z axis 10 mm it does 10 mm exactly.

the hot end has the same fan it came with, but the duct was printed for suppirting these cooling fans..... I had printed before fan duct very simmilar to the one on the video you show, but now changed for these kind of fan ducts as you see in the pictures. the max current for the Motor should be 1.8 A, right now the current i've set for it is 1.7A and of course i'm noticing that the mottor heats up more than just the regular nice warming.

Oh also another detail, the orioginal e3d v6 thermistor was broken so I replaced it for the common 100k beta 3950 1% thermistor (4.7k pullup) (#11 in marlin config) which I also use for the heated Bed, but after testing the temps with a thermometer at low temps it seemed to be alright... i have currently no way to measure larget temps with more accuracy.


Under extrusion
PLA(Grey vs XT copolyester (black)
filaments texture
Printer
Motor
Extruder



regards,

Gabe

Gabe,

At this stage there are quite a few things you can try to optimize your extruder.

First, imho, you can try to check whether your nozzle assembly is OK. BTW, one of the first things to do as I am observing the picture of your hotend cooling setup, is to reorient the two layer fans so that they blow cool air only on the printed part, and not on the heat block/nozzle.

Now remove the bowden ptfe tube from the E3D, heatup the hotend to 205C and try to feed some filament manually and check whether it comes out of the nozzle without requiring too much force. If you feel too much force is required there may be a small debris that is partially blocking the nozzle. If you can extrude easily then you can move on to some further testing.

Alright Andrew, So just for the kicks, I decided to test once again to share the paramethers I'm using:

this time, I lowered the current of the motor to 1.3 A (72% of the operating current 1.8A), and increased th tension of the spring as much as possible. Also pre.heated the filament hotend before inserting the filament. retraction set to 3 mm at 40 mm/s and print speed 40 mm/s (first layer 20mm/s) ... finally the temp used 210°C for the hot end and 60°C for the heated bed. Cooling Fans ON (max speed as still have no speed regulator)... .4 mm nozzle (cleaned before this print with the atomic method), 2 mm/layer, Flow 100%... ... ...check the results.


Temp maintained constant
Printed blocks 1
Printed blocks 2
easily breaks.

As you can see, at some point even after may changes and tunning, the printer start missing extrusion. also not sure if you see it but in some corners i have over extrusion.. i guess that's another issue


Now, following your advise, after that impression, it cold a bit while I was reading this post, but I heated up to 205 the extruder again and pushed the filament manually.. ti moves thru with no issues other than the normal pressure you would expect .....

EDIT: BTW, after the filament stucks... if i lift the nozzle and leave it at the same temperature i was printing, the filament actually starts dripping of slowly until the congestion disappears (it looks like) then it's easy to push the filament.. but not before!... wondering if I should change the nozzle? this was the only original e3d nozzle of .4 mm i had.. but i have some other chinese clones that i can put in and try...?


thanks again,

Gabe

Edited 1 time(s). Last edit at 05/14/2015 07:12PM by gabrielcr78.

Wow

I thought it was just me. i have been unable to survive an entire print with this e3d v6. i have almost the exact setup and problems. however, im running 16 microstep drivers.

what I have observed is the filament is swelling in the threaded tube where it exits the ptfe.

one thing to make sure of, is to bevel the end of your bowden tube so it inserts properly into the stainless steel threaded tube. im really pissed off about this purchase. the bowden lock ring melted on mine so i had to drill a hole and put a screw to lock the bowden tube into the neck of the hotend. i have to be careful not to pinch the filament.

ps make sure to run the heatsink fan when heating up and idling. need to keep the lower part of the heatsink cooler

Edited 1 time(s). Last edit at 05/15/2015 12:43AM by thetazzbot.

that's right tthetazzbot, one time I failed to connect the heatsink fan, i realized soon enought so i removed the PTFE tube and it was ruined, luckyly I learned my lesson with no more damage than that. but the thing is that i printed several stuff with this e3d v6 in pretty good quality before swaping to this new extruder... that's the reason it thought it was related to that change.. maybe it's just that i did not notice the jamming because the previous direct greg's extruder offeed much more power... one thing i noticed though is that the filament was stuck when the print finished and I tried to remove the filament.. a couple of ties i had to dissabemble the whole thing and clean the hotend (another reason to move to bowden as it's easier to dissasemble...)

ayhow.. do you also hear the clacking of the motor and have over extrusion after a few of the printing?

Something else worth checking is the path of the filament going into the extruder from the spool - we cant see that in the photos.

For example, since the filament feeds into the extruder horizontally, then its possible (depending of course where the spool is located) that when you set it up there is some slack in the filament back to the spool, and starts off all working fine. As more filament is used, it tightens, and pulls the filament down/up at a sharper angle as it enters the extruder and becomes harder to feed which can cause motor skips.

Hello sdavi, attaching pictures of the feeding mechanism, i tried to reduce any resistance from he spool bu using bearings and also placed the spool in a position very close to the input of the filament in the Extruder....

spool location
spool bearings

now i have a question for all the forum, which hit my mind.. has any of you used the 100K ohm NTC 3950 thermistor from aliexpress on a hotend? i used one of those since my original thermistor from e3d (104gt2) died... i'm wondering if that could be the reason of this problem...

