guru_florida
Posts: 6
Joined: Fri Dec 02, 2016 10:21 am

Vertical curling on first 20 layers or so

Thu Nov 02, 2017 10:07 pm

Hi. My printer overall is working great but I am getting some bad quality on the outline for the first 20-30 layers then it seems to be perfect. Printing ABS with heated bed (110degC) and fully enclosed printer. It happens on all parts. I've been printing parts 30 layers off the bed using supports and the supports takes the brunt and the parts are great but I would like to be able to print without supports.

See pic. I traced a few sample layers as yellow lines. It seems like the edges curl up vertically and that likely means less plastic gets deposited and this it ends up shrinking. I tried 35% and 50% underspeed on perimeter layers. (pic shows 35%)

One thing to note, my extrusion head is water cooled so I have no fans on the head. My nozzle temps and heat break perform awesome with the water cooling but maybe I need fan cooling on the workpiece?

Any suggestions?


More details:
* Using IC3D filament.
* 221degC extruder temp. Also tried 230 and quality overall is worse. Arrived at 221 by printing temp calibration tower.
MakerbotCurledStart.jpg
Last edited by guru_florida on Thu Nov 02, 2017 10:43 pm, edited 1 time in total.

upsm
Posts: 151
Joined: Sun Mar 12, 2017 5:37 am

Re: Vertical curling on first 20 layers or so

Thu Nov 02, 2017 10:42 pm

ABS is tricky that way, you want lot of heat to stop it from warping but you want it even inside the chamber; you need print bed to be hot so that part stick but you don't want it too hot so that part shrinks.

For start, find the lowest temp of the heated print bed you can use that will hold the part down and use it. This is for e.g. the reason I'm not using printBite for ABS in many cases as it requires (the old version I have, the new version is bit better) 110-120C to properly hold on to ABS and at those temps my first 3-5mm of the part come out very very very bad (the worse possible combination of elephant's foot and shrinkage, so bottom few layers are wider then they should be, then part start to shrink in so you have a bow instead of straight line up, and then after 3-5mm it goes properly up - crazy).

If the lowering bed temperature with your print bed surface does not work (you can't lower it enough), you have to add some "miniature" cooling for 2-30 layer .. talking 2-3% fan speed, or whatever's minimal your part cooling fan can do without stalling. Since you are circulating air inside heated chamber nothing to worry about warping, still, min possible speed is required.

Now you have to tweak this yourself, for me I increase the bed temp after 5mm ... I get stronger adhesion and it does not deform already printed part.

Finally, you have to try few other brands of ABS! Search for ABS that needs to be printed at higher temps. I assume you have all metal hotend as you are running a chamber, find ABS that's 250-270C range (for e.g. TearTime ABS is like this), that ABS will work much better then for e.g. ABS that goes from 200 - 250C or 220-250C; The higher temp one will stick better, will not be affected nearly as much by heat from the heated bed, will warp less... The higher temp ones are usually tad more expensive then the regular ones but are much easier to work with (when you have chamber and all metal hotend). For example https://nodna.de/ORIGINAL-UP-ABS-on-Spo ... white-2-pc
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wirlybird
Posts: 1143
Joined: Sun Jul 17, 2016 1:32 pm

Re: Vertical curling on first 20 layers or so

Fri Nov 03, 2017 6:53 am

Bed is too hot. On a small part start out at 100-105 and drop after the first layer or so to 95. On smaller parts I am at 85-90 after the first few layers.
Also on smaller parts you may need to open up the printer if it is enclosed to let off a little heat.
Takes some experimentation.

tpete61
Posts: 13
Joined: Sat Apr 04, 2015 12:04 pm

Re: Vertical curling on first 20 layers or so

Fri Nov 03, 2017 1:04 pm

Yes, drop the bed temp. is probably a fair assessment.
I print ABS with a 75C Bed Temperature and hair spray for adhesion and rarely have a warping problem.
I'm print with an ABS temperature of 205C.

gearsawe
Posts: 141
Joined: Sun Sep 10, 2017 11:06 pm

Re: Vertical curling on first 20 layers or so

Sat Nov 04, 2017 11:08 pm

At work the Professional $100K printer Heats the chamber to about 95C. Blowers hit the print area directly to cool it quickly and keep it to just below the glass transition state. Also it prints at over 300C with ABS. It does not use a heated bed since everything is pretty hot. The trick is cool it quickly but keep it hot.

guru_florida
Posts: 6
Joined: Fri Dec 02, 2016 10:21 am

Re: Vertical curling on first 20 layers or so

Sun Nov 05, 2017 4:20 pm

It worked! There is basically two things I did. I reduced the speed down to 25-30% for the first 2mm, and as you guys suggested reduced the build plate temperature. Build plate is 110 for first layer, 100 for next 1mm, then 95 for the rest. I had reduced speed to 25% first and still kept build plate temp high and it worked too, but was able to up the speed with the lower plate temp. So I think both have a play in the solution.

There is noticable shrinkage as the layers increase, so the bottom few layers are larger but that is expected with ABS. Is there a way to adjust for this, like make first few layers smaller? Either way not a big deal and I am very happy with how my printer is working and with Simplify3D!

Thanks! :)
BP2.jpg
BP3.jpg

arhi
Posts: 368
Joined: Thu Oct 06, 2016 5:13 pm

Re: Vertical curling on first 20 layers or so

Mon Nov 06, 2017 5:34 am

guru_florida wrote:There is noticable shrinkage as the layers increase, so the bottom few layers are larger but that is expected with ABS.
not "that much" :( .. I'd try lowering bed temp further and even tried using a little bit of fan on layers 2-20

for e.g. this is gold abs and yellow abs (cheap esun and colido), as you can see I do have a little bit of elephant foot there (and that too can be solved) but is not nearly as bad as what you are getting... I marked RED the "bottom" of the part

so try lowering the temp on the second layer+ and try adding tiny bit of fan on the second layer for few mm (you measure how much you need from those prints where you have the problem).

also, if you have issues with adhesion to bed you can increase the temp of the extruder for first 1-2-3 layers
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