How many times do YOU press the Unload Filament button?  

Re: How many times do YOU press the Unload Filament button?

Once works ok for me. With many different materials. Check your hobnut spring settings maybe?

Re: How many times do YOU press the Unload Filament button?

When you are unloading a spool of filament, do you select "UNLOAD FILAMENT" once and the machine kicks it out all the way, or do you have to do it multiple times?

I usually end up pressing unload a couple of times while gently yanking out the filament. Very rarely does it work on the first try.

And if i am especially lucky, the end of the filament is deformed in such a way that it is too thick to go back out of the hole on top, so i gotta unscrew the 2 tensioning screws, open it up, cut the end of the filament, put everything back together before i can load new filament. Which then gets stuck because I forgot to cut the tip at an angle.

If I didn't already have the multicolor kit on pre-order (which I think replaces all that), i'd have installed some 3rd party extruder/feeder by now.

This is my biggest gripe with the MK2.

Re: How many times do YOU press the Unload Filament button?

This is very strange; there have been a couple of other threads about this previously.

Seems to have started happening on one of the firmware upgrade (3.0.7 I think) when the unload speed was increased significantly to reduce the possibility of leaving material in the extruder.

Personally, I didn't have a problem before and I still don't with the later firmware. With the nozzle at 200 degrees, I press unload and the filament is unloaded cleanly without me having to pull on it.

Of course, the multi-filament upgrade will require the unload procedure to work every time without fail otherwise the print will be rubbish.

There must be a reason why some users have the problem and others don't; the problem is that I have no idea why some do have the problem.

Peter

Re: How many times do YOU press the Unload Filament button?

I have not updated the firmware since I bought the printer in Oct 2016. I have not seen a reason for it and it sounds complicated.

I have from early on found that I prefer to pull on the filament when pressing Unload filament, and i usually have to do this twice.

On the second "Unload filament" the filament comes out and pulls a thin trail of plastic behind.

I never had a blockage that I think was caused during the Unload filament procedure, only blockages that happened when I was messing around without cooling fans or repeatedly measuring cooldown times for fan testing.

Yank it, I say! 😆

Re: How many times do YOU press the Unload Filament button?

Seems to have started happening on one of the firmware upgrade (3.0.7 I think) when the unload speed was increased significantly to reduce the possibility of leaving material in the extruder.

My kit was delivered with v3.0.8, i haven't updated yet.

Would fit your theory that it started with 3.0.7+.. Next time i change filamenmt, i'll rec a video of whats happening & shoot some closeups of the "bite marks" from the gear. Maybe that gives a few hints whats going on.

Re: How many times do YOU press the Unload Filament button?

From what I understood about the multi-material upgrade, switching works by quickly "ramming" the filament down to push out any molten material, then retracting the filament. Dunno if the same principle is currently applied with regular Mk2's for unloading (as we have to preheat before unloading).

I have found that if the idler is screwed on too tightly, retraction/unloading fails with the extruder motor skipping steps or stripping the filament, or requiring you to pull as well (needless to say, that's very undesirable). Perhaps you should loosen the idler screws in steps of 1-2 rotations each time and see how it affects your unloading?

Re: How many times do YOU press the Unload Filament button?

Jonny

Yes, the Change Filament code is different from the unload, but there no longer appears to be the positive feed first:

#define FILAMENTCHANGE_FIRSTRETRACT -2
#define FILAMENTCHANGE_FINALRETRACT -80


and

#define FILAMENTCHANGE_FIRSTFEED 70
#define FILAMENTCHANGE_FINALFEED 50


The unload is simply this:

G1 E-80 F7000

The same unload code was included in 3.0.7, so I guess that was when the unload feed rate was increased from 400mm/min.

Peter

Re: How many times do YOU press the Unload Filament button?

I have to do it twice. I do a preheat then hit filament unload and it goes real slow and stops. I hit it again and zip it pops out. Maybe my process is wrong!

Re: How many times do YOU press the Unload Filament button?

I have to press unload multiple times while also pulling up on the filament from the top to get it to unload. I have the spring screws right at the specified length. I did one colorprint, but the firmware doesn't give you an option to unload multiple times, so I have to take off the cover and unload manually, then put everything back together again.

Looking at the video for the quad upgrade kit, it shows the filament motor moving from right next to the print head to being one of the 4 motors mounted on top. Since my motor won't unload, not sure how this would work.

I'd be interested to hear if anyone figures out this issue.

Re: How many times do YOU press the Unload Filament button?

When you are unloading a spool of filament, do you select "UNLOAD FILAMENT" once and the machine kicks it out all the way, or do you have to do it multiple times?

After pre-heating, I usually have to press UNLOAD twice. I -gentle- pull the filament as I press unload. It usually comes out cleanly on the second press of UNLOAD.

To date, all my tests were with PLA. I currently flexible filament loaded, so we shall see if that differs.

