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swq0603

What is the "meterial flow"?

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Hi,

Now I am using the UM2 machine and I find that there is too much meterial from the nozzle, so the model is not smooth. I check the meterial flow , it is 100%. Can I adjust this value to a smaller one to fix this issue? Generally, what value should I set for my printing? Thanks a lot.

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I am using the PLA, the temp is 210 and speed=90. The flow is 63%. The pic is as following.From the pic 1, I think it is not a overextruding issue since there is still a little gap between each line. But from pic 2, I use the same parameter, it looks like overextruding. Now I suspected it is a cooling fan issue, maybe the fan speed cannot meet the requirement, which make the meterial cannot be cooled quickly. Then there is a poor surface. Not sure whether someone also hit the similiar issue before. Hope you can give some suggestions.

Pic1:IMG_3049.thumb.JPG.9c5638f50268ba0a68aae6f66f2fd8fa.JPG

Pic2:IMG_3010(1).thumb.JPG.9c062f676258b9e7f9962537453209cb.JPG

IMG_3049.thumb.JPG.9c5638f50268ba0a68aae6f66f2fd8fa.JPG

IMG_3010(1).thumb.JPG.9c062f676258b9e7f9962537453209cb.JPG

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You have 2 completely unrelated issues.

Bottom picture:

The top of Marvin is too small and doesn't have time to cool. No amount of fan will help - the only fix is to print something else nearby to give marvin 3 seconds to cool between layers so the nozzle isn't always touching molten PLA and keeping it hot.

Usually I will just print 2 marvin's side by side. Alternatively you could print a tower. Make sure you are in "print all at once" mode otherwise it will print one marvin and then print the next and both will have bad top.

Top picture:

Try to keep the flow always at 100%. 90mm/sec at 210C and .2mm layers is too fast - you will get underextrusion (as shown in photo).

Here are my recommended top speeds for .2mm layers (twice as fast for .1mm layers):

20mm/sec at 200C

30mm/sec at 210C

40mm/sec at 225C

50mm/sec at 240C

The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.

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Thanks gr5 for the explaination. I think I hit not only one isssue with my machine. The first one is the over extrusion as I mentioned in this thread, which I have fixed it by changing the wrong step per unit value in my firmware. But when I printing the Marvin again, the surface of it still not smooth just like the bottom picture. I suspected it is related to the cooling fan. Since I changed a new fan days ago. Maybe the fan speed cannot meet the requirement. So I kick off another thread for help. Is it because the cooling fan? Yes, also I think the 90mm/s is a liitle fast for my printing, which can cause the under extrusion. But in my printing, it looks like the over extrusion. Do you think it is related to the cooling fan? Thanks in advance!:)

 

You have 2 completely unrelated issues.

Bottom picture:

The top of Marvin is too small and doesn't have time to cool.  No amount of fan will help - the only fix is to print something else nearby to give marvin 3 seconds to cool between layers so the nozzle isn't always touching molten PLA and keeping it hot.

Usually I will just print 2 marvin's side by side.  Alternatively you could print a tower.  Make sure you are in "print all at once" mode otherwise it will print one marvin and then print the next and both will have bad top.

Top picture:

Try to keep the flow always at 100%.  90mm/sec at 210C and .2mm layers is too fast - you will get underextrusion (as shown in photo).

Here are my recommended top speeds for .2mm layers (twice as fast for .1mm layers):

20mm/sec at 200C

30mm/sec at 210C

40mm/sec at 225C

50mm/sec at 240C

The printer can do double these speeds but with huge difficulty and usually with a loss in part quality due to underextrusion. Different colors print best at quite different temperatures and due to imperfect temp sensors, some printers print 10C cool so use these values as an initial starting guideline and if you are still underextruding try raising the temp. But don't go over 240C with PLA.

 

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