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kaidro

Problems with warping by shrinkin holes

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Hi,

i have Problems by printing this parts. I think it's because of the shrinking holes.

When I'm only printing one part the warping is not to much. Like in the first two pictures.

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But If I am printing more than one at the same time. The sides of the parts going up like in the third picture. In the last picture I have abortet the print because don't stick to the bed anymore

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Do you have any solution for this. I want to load up the bed and print maybe 30 at the same time.

At the moment I have the following Configuration in Cura:

First Layer:

Bed: 75°C

Nozzle: 230°C

Fan: 0%

Printing:

Bed:65°C

Nozzle: 200°C

Fan: 100% (4th Layer)

Thanks for your replys

Kai

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WP_20171109_11_45_14_Pro.thumb.jpg.43088b7b086fd8022fdcb4a911a10b07.jpg

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I only use Skirt as bonding method but have set the line width of the first layer at 80% and a layer thickness of 0.15

I only use the heated bed and no glue or hairspray. To clean the bed I use window cleaner.

I had problems with the automatic bed calibration until today. I found that the screw for set the deepest bed point wasn't tight. So I fix it and screw an nut on it.

So I do first the manually leveling and let than level the ultimaker itself.

Hope that helps. Thanks for your replys

Kai

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Perhaps the bed is slightly lower in the area of the warping parts? It's hard to tell from the pictures but it looks like your nozzle needs to be closer to the bed on the first layer. Or, put another way, the bed may need to be a hair higher. I think adding a brim would help these parts. If you're not already using some kind of adhesive on your glass, try some. I like Aquanet hair spray. Others like glue stick, or diluted craft glue...

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I think the bed is good leveled. The skirt looks very similar around the printing parts. Also the first layers look in My opinion very good.

During this print I tryed hair spray.

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Brim is not really a option for me because it is a lot of work to remove this and I like to skip this work.

I think the problem is time and cooling down of the parts before finishing. Because when I am printing only one. The parts are ok and I have only light warping on one side. when I am trying to do five 3 of 5 going up dooring the print. Maybe the print fails.

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When I am doing 10 parts, like in the picture at the beginning, all parts looks like the have warped at both sides. The whole print fails.

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Do you think that a higher bed temperatur helps to slow down the cooling of the parts?

How do I set cura to print every peace for its own. or ist this not possible with my dual extruder?

Thanks

Kai

Edited by Guest

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Hi,

I want to share with you my solution. In my opinion it is easier than put glue or hair spray on your Bild plate.

So I used my dual extruder to put a brim surface with PVA under my parts. The PVA sticks much better than the PLA to the build plate. When you take out the parts they come of the PVA bevore the it looses from the buildplate. So you don't need to put yor parts in water after printing and not need a knife to round edges.

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Edited by Guest

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If this is Ultimaker or colorFabb PLA, have you tried my "salt method"? Also read the section about cleaning.

See: https://www.uantwerpen.be/nl/personeel/geert-keteleer/manuals/

I have printed quite a lot of long models with holes, similar to yours, without any problems. They usually are 100 à 150mm long, 10 à 15mm wide, and 3 à 6mm high, with sharp corners.

The only things I can not print are inverted pyramids and prisms, with a very small base and huge overhangs. Here the warping forces are to high for the very small base.

(Actually, I thought you were printing in ABS, with that amount of warping..., and my salt method does not work for ABS.)

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I've tryed the salt method yersterday. The first try with 16 peaces runs nearly perfekt.

But this was the second try over night????

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Mybe i put to much salt on the build plate after the first try. How do i get the right amount of salt? I think that i don't have an even salt amount on the build plate. How do i get it?

Thanks

Kai

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I clean the glass plate with warm tap water first, with a paper tissue. And then I put a few drops of salt water on the glass, and gently wipe and keep wiping until it dries. The salt should not be visible as such. It should only be a very thin almost invisible mist. Like a wine glass that has been sitting in a cabinet for a year without using: if you look through it to the light, it has some sort of thin grey mist to it. That is how the glass plate should look for best bonding.

Also, it does not work equally well with all PLA: the ICE brand still worked, but occasionally corners did lift. Ultimaker and colorFabb gave an excellent bonding.

But if the lifting always occurs in one corner, it could also be that your bed calibration could be improved in that corner? Or that the glass may not be totally flat: even if it is only 0.1mm unflat, that is half of a first layer of 0.2mm.

