Getting started: settings, tips to nice prints

[illuminarti 18]

I think 250 travel will be fine. Since it's not extruding during those moves, it doesn't greatly impact visible quality - indeed it helps improve quality by reducing stringing, and the amount of ooze time on moves. I use 250 for everything, unless I'm worried about knocking over fragile parts - like tall meshmixer support, which I don't think will be an issue on this one.

The only possible issue would be that the prints might totally fail if the new printer's motion is too stiff/not fully bedded-in and it just can't do 250 yet. But then you'll know because the layers will stop lining up properly - in a big way.

But it will probably be just fine, so don't worry about it unless you have to :-)

[tomaszklos 1]

ok great. so far the print looks good. I can see there is some small debrie inside the hexagon shaped hole. Also the free bridge next to the arc caved in a little on the first layer or two but then became solid. Pictures later will show what i mean... other than that looks good, at least to me...

 

[gr5 2,224]

250mm/sec should be fine. But it probably never accelerates up to that speed on a small print like this.

 

[illuminarti 18]

If

You haven't already, you should tweak your retraction settings in the printer to 5.5mm at 35mm/s.

Also, what retraction settings do you have in Cura's 'expert' settings?

[Nicolinux 288]

Ok, note taken. 250mm/s sure sounds scary. Gotta try it too

 

[tomaszklos 1]

Yes the retraction setting was set on the begining to 5.5 and 35. I dont see any settings in the cura for the retraction....

 

[tomaszklos 1]

the only thing about retraction in the cura i see that is ENABLED.

 

[tomaszklos 1]

minimal extrusion before retracting 0.02mm is that what you are looking for?

 

[illuminarti 18]

Yes - there are 3 settings with that one in expert settings... Minimum travel - you probably want that to be quite small - 1.5mm or so - since any move under that size will not have retractions, and so may cause strings.

Minimal extrusion can probably be set to 0 for the UM2 - that's the minimum amount of filament to feed in, after one retraction, before another is allowed. It may be helpful on the UM1, but I'm not sure its needed on the UM2, provided the minimum travel setting isn't so small that it retracts at the end of every line of solid infill.

The third setting is 'enable combing'. I recommend turning that off when quality matters; when turned on, it tries to always move the print head inside of printed parts when it can, rather than crossing edges (and potentially damaging them). That is a good thing, but the flip side is that when it is enabled, it always turns OFF retraction for those moves. That causes the head to ooze - which can damage exposed top and bottom surfaces, and also cause under-extrusion temporarily when the head starts doing the perimeter again, as the pressure has to build back up in the print head.

 

[tomaszklos 1]

I feel so stupid now... How did I not see all these settings. It says RETRACTION in capital letters hahaha...My fault.

Minimum travel is @ 1.5mm

Enable coming YES

Minimal extrusion before retracting 0.02mm

That what it is now.

 

[tomaszklos 1]

Small update of the print. I see the ARC on the back of the print (one of the legs) got pushed over and its printing "junk" on that leg...

 

[hieronymus 0]

hehe, yeah that arc is a tricky one :smile:

as with all overhangs the general rule is cool and slow, for a specific feature like that I usually go back to 25-30 mm/s printspeed and around 200C.

Also manually increasing the fanspeed during those last couple of layers in which the overhang is most extreme (just before the two halves of the arc meet in the middle) may help, although if you cool too much (especially the nozzle) you might harden the plastic before it exits the nozzle which will at first start to lead to under-extrusion and eventually a clogg. So it's one of those interesting balancing-acts you're going to have to get a feel for.

Also, in general, lowering the layer-height will make overhangs better, because the overhang approaches more gradually and it takes a steeper angle befor the entire width of the nozzle-diameter in a new layer is no longer supported by any layers beneith it. (Am I saying that right, steeper? or do I mean flatter?...not really sure if I'm explaining this all that well, anyway.....)

If the rest of the torture test is going well or is at least to your satisfaction, you can further test your 'overhang-skills' :grin:

without wasting time and filament by using this model: http://www.thingiverse.com/thing:174611

 

[tomaszklos 1]

Good morning.

Ok the "Torture_test" is done. 3 things I see that I'm having issues with is

1. There is some small "junk" inside the hexagon shaped holes. Nothing in the round ones.

2. The "arc"

3. The longer bridge on the side of the arc, the first layers are stringy, then it started to look ok.

Thanks to Hieronymus I have the file just for the ARC. I want to practice this. Any tips on how to tackle it??? Thanks

PS: disregard the "sharp" edges on the bottom of the whole thing. I didn't cut the brim very clean, i just ripped it away by hand.