John

Re: How many times do YOU press the Unload Filament button?

That's usually what I get but I had to do it 4 times yesterday.

Re: How many times do YOU press the Unload Filament button?

So long as I am pulling on the filament, I only ever have to press it once.

If you have to do it more, I suggest you loosen the the tensioners on the extruder wheel slightly.

Re: How many times do YOU press the Unload Filament button?

Just the once, Mrs Wembley! 😉

Re: How many times do YOU press the Unload Filament button?

After reading the comments from JohnnyricoMC
I have found that if the idler is screwed on too tightly, retraction/unloading fails with the extruder motor skipping steps or stripping the filament, or requiring you to pull as well (needless to say, that's very undesirable). Perhaps you should loosen the idler screws in steps of 1-2 rotations each time and see how it affects your unloading?
I decided to loosen my idler screws. Ended up going from 13mm to 13.8mm. Once I did that, the filament unloaded the first time I hit unload. Tried a couple of more times and it worked each time!

Re: How many times do YOU press the Unload Filament button?

This probably comes down to the question if you adjust the springs when the filament is loaded, or when not.

Maybe it should be 13mm when the filament is loaded, which will make it about 13.8mm when not loaded.

I will try that out, too, when my current large print has finished.

Re: How many times do YOU press the Unload Filament button?

Finally got to change filaments today, so I changed the tensioning spring length to 13.0mm with filament loaded.

Result: Perfect "Unload filament" on first attempt, unaided. That's unusual for my i3 MK2. But I always had the spring length set to 13.0mm empty.

Re-measuring spring length ampty after unloading so nicely: 13.8mm

So the tensioner spring length should be set to 13.8mm empty, and 13.0mm loaded.

🙂

Re: How many times do YOU press the Unload Filament button?

So I decided I loved trying out the PRUSA dual color logo so much, I wanted to do another print with it. I decided since I was going to have more than one spool in use, might as well make a dual color spool bracket for the metal frame. The left extruder on my FF Creator Pro was pretty mangled when I changed out nozzles for hardened plated steel/brass nozzles, so it has been a while since I have been able to print in two colors. Here's what went wrong for me:

I followed all Prusa guidelines for creating dual color g-code and loaded. It got to 4.95mm at which point it was to switch colors, which it did. After I heard the beep, I unloaded the filament--like the previous poster, it didn't come out with the first try and I had to kind of gently pull it through the hole in the top as it may have become deformed on its way out. No biggie! Then I went to put new color in (btw, both were colored PLA, previously printed with both at the same extruder/bed temps) and waited for it to come out the other end... and I waited.... nothing. It asked did it go through, well...no! Tried again, nothing. So I unloaded, cut the filament off above where it stripped the filament down, and tried again, and again, and again. It was obvious I needed to cancel my print halfway through and figure this out.

I cleaned the nozzle on the outside with my small steel bristle brush and used the acupuncture needle to clear it out. Still nothing came out. Then I used aftermarket .4mm nozzle clearing needle tool, it took nothing out, but then broke off in the extruder!! Ugh!! 😥 😡 Thinking now I was in a bit of trouble, I tried to see if I could get the nozzle off and took the extruder assembly apart to access the heater block and nozzle to get it off. I used the Prusa method again, but it just wouldn't budge! Yes, I did preheat the nozzle, yes, I did try to take it off with the supplied wrench and pliers, and yes I changed the heat settings to a few different temps (always higher, not lower temps) to try seeing if that worked. The nozzle is screwed on very tightly (uh oh, flashbacks of my FF creator and replacing those brass nozzles), I let alone, and here I am. I put it all back together for now and give up until I can find a reasonable solution that doesn't involve brute force.

I understand dual extrusion can be a pain in the buttocks, that has always been the case with the FFCP! However, those vids of Prusa unloading and loading in the filament like nobody's business left me with such excitement I immediately ordered a multimaterial upgrade. After a week with the printer, and already trouble in paradise, I'm wondering if it is smarter to cancel my order now. Can anyone shed any light on this and give me renewed hope for dual/multimaterial extrusion on the i3 MK2?

Re: How many times do YOU press the Unload Filament button?

I am not in the MultiMaterial beta so all i have is hearsay while I am waiting for mine to ship.

A few days ago I saw a post from Josef Prusa on Twitter claiming that the multi material upgrade will use a different drive gear supplied by Bondtech. I am hoping that the process will be more reliable with this upgrade. Source: check @josefprusa twitter feed https://twitter.com/josefprusa and scroll down to January 1st.

I never figured out how to link to a tweet.

( I find it a bit sad that Josef isn't posting here as well.. )

Re: How many times do YOU press the Unload Filament button?

Apologies for the poor photo.

I can confirm that filament changing works for me. And that the new drive pulleys are reliable (but I also found that the "old" drive pulleys were reliable with correctly set tension).

Peter