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bluesnosrap

new user confusion - messy bottom half of print

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Hi,

I've had my UM2 for a month now so i'm still relatively new to 3d printing. I'm trying to print this voronoi chess set as a gift:

http://www.thingiverse.com/thing:182824

but every time I try, the bottom half comes out looking very messy, it just looks a bit clumpy. I've tried a slower speed, higher temperature, lower temperature, different resolutions (0.1 and 0.2), but every time the lower parts look very messy. Im printing with white PLA. Im also printing the model at 0.4 times the original size because the original model is huge for a chess piece.

I'd really appreciate any help?

thanks

 

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Pictures of your failed prints together with the settings used would help.

But, if I were to have a guess I'd say lowering the bed temperature is a good bet. If you haven't changed it I believe it defaults to 70 or 75C which is way to hot IMHO (I'm assuming you're using PLA). Try 60C. Or you might even get away with a cold bed and glue if the pieces are small.

 

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This is probably a bit of a difficult print for a beginner. Did you print some simple cubes or test pieces to see if these come out fine?

It helped me a lot for my first prints to just watch the printer do it's work on a simple thing where I could actually see if the result was what I expected. It's easier to get everything well adjusted with a simple form like a cube, because you'll see very quickly if it comes out nice or not.

 

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Jonny is right, that is pretty difficult geometry for a beginner to print. You might want to first get this calibration set and see how you go printing these - http://www.thingiverse.com/thing:5573.

But you probably do not want to wait- birthdays do not J

 

I was thinking of printing this chess set. If I did I would start with…

Layer height: no more than 100 microns, probably 50 if I can wait that long

Speed: probably 15 m/s, might try 20m/s first

Bed temperature for 1st layer 60c

Extruder temp: 1st layer 210c 2nd layer onwards 200c (if you have a UM2 you may need to go higher than these)

Fans: 100% on from layer 2 (it will sort of depend on the size but that is where I would start)

Retraction: I think I would turn it off; actually I think I would definitely turn it off

 

HTH

 

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Based on my experiences with some tricky prints, I'd print these with 0.1mm layers, 30mm/s, 230°. As noted above, lower the bed temp to 60°. I'd definitely leave retraction on, otherwise you'll just get a stringy mess. Increase the retraction settings in the printer to 5.5mm at 35mm/s.

Set your minimum layer time to maybe 7 seconds - or for best results, print several pieces at once.

Set your travel speed to 250mm/s. In advanced settings' retraction settings, set minimum travel to 1mm, combing off, and minimal extrusion to zero.

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I think I am right in saying that Cura like most slicers only lets you differentiate between the 1st layer and the then all the other layers as one entity. Normally you want the first layer to be run at a slow speed , with a higher extruder and bed temperature and with a larger layer depth to ensure good adhesion of the first layer.

In principle this is because the bed may not be completely flat and you need the first layer to absorb the unevenness and provide a flat surface for the 2nd and subsequent layers to sit on.

Typical layer 1 settings would be

Layer depth 300 microns

Temperatures 5 or 10 degrees higher (although personally once I get to 210 and 60 I tend to use the same temp unless I am using a tricky filament).

Speed 20m/s or 30 m/s

No fan

It is though less important for a small item such as a chess piece than for an item which has a large base such as most of the build platform.

If you select the Advanced tab in Cura you will see initial layer thickness (i.e. layer 1) and bottom layer speed (i.e. layer1) where you can set alternate values to those you set under the Basic tab.

I do not see anything in Cura for controlling the layer 1 temperatures so I guess (and may well be corrected) that if you want to have different temps for layer 1 you set them as the print and bed temps under the Basic tab and then change the temps manually via the printer controls once layer 1 has been printed.

For that chess piece I suspect you want each printed layer to cool down as quickly as possible, especially up at the top part hence my suggested settings; whether you will get away without having any heat in the bed for layer 1 I am not sure. Possibly I guess, as the footprint of the chess piece is very small.

One way to find out…J

 

 

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Interesting Illuminarti. I procrastinated for a while over retraction but in the end figured that given the design you would do more retracting than printing! Plus the UM2 seems to be having some problems in that area for some users. You may be right but I would not put a lot of money on the table on either suggestion! I have printed the standard test cube with holes for testing bridging using no retraction and have not suffered, which I think is because the travel distance is so small, like the chess piece.

Normally I would contest that for this piece 7 seconds layer speed is probably too low but I have not run a small piece like this with the fans blasting out before so I guess you might get away with 7 seconds.

I think I will give it a go today.

 

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Granted it's late and I'm tired but I can't remember retraction as being something people have complained about a lot on the UM2. In my experience retraction works extremely well on the UM2, better than on the UM1 I would say.

Setting the minimum layer time too high on a small piece will melt it as the head will be moving so slowly that it transfers too much heat into the piece. If you need more cooling time it's better to print more than one piece at once like illuminarti suggested.

