ABS Printing Bad (Cooling Issue?)

Dear All,

I'm having trouble in printing ABS. I've got used to printing PLA and it's always printed good. When it comes to ABS, it's a lot different.



I'm trying to print this usual marvin and won't be moving on until it comes out good. My greatest challenge here is about temperature.
I'm using Prusa i3-styled printer, without closed chamber and with a heated bed. The bed material is masking tape or kapton (I've only tried those two, and still good enough for printing these) with a temperature of 100 deg C. I'm varying my extruding temperature between 200 and 250 deg C, which 200 is too cold to stick with other layer and 250 is too hot even the black ABS smeared white; I stick with 230 deg C for most of the tries.

The problem is mostly on the top loop, where the layer size is very small. I'm using slic3r's auto-cooling feature where the printer slow down if layer time got small (5s) and the minimum speed is 10mm/s. Still, it seems like the previous layers are still too hot to be layered again onto, and ABS really takes years to cool down. Using fan? I've tried that and this little marvin got popped off the bed.

How do I overcome this temperature requirements for this tricky ABS?
Thanks alot.

You need far more than 5 seconds to be able to lay another layer on ABS (probably more like 20-30 seconds depending on other settings). I have printed that generally successfully with very aggressive automatic-cooling settings and a very low minimum speed, but it would be easier just to print two of them, separated by far enough for travel time to be significant, to kill time. You can also make anything else that is at least equal in height or even just a cylinder of the same height as the part.

Don't use the fan at the first 5 to ten layers. Here (Youtube) I have got success with small prints, ABS and a fan with duct. I turned the fan ( very faint ) on after few base layers:

3D Printed MakeHuman Character
[youtu.be]

Edited 1 time(s). Last edit at 02/29/2016 06:55AM by Plasteroid.

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Yes ABS can be a hard plastic to print with but is rewarding when you get it right.

It sounds like you are printing a very small print and therefore I would agree with the above advice. Basically:
- Slow the print down
- Don't use a cooling fan (especially on such a small print)
- Wait 30 seconds before starting a new layer.
- You might benefit from a higher bed temperature such as 110deg.

I hope some of this helps.

If you ever need more advice feel free to contact us at support@3dexfilament.com

Cheers
www.3dexfilament.co.uk

ABS can benefit from a weak fan aimed at the bed from a distance, my marvins had all sorts of issues before I started using a fan. It's all about getting the balance right. Too much fan is just as bad as no fan.

it is clearly too much heat radiation there. I would suggest to use fan upon reaching those small parts. I sometimes print a single 3-5mm rod standing up and without fans it would give an imperfect rods. I start the fan after about 3 layers of printing these rods and the fan often running at least 50% (manually activated)

My print parameters are as follows

speed at 60
abs temp at 240

You could get away with lower temp but it won't bond efficiently, so using a fan is another work around too

I find that slic3rs auto-cooling feature is really more detrimental than helpful. It slows down on small layers by decreasing the print speed. All this does for me is drag the very-hot print nozzle around on the ABS slower, allowing it more time to heat up the top layer and the next 5 or 6 layers below that one. It might be more useful if it simply went somewhere else for the extra time to allow the just-printed layer to actually cool down away from the print-head. But it doesn't. So you might add a "cooling tower" to your built plate (a cylinder you print and throw away) to cause the head to go somewhere else for a while between layers.