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weak ABS

Posted by AudaciousTuddle 
weak ABS
April 04, 2016 05:34PM
I'm having problems with ABS. I have been able to get it to stick to the print bed, however my prints are really weak. I Am able to easily snap abs prints in half, even ones where the PLA counterpart is too strong to break. There does seem to be some layer separation, but the print will snap across (perpendicular) to the grain. What can I do to make my prints stronger? I switched to ABS from PLA because I was under the impression that ABS was tougher, is that a false assumption?

I've been printing using wyz 1.75mm filament (it's a cheap brand).
80 bed temp
Tested at 230C, 240C and 250C with no difference in strength
Prusa i3 in sealed enclosure
Printing a file that I know works in PLA.

Note: i have done a lot of googling, but haven't come up with anything, (except exercise routines smiling smiley

Edited 1 time(s). Last edit at 04/04/2016 05:35PM by AudaciousTuddle.
Re: weak ABS
April 04, 2016 08:29PM
Abs should flew and bend before it breaks.
If your layers last but the part breaks in other directions I only see two possible causes:
A ) Your print temp is too high, to check try some testprints at a slower speed and with the temps of 220 215 and 210° - if the strenght improves try to go lower but not so low that the layers start to seperate.
B ) You simply got a bad batch of filament. Try a different brand or color.

I had problems with a few ABS rolls myself where the extruded plastic became very brittle and hard.
Where I would usually print around 60mm/s @ 240° I had to go down to 25mm/s and just 210°, still the parts would shatter if hit with a hammer.
For parts that need to be really strong I prefer natural ABS and PLA as I find the natural ones won't give you any headaches.
Re: weak ABS
April 04, 2016 11:07PM
I haven't tried lower than 230C. I'll do that right away. I have contact the seller, and they seam like they are willing to work with me. Thanks!
Re: weak ABS
April 08, 2016 05:51PM
Use a thermometer and measure the temperature inside the enclosure, if under 90 degrees use a lamp 150 to 200 watts to heat up the air inside.
230 to 240 should be fine for ABS.
You haven't mention the speed you are printing? maybe too fast?
Re: weak ABS
April 08, 2016 06:03PM
The enclosure never gets above 50C. I have always been afraid to get it too hot in fear of hurting my electronics. I actually have a heat controller designed with an arduino and a hairdryer, but am waiting until I get my electronics outside the enclosure. And I have tried normal speed, and slowing it down to around 25mm/sec.
Re: weak ABS
April 10, 2016 05:47PM
How consistent are the filament diameters between the ABS and PLA reals? You might want to try another brand of ABS and see if it's the same.

Half a year ago I had a role of Inland ABS from microcenter that I could never get to print. It would always jam not immediately but eventually during the print. I made a lot of improvements to the printer during that time but could never get it to go. Other ABS brands were just fine. I just threw it away the last time I tried it to stop wasting my time with it.

I had to tweak my extruder steps per mm slightly moving from nylon to abs. You can do this during the print with by sending M92 Ennnn comands to the printer. I would think you would notice if layers weren't solid or touching though. I would be particularly pronounced when looking at a light or the sun through the part on a side view.

Edited 1 time(s). Last edit at 04/10/2016 05:51PM by CTCHunter1.
Re: weak ABS
April 10, 2016 06:17PM
The diameters seem to be ok. I sent the manufacturer a message and they are replacing it for me. I think I was just shipped a defective product.
Re: weak ABS
April 10, 2016 07:37PM
I've had fine results with Gizmodorks and Hatchbox ABSs I've purchased from amazon.com. At work we've been using 3mm IC3D abs on a Taz5 that has worked too. I would recommend having ABS from a second manufacture on hand for trouble shooting purposes.
Re: weak ABS
April 11, 2016 05:19PM
Hi there,

There does seem to be some layer separation, but the print will snap across (perpendicular) to the grain. What can I do to make my prints stronger?

It would be helpful if you listed your nozzle diameter, layer height, extrusion width settings, and speeds. (Are you using Slic3r?)

I'm not discounting at all that it could be a bad batch, but without the above info one can only speculate.

"Some layer separation" is a good clue tho, so you need to consider the mechanics of layer adhesion (yes ABS and PLA flow and stick differently).

Say for instance you have a .40 diameter nozzle:

On the left: Perimeters = .40mm, Layer height = .32
On the right: Perimeters = .50mm, Layer height = .20

On the left the layers are not pressed together so there is little connection - the extrusion width is nozzle diameter, and using max rule-of-thumb layer height - any variation in extrusion or nozzle path will cause failure.

On the right however you can see how a wider extrusion width forces the filament to be squeezed onto the previous layer and spread out to the .5mm width. This is much stronger.

The general rules of thumb are:
Layer height < 80% of nozzle diameter
Minimum extrusion width >= nozzle diameter * 1.05 (any smaller and it is stretched - poor adhesion)
Max extrusion width <= 1.7 * nozzle diameter (or it starts curling - depends on nozzle end width)

However, you will get poor results if you go to the extremes.

I know that for my printer and my ABS filament I have problems extruding below 235C, and generally extrude at 260 with internal perimeters at .68 with layer height of .20, and prints are very strong (using a .57mm nozzle).

Hope that helps.

Edited 1 time(s). Last edit at 04/11/2016 07:11PM by Paul Wanamaker.

My printer: Raptosaur - Large Format Delta - [www.paulwanamaker.wordpress.com]
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Re: weak ABS
April 15, 2016 01:26PM
A couple updates:

The seller was super helpful and replaced my role of ABS. On the role, the plastic feels much less brittle and does not snap like the other ABS does, though it still does feel more brittle than i feel like it should. I unfortunately only got 2 or 3 layer of a test item printed before my extruder broke. I have a new bearing in the mail, it should be here on Monday. I'll update you all on Monday, but here are my settings you asked for.

Nozzle Diameter: 0.5mm
Layer Height: .3mm
Temp: 230, 240 and 250
Speed: 35mm/s originally and then 20 mm/s when i realized i was having issues.
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