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Printing small objects with a bowden extruder

Posted by JerseyGirl 
Printing small objects with a bowden extruder
June 25, 2014 06:28PM
Hi all! I'm sort of losing my mind trying to figure out what slice settings I should be using for this:
[www.thingiverse.com]
It's really killing me that everyone else's looks fab and mine is a failure.
The dark pink (PLA) and light pink (ABS) both have this oozy look. I'm thinking it's maybe cause my printer uses a Bowden extruder. I've never had any printing issues with normal size objects.
I've tried Cura & Slic3r, printing at slow speeds, printing at low temps, reducing the flow rate, etc. The only thing I haven't tried yet was printing multiple parts on the bed to slow it down even more.
Please help.... :-)
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Re: Printing small objects with a bowden extruder
June 26, 2014 01:01AM
I just looked had a quick look at the model in gcode editor and it seems to me that you have simple bridging problem.
The ugly areas on your pictures (above the eyes) are small overhangs that should be curable with the right settings, depending on your printer model.
Sorry I can't give you more exact answer, I am just printing it on my RostockMini with bowden extruder and will have more answers later
when it finishes.
Re: Printing small objects with a bowden extruder
June 26, 2014 01:48AM
What kind of nozzle are you using? The best bridges and overhangs can be printed by using a very pointed nozzle. Flat tipped nozzles make it easy to create smooth surfaces, but they will not be able to make really good bridges.


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Re: Printing small objects with a bowden extruder
June 26, 2014 05:14AM
I've known but always wondered about that, how does a flat nozzle not make good bridges?

Otherwise, getting good overhang with my PLA has always been an issue, ABS not so much, just take it super slow and for me at least that did the trick. Sli3r has settings for different bridging speed. I would make a test overhang and try playing with the bridging settings. I believe PLA needs speeding up, ABS needs slowing down.


Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus
Re: Printing small objects with a bowden extruder
June 26, 2014 07:20AM
Quote
Srek
What kind of nozzle are you using? The best bridges and overhangs can be printed by using a very pointed nozzle. Flat tipped nozzles make it easy to create smooth surfaces, but they will not be able to make really good bridges.

That's so interesting. The tip on mine is flat but it tapers down a bit.

[airwolf3d.com]#

I have an airwolf 3d HD
Re: Printing small objects with a bowden extruder
June 26, 2014 07:35AM
That's a really wide flat zone. Not sure you'll ever get perfect overhang and bridging.


Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus
Re: Printing small objects with a bowden extruder
June 26, 2014 08:28AM
I would say your prints are almost perfect except for heat. Also an overhang has nothing to do with bridging, they are seen as completely different things by the slicing software.

You should add a large cooling fan for the PLA prints and possibly a small one for printing such small ABS parts (not large ABS parts). Then you should try printing a couple of them at once. After that you can try slowing down at the same time as reducing your extrusion temperature. You can use the calculator in my signature to see what temperatures and speeds I would recommend.


FFF Settings Calculator Gcode post processors Geometric Object Deposition Tool Blog
Tantillus.org Mini Printable Lathe How NOT to install a Pololu driver
Re: Printing small objects with a bowden extruder
June 26, 2014 11:55AM
Quote
Sublime
I would say your prints are almost perfect except for heat.

I also like JerseyGirl's print over my own. I tried 3 prints and still haven't perfected the settings.


Quote
Sublime
Also an overhang has nothing to do with bridging, they are seen as completely different things by the slicing software.
Didn't know that, always treated them the same, thank you for that revelation.
Must also compliment your calculator, it made a huge improvement in quality of my prints. Only wish there would be an offline version available.


All about delta 3d printers in one place [www.deltarap.org]
Re: Printing small objects with a bowden extruder
June 26, 2014 12:10PM
Quote
DinoK
Quote
Sublime
I would say your prints are almost perfect except for heat.

I also like JerseyGirl's print over my own. I tried 3 prints and still haven't perfected the settings.


Quote
Sublime
Also an overhang has nothing to do with bridging, they are seen as completely different things by the slicing software.
Didn't know that, always treated them the same, thank you for that revelation.
Must also compliment your calculator, it made a huge improvement in quality of my prints. Only wish there would be an offline version available.

