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Ronan

Printing PLA flat (minimize seam lines)

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How do you guys print with PLA for perfectly flat prints against the glass?

I keep getting corners lifting just enough to create a ugly seem line.... Which is annoying because the bed is perfectly leveled and even printing with a brim or a raft the issue persist... It seems to happen when the edges/parts are thinner and the prints are long (a few hours to 12+ hour long prints).

I use standard Ultimaker 2+ PLA settings (in a heated chamber, bed is set at 70 degree's). Do i go hotter bed? Colder bed?

Thanks :)

Edit:

Settings used:

I tried 3 prints with Colorfabb PLA Sky Blue and with Colorfabb PLA Dutch Orange. Both came out with the exact problems.

Print/Cura Setting:

Layer height 0.1

Shell thickness 1.2

Retractions On

Bottom/Top Thickness 0.72

Fill Density 22%

Print speed 30

No Support

No Platform Adhesion (i tried brim and raft, same issue happens, less on the raft but the bottom 'flat' quality suffers too much)

Nozzle Size 0.4

Initial layer thickness 0.15

Initial layer line width 100%

Travel speed 120

Bottom layer speed 20

infill speed 50

top/bottom speed 20

outer shell speed 30

inner shell speed 40

minimal layer time 10

Cooling fan ON after 0.5mm

Printer Setting:

PLA Setting of 210 degree, Heated Bed 60 degree, Flow 100%, Fan 100% (turns on at 0.5mm layer height).

Edited by Guest

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Hi Ronan,

I think your problem is called Elephant feet (see image below).

What you can do to prevent this, is turning down your bed temperature, or make the gap between your bed and nozzle a little bit bigger.

Normaly i print PLA at 60°C bed temperature (PLA does stick very well to a degreased glass plate, so high bed temperatures are less necessary than with ABS for example.)

Prints with a big touching surface between the glass and object even lower, about 55°C bed temperature

Hopefully this helps you out!

file-NZnhvOw08g.jpg

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Thank you, i will try to lower the build temp.

I am not sure if the elephant feet is the issue, since to me it seems to 'peel back onto itself' on the edges, but maybe thats a side effect of the elephant feet after hours being heated at 70 degrees...

I will try tonight :)

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Well it is a trade off. It is caused, intentionally or not, by having the nozzle closer to the print bed so that the filament is well squished to improve adhesion of the first layer. You probably have your nozzle too close to the bed so increase the gap to remove the elephants feet. If you then have trouble with adhesion, obviously test to make sure you have not moved it too far away but if the feet come back then try to address the adhesion by a method other than using the nozzle distance. It is perfectly possible, I have good adhesion and no elephant's feet

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I have perfect adhesion, the problem comes from the print touching the glass curling back on the edges. I don't have a macro lens so i can't take a photo, but instead of everything being flat, i'll have 1-2mm of plastic that seems to melt after a few hours touching the bed and then curls backward creating an ugly seam.

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When you say it curls backwards. do you mean that the corners are lifting 1-2mm? I read you 1st post as saying this only happens at the corners.

You also said that it happens when the edges are thinner and the prints are long. Are you saying that the base may be just a mm or so, the model itself is a lot taller?

A pic of the melted 1-2mm would be helpful. I printed this today, the piece is 1.6mm tall. I have also printed quite a few similar type pieces almost the size of the build plate without the problems you describe.

Sat.JPG.a74e5c31e263e529a0ca7742d7bfe1f6.JPG

Rounding the corners, as in my pic, rather than having right angles will help corner adhesion, been there done that. Also maybe reducing your bed temp. to 50 or below after layer 1 may help too - I do not do that but I know others who do.

1-2mm melted at the bottom sounds extreme. Have you checked you bed temp. during the print with a digital thermometer to make sure nothing is wrong there, i.e. it is 60-65 and not 105?

I have done pieces as you describe for a few hours but nothing like 12+; I wonder if anyone here has experience of that?

Sat.JPG.a74e5c31e263e529a0ca7742d7bfe1f6.JPG

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It happens on sharp corners but on rounded corners too (less though), which are usually thinner but sometimes they are not.

Imagine a cylinder i am printing vertically. The edges of the cylinder against the bed are going to curl up a bit. If i glue 2 ovals together, they won't match up perfectly and i have to use filler/sand/paint which kills my profit.

My bed temp is a consistent 60 degree's throughout the print. If i print 1 part and it takes 1 hour it's fine, but if it takes longer the edges will start to curl up. If i am printing 5-6 parts and it takes 8-12 hours (which is very common), then the edges will get that 1-2mm curling upward and i have to use filler and then sand it when gluing the parts. It goes from being a 10 minute gluing job to 1-2 hours...

