Extruder Grinding (blocking)

[Stavros 1]

Hey dudes and dudettes.

Every day I get a blocked nozzle. I have even fitted a brand new nozzle but the same thing happens. These are prints I need for work so it's incredibly frustrating.

I have attached a picture of the prints. The Cura settings are a follows, I'm using standard PLA:

Layer H: 0.15 mm

Shell T: 1.2 mm

Bottom/ Top: 1.2 mm

Print Speed: 60 mm/s

Temp: 220c

Bed Temp: 70c

Edited April 19, 2016 by Guest

[Navarre 0]

I think your temperatures could be too high - both the extrusion and Bed.

Can you recheck the recommended temp for the PLA you have (I would usually expect 190-210 as the recomended range) - and for the bed try lowering to ~60c

[Stavros 1]

OK. I will try reducing the temperature on the UMO. I had put the temp up to 220 to try and stop under extrusion.

[Stavros 1]

I think your temperatures could be too high - both the extrusion and Bed.

Can you recheck the recommended temp for the PLA you have (I would usually expect 190-210 as the recomended range) - and for the bed try lowering to ~60c

 

That didn't work. The corners curled up and it still jammed after 6 hours. Here's a pic of the print

[lance-greene 7]

could the problem be filament slippage at the feeder? maybe the tension is set wrong?

[valcrow 144]

at 60mm/s 220C is OK. After it fails, check your filament to see if it's grinded down. (a semi circle?)

Also another thing to check, stick filament in by hand without the bowden tube to feel if there is some excess friction.

[Jtp 1]

I've just been looking into problems with under extrusion on my UM2. I'm using 220C at the head and 60 at the bed. What I did notice while printing (after very much adjusting and fiddling of the temps etc) was that there was a little buzz, every 5 seconds or so, from the back of the machine. Only by coincidence did I find out that this is the filament slipping in the feeder, and that this causes (strangely!) under extrusion! I have now adjusted the tension on my feeder, and the prints have improved, without changing the temps or speeds. It seems counter intuitive to me, but has actually made a difference.

The other thing that I have observed, is that the same settings do not necessarily work for PLA from another manufacturer. I have now tried two, but the second was not successful, and I could not get as good prints from it, despite changing many settings to try to compensate.

I hope these insights help. I would highly recommend http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#underextrusion as a great source of solutions.

[peetree 3]

This sounds like a back-of-the-printer issue. In addition to checking for grinding filament, after a failed print check to see if there is tension on the length of filament between the spool and feeder. Check for tangles on the spool.

Too much friction between the filament on the spool and the feeder will cause stoppage as the feeder can't push the filament to the extruder effectively.

If the prints have very many retractions spaced closely together, this can cause grinding or deformation of the filament as well.

[valcrow 144]

I've just been looking into problems with under extrusion on my UM2. I'm using 220C at the head and 60 at the bed. What I did notice while printing (after very much adjusting and fiddling of the temps etc) was that there was a little buzz, every 5 seconds or so, from the back of the machine. Only by coincidence did I find out that this is the filament slipping in the feeder, and that this causes (strangely!) under extrusion! I have now adjusted the tension on my feeder, and the prints have improved, without changing the temps or speeds. It seems counter intuitive to me, but has actually made a difference.

The other thing that I have observed, is that the same settings do not necessarily work for PLA from another manufacturer. I have now tried two, but the second was not successful, and I could not get as good prints from it, despite changing many settings to try to compensate.

I hope these insights help. I would highly recommend http://support.3dverkstan.se/article/23-a-visual-ultimaker-troubleshooting-guide#underextrusion as a great source of solutions.

 

I think OP has a UMO, the UMO has a geared feeder already so it's pretty strong, and doesn't quite click. It tends to grind filament rather than click if there is excess friction.

I think the main cause of the feeder clicking on the UM2's is speed to temperature ratio. The more volume of material you need to extrude the hotter your nozzle needs to be. There's a few things that affect the extrusion volume, nozzle size, layer height and print speed. If you increase any of those, you need to increase temperature to compensate or it won't melt fast enough.

The infil speed defaulted in Cura was really high way back when compared to the shell speed which caused all sorts of extrusion problems. I think they dialed it back now.