Your blog is great! I'm going to play around with Sublimes calculator tonight.
Re: Printing small objects with a bowden extruder
June 26, 2014 12:13PM
Slic3r, nasty. Turn off "detect bridging perimeters." In my experience, slic3r makes "bridging perimeters" worse with this setting on.

Edited 1 time(s). Last edit at 06/26/2014 12:17PM by MrDoctorDIV.

Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus
Re: Printing small objects with a bowden extruder
June 26, 2014 12:16PM
Quote
DinoK
Quote
Sublime
I would say your prints are almost perfect except for heat.

I also like JerseyGirl's print over my own. I tried 3 prints and still haven't perfected the settings.

Quote
Sublime
Also an overhang has nothing to do with bridging, they are seen as completely different things by the slicing software.
Didn't know that, always treated them the same, thank you for that revelation.
Must also compliment your calculator, it made a huge improvement in quality of my prints. Only wish there would be an offline version available.

Yeah a bridge is defined as having a span supported at both ends (like a bridge). The only slicer that tries to do anything different for overhangs is Slic3r and I am not sure what it tries to do since I do not follow it very closely. I just remember when I did follow it a lot of requests and attempts to prevent things like perimeters starting on overhangs etc.

For the Calculator it is written in PHP so it is not directly offline capable without running a webserver. I have started porting it over to Python to allow Cura to directly use it for its settings. Python does not have all the same functions as PHP making it slow going, combined with my lack of time I have not gotten very far.


FFF Settings Calculator Gcode post processors Geometric Object Deposition Tool Blog
Tantillus.org Mini Printable Lathe How NOT to install a Pololu driver
Re: Printing small objects with a bowden extruder
June 26, 2014 12:19PM
If you have the math, could it be done in Excel? I might be able to draw that one up, work has supplied me with the opportunities to master Excel formulas I never thought were possible before.
EDIT: PM me if you're interested, I don't want to hijack this post.

Edited 1 time(s). Last edit at 06/26/2014 12:20PM by MrDoctorDIV.

Realizer- One who realizes dreams by making them a reality either by possibility or by completion. Also creating or renewing hopes of dreams.
"keep in mind, even the best printer can not print with the best filament if the user is the problem." -Ohmarinus
Re: Printing small objects with a bowden extruder
June 26, 2014 04:36PM
I don't think it would be possible in Excel because it has a bunch of recursive functions, but I could be wrong.


FFF Settings Calculator Gcode post processors Geometric Object Deposition Tool Blog
Tantillus.org Mini Printable Lathe How NOT to install a Pololu driver
Re: Printing small objects with a bowden extruder
June 26, 2014 11:29PM
I just solved my 'curly hair' problem. As my friend ,the computer programmer, likes to say : It's a feature, not a bug smiling smiley
Was looking at gcode and discovered that the path is wrong (like one way street sticking out) at the exact spots where my curls appear:




JerseyGirl would you mind sharing your gcode ?


All about delta 3d printers in one place [www.deltarap.org]
Re: Printing small objects with a bowden extruder
June 27, 2014 10:27AM
Quote
DinoK
I just solved my 'curly hair' problem. As my friend ,the computer programmer, likes to say : It's a feature, not a bug smiling smiley
Was looking at gcode and discovered that the path is wrong (like one way street sticking out) at the exact spots where my curls appear:




JerseyGirl would you mind sharing your gcode ?

My file is larger than 614.4 kb. I've got to figure out a way around that....

I've been trying printing 2 at the same time and it's somewhat helping. I think my first thought of running it slow but using a fan wasn't enough since there is still some heat convection from the nozzle lingering around my small print. Putting down a layer and then moving the nozzle is improving the layer cooling. But I've now run into an issue with these little blobs when the nozzle traveling over to the new print. Argh!! Plus this ABS I'm using is garbage. I don't think whatever I bought from Makergeeks is true ABS because it doesn't have the same material properties I've seen before. I have no way of proving that though.... I'm waiting on some new PLA and will try again tomorrow.
Re: Printing small objects with a bowden extruder
June 27, 2014 04:19PM
I found a sample of PLA I had from Faberdashery and no luck again making a perfect part. I'm ordering a smaller nozzle. Maybe 0.5 is too much for this size.
Re: Printing small objects with a bowden extruder
June 27, 2014 04:27PM
Quote
JerseyGirl
I found a sample of PLA I had from Faberdashery and no luck again making a perfect part. I'm ordering a smaller nozzle. Maybe 0.5 is too much for this size.