Quote
gabrielcr78
that's right tthetazzbot, one time I failed to connect the heatsink fan, i realized soon enought so i removed the PTFE tube and it was ruined, luckyly I learned my lesson with no more damage than that. but the thing is that i printed several stuff with this e3d v6 in pretty good quality before swaping to this new extruder... that's the reason it thought it was related to that change.. maybe it's just that i did not notice the jamming because the previous direct greg's extruder offeed much more power... one thing i noticed though is that the filament was stuck when the print finished and I tried to remove the filament.. a couple of ties i had to dissabemble the whole thing and clean the hotend (another reason to move to bowden as it's easier to dissasemble...)

ayhow.. do you also hear the clacking of the motor and have over extrusion after a few of the printing?

Since i'm using an MK8 gear on 1.75 filament, direct bowden drive, all i get when this happens is the gear grinding the filament in half. i used to get the filament folding up inside the extruder and just getting tangled.

I was thinking my stepper motor was too wimpy for this, but if you're using a geared extruder and having similar issues, I'm not so sure. I have managed to print some stuff reasonably well. But inevitably, it just ends in disaster.

Here is King Marvin. The printer some how skipped at his head and printed an afro instead of a crown, so i reprinted the crown separately. This is with the e3d nozzle.

Quote
thetazzbot
I was thinking my stepper motor was too wimpy for this, but if you're using a geared extruder and having similar issues, I'm not so sure. I have managed to print

I'm not using a geared extruder, i'm using same config as you are: bowden extruder with an MK8 see pics in my last post...

I'm almost sure this problem is actually something happening inside the hotend.. I think filament is heating expanding in places where it should not, which blocks the entrance of filament.. i lowered the retraction to 0.7... still no fix

and i have the same issue than you have ... prints start great untill certain layer... (see my cubes picture above)... and at some point it's mesed up

Edited 1 time(s). Last edit at 05/15/2015 06:10PM by gabrielcr78.

oh,

well here is my assessment based on testing



what I have seen, is when i pull out the filament, it has a section about 30 mm that is swelled to 1.92 mm, after that it goes to normal 1.73 mm.

so that tells me that the "transition" section is getting too hot, and causes the filament to swell. This causes the clog as it cannot go into the "melting" section properly.

It is going to take more experimenting on my part to understand what this hot end really needs as far as setup, fan, heat. I've also observed the very top of the heat sink getting very hot. I also don't like the heat sink, the fits are too thick and polished, doesn't make for a great heat sink. In heat sinks, thin fins, with more horizontal surface area are better at cooling.

regards,
mark

Edited 1 time(s). Last edit at 05/15/2015 06:25PM by thetazzbot.

I agree Mark, I also get the same behavior here.. , the section of the filament that is in the "transit zone" should not be that swelled... that means during reatraction it cannot move back into the PTFE tube, and eventually not even move fwd into the melting zone...

in my case it might have to do with the fan duct i've printed to mount the cooling fans on it... i'm dissasembling everything ang going back to the original fan duct just for experimenting.... although i still don't trust the new thermistor i'm using

downside is that i don't have any thermometer capable of measuring those hot temps that can help me to calibrate and see if the thermistor is giving me actually the right temps...

speaking of that... what temp are you using for PLA?

regards,

Gabe

Edited 1 time(s). Last edit at 05/15/2015 06:39PM by gabrielcr78.

Im actually only doing abs right now. Do u have a bbq probe thermometer the digital kind? It will go that high and accurate.

as a matter of fact i'm heading out to buy one right now.. also already ordered some replacement thermistors from e3d and and two .4 mm nozzles (brass and steal) ... but that will take a few weeks to arrive to my house here in Costa Rica.. so better to find alternatives.. i'l do the tests and let u know

Yeah im about to do some tweaking too.

Something I wanted to mention for your thermistor issue.

I had a problem finding the right table ID value to use. When I first plugged it in, it was way off. Read like 120 when the actual temp was off the scale. That's how I melted the plastic lock ring.

The correct setting for marlin for my e3d v6 full kit that I bought was:

// 5 is 100K thermistor - ATC Semitec 104GT-2 (Used in ParCan & J-Head) (4.7k pullup)
#define TEMP_SENSOR_0 5

I don't see that the tangent has been answered yet. The pictured extruder appears to be the same one used by RepRapPro. The STLs are available on their github.

hello IMBoring25 et all,

Certainly the main topic issue is not yet resolved... my weekend update... i went and purchased a thermometer (did not find anything that could help me to measure more than 120 °C without melting but within those ranks i found that the thermistors i have are not the most exact according to the table I've selected in marlin... (which is supposedly the one for them) so I've ordered 4 of the ones that came originally with the e3d. (yeah I'll replace also the one from the heated bed with one of those. then after that I'll do the PID auto tune thing and report back the results .... untill then.... no printing for me

i hope the package takes less than 2 weeks to arrive from UK to Costa Rica.. after that i'll be on a business tip to Czech Republic and won't be able to work in the printer for 3 weeks anyway

thanks!

Gabe

Edited 1 time(s). Last edit at 05/18/2015 04:02PM by gabrielcr78.

So.. while the parts I ordered Arrive I have a small update.. i have read about the Canola Oil use for the e3d V6 and I must confess even when i read before I did not want to use ( cause it should not be needed, and also. this could affect adherence and well.. many other reasons) however having no other option, i used some and the results have been as expected. no more under extrusion, but also i lowered the retraction to under 1.5mm and reduce retraction speed to under 25 mm/s... which causes some stringing. I'm yet to test if reducing temps as much as possible will make the stringing to go away but just wanted to give an update tot he forum here.

best regards!

Gabe