[Stavros 1]

Thanks for the pointers everyone.

I have backed off the pressure on the extruder and changed the orientation of the print but it failed after 5 hours again. Here is the print.

Also there are these marks on the filament after it has blocked. Shall I back off the extruder pressure more?

Edited April 15, 2016 by Guest

[Stavros 1]

I think we have identified that its a problem with the extruder gear. The filament has ground again. I don't think I can actually back off the screw any further. I just started a print and the big gear started slipping! It is currently at 14mm. I think it should be at 11.

[SandervG 1,521]

Have you opened up your feeder to clean the bolt and see if the bolt has not gone through the delrin part which is inside your feeder? If so it could block the delrin wheel which may apply more pressure because it is not rotating anymore.. or maybe only sometimes.

Is it Ultimaker filament? Are you sure about a consistent diameter?

[Jtp 1]

Having done a lot of prints very recently, many being fairly long in duration (up to 16 hours), I have noticed that there are quite a few things that can go wrong around the print head itself!

On more than one occasion I have had a failed print due to under extrusion and there are two main problems that I have observed:

1: when you change the material, it heats up the filament to allow it to retract it all the way back down the bowden tube. Sometimes (not every time) it leaves a very fine string all the way back down to the hot end, which can snap at any point on it's length. I have found in the past that some of this fine string has been stuck in the bowden tube, adding just a little extra friction, which is really not helpful! You should make sure you blow out the tube with an air can from the hot end (detach obviously first from the hot end).

2: my UM2 gets dirt build up inside the hot end which needs cleaning out every 1/4 spool or so! I follow a set of instructions from "iMakr.com" which is my local supplier. The basics of the instructions is the you first remove the filament, then the bowden tube form the hot end. Then you heat up the hot end to 220 deg C, and when it is at temperature, insert a clean (not imprinted from the feeder wheel) piece of filament till it comes out of the nozzle. Then, with the filament still inserted, reduce the temperature of the head to 90 deg C. When temperature is reached, pull out the filament. If your hot end is dirty, it will come out with black or brown bits stuck to the filament. Repeat the process till the filament comes out without dirt.

By checking these two things regularly, I keep my printer going almost without failure. There is the odd time when I haven't checked the nozzle in time and it's got dirty again, but cleaning it usually fixes it.

I have also noticed a difference between suppliers! FormFutura PLA performs differently from Polymakr PolyPlus PLA, and requires different settings!

I hope these suggestions help.

[Torgeir 242]

Hi Stavros,

You’ve got a lot of good advice here, and I’ll repeat one; don’t go with this high temperature for PLA.

This may not help for your problem, yes we know that, -but it may…

First, I’m a kind of new be for sure, but I’m learning very fast –sometimes.  

Let’s say; this is not a nozzle block. So, how can the filament stop extruding?  Answer; by a feeder that’s stuck in the upper part (cold part) of the extruder.

There can be four reasons for this:

1) The filament has attracted too much humidity (steam bubbles climb fast inside the heath block and will glue the filament). This is the one we fight mostly!

2) Make sure that the Buordon tube is locked well at the feeder and at the extruder. I’m using two clips on each side to make sure that the tube can’t move. Just a little bit of move here is enough to build up a “plastic cooling point” that can glue the feeder.

3) The Buordon tube is not cut exactly 90 degrees (if not, will leak plastic and glue the filament).

4) The Teflon coupler is worn out rounded/misshaped at the hot side (the side toward the hot end) thats will leak plastic and glue the feeder as above.

And again, are you sure that your filament is good???  

If not, even a very good printer as an Ultimaker can’t print what you want.

So, before you do anything else, try to print the cylinder. This is a very good test to see if the filament can be feed at a high flow without a hick up.

Follow the requirements for the test carefully!

The test is made by mr.-wardorf (Arthur) and it is found here: https://www.youmagine.com/designs/test-print-for-ultimaker--2

I’ve also like to confirm “Jtp’s” finding in the answer above, I’ve got the same experience as he mention under item 1.

Ok good luck.

Thanks

Torgeir.

Edited May 14, 2016 by Guest

[Stavros 1]

Thanks to everyone. I think it was the pressure on the extruder spring