Feeder Grinding Material Prevention

[s.partridge 0]

Hi,

My question is how do you prevent the feeder from grinding the material?!!

We have had a costly print failure due to the feeder grind...

I can't be there every hour to do a little push for an 18hr print!

Many Thanks

 

[dieselpower 0]

Ther're some improvement options in this topic

http://umforum.ultimaker.com/index.php?/topic/4393-ultimaker2-feeder-system-improvements-and-ideas/

This one made by Robert seems to work well

https://www.youmagine.com/designs/alternative-um2-feeder-version-two

 

[gr5 2,265]

UM Original or UM2? The UM2 shouldn't grind most filaments as it has a lower current applied to the feeder so that it will slip backwards instead of grind.

And did you have mega retraction? If um2, count the M11 commands in the gcode and look at the final extrusion position in mm and see how many retractions you had per mm. I've done 8 and was fine (same filament went back and forth through feeder 8 times. On average meaning sometimes more than that).

On UM1 in general you can raise temp or lower speed to get less forces, less pressure in the head, which reduces grinding.

 

[conz 0]

gr5, there is sometimes a problem with grinding on the UM2, too. Especially with prints with a lot of retractions (e.g. a lot of Meshmixer support, where there is a retraction on every column).

 

[IRobertI 521]

On the UM2 it can help to check the spring tension. In general if you received your machine prior to March 1st (2014) the white little indicator should be in the top position, if you've received your machine after that it should be in the middle position. But, that's just the default setting and depending on your filament you might benefit from tweaking it.

Unfortunately on the earlier machines you can only make it tighter though. Unless you snip off a ring or two of the spring perhaps? Just a random thought.

Also make sure that the little knurled sleeve that drives the filament is clean.

And of course check that there isn't unnecessary friction on the filament and that you're not printing too fast/cold.

 

[illuminarti 18]

With the original (excessively strong) extruder spring on the Ultimaker², it was very rare to get extruder grinding, even during retractions.

It is more likely to happen with the newer extruder spring that has been shipping since March. On those machines, the key seems to be to increase the extruder tension a little bit if you get grinding... with enough tension, the motor should be able to grab the filament sufficiently tightly that the motor will step back, rather than grind the filament.

 

[aaronalai 2]

Interesting; I get grinding but it happens for very specific reasons: if I print really cold (5C away from no extrusion cold), the buildplate is too close to the nozzle, or I'm trying out new firmware. Do any of these apply to your situation? The only other time I got grinding was actually in the middle of a print because my filament was weaved under itself and knotted up; the extruder pulled like hell on the filament though, it was full of kinks where it interfaced with my filament guides.

 

[deflaminis 0]

I experienced a bit of this when I changed the material for the 2nd time. I've noticed a significant reduction in it by using a different spooler mechanism so the tension isn't so hard on the right side of the feeder intake. This one worked well for me, and it sits under the the table that the printer is on feeding directly upward into the feeder. http://www.thingiverse.com/thing:290064

 

[ccw1984 1]

I've gotten grinding 3 times in the last 3 days, only once on a print with a lot of retractions (Coral Cuffs on Thingiverse). I've touched the stepper feeder shaft before and it was pretty warm, possibly softening the PLA in there now, making it easier to grind. I'm going to give IRobertI's feeder a try and see how that works (if I can get it to print).

 

[supersurfer 0]

Hi,

I had a lot of trouble with grinding/slipping filament with a new elastic PLA from Form Futura; the Flexifil.

After three times removing the filament in the bowden tube I gave up.

I do not know if this has something to do with the tension only; the flexifil is quite flexible and probably has this trouble because it is more easily compressed.

would it be recommendable to screw up the tension even more?

Regards,