Problems with original Prusa silver PLA  

Re: Problems with original Prusa silver PLA

Perhaps problem is in this filament? Try to get another silver. I got same issue long ago, just bad filament...

Re: Problems with original Prusa silver PLA

It would be too expensive to order another reel "just for test", not knowing if it will be ok or not, since postage is almost the same as filament price. Locally i get two reels for this price and i know they work...

I hope i will be able to find correct settings, i guess i'll have to play with them some more...
How do you guys print prusa's filament? Sliced with default "Prusa PLA" profile with slic4r? Default temperatures?

Re: Problems with original Prusa silver PLA

[...] How do you guys print prusa's filament? Sliced with default "Prusa PLA" profile with slic4r? Default temperatures?I've always used the Prusa defaults for their silver, including that same profile in Slic3r. I'm not ordering more simply because there are more economical local options, but I had no issues with it. You could just buy whatever's cheap locally to compare. Worst case, you may have a bad roll of Prusa silver. Come back to it after you've had some success with others and maybe you'll catch something.

Re: Problems with original Prusa silver PLA

... You could just buy whatever's cheap locally to compare...

Well, that's interesting: i have two different local brands and both work perfect (and i'll stick with these two). However, i've got this silver PLA packed with printer and i'd like to use it since it's already here 😀 .
Worst case scenario will be that i'll give it to any of my friends with different brand printer to check out...

Re: Problems with original Prusa silver PLA

You can try to "refresh" your PLA by baking it in the oven at 50°C for 2 hours.

Helped with my cheap China filament (Sunlu). Before, I couldn't make any proper print with this stuff.

Re: Problems with original Prusa silver PLA

Good suggestion, thanks! Will do just that. It can't be worse, i guess...

Re: Problems with original Prusa silver PLA

Today it happened again... and with my local filament. So it seems that thing is getting worse and worse so it must be something in settings or FW...
i'm thinking... it always happen when printer starts to print small pieces where's much retraction ( say big plate first 4mm then a couple of small round towers, like towel hanger) and filament always gets built up below gears just above PTFE tube. I also noticed that extruder motor is quite hot, so maybe if it's too hot then filament starts to soften and gets stuck since small items are printed there's not much flow...
I will start with way less retraction: i'll change min. Length from 1 to 5mm and i will disable forced retraction on layer change. This should cause less stress on motor and hopefully less heat...
But first i must dissasemble extruder to remove filament remainings ( again...)

Re: Problems with original Prusa silver PLA

I am little bit lost. I admit that Prusa Silver PLA is not the best PLA I tried but I always get very good results. When it comes to your actual problems, I have hard time to understand 'filament always gets built up below gears just above PTFE tube' Can you post the photo ?
Concerning retraction settings, which slicer you are using ? With Prusa printers I always use de the default retraction settings (I.e 0.7 for Mk2 and 0.8 for MK3 and it works, some specific filaments like nylon need less but that's separate issue. This applies both for Slic3r and S3D.
To resume, there are couple of issues : Prusa PLA, extruder malfunction, extruder settings. Can you post STL you are trying to print ?

Cheers,

NBO

Re: Problems with original Prusa silver PLA

I use FW 3.3.0 RC1 and Slic3r 1.40.1 beta. Sorry about my languge, English is not my native one, so i try...
In attached pics you can see that filament is widened at the point where PTFE tube starts - picture shows comparison of normal filament vs. stucked one. You can see what extuderd does to filament in second pic.
By the way, is it normal that this tube is so wide at the top - third picture? , In that picture filament is already a bit cut away, since i tried to remove it... sadly without luck, so it seems i'll have to dissasemble whole extruder 😥

Re: Problems with original Prusa silver PLA

sorry, i forgot to attach stl... there are two, bosch (rollers for bosch dishwasher) happened first (failed 3 times in a roll), while dog.stl happened yesterday with non-prusa PLA.
attached photo shows where jams happened.

Re: Problems with original Prusa silver PLA

[...] In that picture filament is already a bit cut away, since i tried to remove it... sadly without luck, so it seems i'll have to dissasemble whole extruder 😥Hang on! Before you go tearing things down too far, try this:

1. Raise Z so you have lots of room and easy access.
2. Remove the part cooling fan duct (the part labeled hot!).
3. Heat up nozzle to 250.
4. Remove nozzle by bracing heat block with a wrench and using a 7mm socket to loosen the nozzle. Be sure to hold the block so it doesn't twist. Also be careful of the 250C nozzle, and have a safe place to set it.
5. Using some wire, clear any accumulated filament you can easily clear out.
6. Using a 1.5mm length of wire (or a handy 1.5mm hex wrench), gently poke it up into the heat block through the nozzle hole until you're able to push it up the length of the hotend into the extruder.

With any luck, that bit of filament will pop out to where you can grab it with needle-nose pliers. If so, reverse the steps to reassemble the unit. Don't torque the nozzle too tightly in. There's a small gap at the top, and 2 fingers pressure is plenty. There is a wrench you can download to avoid over-tightening... which you'll have to print after you get running again.

Re: Problems with original Prusa silver PLA

Thanks for your helpfull info! Fortunately i've been able to remove filament without dissasembling whole unit, but i'll remember for next time...(and i will print wrench, hopefull before another jam...)
I heated to max (255) and waited a while so that whole thing heated as high as possible. Then i used some needles and managed to raise filament just enough to hold it with pliers and remove it.

