Welcome to the SeeMeCNC Community

Guys,

I guess I have 3 questions for printing with PLA...

1) First, take a look at the pyramid. Why does the base look fine, the columns, but the top, a goooy mess? Is my tempature too high? My speed? Both?

2) Next, take a look at the nickel calibration print. That nickel (21.21mm) is suppose to fit perfectly in all spots, but the part is too small (20.69mm). I measure with the calipers on a few prints and everything is coming out slightly smaller than the intended size. Why is this? Whats happening here?

3) Lastly, those PEEK fan shrouds... ignore the half done one, it just popped off the base mid print, but the one that finished looks bad too. Is this the same reason as number 1?

Thanks for your help and time fellas. I am just getting going with my new Rostock Max v2. With the exception of these small issues, I love this machine.

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Boundless wrote: 1) First, take a look at the pyramid. Why does the base look fine, the columns, but the top, a goooy mess? Is my tempature too high? My speed? Both?

It's a goofy mess because it doesn't give the layer below it time to cool. It just keeps adding hot PLA onto squishy hot PLA. For the tip, you could slow down, but definitely get some cooling on there. Hopefully you've got that fan shroud on.

Boundless wrote: 2) Next, take a look at the nickel calibration print. That nickel (21.21mm) is suppose to fit perfectly in all spots, but the part is too small (20.69mm). I measure with the calipers on a few prints and everything is coming out slightly smaller than the intended size. Why is this? Whats happening here?

You may be able to adjust this with the extrusion width settings in Slic3r. Someone with more expertise will have to weigh in on this. I have a slight deviation on my prints as well, but so far, that tiny margin hasn't been an issue.

Boundless wrote: 3) Lastly, those PEEK fan shrouds... ignore the half done one, it just popped off the base mid print, but the one that finished looks bad too. Is this the same reason as number 1?

The PEEK shroud looks like you need a fan on it. If there already is, definitely try lowering the temp. How hot are you printing?

Great replies @TinyHead.

Gooey messes are goofy messes!!! Funny how most of them are driven by our own goofs.

Thank you Tinyhead, appreciate your comments.

Yesterday, I got the PEEK fan shroud in place, and ran the auto-tune function again to find those ki, kp, k-something numbers... Put those into the eeprom and printed another pyramid.

Same gooey mess at the top, but this time, the pyramid legs are poor quality as well. I am pretty certain that I need to drop the temperature from 210 to 190, but my biggest concern is the scale issue.

Everything is still coming out small. Sometimes almost a full mm.

Have any more tips?

You may well need to add a layer fan for the fiddly little stuff to get one layer cool enough to support the next.

Problem with "slowing down" which is the other alternative offered by many slicers on quick layers is that it leaves the hot end in contact with the puddle so the puddle stays hot. I've seen one (can't remember which, sorry) which allows a lift-off option for cooling small layers.

But I know the quality of my prints improved enormously once I added a layer fan.

The smallness is probably going to be caused by shrinking as the part cools. I'd look at getting a layer fan first, then dropping the nozzle temperature for PLA, see if that fixes it. If not, might be time to start oversizing your models by whatever percentage before you print them. Particularly noticeable with small (1/4" diameter and smaller) holes and bores.

Thanks for the tip Capt.

Today I decided to make my own calibration print using SketchUp. I made a cylinder that's 20mm wide 3mm tall and a 10mm hole inside.

The height printed at 3.30mm, so its taller than it should be.

20mm came in at 19.64mm
10mm came in at 9.28mm

I got the temperature worked out I think. I haven't printed another pyramid but does anyone know why the size is coming out short on the sides and taller on the height?

Try reprinting the part at twice the height and see if it is still off by the .3mm
If it is then check to see how high the nozzle is off the bed on the first layer.
If the error in height doubles then I would be checking the steps are set correctly.
Chances are though that your first layer is printed a bit high causing the error.