 

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I thought there were comments on this on our mega thread on under-extrusion ( I did say SOME users) but no problem I stand corrected :)

I have not had problems with using 10 secs for minimum layer time and have found that better than 6 secs which I used to use, but I agree, I do often print multiple pieces.

 

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this thread is just want I needed :) , I am trying to print a voronoi style bear on my UM1. I am printing a ton of these since the elementary kids want them.

anyway...please look at this picture, I was able to make great improvements by using the settings shared by illuminarti. and I think these are going to work, BUT there is still a bit of messy stringing.

my questions are:

1. Would this print better if I printed it bigger? I did scale down to 50% in CURA before printing since I did want to make a lot of them and smaller objects print faster with less plastic, but maybe I could do 70% or 60% and get a much better print?maybe?

2. Should these settings be tweaked at all for UM1? or am I already getting the best prints possible with this difficult model?

thanks, for any advice you have

voronoi bear tests

oh

and if the settings do not show up well in the photo. here's text versions:

Print #3 - only one printed for this test

[profile]

layer_height = 0.1

wall_thickness = 0.8

retraction_enable = True

solid_layer_thickness = 0.8

fill_density = 0

print_speed = 70

print_temperature = 220

retraction_speed = 40.0

retraction_amount = 4.5

retraction_min_travel = 1.5

retraction_combing = False

retraction_minimal_extrusion = 0.02

travel_speed = 150.0

cool_min_layer_time = 3

Print #4 a'la illuminarti - two at once printed for this test

[profile]

layer_height = 0.1

wall_thickness = 0.8

retraction_enable = True

solid_layer_thickness = 0.8

fill_density = 0

print_speed = 30

print_temperature = 230

retraction_speed = 35.0

retraction_amount = 5.5

retraction_min_travel = 1

retraction_combing = False

retraction_minimal_extrusion = 0

travel_speed = 200.0

cool_min_layer_time = 3

 

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Peetersm - the retraction settings I quoted were UM2 specific; for the UM1, I'd use 4.5 at 30mm/s - but also make sure that you're using the firmware from the latest Cura, so that the 'retraction speed bug' is fixed.

It's going to be a bit of a tricky print on a UM1, I think because of the less precise retractions that you get by default. You'll probably need to experiment with settings - making the print a bit larger may help. And maybe reducing the temp and speed some more to reduce the oozing and stringing. The UM2 addresses those problems really well, I find - the UM1, not so much.

 

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You can print this fine on the UM1 but it may be slow.

First about retraction speed. If you have older firmware (very likely) 40mm/sec is the desired speed as that results in 20mm/sec. Using 30mm/sec may result in something very slow like 10mm/sec. You want the fastest possible retraction that the extruder can handle consistently. If you have a relatively new Cura such as 14.02 you can isntall the latest firmware that fixes these bugs and set the retraction speed to a speed around 20 25, or even 30mm/sec.

Retraction distance: You want the minimum distance that brings the filament to the bottom of the tube without actually sucking air into the tip of the nozzle. If you print this you can do it in 4.5mm. If you don't print this you need more - maybe 5.5mm:

http://www.thingiverse.com/thing:46157

 

Stringing. Lower temp works better (less oozing/stringing) but this means you also then need to print even slower. Also every pla is different. Consider 30mm/sec and 210C maybe. I recommend doing the same experiment I did but in your blue pla:

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/

There's no way to get really high quality bears without printing them very slow. These are quite doable on the UM Original but it may take 4 hours per bear! Even if they are only an inch across. I'm just guessing on the print times. Cura will tell you much more accurately.

 

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Thanks again for the spot on advice! here's what I spent my weekend doing.

check list:

-UM firmware , check, at least I think so...I used the CURA 14.01 to update and now my ulticontroller says - firmware=13.12 Dec 16th 2013

-retractions clip thing - check, i have one of these http://www.thingiverse.com/thing:24363

-stringing , love that link gr5 - I want to make that a poster and hang it up in the printing room.

So I really wanted the bears to print closer to ~2hours each. so I did not go slower than 30mm/sec , I am happy with the results and I think the bears look better in person that these photos show since picts are so close up.

For this model I really needed the miminum travel to be 1.5mm see picture. and lower temp helped.

minTravel retractions Voronoi

voronoi bear tests Red

voronoi bears 50% normal size

 

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Hi again, sorry about all the delay,

i'm still not having any luck. I'm definitely out of my depth, although i havent tried calibrating yet (mainly because on the link yellowshark suggested the first test was for a .5mm nozzle rather than a .4mm like the UM2, although being the massive noob that I am, i wouldnt know if that really makes a difference).

Anyway, here are some pictures of the failed prints, and settings in places where i can remember what i used.

These were the first 3 prints, the middle one was printed at 0.2mm i believe, and one has been printed at 210, one at 200 and i think the other might have been 230 but its anyones guess which was which. I think I printed one at 30mm/s and the other two at 50mm/s.

Chess5

Chess6

This next one was printed with a lower bed temp of 60 degrees C, the bottom is still a bit iffy.