Now i changed minimum travel distance for retraction from 1 to 5 mm and disabled "force retraction on layer change". And, since i have printer in closed enclosure i opened front door to lower temperature a bit, since it's summer and hot outside. Extruder motor was (measured with IR temp meter) around 55 degrees. Too much? Definitely i couldn't hold it with my hands. Anyway, i put aluminium cooler on top of the motor, that way i've got down to 45 degrees.

Two prints with local PLA after that were succesfull. Tomorrow i will try prusa pla again with default settings to see if The problem is too hot motor...
However, i just can't imagine why filament would build up above PTFE tube, where shouldn't be hot yet... but still it must of been hot, otherwise it wouldnt be wider there...right? So, i guess that only way to become hot is from motor heat...right? Extruder fan IS working correctly, so this is not the source of heat...

Re: Problems with original Prusa silver PLA

Extruder motor temperature under normal conditions is around 55 degrees C. When printing put your finger on the motor, you should be able to keep it on. For reference teperature you can heat the bed to the same temperature and compare.

Extruder enclosure close to motors gets slightly hotter but that is not enough to melt the filament and clog it just below extruder gears. The clog is formed closer to extruder hotend.

For precution, I will replace PTFE tubing. Prusa can provide you one, it is cheap and you will pay more for the postage.

To answer the question why clogging is taking place, the simpliest answer (if we put aside any hardware issues) is that you are pushing more plastic that you can handle. The pressure is on both sides, the nozzle need to push it out and there is resistance and on the other side motor is pushing in. Since the meleted plastic in the hotend cannot go down, it is pushing up and forming the clog.
If there are clicks from your extruder gear that's the first sign that something going wrong. In normal conditions, extruder gears (on MK3 printer) do not make any sound. If yes, check the screw holding the gear. it need to be tighten well. I preferer to use screwdriver with appropriate tip to do it.
To control the volume when printing, the easiest thing is to reduce the speed. From printer menu reduce the speed to 50%.
For slicing objects, use default settings. From your photo it looks that you are using at least 5 perimeters. 2 is quite enough.

Last thing, the dishwasher rollers are supposed to be inside the dishwasher ? If they are printed in PLA, they will not support the temperature. You need filament which we support at least 85 degrees. If I can suggest, try Colorfabb Ngen. (tested with Bosch dishwasher 🙂 )

Lijep pozdrav,

NB

Re: Problems with original Prusa silver PLA

OK, so...: 5 perimeters are indeed set on pink thing, because it's intended as hanger and i thought that it would be stronger. Ok, second thing would be increase infill to 100%...

Yesterday and today i'm printing without front doors of my enclosure and since then extruder motor temperature is measured 45 degrees, while all prints are perfect so far. If i take into account that IR thermometers are not too accurate temp was probably higher that 55 degrees in closed enclosure. I know that i couldn't keep my finger on for long.

Clicking was audible once clog was there, yes. I'm familiar with these famous extruder "clicks" from my old delta printer - that one was famous to have problems with this. I still have PTFE tube at home from my old delta days, so i will replace it.

As goes to dishwasher: Thanks, you have the point! I really didn't think of temperature, to be honest. I have ABS and PLA3D850, so i will make it from either one of them and see what happens.

Thanks for all info!

Regards, Pavel

Re: Problems with original Prusa silver PLA

Motor temperature indeed wasn't the fault - it happened again today. Today i changed nozzle with a brand new one. Now it's waiting time again...

How long is actually nozzle lifetime?

Re: Problems with original Prusa silver PLA

How long is actually nozzle lifetime?
It will depend on what you print. Abrasives can wear out a brass nozzle quickly. A hardened steel nozzle should last much longer. If you're just doing non-abrasives, I'd expect to get months out of brass. Definitely YMMV though.

It's worth asking what firmware you're running. Recent updates addressed extruder motor heat that could cause filament issues in the extruder.

Re: Problems with original Prusa silver PLA

I print mostly PLA, occasionally ABS and PETG, nothing else. But, since i just experienced another clog it's clear that nozzle is not the problem. I wouldn't exactly bet my hand on it, but i think that problems began with installing FW 3.3.0 RC1, so i guess that next thing is going back to 3.2.1 and hope for the best. I just installed final 3.3.0 earlier today, but since then i've had two clogs already. Before that i've had 3.3.0 RC1.
It's trial and error thing - and it's most painfull... i'm not sure, however what next thing will be, since i'm slowly getting out options...

Re: Problems with original Prusa silver PLA

To all of you who tried to help me: i appreciate it and thanks again! However, when going through (not so) old posts i found out that i'm not the only one with this problem. THIS and THIS threads covery exactly the same issue. i'll try with duct from james to cool filament. I'll keep heatsink on extruder motor, too.

Re: Problems with original Prusa silver PLA

Keeping an eye here. I occasionally have missing extrusions for no good reason - take it all apart, put it all together, it's nice for a random little while again.

With flexibiles, they'll trash the PTFE tube and spit out the side, yards of it laying on the floor.

I filed nearly nothing off the top of the set screws holding my gears on and much of the skipping went away.