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tmrevlje

Stent printing - suggestions?

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stent

stent#2

 

I am attempting to print this stent-like model. At the moment I'm going for a shorter version so I don't lose too much time while in the "figuring out different settings" stage.

How would you guys approach a print of this type of model, it seems so brittle. I've tried printing it vertically, but the initial few layers apparently didn't stick well to the surface, only so few spots where it touches the ground. So I decided to go horizontal.

If anyone has an experiences so far with this type of 3D printing, it would be super-cool if you gave me some tips, regarding the temps, speed, flow etc. whatever would make my life easier with this particular print ;)

Thanks!

 

 

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Hi,

I haven´t printed sth. like this, but I would print it vertically and give it a try without support. For better sticking to the surface you have the option Brim. Activate this, it will help sticking to the surface. The size of the brim can be changed under expert settings. Also I would print it very slow, maybe 40mm/s or even slower. Temps depend on your material and have to be found by you through testing. If it is PLA you don´t need a very high printing temp because of the low extruded volume, but sufficient cooling. The printed layer has to be solid before the next is printed, otherwise it smears. If it smears increase the minimum print time per layer. Flow: set it to 100%. Thnik this should work. But it´s all up to you if you see sth. does not work as assumed you have to tweak the required settings. Hope this helps.

Philip

 

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Thanks Duesentrieb it's one hell of a good start, your information. Currently I'm printing it in horizontal as with the first vertical try, it tipped the model over :( and started dragging it (the nozzle) all over the place. The brim around the print was so small, I usually see larger brim around it.

So what you said about smearing the printed material is exactly what happened to me with the vertical alignment, should I lift the nozzle a bit more? Not sure.

Horizontal is going quite ok now, but I do see some "stringing" or not very well fused layers. But at 0.1 layer resolution that's what's to be expected I guess.

Check the last to pictures in the album, to see what I mean.

 

stent#2stent20140721 12190820140721 121945stent vertical settings#2stent vertical settings#3stent vertical settings20140721 134432

 

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Going for the following settings with the vertical attempt next, following your suggestions. Would you be kind enough Phillip, to check the screenshots of the settings and either slap me in the face and say you're a newb, or correct/suggest any changes that you might think would help the process.

I'm using Colorfabb's PLA material (Traffic Red) currently.

What bed temp, nozzle temp, travel speed etc should I use? Leave it at default or Tune it before print?

stent vertical settings

stent vertical settings#3

stent vertical settings#2

 

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You have to print VERY slowly. Like 10 or 15 mm/s. And cooling fan at 100% (except for the first layer of course. I generally ramp up the fan from 0 to 100% in the first 2mm build height - See Cura expert settings). Heated bed not too hot (you don't want the part to remain too soft). 55-60 °C for PLA should be enough. (Standard setting of 75°C is much too high, don't know why they keep it there..)

Make sure it always retracts at every "jump".

I wouldn't use the Z-hop feature here! This would mean a huge stress on the z-stage. It is not built for such stresses. Z-hop is great for Delta-printers which can easily move the printhead up and down. But for an Ultimaker this is not suitable if there are too many retractions (note that Cura is not just made for Ultimakers!).

I would print it vertically and with supports (touching buildplate) AND brim (20 - 30 lines). You should be able to leave the support away, but if it doesn't work that way - try with support.

/edit:

Seeing your settings, I'd change the following:

1. Lower speed (15mm/s)

2. Set "minimum travel" in the retraction settings to 0.5mm

You may actually want to adjust this setting for every model you print! If you have many small gaps which can easily be bridged without retracting, but also some larger gaps which need retracting, then you can set the minimum travel to be larger than the small gaps, but smaller than the large gaps. Then the printer will only retract when necessary for this model. And usually, it's best to only retract when necessary.

3. Set "Fan full on at height" to 2mm

Actually, you may be better off leaving this at 5mm.

If you cool your parts too quickly, they may contract and pop off the build plate. That's why you want your fans to ramp up nice and slowly. The UM2 has a pretty strong cooling setup, so it's probably best like this.

/edit:

One more thing:

About the stringing: You'll want to lower the printing temperature as much as possible, because that will reduce stringing. BUT if you print too cold, you'll get underextrusion and / or bad layer adhesion.

So, if you still have a lot of stringing, try lowering the temperature (use the "Tune" menu right while the print is running). Do that slowly, like only 5°C at a time, and then wait for 2-5 minutes and see how it changes before you go lower again.

 

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I would suggest using the brim as Duesentrieb suggests. In the recent versions of Cura, it works wonders for prints such as these. For the rest of the settings, go with JonnyBischof, except the fan. If you'll use the brim, fan can be brought to 100% even at 1mm height already.

My Colorfabbs printed well even at 190C once, but never tried the red one.

Would love to see the results, good luck!

 

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20140721 134432

It started off nicely, but then stringing began and once that started happening, the nozzle was moving some layers around and started to drag them (smear them like a brush) and as a result, the next layers weren't where they were supposed to be, so yea I aborted the print, read on stringing and pushed the travel speed to 250 so it "cuts off" the strins before they happen - let's see what that does.

Oh and I just noticed, so setting the retraction speed and length in Cura isn't helpful, since in UM2 that is done in the Tune settings of the printer... so making changes in Cura won't do anything for those two settings? :D

 

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One thing I do is put the first layer down "hot". This means a bed temp of 70 and a nozzle temp of 225. Then use the tweak at Z deleting the height value and using the layer value of 1 to reset the temps to more suitable. Contrary to what others have said, and it may just be me or the material I print, if the bed temp is less than 62, the part can be come unstuck for me. So I usually use TweakAZ to change layer 1 and beyond to something like 210 and 62. However, you might go cooler on the nozzle.

Or this could be completely wrong.

 

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