Chess8

 

 

And these ones were printed all at the same time using illuminarti's suggested settings. They looked promising at the beginning but then they came out quite rough.

 

Chess1

Chess2

Chess3

I'd really appreciate any more advice

Thanks!

 

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If you only post once every 9 days this could take a long time... maybe a month or two.

because on the link yellowshark suggested the first test was for a .5mm nozzle rather than a .4mm lik

Huh? The nozzle on the UM2 has a .4mm diameter hole so it is best to tell Cura that. You should be entering .4mm for the nozzle hole.

Okay well you need to take good notes. I usuall put a number with a permanent marker on the bottom so I can refer to my notes and see what settings I used for everything. Every gcode file on your SD card can be opened in Cura with the "load profile from gcode..." option under the File menu and you can review settings.

You need to pick one result you got - the best one - and print it again - and take a picture.

I'm not sure what's bothering you the most. Is it those tiny strings? Or the lumpyness?

Your retraction doesn't look so good. I think you will get better results on the stinging issues if you:

1) Set retraction distance to at least 5.5mm - while printing and doing hundreds of retractions you should see the filament go from the top of the bowden tube (up at the top of the arc) to the bottom but no extra retraction. You might just want to experiment yourself. I used 5.5mm on my UM2 for a few months, then I reseated the bowden in the test head so that it doesn't move anymore and now 4.5mm works better for me. I always use the max speed (I think it's 35mm/sec) for retraction speed.

2) In expert menu set both retraction distances to 0. ZERO! zero. You can uncheck "combing" for this part and it may help quality a little although I don't think this matters much for this particular part.

3) Print .1mm layers - this will help the overall quality - personally I think your quality is not too bad but you don't seem to like it so go with .1mm layers, not .2 or thicker. It will also help your stringing.

4) Print at 30mm/sec (or slower). Printing at 30mm/sec and .1mm layer will greatly increase quality.

5) Print as cold as you can. I would start out with 230C. Once the first layer is done you can go into the TUNE menu and experiment with lower temperatures. If you go too low you will get underextrusion. Here is a picture of what underextrusion looks like (second photo with white cubes):

http://umforum.ultimaker.com/index.php?/topic/1872-some-calibration-photographs/

6) Print two. This allows layers to cool more and can make a big difference.

7) Use fan - set it to the defaults which are 100% by 5mm. It will come on gradually. Make sure it really comes on - by 5mm above the bed the fans on both sides should be on (the rear fan should always be on). Don't let the fan come on suddenly or you might get some underextrusion because the PID controller is surprised and doesn't compensate until the nozzle has dropped 15C. Or you can have the head stay at 230C until the fan is on and *then* lower it.

8) Check "retraction" on the basic settings page

9) Bed at 60C

10) Travel speed should be AT LEAST 150mm/sec. This can help break the strings between "islands" of printing.

That should do it. If you are getting stringing, lower temp to 220, if you still have stringing, lower to 210. If you still have stringing lower to 200C. If you still have stringing lower to 190C. Don't go below 190C. If you start to get underextrusion, raise the temp up again. If you still have stringing at 190C then your filament sucks. White is a particularly difficult filament for stringing - at least the white filament that comes from printbl. There is something about it that is tackier/stickier than most filaments.

Next time you post something please first save the settings you used "file" "save profile..." and post the whole thing. Sometimes there is some obscure setting that you might have accidentally turned on that messes things up. Like "spiralize".

 

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I never print anything lower res than 0.06 To me, 0.1 is rough, and you'll never be happy with the output at that resolution if you're hoping for smooth prints.

Also, print slowly, no faster than 40mm/s and most definitely set your retraction settings to 0 and 0 as gr5 says.

One thing to remember also, is any FFF printer is going to have a less then perfect underside to it's prints, the only way to avoid it is to cut models up, and piece together. The blue Chihuahua head here was done this way, printed in two halves, and the skul with headphones shows a poor underside, even at 0.06

These were all printed at 0.06

 

DSC04176 small

wing 01

were head 01

1502564 10151780614651814 1564588956 N

rough smooth 004

 

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The top section of the head actually failed,

 

Yes - I know - the original has a chunk of steel or something sticking out of the head. It looks awesome anyway. I explained how it was made to maybe 300 people. "You buy this special set of 'metalic' paints that aren't really metalic and you paint it with the bronze color first then you let it dry...". Everyone was surprised how light it was when I handed it to them. There must have been 1000 high school kids on the second day - any teacher who brought 25 or more kids got a free 3d printer for their school. The kids all thought that print was great.

 

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Hey, that's great! thanks for the feedback, I was wondering how it was received.

 

Yes - I know - the original has a chunk of steel or something sticking out of the head. It looks awesome anyway. I explained how it was made to maybe 300 people. "You buy this special set of 'metalic' paints that aren't really metalic and you paint it with the bronze color first then you let it dry...". Everyone was surprised how light it was when I handed it to them. There must have been 1000 high school kids on the second day - any teacher who brought 25 or more kids got a free 3d printer for their school. The kids all thought that print was great.

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