[Solved] Prusa Mini: Filament frequently jams after about 2 hours of printing  

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@sylvain-t2

Thanks, but I'm talking about the 275 mm long bowden tube.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

If anyone needs a new tube this is a great tool.

https://www.thingiverse.com/thing:3121653

the cutter cuts a perfect length, and the 120 degree too gives the necessary champfer

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@jweaver

This is a real nice link. 👍 

I am going to print and test this asap!

thank you!

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Posted by: @sylvain-t2

@jweaver

This is a real nice link. 👍 

I am going to print and test this asap!

thank you!

Its an awesome tool.. I used it before to make a tube for my MK3.. Perfect length and perfect 60 degree chamfer.

I was really pleased to see he made one for the Mini.. The 120 degree chamfer is surprisingly "flat". The only thing I found was that the length was slightly off of the tube cutter (tubers were 0.2mm too short).. It could be a calibration error on my Printer, so I just made a new version of the STL which was 0.2mm longer and then cut myself a lifetimes supply of tubes.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Posted by: @charlesnramsay

@sylvain-t2

Thanks, but I'm talking about the 275 mm long bowden tube.

I guess you already found the answer.

I haven't found a comprehensive BOM for the Mini, but details of many of the parts can be found on the web store, in this case https://shop.prusa3d.com/en/mini/1067-extruder-print-head-ptfe-tube-mini.html

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@stoddard

so sad to hear that, i am also beginner too. do they give you new machine? 

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Those that have those delivered in April/May , is this issue still there ?

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

I had two MINIs delivered in April and both arrived with misadjusted hotends and missing nuts.  After a few weeks the company did respond to the missing parts request and I see I have a DHL delivery scheduled (I raided my MK3S extras bag to get running quicker).  The good news for beginners is that you can learn to take apart your machine right from the start and get familiar with its inner workings.  The bad news is that you must do it, assuming you want consistently successful printing results (who doesn’t?).  Purchase a set of metric hex drivers (e.g., Wiha) and good digital caliper (e.g., Mitotoyo) right away if you don’t already own them  As others have said, once you get the MINI working properly, it’s delightful.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Typo in the last post: every time I tried to spell “Mitutoyo” it the computer changed the spelling.  

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@stoddard

that 's very good advice,

can you suggest weekly, monthly, maintenance of machine?
I am very newbie.

thank you

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@stoddard

that 's very good advice,

can you suggest weekly, monthly, maintenance of machine?
I am very newbie.

thank you

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@jweaver

very cool thank you

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Several more things beginners need to purchase for keeping their MINI happy: high on the list are small brass wire brushes (cheap) for removing melted filament that adheres to the nozzle and other hot metal parts after long prints (or failed prints, heaven forbid). Routine maintenance tips don't fit this thread topic, but email me <[email protected]> and I'll be happy to assist.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Posted by: @stoddard

Several more things beginners need to purchase for keeping their MINI happy: high on the list are small brass wire brushes (cheap) for removing melted filament that adheres to the nozzle and other hot metal parts after long prints (or failed prints, heaven forbid). Routine maintenance tips don't fit this thread topic, but email me <[email protected]> and I'll be happy to assist.

The small wire brush ... I (direct drive, Anet ) usually wait  till it get hot and then with paper towel  go over the nozzle. Anyway, what would you suggest to buy as a recommendation for starting person (has some tools, just non or few printer specific items).

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

These are the tools I keep near the printers, in order of frequency of use:  

• small squirt bottle for 90% isopropyl alcohol,
• wire brushes,
• small diagonal cutters,
• small flashlight & inspection mirror (to check for melted filament on the extruder),
• scalpel or X-acto knife,
• box-cutter type utility knife,
• curved forceps with pointy tips, 
• needle-nosed pliers,
• digital caliper (Mitutoyo),
• 2.5 & 1.5 mm hex drivers (Wiha).  
• cleaning filament for cold pulls,
• wrench for changing nozzles,
• wrench for gripping heater block while changing nozzles,
• acupuncture needles for cleaning clogged nozzles,
• filament dryer (PrintDry is pricy but worth it).