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OK if you want to drop your cylinder somewhere I will try the print so we can see if the problem is inherent or specific to you. If you could post your settings too that would be helpful. Are you printing one at a time or all at once?

What adhesive are you using? I always use hairspray on my glass bed and will be using that - you might want to try it.

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Ronan next time show a photo - cell phones have great macro lenses built in. yellowshark was giving you the wrong advice as you are describing "warping corners" and not "elephant foot". Anyway you need to get your part to stick to the glass better:

lifting corners, curling corners, part sticking to glass

1) Make sure the glass is clean if you haven't cleaned it for a few weeks. You want a very thin coat of PVA glue which is found in hairspray, glue stick, wood glue. If you use glue stick or wood glue you need to dilute it with water - about 5 to 10 parts water to 1 part glue. So for example if you use glue stick, apply only to the outer edge of your model outline then add a tablespoon of water and spread with a tissue such that you thin it so much you can't see it anymore. wood glue is better. hairspray doesn't need to be diluted. When it dries it should be invisible. This glue works well for most plastics.

2) Heat the bed. This helps the plastic fill in completely (no air pockets) so you have better contact with the glass. For PLA any temp above 40C is safe. I often print at 60C bed.

3) heat the bed (didn't I already say that?). Keeping the bottom layers above the glass temp of the material makes it so the bottom layers can flex a bit (very very tiny amount) and relieve the tension/stress. For PLA 60C is better than 50C. 70C is even better but then you get other "warping" like issues at the corners where they move inward but if you are desperate it's worth it. For ABS you want 110C (100C is good enough).

4) rounded corners - having square corners puts all the lifting force on a tiny spot. Rounding the corner spreads the force out more. This is optional if you use brim.

5) Brim - this is the most important of all. Turn on the brim feature in cura and do 10 passes of brim. This is awesome.

6) Squish - make sure the bottom layer is squishing onto the glass with no gaps in the brim. The first trace going down should be flat like a pancake, not rounded like string. don't run the leveling procedure if it is off, just turn the 3 screws the same amount while it is printing the skirt or brim. Counter clockwise from below gets the bed closer to the nozzle. Don't panic, take a breath, think about which way to move the glass, think about how the screw works, then twist. This may take 30 seconds but it's worth it to not rush it. You can always restart the print.

If you do all this you will then ask me "how the hell do I get my part off the glass?". Well first let it cool completely. Or even put it in the freezer. Then use a sharp putty knife under a corner and it should pop off.

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I tried taking photos with my new cell, it all comes out quite blurry. I did buy a new camera so should make life easier!

1) Glass is spotless, everytime. I'll try the glue stick trick, i'v been told (and printed a lot) on bareglass and it alwaya comes out great... but not those new prints :(

2) Bed is always set at 60 degree's when printing PLA, in a closed environment (ulti door+hood)

3) See above :)

4) can't round those corners

5) tried with brim, it actually lifted part of the brim where the edge lifted and curled back (rest of the brim was fine, but it created a 'lifted pocket' where that corner was). Also brims DESTROYS the finish every time so its a huge hassle (it leaves nasty marks/etc and all the sharp edges are gone).

6) Iv leveled it, to what i think was perfect, now i wonder. I'v printed tiny parts perfectly, but all on round bases... Now those need a perfect fitment and it's just not working out and driving me nuts (at 10ish hours per print, it's such a waste).

I always let the parts cool off completely, they just pop off = yay easy. Learned that one the first day after wanting to get something off quickly and breaking it! lol

I'll check my bed alignment for the 100th time and try the pva glue trick to see if it helps (and go back to using brim).

Edit: I have added the settings to the original post.

Edited by Guest

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Imagine a cylinder i am printing vertically. The edges of the cylinder against the bed are going to curl up a bit. If i glue 2 ovals together, they won't match up perfectly and i have to use filler/sand/paint which kills my profit.

 

My advice in this case: print it on a cold buildplate, covered with bluetape (like on the UM2go).

Don't forget to re-level the buildplate (because of the bluetape...) and clean the tape with isopropyl alcohol before printing (to get the wax off).

Benefits are: strong adhesion on the tape and a nice rough surface on the bottom - perfect for glueing.

as an explanation:

You're printing with a lot of cooling fan. The plastic shrinks at the higher layers and curls up the edges, because the lower layers are still soft (above the glass temp). It's not a big problem for large flat objects, but for other things (like tall boxes) a cold buildplate works much better.

Edited by Guest

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I'll try that Tinkergnome, picking up some of that hairspray to try that first and then your cold methode. I tried a new print last night, of a different model i created that i am able to share, the same issue happened, this time i used Valcrow's setting and it didn't change anything.

