A Tale of Two Printers

[Labern 774]

Normally you can tell if the print is really hot on PLA as the part has a gritty feel and looks like this sample that came with the printer. In the holes it has stringing.

[Labern 774]

 

I just got a printer that had similar issues. I couldn't get a decent print with no stringing unless I lowered the temp to 175deg and 30mm/s print speed.

I put an external temp probe into the nozzle and when the machine was set to 100deg I got a reading of 122deg.on my meter. I changed the temp sensor and now its printing fine with no stringing.

 

If this has resolved the issue then contact support with a before and after photo and ask for a replacement temp sensor.

That seems to have been the problem! I replaced the thermal sensor and started a new print. So far no stringing and better looking walls.

 

[taikonaught 2]

Right, so the helpful folk over at Imaginables sent me a set of replacement fans to try out, believing that to be the source of both the noise and the stringing/retraction problem. So I swapped them over and printed my little bumper car control unit, and I can report good and bad news. The good news is that most of the noise seems to have stopped. There is still a kind of grinding sound that the other machine didn't have, but it is not nearly as bad as it was. However, when I printed my little bumper car control unit, the stringing was still happening:

So I dropped the temperature down to 190 and upped the retraction distance to 6.5 and it was better, but the problem is not solved:

[neotko 1,417]

Have you tested with the nozzle heat off to check if the air it's really hitting the area where the nozzle it's? Maybe post a photo of the fan cap. Maybe the air it's ok but the cap it's rotated and the air isn't hitting the correct spot. Since it's a 0.5mm stainless steel cap it could have been flexed some, moved or maybe badly installed.

Edited August 29, 2015 by Guest

[taikonaught 2]

I may have spoken too soon when i said that it didn't make noise anymore. It does make quite a bit of noise over certain areas of the build plate, but not others... Does this point to a misalignment of the guide rails, as someone suggested earlier in the thread?

When the machine arrived, the rods that run through the print head were both hanging loose, and I had to pop them back into the runners on the perimeter.

[JohnK 30]

I had some noise on mine, which sounded a lot like a noisy fan. In the end, I found out that it was just on of the folded corners of the metal shroud (circled in the picture) that was vibrating against itself, it got noisier and quieter depending on what the printer was doing at the time. I just bent it slightly and the noise went away.

[mendells 55]

Right, so the helpful folk over at Imaginables sent me a set of replacement fans to try out, believing that to be the source of both the noise and the stringing/retraction problem. So I swapped them over and printed my little bumper car control unit, and I can report good and bad news. The good news is that most of the noise seems to have stopped. There is still a kind of grinding sound that the other machine didn't have, but it is not nearly as bad as it was. However, when I printed my little bumper car control unit, the stringing was still happening:

So I dropped the temperature down to 190 and upped the retraction distance to 6.5 and it was better, but the problem is not solved:

 

I was having the exact same stringing problem with one of our Ultimaker 2s. It turned out to be a bad temperature sensor. After replacing it (which is a bit of a pain) the stringing went away.

[Labern 774]

 

Right, so the helpful folk over at Imaginables sent me a set of replacement fans to try out, believing that to be the source of both the noise and the stringing/retraction problem. So I swapped them over and printed my little bumper car control unit, and I can report good and bad news. The good news is that most of the noise seems to have stopped. There is still a kind of grinding sound that the other machine didn't have, but it is not nearly as bad as it was. However, when I printed my little bumper car control unit, the stringing was still happening:

So I dropped the temperature down to 190 and upped the retraction distance to 6.5 and it was better, but the problem is not solved:

 

I was having the exact same stringing problem with one of our Ultimaker 2s. It turned out to be a bad temperature sensor. After replacing it (which is a bit of a pain) the stringing went away.

 

Seems like there has been a bad batch of temp sensors, I had one and seen a few others on here 2. UM also told me that the new filament requires lower temp. 190 to 200 deg.

[taikonaught 2]

Right, so after replacing all the fans, the heater and temperature sensor, I think I may have gotten to the root of the problem, but it was none of those things.

I decided to do a material test, similar to this one, to test the properties of the material I am using. I knew from an earlier test that 190 was about right, so in Cura, I set the starting temperature to 190, and planned to incrementally increase the heat until stringing occurred. Frustratingly, it started stringing immediately, as if has done on my little bumper car control unit. So I went to tune the temperature while it was still printing, only to find that it was printing at 210 degrees... Furthermore, the bed temperature was not as I had it set in Cura, neither were the retraction settings...

In short, the machine was not reading all the info in the gcode. The slicer and the firmware versions I have installed are not compatible.

For the record, I am running Firmware version 15.04 and Cura is 15.06.03

It was recommended that I revert to Cura 15.04.02, which I have done, but haven't had a chance to try out yet.

Here is an image of the temperature test I conducted

[LePaul 321]

I'm really curious how your test works with 15.04.02

On my Ultimaker Original, 200-210 is the sweet spot for me, especially with ColorFabb PLA/PHA. I start out at 215 to get a good flow, then back the temp down to 210, then low 200s.

Good luck with your next test.

[eldrick 65]

Try three things:

- Increase retraction - I use 5.1-5.25mm

- Increase travel speed - faster travel "breaks" the threads instead of stretching them out.

- Print a set of bowden clips that have variable height, like these: https://www.youmagine.com/designs/ultimaker-2-bowden-clips.

Watch the ends of the Bowden tube when a retraction happens. If you see the ends move at all relative to the head or feeder, you need to use a thicker clip. There should be No visible movement of the Bowden tube during retractions.

- Turn off retraction if at all possible...

[Gencab 19]

Try three things:

- Increase retraction - I use 5.1-5.25mm

- Increase travel speed - faster travel "breaks" the threads instead of stretching them out.

- Print a set of bowden clips that have variable height, like these: https://www.youmagine.com/designs/ultimaker-2-bowden-clips.

Watch the ends of the Bowden tube when a retraction happens. If you see the ends move at all relative to the head or feeder, you need to use a thicker clip. There should be No visible movement of the Bowden tube during retractions.

- Turn off retraction if at all possible...

 

eldrick seems that link is not working. Can you refresh the link please

[SandervG 1,521]

Here ya go:

https://www.youmagine.com/designs/ultimaker-2-bowden-clips

(just removed the dot)