Stringing and overall messing up print
So i got my printer in a few days ago, got it built up went through a few test prints with the included silver and had some issues with the prints which i have mostly resolved at this point.
Then I tried to change the filament. It is the pearl green color from Prusa that I ordered with the kit. All it does is string everywhere half of my prints are now strings and it often times messes up things and makes points look very ugly. I have done live z adjust numerous times. I have also played with the nozzle temp as well as retraction speed and distance's. Would greatly appreciate some help.
The settings that the object in the images below was printed at were
Temp 200 (reduced to 190 about half way up the pillar)
Extraction Speed 55mm/s
Extraction Distance 0.8mm
Here is the silver on benchy boat using the default file that comes with the mk3. This was the only spot i could find on it that looked messed up.
I do also have larger image versions if you want I just uploaded the small ones for now.
Re: Stringing and overall messing up print
Ok so further research has resulted in something strange. So I tried to put the gray back in. This actually resulted in the same effect on the same pillar file. I was getting a lot of strings.
I noticed that the strings were not happening equally they were much more apparent on the front than on the left. So I tried to turn the fan off. This worked! No strings! Now the print looks terrible but there are no strings! So now its a delicate balance between temp and fan speed.
The thing I have noticed though is that cura asks to set a fan % but the mk3 does not follow this same logic it seems. I am unsure how to translate this.
I set cura fan speed to 50% but the mk3 was reporting fan speed as 127, I guess its stored as hex? So as I adjusted it on the mk3 as it was running I had it down to 25 so I guess that would be like 10% speed.
Something about this seems wrong though, I was still getting some strings but they were super thin and the build was going along just fine. Turning it below 25 seemed to turn the fan off and make a buzzing sound (not enough power to spin i guess).
Re: Stringing and overall messing up print
I found the solution in case anyone comes across my lonely little thread here.
I have been using Cura I have been using the Prusa Cura settings, I have been doing that because I could not download slicer from the Prusa site. So I downloaded the beta instead and just used defaults without changing anything and it works great! I will be trying to look at the settings and determine what the problem is.
TLDR: Use Slicer from Prusa.
Re: Stringing and overall messing up print
100% is 255, 50% is 127
Re: Stringing and overall messing up print
Not hex, but the printer is using a decimal representation of an 8 bit value, which has a range of 0-255. 127 is 50%, so what you entered in Cura was being used on the printer. The hex representation of that value would be 7F.
[...] I set cura fan speed to 50% but the mk3 was reporting fan speed as 127, I guess its stored as hex? So as I adjusted it on the mk3 as it was running I had it down to 25 so I guess that would be like 10% speed.
Something about this seems wrong though, I was still getting some strings but they were super thin and the build was going along just fine. Turning it below 25 seemed to turn the fan off and make a buzzing sound (not enough power to spin i guess).
The fan speeds are controlled with Pulse Width Modulation (PWM) which essentially pulses the fan at intervals to maintain a speed. If the rate is too low (not enough blips rapidly enough), there's not enough push to overcome the fan's momentum. Simplify 3D includes a nice feature to "blip" the fan to 100% on any speed change to deal with this problem.
You may hear a sound whenever PWM is being used when the rates match audible frequencies. I hear soft clicks when my bed is warming.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
Re: Stringing and overall messing up print
I am guessing a bit, but wonder if the stringing could be caused by too much heat. Can you try lowering the nozzle temperature by 5-10 degrees?
Steve
Re: Stringing and overall messing up print
Not hex, but the printer is using a decimal representation of an 8 bit value, which has a range of 0-255. 127 is 50%, so what you entered in Cura was being used on the printer. The hex representation of that value would be 7F.
[...] I set cura fan speed to 50% but the mk3 was reporting fan speed as 127, I guess its stored as hex? So as I adjusted it on the mk3 as it was running I had it down to 25 so I guess that would be like 10% speed.
Something about this seems wrong though, I was still getting some strings but they were super thin and the build was going along just fine. Turning it below 25 seemed to turn the fan off and make a buzzing sound (not enough power to spin i guess).
The fan speeds are controlled with Pulse Width Modulation (PWM) which essentially pulses the fan at intervals to maintain a speed. If the rate is too low (not enough blips rapidly enough), there's not enough push to overcome the fan's momentum. Simplify 3D includes a nice feature to "blip" the fan to 100% on any speed change to deal with this problem.
You may hear a sound whenever PWM is being used when the rates match audible frequencies. I hear soft clicks when my bed is warming.
Great info thank you! It makes sense to use a straight decimal representation I suppose but wouldn't it be easier for it to reference this value as hex instead? I guess the decimal value makes it more user friendly at very little cost.
I was unaware that fans worked in this way or at least this fan and i am sure others. Though it does make sense if you kept giving it power it would increase in speed and likely break or it would be very consuming of power comparative to this.
Re: Stringing and overall messing up print
I am guessing a bit, but wonder if the stringing could be caused by too much heat. Can you try lowering the nozzle temperature by 5-10 degrees?
Steve
Yeah I tried lowering it to the point that it stopped printing and I got it clogged. It was being caused by settings in Cura. I guess the default profiles provided on the site here do not work as well as Slicer does. I was going to tear apart a two files with the same object to see the differences. But it turns out the files are far more complex then a bunch of coordinates and some settings. So now I am learning how these files are constructed then I will work on finding the differences.