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Poorly adhered layers with ABS

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I am having problems getting ABS to adhere well to previous layers. This is happening mostly with prints that have very thin walls, .8 to 1.6mm, but happens with small sized prints as well.

I have not yet enclosed my UM2. I have tried changing the layer height from .15 to .1 with no effect. My print speed is 100 mm/s. I am using the default temps of 90C on the bed and 260C for the extruder.

Thanks for any advice.

 

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I think the first thing you should do is print a little slower, maybe 75 mm/s or even 50mm/s while you're trying to get this sorted. I hardly ever print faster than 75mm/s, especially when I have problems with the print.

The slower you print, the more time there is for the nozzle to bond the fluid plastic onto the solid layer below it.

I think I printed my ABS prints very slowly, like 40mm/s. But it's been some weeks so I'm not sure anymore.

Next thing: Maybe your temperature is too high. If it is too high, the ABS plastic will take degrade inside the printhead. Try decreasing the temperature in small steps, maybe 5°C.

I don't have much experience with ABS, but I had to carefully tune the nozzle temperature as well as the bed temperature in order to get a useful result.

I never had layer adhesion problems though - in fact my ABS prints were rock solid (had to crush them with a hammer in order to destroy them. Yes, I do these kinds of tests :D).

My ABS prints just warped and shrinked so badly that I decided to go back to PLA whenever possible...

 

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You may remember Jonny that I am attempting to make a C-130 Hercules for remote controlled flight. After re-researching the topic I'm not 100% sure why I went with ABS. What I read today indicates that PLA has better bonding between layers and is stronger overall. It might be that I was concerned about softening in the summer sun - better not make it a dark color.

I also am experiencing warping with ABS.

I am at the point with the plane that I want to start printing it. I think I'll try PLA next. I had been making the sections of the plane thicker adding "ribs" to prevent warping and help the layers adhere. I'd really prefer to keep things thinner and lighter as I am concerned about the overall weight of the plane. Right now the skin averages .8mm thick.

 

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Layer adhesion with ABS depends on the print temp and the cooling. I usually don't exceed 30% fan speed, usually 25%, and the "fan only on loops" (available in kisslicer) helps a lot. ABS requires the previous layer to be partly remelted to get any sort of bonding (meaning the previous layer need to get back up >120C). you can try printing thinner layers. contrary to what JonnyBishof wrote earlier, you can not really overcook ABS in the printhead (with the exception of white or natural ABS). assuming the temp reading is correct, 260C should be a good print temp (for black abs), but you can go to 265 and 270, if necessary, and if all the previous steps in the order mentioned failed.

 

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If you switch from ABS back to PLA beware - it's easy to get clogs. Print a lot of PLA into some test print such as a cube - or anything really but it's faster to print something with long straight lines like solid infill. Print at 250C to get all the ABS out. You will think it's all out and then 5 minutes later a tiny black speck of ABS will come. And then you will think you got it all and 5 minutes later another. If you don't do this you will regret it when your print fails 5 hours in because some ABS clogged the nozzle.

Also clean any thin threads or hair like pieces of ABS from the bowden tube and feeder (maybe take the feeder apart and clean out the teeth).

If you *do* get a clog part way through a print there are tricks to halt the print, turn of the printer, go to bed, cry into your pillow, come back the next day, clean the nozzle and continue where you left off. You have to edit the gcode and stuff but it's possible as long as the part hasn't moved on the bed.

 

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Yep, noticed the problem switching to PLA. I had many layers that look like the nozzle clogged and then opened again. I hadn't considered cleaning the tube and drive motor. That is a good suggestion. I was also printing at the default temp for PLA.

What do I use to see the gcode? I have not figured that out yet.

 

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What do I use to see the gcode?

 

A text editor. If you have windows, then notepad works okay. Any text editor will work (not microsoft word - a text editor). I prefer notepad++. It's free and I use it probably 10 hours per day. When you edit stuff 10 hours per day you want a good editor.

 

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