Need ABS Help / Suggestions  

Re: Need ABS Help / Suggestions

Here's a top view for perspective.

Re: Need ABS Help / Suggestions

I'm having similar issues which I'm trying to figure out with practice and many many failures.

Works like this:

looking at your part it is melting and overheating. when ABS is hot it lifts up at the edges the nozzle doesn't know any problem is occurring and it just keeps going with each layer the lifts get worse and the larger mass of the object being printed retains more heat.

so looking at the gear, notice how the bottom looks better then the top as the layers progress it gets worse. it tells you that the things are too hot.

now a lot of the default settings in various slicers have the Fan turned on for ABS and PLA. The fan either cools at a certain percentage or autocool which varies by layer time to print. for ABS this is fine when you want the prints to look amazing. the fan basically locks in the layers as they print so they are very close to optimal placement. the problem is ABS will not bond correctly to the layer below and above making the parts VERY brittle on the layer plane. IE you can snap them in half on the layering,side to side the part will have strength, up and down it won't
ABS also shrinks leading to more problems while PLA has VERY little shrinkage.

So that leads to the problem to be solved, you need to print the part without the cooling fan(extruder fan is left alone) but it must be at melt temperature and the nozzle moving at a fast enough speed such that the ABS has time to harden just enough before the next layer so that it looks just like when the Cooling fan is running. that gives you the nice parts you want.

next problem. each part made will have different layer times and heat dissipation meaning there is no perfect overall setting, there are settings that get you 90-95% there but then you have to tweak it.

another issue is knowing the time each layer takes to print. to help you adjust your settings.
now i found this amazing piece of software that works in the browser.

http://www.thingiverse.com/thing:35248

you can follow the links and DL the source from GIBHUB

https://github.com/hudbrog/gCodeViewer

The key thing you get from this is you can see how long Each layer takes to print with the current Gcode setup you have, that helps you figure out if you should slow down or speed up your Travel times and infill/perimeter speeds.

it is not easy i'm a novice as well and have not been happy with how my prints in ABS have been happening, they are melted or look great and fall apart just touching them.

now the extruder temperature effects the speed as well, typically (my understanding) higher the extruder the faster you want to go, however if you get so a level smaller then 20m/s you can't go fast in fact you may have to retract the nozzle away from the part to remove heat and let it cool before hitting it with the next layer. if you cheat with the fan it seems to introduce brittleness into the part.

so you can also see your settings for a narrow or wide part will be very different because the travel time from one layer to the next in a wide part will be cold compared to a narrow part which will be super hot and not ready to take the next layer.

what i see in your pictures: the part is getting too hot too fast. so now you have to play around, drop the extruder 5 degrees at a time, and or tell the nozzle speed to slow down on each layer. or even add a rest between layers so the ABS tempature comes down just enough to accept the next layer in the gcode.

what is frustration is almost nobody shares there Profile information for materials. the profiles out there are VERY outdated and for software no longer used. Add to this all the different slicers and how they program the gcode.

example i some luck with Slic3r however the way supports are made in it was not working. i switched to CURA and the defaults gave me Beautiful prints, until i found out they are super brittle.

now i'm back to making test pieces trying to find how the slicers work in making good looking parts that have strength, and while the autocooling makes everything pretty i found you must turn it off.

Additionally for ABS you must enclose the printer to retain heat.

I'm also Drying my Filaments in a fruit drier to pull the moisture out.

Re: Need ABS Help / Suggestions

Tks for the very detailed reply as it seems I am not alone. I'm beginning to wonder whether ABS is worth it for a small detailed part. I was looking to have extra strength for this gear that will spin pretty fast driving a small belt.

The cooling fan is off by default for Prusa ABS Filament selections... see attachment.

The Gcode Analyzer is pretty slick and my print has a layer print time of 3.1 seconds which is pretty quick given it is a small part.

I'm not sure how to delay the time between layers in Slic3r or were you editing the gcode directly? Same for retraction - can this be controlled in the Slic3r program? There are a lot of controls it seems.