Expendable supplies:

• 2.5-gallon zip-bags to store filament,
• color-indicating desiccant gel beads,
• 90% isopropyl alcohol
• acetone
• paper towels
• cyanoacrylate glue ("superglue")

You can find kits that include a bunch of the cheaper goodies in one package.  Maybe others have essential tools they can add, but this list has covered my needs, though I'm coveting a good digital micrometer with more digits than the caliper.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

@stoddard

this is awesome 😀

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

For anyone reading this in the future, if you're getting clogs constantly when using filament that is 0.03mm tolerant, not Prusament, it is likely due to the PTFE tube within the heatbreak being ~2mm too short.

Remove the PTFE tube and verify its length with calipers. For me it was 2mm too short and was causing the clog which was only evident when using 0.03mm tolerant filament. You should have received a spare PTFE tube, verify its length and if correct per the support article length, somewhere around 44mm I think, insert that and try printing again.

I spent hours debugging this and it was simply this.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

I am new to 3D printing and have had my Mini for about two weeks.  From the outset I have been plagued with poor extrusion, nozzle clogging and poor layer adhesion, to the point where I was about to give up.   The problem was less evident with Prusament PLA, but still occured, and clearly stuff needed adjusting.

I could not undo the three grubscrews holding the heatbreak in place, as the socket was too big for the 1.5mm allen key, and too small for a 2.0mm allen key.    My Aussie Prusa retailer sent me a new nozzle, PTFE tube, new grub screws, two 1.5mm allen keys that actually fitted the relacement grub screws, and a modified allen key that would fit the screws that were stuck.

With clear instructions from the Prusa Knowledgebase, I replaced the PTFE tube, replaced the odd size grub screws, replaced the clogged nozzle, and reset the height of the Pinda probe.    She was set up prefectly, but underextrusion and nozzle clogs continued.

I then printed a series of test blocks at different nozzle temps and print speeds, and got some significant and informative results.    As others have suggested, I reckon that the indicated 215 degrees for PLA on the Mini is too low, but have no way to check the actual temperature of the Mini nozzle, but like others, I reckon it's not up to the indicated temperature.

At an incicated 215 degrees I was getting underextrusion and clogging, and at 230 degrees was getting OK results but excessive stringing.    I am now printing Prusament and other brand PLA at an indicated 225 degrees at 80% speed and getting prefect results.

Using Prusa Slicer I have created a Filament Profile for PLA with a nozzle temp of 225 degrees and this nozzle temperaturte is carried over to the printer within the g-code file for the item I am printing.    All is well and I trust this info is helpful to others.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

Posted by: @anthonycvella

For anyone reading this in the future, if you're getting clogs constantly when using filament that is 0.03mm tolerant, not Prusament, it is likely due to the PTFE tube within the heatbreak being ~2mm too short.

Remove the PTFE tube and verify its length with calipers. For me it was 2mm too short and was causing the clog which was only evident when using 0.03mm tolerant filament. You should have received a spare PTFE tube, verify its length and if correct per the support article length, somewhere around 44mm I think, insert that and try printing again.

I spent hours debugging this and it was simply this.

Many of us have verified the same.. And its not that the tube is too short.. It shrinks when installed (most certainly by compression).. So even if you put in a new tube now which is verified the correct length, give it a few weeks and the problems will return and when you check the tube it will be shorted.

I did exactly this last week.. I know a month ago the tube I installed was 43.4mm, but I started to get problems with certain filaments and when I checked the tube is now around 42mm.

The solution I fear is to just get a stock of tubes and replace them regularly..... I am not convinced you need to change the tube..

Next time this happens, I am going to do this:

1.Releasethe top nut 1/4 turn.

2. Slaken the 3 gub screws holding the hot end

3. Push it up

4. Tighten the 3 gubs screews

5. Tighten the top nut

Essentially the standard process, but without swapping the tube.. This will of course change the Z height which will need to be recalibrated.. But i am wondering if the tube can keep compressing and perhaps doing this a few time might allow it to find its natural compressed lenght.

If that fails, then I will simply replace the tube each time I do this.. Its a 5 mins job and no big deal.. Just a shame you have to calibrate Z every time you do this.

RE: Prusa Mini: Filament frequently jams after about 2 hours of printing

It sounds like this is a manufacturing defect then that needs to be permanently resolved by Prusa. In the mean time doing tube swaps every time it shrinks sounds like a good plan.