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happy-robot

Ghosting comparison with UM original and UM2

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Hi everyone,

Before anyone wonders I will start by saying that the word on the opener in the picture is an internal joke between me and a friend and has very little to do with this topic. It was just the model that I printed when I realized there was a difference in printing quality between our Ultimaker original and our UM2.

Ghosting comparison

This is my first post in the forum but I am an old Ultimaker fan and user.

We have an old Ultimaker original (about 2,5 years old) at our office and since we bought an UM2 it has not got the attention it deserves =(

But yesterday we test printed the classic bottle opener just to see if it was still working and as always, it worked like a charm =)

This is the model: http://www.thingiverse.com/thing:6661

And I just made holes for the text in cinema 4D

I felt that the print came out really nice. I would say nicer than in the UM2...

So I decided to take the same SD-card with the same UM1 g-code and print it in the UM2, with the exact same roll of filament. So the only difference would be the machines and the heated bed.

What we saw was that there's a lot more ghosting on our UM2.

In the attached picture I have increased the contrast so that it's easer to see the difference.

You may for example look at the part by the hole in the back of the opener (see the circle on the left side) or anywhere around the text. You can also see it at the curve in the model in the middle (it starts around the end of the D and ends around the A, where the light reflects on the model)

There was also an issue with the first layers, where the UM2 had problems printing the angle of the first part of the print (the bottom part of both models, see the green circle on the right side).

This is a bit hard to explain but i will give it a try.

What happened was that the layers got slightly warped around the edge since the angle and the layer height didn't place that much material around the outer perimeter on each layer. So the layers bended a bit inwards but as the layers became bigger in area the problem fixed it self.

That is why it looks like there's a notch in the angle caused by the warp and then the layers on top attached to that warped edge.

I had no problem getting the print to stick to the bed, so no warping there. It was just the outer perimeter on each layer that got a bit warped once it started to print the overhang.

Has anyone else experienced these issues?

 

A few notes on settings and the printers.

The settings in cura:

100% infill

0.1 layer height

40mm/s print speed

The Ultimaker 2 had the printbed set to 60C

It should also be noted that we have upgraded our Ultimaker original with an Ulticontroller and and the special CNC pullies from Foehnsturm.

http://umforum.ultimaker.com/index.php?/topic/1611-fixing-pulley-innacuracy

This could of course be part of the issue but it still feels like and interesting discussion. I hope you all agree.

Thanks

 

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Hi Happy! (Or do you prefer 'Robot'?) :-)

I've also noticed a little more ringing on some prints, and also a tendency to get vertical banding that appears to be related to belt tooth pitch. It shows up more on certain shapes and plastics: it was quite visible, for instance, in the side panels on a Tardis that my daughter printed last weekend:

Tardis

 

I suspect that lowering the acceleration from it's default of 5000 to a lower value like 3000 (which was the default on original UM's - at least until quite recently), or even 1500, might make the effect less noticeable. I'll do some tests - you might try lowering the acceleration (via Maintenance -> Advanced -> Motion on the UM2 controller) and repeating your tests.

 

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Ghosting = Ringing

Same thing - different words. Ringing is indeed fixed by reducing acceleration. It's amazing how little it slows down a print. Note also that if you change this and power cycle the machine it probably will lose your setting. I'm not sure how to save the acceleration value on the UM2 - there might be a save option in there.

Regarding the overhang/notch issue:

Typically this is fixed best with the fan. Were both fans on the UM2 at 100%? Many people got UM2's with the fans not working - takes seconds to fix as the connectors simply pulled out - let us know if this is the problem. Also Cura now has a new way to turn the fans on very gradually on the UM2. It sounds like you didn't use the latest Cura though.

How to check all 3 fans real quick on UM2:

1) Turn on the UM2. Before even the lights come on the 3rd rear fan should come on. Make sure it does.

2) Select "PRINT", choose a print from the sd card, then quickly go to TUNE menu. As long as you stay in TUNE menu it will not print and you can just hit the power switch when you are done with fans because as soon as you leave the tune menu it is likely to start printing.

3) In TUNE menu set fans to 100%. Make sure both side fans spin. make sure both blow and not suck. If you set speed to 0% and gradually increase they should come on for sure by 30%. Probably closer to 15 or 25%. Once spinning they will continue to spin even down to around 10%.

 

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Thank you illuminarti and gr5 for quick responses.

I will definitely try to print it again with lowered acceleration.

Regarding the angle/notch

All three fans are working properly. I had to change polarity on the hot end fan when the machine was delivered but other than that they have worked fine. I have tried different speeds on the fans in the tune/fan menu and it's no problem there.

The Cura used for slicing was 13.12 since it was actually sliced before christmas. I will double check if the fans turn on gradually but I believe they do.

The fact the the UM2 doesn't save all the setting when its power cycled is a bit annoying but I'm aware of that since I have played around with the retraction setting a bit when printing support with meshmixer 2.0.

It seems that some settings are easier to save than others and that you sometimes can exploit that by "fake" changing that setting as well (like the LED strips), thus getting the one you want changed to be saved but I have not got any consistent results.

Anyway, I will get back to you with a print with changed acceleration and the same g-code.

 

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I have learned more about this issue in the months since (the lower right green circle in original photo) and it is most easly fixed by lowering bed temp to 60C. Oops - it *was* at 60C. Well what I said earlier then - get that fan on sooner. Or slow things down. Or go down to 50C. The problem is that the lower levels are still too hot when the next layer is laid down and the lower level is pulled inward at corners.

 

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