Re: Need ABS Help / Suggestions

Through Daniels great detailed post here and looking at his original post here:

http://shop.prusa3d.com/forum/-f0/new-member-with-problems-printing-abs-t4213.html

it gave me enough ideas to go try a few things and with success. As suggested I was printing too hot for my materiel and probably too fast. So I did the following and made my own profiles for the filament and the Print settings. The keys for me were:

1. On the Filament I brought it down to 240.
2. I turned on the Auto-cooling which is off by default for Prusa ABS filament.
3. Also turned on infill to 100% (not sure this helped as the layers and walls are pretty tight anyway.

Using the Gcode.ws Browser suggested by Daniel to review my print layers I had taken the original melt version that was 3.1 seconds per layer to 11.5 seconds - see attachment.

This contributed to a pretty solid print equal to the PLA version. My updated gear has flanges on both ends (to keep the belt on) and I need to tweak the initial layers a bit more but the gears turned out good. Shrinkage is pretty much gone now too.

Here's the new end product followed by my settings, the purple ones are all ABS and the Gold one is PLA.

Kevin

Re: Need ABS Help / Suggestions

Here's the Gcode Analyzer... showing thePrint time for layer which is a lot slower and with a little bit of fan it stopped the melt.

Re: Need ABS Help / Suggestions

now the only issue you may have as i walked this path the last 2 days is; the prints look good, REALLY good in some cases, but the ABS turns out VERY brittle.... I've been making 10x10X50 Bars at 20% fill for strength testing and have not found a balance yet. either i get VERY sharp prints that i can snap by breathing on them or I get a melted stick of butter with very little dimensional relationship with the original box shape but they bend over in the vice before i snap them. this all comes back to the use of the cooling fan as it does not allow full layer bonding to occur and the crystallization of the plastic from being rapidly cooled makes it much weaker.

delaying layers; it is possible to change the minimum layer time you can then force the machine to wait the extra time with a Z hop.

so lets say you set the min layer time to 15s and you look at the gcode in the viewer and see that it will mostly be 5.7s per layer.
the machine will then Print the layer, then Zhop away from the material and wait the extra 9.3s with a pause per layer and then start the next layer.
obviously this shoots your printing time to the moon as most of the time the printer will be paused waiting for a cool down.

you can also set a threshold for the cooling fans to kick in. again lets say it is 15s and you find most of the print and 90% of the model will take 25s per layer with the fan at 0% then when it hits the narrow part of the model the fan kicks in at a setting between 0 and 100%. well this solves one issue and starts more.... first the area where the fan suddenly kicks in will shrink, mushroom in slightly and that area will now be even weaker then it was before. i found it was impossible to time it just right without spending forever tweaking the settings and even then it would only work for that one part and no where else.

another problem i have been chasing my own tail in some ways... if i vary the temperature and the speed together i see i make the mistake of doing the same thing but in a slightly different way. all the abs filaments are different as well. i have hatchbox and ninjatek and they react very differently in my machine with the same settings. things going under 10mm in dimension i can see needing special settings to compensate as there is no overall that would work.

Re: Need ABS Help / Suggestions

after i spent the last 2-3 days making test after test my conclusion is this:

at a certain point of layer size it is impossible to make an ABS print without having some amount of cooling fan running, or get something completely unusable.

it is just flat out impossible to make lets say a 3mm detailed part with 100% fill with cooling fans turned off, with a layer time of 9-0s

even if you time the layers with delay factors over 15s what happens is the bottom layer starts to curl on the surface but the inside is still too hot. the gcode delays the next layer but then when it continues to stick the next layer on top of a layer with problems, more layers and the problems multiply. thus you have to introduce some cooling into the Gcode to force the ABS to semi lock in place so the next layer has less errors up the chain to the end of the Gcode, and this weakens the ABS structure. so for a larger part ABS acts like you expect, as the parts get smaller not only do you have to deal with the loss of ABS strength from dimension but also the added loss of strength from forced cooling. Thus an injection molded sub 3mm ABS part will always be super strong compared to a 3d print.

Thus for me ABS might be a dead end and i need to move on to Nylon since i'm dealing with parts with layer length under 12s.

i'm no stranger to having to make cast gears and machining the casting to get the strength i need.