Photos:

This is the bottom of the part that prints against the glass, you can see on the left it lifted:

IMG_20160425_131443.jpg

2 Parts attached, blah! Unusable :(

IMG_20160425_131530.jpg

Printer Settings, clean heated glass:

Layer height 0.09

Shell thickness 0.8

Bottom/top thickness 0.8

Fill density 20

Speed and Temperature

Print speed 40

Support None

Platform adhesion None

Nozzle size 0.4

Initial layer thickness 0

Initial layer line width 100

Travel speed 170

Bottom layer speed 20

infill speed 50

top/bottom speed 20

outer shell speed 30

inner shell speed 40

minimal layer time 10

Cooling fan ON after 0.5mm

PLA Setting of 210 degree, Heated Bed 60 degree, Flow 100%, Fan 100% (turns on at 0.5mm layer height).

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I wish I could see your pictures. All of your posts Ronan and no pictures still :(

Blue tape works great but glass is better for most prints I think. More convenient.

For small parts I often level at the normal/nominal leveling height that the procedure suggests and the bottom layer is indeed .3mm thick. But for 95% of what I print I want it to stick so I level it much closer such that the bottom layer is thinner than .3mm even though I tell cura to make it .3mm.

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I wish I could see your pictures.  All of your posts Ronan and no pictures still :(

Blue tape works great but glass is better for most prints I think.  More convenient.

For small parts I often level at the normal/nominal leveling height that the procedure suggests and the bottom layer is indeed .3mm thick.  But for 95% of what I print I want it to stick so I level it much closer such that the bottom layer is thinner than .3mm even though I tell cura to make it .3mm.

 

I put up a few photos, i don't know why your browser isn't showing them...

I have done 2 test prints, with glue stick it eliminates 80% of the issue, with pva/water mix about 90% of the issue. I will try with Aqua Net Hairspray tonight.

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Hi Ronan, with the Aqua Net something I for got to mention. Just sometimes on the first print I might get a bit of unstickiness. Removing the plate and applying another two coats fixes it. Now an Intelligent person might say, well it that case apply four coats the first time dumbo! Just a habit I have gotten into :)

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Thanks, well i have bad news... i thought the prints came out fine... they did not. While the peeling/curving back has been greatly reduced it's still a bit there... and much worse, the parts are no longer straight!

Part_21.jpg

http://s32.postimg.org/5k7miok44/Part_21.jpg

The edge on the left/right of the parts are suppose to be straight. What a mess! Since those parts are suppose to connect, it looks horrible...

Any ideas?

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Hi Ronan, for your latest post, were the settings you used exactly the same as the settings you used for the print that posted success with at April 25th 10:28? If so were those settings for both print jobs the same as you posted April 25th 7:30? If not what were the differences. Also was the same filament used for both jobs and was the ambient temp. the same( all but dammit)? Anything else that was different between the two jobs and were the models the same?

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Hi Ronan, for your latest post, were the settings you used exactly the same as the settings you used for the print that posted success with at April 25th 10:28? If so were those settings for both print jobs the same as you posted April 25th 7:30? If not what were the differences. Also was the same filament used for both jobs and was the ambient temp. the same( all  but dammit)? Anything else that was different between the two jobs and were the models the same?

 

Everything the same except: Part was printed at 1.5 scale instead of 1.25 (so it was bigger), and i changed the bottom layer from 0.25 to 0.3.

I'm going to try again, but with a raft (and using the glue). I'm curious to see if the raft will help prevent the bottom deforming and stop the rest of the curling. I had to get it spot on, since this is a major project that i will be releasing soon.

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Damm*t I cannot access your picture now, but. Firstly I would set infill speed, top/bottom speed, outer shell speed and inner shell speed all to 0. If you want to set your print speed to 30 as per the outer wall then do so. With a .09 layer and 30 or 40mm/s speed the 210 should be too hot, you ought to be below 200. I read your post as saying that at .5mm height your fan comes on at 100%. I think you will be better starting it 20 or 30 with it reaching 100% at say 1.2mm.

Did you wash the hairspray off before using the glue again, and did you wash the glue of before applying the hairspray? I ask as I have never used glue so no idea if the two materials are compatible. What is the surface are of the part, it looks quite small? What/who's PLA is it?

Personally I would print a simple 10mm cube with the settings with another PLA just to see if you get straight lines.

Having said all that I have a suspicion it might be the fan and extruder temp that are the culprits. Having different speeds all over the place with a small model will not help but I am not sure if they would contribute to you leaning tower of Pisa.

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