For PLA (Ultimaker and colorFabb), I mostly use 210°C nozzle temp, 60°C bed temp, 50mm/s speed, thus the default values on my UM2. First layer 0.2mm thick, the rest 0.1mm. For higher accuracy, I use 195 to 200°C nozzle, 60°C bed, 25mm/s speed. I never have lifting like in your photo.

If the bed temp is too low, the model gets stiffer, but bonding is less. Below 50°C bed temp, it may suddenly pop off. If the bed temp is too high, the plastic stays too soft, and the model may be peeled off, in addition to sagging and deformation. I have seen this at 70°C bed temp. For my sort of models, optimal bed temp is between 55°C and 65°C.

But I think gr5's method (10% dilluted wood glue in water) and neotko's method (strong hair spray) should also work equally well for these models. These methods are only a bit more messy to remove the models (that is why I prefer my salt method). Both have shown bigger and more complex models that worked very well. So if it doesn't, I tend to believe there is still some other unresolved issue?

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Hi guys,

thank you for your support. I finished the printjob. What I can say is, that I have more problems with warping near the corners than in the middle. Maybe my build Plate is not 100% leveld like Nicolinux says. But the build plate isn't bent.

The salt water methode works better than glue or hair spray. But not as good as printing with pva under the pla parts. But I'm with geert_2 that it is the best method to clean the build plate only with warm water.

When I have to print these parts again I want to try a material that has not this much shrinkage. Maybe PETG or pla pro/+. Or try to do less infill.

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It's extremely common for the rear right and left corners to be lower than the rest of the bed due to the shape of the glass and the leveling procedure (the location of the 3 screws which are leveled).

So that is probably the main issue.

Yes you can print "one at a time" mode but it won't let you put the parts quite as close together because it assumes (incorrectly) that your parts are very tall and might hit the head.

I recommend you avoid putting any parts in the rear 2 corners and also ask your reseller for some flatter glass so you can use the whole bed (test the glass first of course).

First layer at 75C and second layer at a lower temperature is not a good idea because the part will shrink a bit and is more likely to warp.

Keeping the glass always at 75C will be less likely to lift off the glass bed but the quality of the vertical edges won't be as good so you have to decide which is more important.

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As gr5 said, I also found that printing in the left-back corner is more prone to problems. I am not sure , but I think this might be due to the leveling, to light warping of the glass (even if only 0.05mm), and to the tight bending radius of the bowden tube in that area: this causes much higher friction of the filament in the tube and nozzle, which might lead to slight underextrusion, and thus less good bonding?

Anyway, I get best results when printing in the center and front-right areas. This is for my UM2 (non-plus) printers, which are more sensitive to feeding problems than UM2+ and UM3.

Also, you could put your models closer together by alternating them, so that the wide parts of one model slide into the openings of the other model. If your Cura-version would not allow this (I have no experience with the latest versions), you could do this in a 3D-editor. For example, if I would have to print two "E" characters, I would turn one upside-down and shove that tightly into the other, so it occupies only half the space on the build plate.

Concerning optimal bed temperature, I did several tests some years ago, and I found that a too low temp makes the models pop-off suddenly. And a too high temp makes the models too flexible, and makes its corners peel off the glass due to warping. You have to find the exact spot inbetween, where the bonding is still good, and the model stays stiff enough not to peel off. This is different for each material, and might also differ a bit from printer to printer. You could place a test object in the most critical area, and print that with changes in bed temp in steps of 5°C up and down, until you get both effects. Stay around to see what happens. Then choose a value halfway inbetween. For my Ultimaker PLA and colorFabb PLA/PHA, 50°C is too low, and 70°C is too high, for use with my salt method (may be different for other bonding methods!). I need to stay between 55°C and 65°C, thus I just leave it on 60°C, the default.

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Also, you could put your models closer together by alternating them, so that the wide parts of one model slide into the openings of the other model. If your Cura-version would not allow this.....

You can in Cura 2.3X and up (The versions I have used). Just go into preferences and uncheck "Ensure Models are Kept Apart" in the general settings.

It will let you place your models any way you wish. I have found this to be important as, say, you have an "X" shaped object. the bounding box will make a square that nothing can go into the voids of the "X". Unchecking that will allow you maximize your printing area when really stacking parts. But, it makes the user responsible for not overlapping models manually though.

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