is this over or under extrusion or something else (ABS/HIPS)

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Jab136
Posts: 26
Joined: Sun Jul 16, 2017 12:00 pm

is this over or under extrusion or something else (ABS/HIPS)

Postby Jab136 » Sun Sep 03, 2017 10:18 am

I am fairly new to 3d printing, and am trying to dial in the settings for dual printing ABS/HIPS, the HIPS raft is printing fine, but when I start printing the first layer of ABS it does this
IMG_20170903_130643.jpg
I am printing at a .3mm layer height at 240 degrees for ABS and 230 degrees for HIPS with the bed at 110 degrees, also I covered the bottom of the fans. Does anyone have some good settings for ABS/HIPS that they have tested?

Jab136
Posts: 26
Joined: Sun Jul 16, 2017 12:00 pm

Re: is this over or under extrusion or something else (ABS/HIPS)

Postby Jab136 » Sun Sep 03, 2017 2:31 pm

Ok, so I seem to have solved this by reducing the offset of the raft from the model and re-leveling the nozzles, but we will see how well it ends up separating from the raft when it is done printing...

Jetguy
Posts: 1595
Joined: Tue Mar 22, 2016 1:40 am

Re: is this over or under extrusion or something else (ABS/HIPS)

Postby Jetguy » Sun Sep 03, 2017 2:52 pm

The missing lines indicate severe under extrusion.

Over or under extrusion is a slight fine tuning adjustment that often happens because users fail to measure actual filament diameter and leave the software at the default of 1.75mm. When actual is different (often up to about 1.83mm diameter for many brands) yes, the same linear distance of filament is more plastic because it's a larger diameter. Under extrusion almost always indicates a failure of the hardware to properly push the commanded linear distance of filament into the extruder (drive gear slipping and grinding or skipped steps).

Again, let's get down to brass tacks.
Under extrusion is a slight tuning factor.
Skipping steps and not extruding entire lines of infill- not really the same thing.

The bottom line is what is different about your specific roll of ABS VS the other filaments you are printing besides the fact it's ABS.
More likely than not, it's a different filament diameter. If using the stock as supplied Raise 3D upper feeder motor assembly, the user is responsible to adjust the motor to V-groove bearing pinch gap distance. If it is too loose (wide of a gap) the filament is not gripped by the drive gear and slips and grinds away a divot out of the side of the filament. Too tight of a gap this makes huge friction to the motor and thus less force available to push the filament into the nozzle. Something has to give and that results in lost motion called skipped steps (the sound of the motor ticking or thumping is clearly audible and should be a sound you should be able to identify from across the room. Yes, you can hear it that far on these printers.

Again, this gap is very sensitive and needs to be adjusted per filament- even maybe as often as per spool. Different plastic is a different hardness and gripped differently and also each brand and spool can be a slight difference and that small change is enough to go from working to not working.

Jetguy
Posts: 1595
Joined: Tue Mar 22, 2016 1:40 am

Re: is this over or under extrusion or something else (ABS/HIPS)

Postby Jetguy » Sun Sep 03, 2017 3:40 pm

Related topics to solving skipping steps or general extrusion inconsistency issues (skipping steps, slipping, grinding, massive under extrusion).

First- adjusting the stock feeders as mentioned above. viewtopic.php?f=2&t=879&p=8367&hilit=paper+shim#p8342
Also here viewtopic.php?f=4&t=867&p=8229&hilit=shim#p8229

Next, potentially motors heating up the body of the extruder can cause issues even with ABS. Because for ABS you use a hotter ambient temp by using the lid on the printer and ensuring the doors are closed and the heated bed is run much higher temperature the extruder motors hanging out in the top of the printer can heat up and cause this exact issue not seen with PLA printing because the lid is off for PLA.
Add to that that Raise 3D did a motor supplier change and kept the exact same electrical settings and specification- can potentially be a complaint that I myself saw as did several other users. Bottom line, if the motor and body of the feeder is getting hot to the touch- that is not ideal for 3D printing. Something has to change and highly suggest you open a support ticket if you find this to be the case- especially if you have the BOHONG brand motors.
viewtopic.php?f=4&t=1887&p=15531&hilit=overheating#p15531

Again, what we have is a double issue. The newer Bohong brand motors are different from the Minbea brand motors shipped on original Kickstarter and early units shipped for the first several months. There are enough reports and I have done the math and testing- these motors run hotter at the factory settings than original Kickstarter units. That coupled with higher ambient temps during ABS printing causes the double effect of even hotter motors- so much so it heats the entire upper section of the extruder system and can cause jams when printing with the lid on.

User Olivers is fighting this right now viewtopic.php?f=7&t=1347&p=18445#p18165

Even John who specifically prints a lot of ABS said this viewtopic.php?f=4&t=1709&p=17735#p17735
Look back at my posts on the same subject. I solved it. I found that the motors were getting way too hot with the cover closed during ABS printing. I have not had a clog since I simply started venting the air temperature down below 55C.


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