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raychar1234
04-08-2017, 08:24 AM
Hello everybody,

Having to possess a dual nozzle type 3d printer for several weeks and having the following harassments:

>In printing PLA, the made prototype which has small details and thin wall is perfect and now I have confident in using this material to do printing

>however, wanting to have better strength, I start to print it with ABS.

First trial, very poor, a) inside was unfilled, b) filaments and inter-layers not adhered together, c) tall portion broke down during printing..

Second trial, increase temp. from 220 to 250~255 degree C, slow down speed from 90 to 40, infill increase from 30 to 100%. After checking the filament diameter, it is smaller; only 1.66mm. So flow are increase from 100 to 110~115%. However, the outcome of the second trial is still far from satisfactory.
The defect of a)almost improved, b)improved a little, some portion still loosened packed, tall portions still fell down, it is because some areas was still not dense enough and filament are not fully welded together. Some small details also detached during print.

>after trial for three times more, I totally lost confident. As PLA is no problem, I assumed that it is not the machine's mechanical problem,
the only variable is the filament, its appearance looks good. Is that a 0.1mm smaller in diameter has such big issue or something else?
I cannot adjust the feeder roller tension, is there any grinding of filament occurrence?

Hope to have somebody give help! Thanks,

the_real_skimmy
01-14-2018, 04:49 PM
I am new to this forum but very well experienced in 3d-printing. Let me suggest you the following:
1. stop printing ABS, despite you need its exact properties e.g. aceton smoothing. There are way better materials out there, there is nood for printing ABS anymore ;)
2. The filament diameter is crucial to for the final quality of the print. When the diameter is fluctuating (smaller but constant diameter is ok) you got probably cheap filament. Try to get brand-named filament to save you a lot of hassle.
3. dont print 100% infill. 90% infill gives you maximum strength of the part, above that it gets weaker (don't ask me why). Most "bang for buck" is like 70% infill. But I do print most of my parts with 5 to 10% infill only.
4. Print "linear infill". Its stronger, faster, cheaper. I know, honey-comb infill looks promising, but thats not how 3d-printing works. ;)
5. Less feeder tension is better. Dont press to much.

dharmic
01-15-2018, 05:51 PM
Disagree 100%. I've yet to find a replacement for ABS that fits as well with part stiffness and strength, thermal stability, ease of surface treatment and price. I print nylon if stiffness and surface finish don't matter, otherwise it's back to ABS.

It can be a swine to print with bed adhesion and shrinkage causing pop-offs and lift-ups all over the place. But mouse-ears on part corners, switching bed materials (I'm using perforated FR4) and a heated chamber sort out a lot of these issues.

Ray your issues sound like something else. If the extruder can shove through the filament without issue when there's no nozzle attached, it'll be the nozzle blocking causing your pain.

Is your hot end actually capable of maintaining 250ยบ without having problems? Lack of adhesion is going to be either too high a layer height for the nozzle diameter (should be no more than 50% or so of the layer height eg 0.4mm nozzle => max 0.2mm layers) so there's insufficient squish going on, or the hot end isn't hot enough to get the zone melting properly. Choking or missing sections often caused by a too-cold hot end, maybe the infill is coming through too fast for the heater to keep up. But on my printer I'm belting out infill at 0.2mm height at 100mm/s.