Re: Need ABS Help / Suggestions

Good stuff and dialog and really appreciate you sharing as it will probably help others. So far I am not having issues with brittleness but the key will be when this gear actually gets put to work in the head of a small vacuum cleaner.

delaying layers; it is possible to change the minimum layer time you can then force the machine to wait the extra time with a Z hop.
so lets say you set the min layer time to 15s and you look at the gcode in the viewer and see that it will mostly be 5.7s per layer.
the machine will then Print the layer, then Zhop away from the material and wait the extra 9.3s with a pause per layer and then start the next layer.
obviously this shoots your printing time to the moon as most of the time the printer will be paused waiting for a cool down.

Where are you setting the minimum layer time so it waits for a ZHop? Is that done within Slic3r or is that custom manipulation in the gcode?

The one thing I further tweaked in "Slic3r -> Filament Settings -> Cooling -> Disable fan for the first " setting which the default was 3. I tried 0 and that was a no go as expected adhesion could not take place to the bed with the cooling fan on. I tried 1 and was not thrilled with the first layer but settled with 2.

Also one thing that I do in addition to these setting is I further turn down the print speed by turning down the dial on the printer to change the speed from 100% to 83%... this helped a ton to secure first layer adhesion. I am using a glue stick to help with this.

I have not tried ABS Juice as it was never sent with my order. One subsequent support person said it was not needed and I have seen conflicting information in documentation whether it is needed or not with the PEI surface which I pointed out to them. In any case I have requested from support to send it to me twice now so hopefully I will get it. The glue stick approach does seem to work for me currently. I only had one print come off the bed towards the end for these tiny parts.

Re: Need ABS Help / Suggestions

i went back to Slic3r and it does not have what i was talking about as far as making the machine wait on a short layer, that feature is in CURA.
i started to use CURA a few days ago. one frustrating thing about CURA is there is no Bridge setting information you can mess you.

in CURA you have the 'lift head' function which is tied to 'Z-hop' and 'minimum layer time' you can turn them on and adjust the settings and make the machine wait between layers.

another setting that helps with abs is in CURA under shell change 'Z seam Alignment' to Random this is the same as 'seam position" under "print settings" in slic3r what happens if you leave the seam on edge, aligned, nearest,,, is the nozzle will always go to the same area to start the next layer that causes that area of the ABS print to warp due to excess heating of one spot over and over. so switching to random helps move the hot spot around and improve the overall print.

For the PEI surface, small things stick ok, you put a large brim for extra security and the glue is ok, but went you have something tall and skinny it can pop off during a Z-hop, i decided to just make juice... very simple:
get an old Glass paint holder with a PC cap or metal cap, get 100% acetone from local home store, then take some of your 3d print scraps or cut a piece of filament just a little and put it into the glass bottom and fill with Acetone. let it sit over night and shake it up in the morning should look like milk with white ABS. then use a paint brush and brush the PEI in the area you want to print in based on the bed preview.

the abs sticks hard but i used a standard razor blade on its side to pop the prints off. once i carefully get the blade under the brim i lay it flat and carefully push it into the print and it pops right off.

clean up is a clean lint free cloth soaked in acetone a little and wipe the extra ABS off the print bed. no more popped ABS prints. watch how you handle the acetone since the PRUSA parts are made of ABS as well, but i have not had any issues.

some people spray the ABS juice, i felt that was going to cause more issues so i brush it on like hand paint.

i will need to clean my bed very well when i change to PLA or something else.

i will need to use glue or painters tape for Nylon. I ordered some to try out.

