Print this one if you can https://www.youmagine.com/designs/alternative-um2-feeder-version-two
Its the most widely used and is very good. It also make it faster to change materials and easier to clean the knurled knob.
If you are unable to print it, then I'm sure someone near you could.
Not good that you are having these issues but as hal-9000 said. once you are passed them im sure you will love it.
I had a few issues to start with but I stuck with it and I'm really glad i did.
Hal, I would agree I do believe the machine is solid, my boys did a lot of research on the available printers in this price range and the UTM was their choice. We did talk to you via phone a few weeks ago from Arizona about the issues we were having with the printer. At this point the temp sensor and the rest are performing so that hurdle has been crossed, the fractured casing is another issue which I would like to know what that may have happened, I do not believe the four screws were too tight after the temp sensor replacement.
All that aside, the feeder mechanism is the issue for us at this point, as it appears to be for others as well, Labern I appreciate the link I had looked at that option as well and thank you for suggesting it as well. Hal we did reseat the Bowden after we replaced the temp sensor although will look at it again to verify that it is in place. With regard to the knurled bolt I have noticed flecks of filament build up within the mechanism and have attempted to clear that out, are methods for doing so, canned air perhaps. We have also tried unrolling the filament and re-rolling the the filament more loosely, that was mentioned on one of the forums. So that is where we are at this point, appreciate the advice.
What did you do to get fractures on the black part of the printer head? I've never heard this happen. Do you have any idea what might have caused this?
It's not totally clear what problems you are having with the feeder or the bowden tube. Can you elucidate?
Grinding the filament is not a hardware or software problem; it is inherent to the physical properties of plastics. When the feeder is trying to move the material, but it can't or when it moves over the same patch of filament a lot of times the plastic there wears down.
Bagel, I have no idea how the fractures/ cracks were caused, if there is a way to post pictures on this thread I would be glad to do so in an effort find out. The fractures are on the lower part of the black casing which encloses the bearing for the Y axis. I was told by tech support in the US that perhaps the thumb screws were to tight, after the temp sensor was replaced, however I do not think they were.
We are not completely new to 3D printing but we are still learning the ins and outs. We have been experiencing many of the same issues with regard to the feeder expressed on the forums. It appears that with heavy retractions the filament grinds down as you describe, we also have noticed that when that happens and we use the change filament function on the machine and reinsert the filament that the feeder grinds down almost immediately on the filament. We have adjusted the tension on the feeder, it was on its tightest setting when we received the printer, so that's where it is.
Bagel, I have uploaded images of the fractured casing if you would like to view them.
The cause of the cracks is exactly as was explained to you; the blocks crack if the corner screws are too tight and/or if the bearings are not properly seated in the head blocks when the screws are done up. There is a raised lip that fits into the groove in the bearing; if those do not line up, there ends up being a slight gap between the blocks, and when the corner thumbscrews are done up, the plastic parts get bent down in the corners, and the stress can crack the plastic.
As has been pointed out, it's not a huge deal anyway. There's not that much lateral stress on the sliding blocks normally; the presence of the cracks will usually not have any impact, and often the most effective fix is just to use drop of superglue to seal the cracks back up. Alternatively, replacing the blocks is quite straightforward, the only nuisance is that you have to remove the nozzle block in order to feed it up through the stack of blocks - which is why the glue route is often preferable - at least until you have a reason to take the head apart again.
Also, when you received the printer, the extruder tension was not on the tightest setting. The printers are shipped with the tension setting in the right position to be able to pass an 8 cubic mm/s extrusion speed test, which varies on each machine due to the natural variation in the tension springs, and can also need some adjustment to allow for different materials and print styles. Generally speaking, the best position for the tension indicator is somewhere above the second mark from the top of the scale; higher positions indicate lower tension. You should avoid moving the tension indicator below the midway point, as that over-compresses the spring and can damage it.
If you get grinding of filament during prints with lots of retractions, then you need to increase the tension if the filament seems to be getting sanded flat, and doesn't have clearly defined teeth marks - and decrease the tension if the filament is getting squashed flat and deformed, so that it no longer has clean edges on the flattened part, and cannot fit into the Bowden Tube.
Generally speaking, if you are having problems with retractions, once you have the tension correct, look at adjusting the slicing settings to have fewer retractions (e.g., by increasing the minimal extrusion distance, enabling combing, increasing the minimum move distance, etc), and raise the temperature of the filament to make it as easy as possible for the filament to flow.
Thank you for the advice and response and want to say again that tech support has been excellent, extrodinarily patient and helpful both with time and advice even in the midst very bad weather. With regard to the tension setting when we received the printer the white indicator on the side of the feeder mechanism, if referring to the same thing you are, was at the very top of the range, we were advised to reduce that setting as you described and did so, it took a number of turns before it responded. I appreciate your explanation with regard to grinding, and want to clarify, most of time the filament has a gash to the point were when using the Change filament function the filament cannot be backed out and is removed manually. In this case as you described we should decrease the tension to somewhere in the area of the second guide line.
I have heard there was some change on extruder since March-2014. Which is the difference with regards to previous extruder versions?. I received my printer in March but my order was posted in December-2013 so i assume i have the old version. In my extruder i cannot change a bit the position of the tension indicator by turning the screw.
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hal-9000 0
Let me first say that even though you have experienced issues with the printer and it looks daunting now, you're bound to experience these or a multitude of other problems with other brands too. The device is solid and I believe you'll be happy once you get over this hump.
Now about your issue, from reading it seems like the issue outstanding is the Bowden tube and feeder, is that right? I can speak to issues with the U1 where I have had this problem if there is a slight build up on the knurled bolt or if the mechanism is too tight.
You may also want to look at printing a replacement ring for under your Bowden clip as maybe your not in alignment (goes under the white plug where the tube enters). Have you also tried maybe re-seating the tube itself? I am thinking since you took it apart to fix the temp sensor and all it may not be all the way seated or seated incorrectly.
Even before that I would email support and replace the cracked pieces so you can start clean.
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