printing imperfections - kossel 2020

Hi all,

Finally, after much help from all of you, I am able to print structures with support that can be relatively easy to remove, and the structures don't look to be over-filled.
- I always print with a raft otherwise I often have issues with the first layer peeling off when I put on my subsequent layers.

Here are a few prints I've done, there are a few points I'm not too satisfied.

1- the top of shapes does not look complete. We can see the strands and the unfinished structure.
-->1644 shows the top of what should be a skull, but you can see a flat circle on top of the skull.
-->1648 shows the top of a cup which is not smooth
--> 1650 and 1652 show the top of a hunger games pin that is not

2- the bottom of the shapes looks like it is not filled either once I remove the raft.
--> 1645 --> This is the bottom of the skull I printed. As you can see, it is very rough, and has a lot of lines on it.
--> 1649 --> This is the bottom of the cup I was printing. It is not flat so the cup does not stand properly. Additionally, this cup is supposed to be made of one straw so you could drink from the top straw and it drinks water from inside the cup into the body of the cup and to the tip, however, it leaks!
--> 1651 --> this shows you what the bottom layer looks like. It is quite unfilled. I'd like it to be more filled.
--> 1653 --> this is a case where the raft was badly removed. Shows you how the raft would look like

Does anyone see anything obvious and corrections I need to make to make better prints?

The problems on the top looks to be cooling related. When the print area gets smaller the plastic don't get a chance too cool and get set before new hot plastic is added and the print simply melts. More fan on the print and the "Minimum layer time" and "Cool head lift" settings in your slicer can help. Also cooling can get worse the higher the print is, if a fan blows down towards the print bed the air is reflected close to the bed and the colling is much better then higher up.

What temperatures are you using at the hot end and bed and what kind of filament?

I just installed a fan and duct. It really does appear to make a big difference in quality. I couldn't print anything sphereish shaped because the wispy edge stayed to warm and curled until the nozzle knocked the part off the bed. As you can see, this "Professor Farnsworth" head ( my printing nemesis ) has some fine surface detail. Fan running at 100%. PLA @ 170c, bed @ 70c and 30mm/sec speed.

Slowfoot:
I only have a fan blowing on the heatsink of the hot end. I am printing in PLA 1.75mm (measured to be 1.68mm) with hot end temperature of 200C, and a hotbed temperature of 70degrees for the first layer. THen 195C and 55C for subsequent layers. Should I change these?

I don't see the "Minimum layer time" and "Cool head lift". I have Slic3r version 1.1.7. The closest settings I have are filament settings-->cooling-->cooling thresholds-->slow down if layer print time is below: 30s and nothing similar to "cool head lift" except for Printer settings-->Exruder 1-->Retraction-->lift Z: 1mm
Would those work?

Elwood:
I see you have a fan blowing in a vent toward the printed parts to further cool it. Do you connect the fan to DC or to a controlled output?

Long time since I ran Slic3r. IIRC there is a setting that slow the printer down if the layers are small. I had trouble with the radiation heat from the hot end melting the top layers but I don't remember what setting it was. Also resulted in very long print times. I switched to the Cura engine, pity cause I liked Slic3r better.
A extra fan to cool the print, as in elwood127's pic will help you a lot.
You can always try to lower the temperatures in 3-5 degree steps or better, run a print temperature calibration.

I've just printed a temperature calibration pattern. I'm not sure the temperatures were correct and you will see in the results. I printed this pattern.

[www.thingiverse.com]

I added M104 commands all over the place to change temperature every 1cm.
From the print shown here shows how a curved groove is under each temperature. It looks like the part at the top of the print is the best, with nozzle head is 225degrees.

A nozzle temperature of 170degrees really did not perform well. But this might also be because it was close to the bed which was heated at 55degrees.
Temperatures of 180degrees performed ok but we can see more striations.

This would suggest that my prints would look better at higher nozzle temperatures. Does this make sense?

If this is the case, then why would we need a part fan as it'll bring the print temperature down too fast?

Edited 1 time(s). Last edit at 11/12/2015 01:25AM by djtrance2.