 

[illuminarti 18]

The only thing that really looks wrong with your arc is that the left part fell over. Because of that, the upper layers didn't have anything to print on. Overhangs like that are going to tend to curl at the edge slightly, and if the head hits them, it can tend to knock them loose. It's especially a problem with this piece because it has a lot of overhang, and only a very small footprint sticking it to the bed.

So the main way to avoid the problem is to make sure you have glue well applied, and more brim to help keep the part anchored. You could try reducing your travel speed so that the head is moving more slowly when/if it catches the edge of the arc, and printing colder and thinner layers might help reduce the curling.

But mostly, I just wouldn't worry. It's called a torture test for a reason. It's not supposed to be something that can be printed with great reliability - and arguably that's as much about the poor design (from a 'printability' perspective) as it is about the capabilities of the printer.

In general, the print looks pretty good; the stringing on the hex hole is probably due to your 'minimal extrusion' setting.

 

[tomaszklos 1]

Thanks for some words of hope... I tired the modified version of that print with just the arc. Few things I adjusted:

print speed 25mm/s

layer 0.06mm

temp 200C

travel speed 200mm/s

minimal extrusion 0.0

enable coming OFF

 

[tomaszklos 1]

I noticed that my brim and the very first layers didnt print. I think i might have mine plate a little too close. Next I downloaded some prints to test the overhangs and the bridge. Will see how that is going to come out.

 

[illuminarti 18]

I have a better idea...

Just print things you want to print. Things that are useful, or pretty, or relevant to your work. You can always find things to print that will fail - intentionally or otherwise. What's more relevant is figuring out how to best print the things you actually want/need to print. And for those, experience is key. Print them, and see what happens.

There are no right/wrong settings - everything is a tradeoff. Some things are easier to print than others, but it will take experience to figure out how to get the best from the printer - and not experience of test pieces, but of the real things you want to print. The technology has limitations, and you have to learn to live with or work around those.

Your printer is clearly set up pretty well - it's covering all the bases ok... start having some fun using it; printing lots of tests will just confuse you at this point. There are quite a few variables to manage, but mostly comes down to speed, temp and layer height. If you spend all your time as a new user printing things that are basically designed to fail at some point, you'll just disappoint yourself. :-) Focus on printing the things that are important to you, and worry less about others' ideas of perfection :-)

 

[tomaszklos 1]

Also during the print I was watching the approach of the head to the overhangs. It does enter from the side where the overhang is happening. How would i change the direction so the head will come into it from the other side (from the outside of the arc not the inside, through the overhang)?

 

[tomaszklos 1]

Hahahah thats good to hear. I always seem to start from the most difficult tasks and make them right. But in this case you are right. Tweaking something that was designed to fail will be pointless. Something that I want to print and getting that right that is what this should be about. Ok then. I'm going to look through designs and find something in mid range if it comes to difficulties. Will let you know soon... thanks a lot

 

[gr5 2,224]

How would i change the direction so the head will come into it from the other side

 

Yeah - this is a feature I'd like to see in cura - the nozzle should always head off an "island" (as we call it) towards the overhang edge and into the air instead of the other way around (when it leaves the island). This would be an awesome feature.

No I think you missed a very important point Illuminarti made. The way to fix the arc is to get the part to stick better to the bed.

There are lots of tricks to get the part to stick. Some of them are here:

http://umforum.ultimaker.com/index.php?/topic/3404-printing-on-glass/

Also I've found that wood glue&water works even better than glue stick and lasts "forever".

 

[illuminarti 18]

Sounds like a good plan :-)

There's no way to control the tool path manually in Cura, although we have discussed some ways that it could be optimized here on the forum, and I know Daid (the developer of Cura) is considering at least some of them. For instance, avoiding crossing printed parts when moving between areas would be useful for prints with multiple freestanding parts. There are some smarts already when moving within areas (the combing setting) but it currently moves in straight lines between parts. Also, I had suggested recently looking to see if print islands could be approached from the non-overhanging side whenever possible - for exactly the reason you mentioned.

[tomaszklos 1]

Nice. That would be very helpful. I found a cool, simple planetary gears set. Printing it as we speak. Guys here would like to see some mechanical parts that are actually printed, specially bolts and nuts, which this project has. Adjusted the settings back to where i was comfortable with and we will see how that goes. So far so good, brim is down.

 

[tomaszklos 1]

Good morning.

So the gear set is complete. Everything seems to be there and the quality looks very good. I'm going to cut it all out from the brim, clean it and put it together. We will see if it works

 

[DidierKlein 729]

Nice print it looks like the town of winterfell from game of thrones

 

[3d-magic 0]

Looks nice Tom! May I ask where you've found this gearset? Think it would be a good excercise for me also. :-)