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samsfisher

UM2 - Calibration cone under extrusion

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Hi,

Attached are the pictures from cone test. I find it puzzling to see that in the layers there is under extrusion only in the area right after the text. Post that there is no under extrusion.

I need to understand what need to be fixed in my UM2. The extrusion length seems to be ok which means my e-steps are fine. I primed my nozzle before conducting the test so clogging may not be an issue.

the cone test was done using

PLA, 230C.

Uma

Photo Jul 13, 3 46 49 PMPhoto Jul 13, 3 47 18 PM10615886 10152243319950877 1405206886 N

 

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Please post pictures. The printer probably slowed down for the letters and then speed up for a straight away and it takes a bit of time for the extruder to get the nozzle pressure back up to fast printing speeds so you can get underextrusion. You could print slower so that it never slows down for the letters. But really I need to see the picture of what you are talking about.

 

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Hi @gr5

Sorry i did upload pictures but something went awry.

Here you go pictures attached.!

Photo Jul 13, 3 47 18 PM

Photo Jul 13, 3 46 49 PM

 

On another topic I was printing a box that had to be very close to the nominal dimensions.

So the settings I used were

Layer Height: .25

Speed: 50 mm/s

Infill: 30%

2 top and bottom layers

Temperature: 217 @ PLA

Nozzle: .4

Multiplier: 1.05

Extusion width: .4

I am not exceeding 5 mm/s in extrusion rate here. But my printer is clicking at a definite interval and its causing under extrusion making the print quality bad. However I am able to hit the dimensions on holes and exterior within .10 mm (is this a decent tolerance to shoot for with UM2?)

The biggest question I have is how are people figuring out what speed to go? I am fed up with how it clicks all the time for what i want to do.

P.S I did tighten the bowden extruder by lowering the nozzle plate a bit and then pushing the bowden into the white nylon holder. I cleaned the extruder mechanism checked the tooth for grinding etc. I would be happy if someone can find a checklist for weekly maintenance.

Thanks for your time

 

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Those holes by the letters are normal for this print. That is expected. This is a special test and is printed at very high speeds. You normally don't want to print that fast if you want a pretty result.

Your printer passed the test perfectly.

 

I am fed up with how it clicks all the time

 

Is it slipping backwards when it clicks?

 

how are people figuring out what speed to go?

 

The dark blue line on this graph shows absolute fastest possible print speeds:

http://umforum.ultimaker.com/index.php?/topic/4127-um2-extrusion-rates-revisited/

I try to never go faster than half that speed. Reading off the graph you can go 70mm/sec at .2mm layers which translates to .25/.2*70 or 56mm/sec at .25mm layers. So for .25mm layers and 217C I would print at 25mm/sec. Or you can stay at 50mm/sec and raise the temperature to 250C but I don't recommend going over 240C.

240C will be hot enough to print at 50mm/sec .25mm layers.

Note that the quality isn't as good when you print faster XY speeds. For extra good quality you want to print 20-35mm/sec. But if quality is "good enough" then print at 25mm/sec 217C or 50mm/sec at 240C.

 

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