Different printed holes between UM2+ and UM3

[dmitsas 0]

Greetings all,

 

We currently have 3 UM2+ and 1 UM3 printers. The problem we have is that the printed holes in the UM3 printer are smaller compared to the parts that come out of the UM2+ printers. We are of course using the same files in both types of printers. Is there a way around it, something that doesn't include having 2 different sets of drawings for the two types of printers that we have?

 

Thank you for reading me.

[Smithy 1,146]

Holes are always a problem and comes out slightly smaller than designed. The difference between the two printers could be the speed and jerk settings. The UM3 print head is heavier than the UM2, so there are other default settings, specially the jerk speeds. So to get a consistent result, you have to play with these settings. Slower speeds and slower jerk speeds (best to set it to the same value as the print speeds) helps a lot. And equalizing the print speeds (inner, outer wall, infill, ...) helps too.

[dmitsas 0]

Hello Smithy and thank you very much for the reply. I will forward your suggestions to our engineer.

[gr5 2,234]

The machines are more similar I think than their profiles.  I would check all the settings and see what is different.  Make the speeds the same speed for all printing speeds (on both UM2 and UM3).  For accuracy, disable accel and jerk control on both machiens.  Make sure line width is the same - pay attention to the "outer before inner walls" - make sure they are the same.  Speeds the same.  Temperature the same.  And if you are lucky the shrinkage for vertical holes will be the same.  I usually increase my hole diameters by 0.4 to 0.5 in cad and leave it at that.

 

Another choice is to drill out the holes after.  It's very easy to drill out holes when they are already within 0.3mm of desired size.

 

[geert_2 558]

My experience is that usually I have to drill out holes anyway, because of occasional little blobs, strings and hairs. I also tend to make them 0.5mm wider in CAD than necessary: thus 4.5mm for a 4mm hole to slide an M4 bolt through. And then I *manually* drill it out (see photo). This only takes a few seconds. No electric drilling, especially not in PLA, because it melts immediately.

 

 

Edited November 4, 2019 by geert_2