A large dense part like a Gear works for ABS, but going to a tiny gear would be a major issue.

for the Open R/C project i found out Barspin "Daniel Noree" printed the gears in ABS but used nylon for pretty much everything else. ABS for the chassis as it was a huge thick block.

i would say if you want to mess around, make a small round tube or a rectangle lets say 1-2mm thick, 10-20mm wide, stand it up so the layers horizontal make it long enough you can handle it and then let it print with your settings and see how brittle your parts come out and try to mess around and see if you can make it stronger.

what i found was i could make Amazing looking parts super smooth .05 resolution and they had no strength at all once they cooled down. Off the printer they were flexible and seemed strong. a few hours later they literally crumbled in my hand.

i looked at post print processing also.. there is an Acetone Bath with Vacuum chamber. basically you soak the parts and the acetone soaks into the pours of the ABS and you put it in a vacuum chamber to get all the Acetone through the center of the part and let it sit for a few hours. then pop the chamber and let the part cure for like 3 days. i have a vacuum chamber but i can't see going that crazy. it would make more sense to use the 3d printer to make negative molds of the parts you need and then back fill the cavities with Nylon resin, that would take under 24 hours verse a week for some of these post process 3d printer parts out of ABS

i had one ABS test print from a few days ago that showed some promise and so i just tried loading my Slic3r settings in CURA.... it will take 7 hours to find out if what i did is any good... i had the Fan on autocool set for between 10% and 40% max. another thing is i always seem to return to 255 degrees for the extrude temp... i tried everything from 215-255 and while i get burn marks starting around 235 the adhesion gets better between layers the hotter you go.

Re: Need ABS Help / Suggestions

i just read about changing the wall thickness to increase strength.

default is .8mm in most slicers.

you can see the change here (this is what makes cura so cool see changes on the fly)

i'm going to run it and see that happens with this part at 2mm

Re: Need ABS Help / Suggestions

finished print and finish did not come out well, strength tested and it Snapped right where the layer went from about 17s to 24s. i can see the ABS stressed at this point either from the change in fan speed from the auto cool or the sudden change in plastic density due to geometry.

i'm changing my design for more strength and I went from auto cool to a locked in fixed low fan speed of about 25% from start to finish. my thought is keep the cooling consistent the entire print instead of sudden shifts.

well shall see what happens.

Re: Need ABS Help / Suggestions

well the changes i made have resulted in a much stronger part i could not break the latest one by hand compared to the older ones that basically snapped apart without much effort in my bare hands.

now i'm running into either a Pillowing issue or an under Extruding issue for the surface finish. I'm running tests with more and more cooling fan to see what happens. if there is no change i will need to bump my multiplier and see if that does anything.

I need to change ABS filaments and retest as well..

what i found so far
Ninjatek ABS tends to under extrude compared to Hatchbox ABS.
i feel hatchbox is more brittle but more testing is needed.

Re: Need ABS Help / Suggestions

Well running at 45% fan at 255f with increasing extrusion 5% over 100% fixed the surface defect I was able to increase the strength of the abs however it will never be strong enough for my needs so I need to move on to nylon.

In slicer I had to get rid of infill completely to increase strength as well. Plus run at 100% infill and slow things down.

I read another article from 2016 about abs and the conclusion was you must run the cooling fan for parts under 10mm diameter.

Re: Need ABS Help / Suggestions

I have a really solid PRUSA ABS-T profile that I'm willing to share. I can print just as good with ABS as PLA at this point without an enclosure or glue. In fact, the part sticks to good. See the attached photos. The gold foot is PLA and the Silver is Prusa ABS. Also attached is a xyz calibration cube in ABS. The cube is nearly perfect.

Re: Need ABS Help / Suggestions

I'd be interested in the profile 🙂

Re: Need ABS Help / Suggestions

I have a really solid PRUSA ABS-T profile that I'm willing to share. I can print just as good with ABS as PLA at this point without an enclosure or glue. In fact, the part sticks to good. See the attached photos. The gold foot is PLA and the Silver is Prusa ABS. Also attached is a xyz calibration cube in ABS. The cube is nearly perfect.

@alexander.n7
I would be please if you can share your setting! Thanks!

Re: Need ABS Help / Suggestions

I'd like to see the profile, too ... I've been struggling with ABS vs. PLA and PET.

Thanks,
Kevin

Re: Need ABS Help / Suggestions

I am printing 3DXTECH asamax 1.75 with a .6 mm nozzle and cannot get it to work with standard Prusa profile. The .4 mm nozzle worked great so I must need to do something to get better results. Thanks Dana [email protected]

Re: Need ABS Help / Suggestions

Sorry for the delay. I'll attach in a second.