That will not help. Print 4 at a time. Reduce the speed and reduce the temperature to match the new lower speed. Also use Kisslicer or Cura, not Slic3r.

I won the tiny printing competition printing stuff the size of a kernel of corn using a 0.5mm nozzle [forums.reprap.org]


Edited 2 time(s). Last edit at 06/27/2014 05:05PM by Sublime.

FFF Settings Calculator Gcode post processors Geometric Object Deposition Tool Blog
Tantillus.org Mini Printable Lathe How NOT to install a Pololu driver

Re: Printing small objects with a bowden extruder
June 28, 2014 02:59PM
Listen to Sublime, reduce the temperature, use his FFF Settings Calculator and improve cooling. I did this today and was able to print the same kitten and squirrel as he did when he won that competition. My print is slightly biger but am very proud of it:



I wrote more details about it in the update of the post I mentioned at the beginning

Just found another topic about proper cooling:

Quote

I turn two 40mm fans on after the first layer is laid down. I had the exact same problem. I couldn't build the heart gears until I added cooling. The print bed stays hot enough to keep the part down even when cooling. Commercial printers have ridiculous amounts of cooling inside. Its their little secret.

Quote

How "dry" is it when the next layer goes down? ..... if there is any wiggle or "jello" to the last layer when
the new one is going down, you are going to have this problem. The tension of the extruder moving away from the corner I SUSPECT
pulls up the corner, so the softer it is, the bigger the problem.

Edited 2 time(s). Last edit at 06/28/2014 03:06PM by DinoK.

All about delta 3d printers in one place [www.deltarap.org]
Re: Printing small objects with a bowden extruder
June 29, 2014 05:41AM
imho, there are 2 possibilites
1) too hot temp while printing the eyebrow.
2) there is pause during direction change on the eyebrow (bridge) that caused oozing or too much extruded plastic on the area.
if you cant fine tune the temp in problem (1), maybe you have to find better slicer (or setting) that wont pause on the bridge. of maybe you can edit the gcode on the affected area, my humble suggestion is to try to view and posibly edit the output gcode with RapR3D Visual GCode Editor... [www.soasystem.com] fwiw. i'm a newbie myself.
Re: Printing small objects with a bowden extruder
June 29, 2014 08:20AM
I'm so impressed by Sublime & DinoK's kitten and squirrel I want to give that a go. I'm fairly new to this so I'm checking out DinoK's slicer settings to understand the parameters picked. I've got to get beyond the default lol.
Re: Printing small objects with a bowden extruder
October 02, 2014 12:13PM
I'm a bit late to the game on this thread, but I've been experimenting lately with different nozzle tip tapers, flat sizes and cooling. It seems the problem with a large flat is that is simply pumps too much heat into the surrounding material as it lays down each line. Same with a flatter tip taper - it radiates more heat down into the existing material. My latest iteration has a total cone angle of about 80 deg. (pretty similar you your Airwolf nozzle) but a flat on the tip of about 1mm dia. I noticed that your Airwolf nozzle has two black-oxide cap screws that ride just above the print surface - these are going to radiate a lot of extra heat into the material as well.

Cooling is also crucial. I started off with a ducted fan, but after looking at a Makerbot Replicator, I switched to a ducted blower (an actual blower rather than a blower-fan) which can produce a much higher velocity airflow. It nearly whistles as it moves across the print.

My test print has been a single, hollow 12mm ball with no supports, raft or brim. Any curling of the overhang will cause the print to dislodge, which makes for a pretty good acid test. It's also easy to measure the final print to look for irregularities - particularly in the steep overhang on the lower part of the ball.
Re: Printing small objects with a bowden extruder
October 03, 2014 02:06PM
There's definitely something with nozzle geometry. My small parts still aren't 100% perfect. I wanna build a mini delta so this is something I can explore with my next printer.


Quote
LoboCNC
I'm a bit late to the game on this thread, but I've been experimenting lately with different nozzle tip tapers, flat sizes and cooling. It seems the problem with a large flat is that is simply pumps too much heat into the surrounding material as it lays down each line. Same with a flatter tip taper - it radiates more heat down into the existing material. My latest iteration has a total cone angle of about 80 deg. (pretty similar you your Airwolf nozzle) but a flat on the tip of about 1mm dia. I noticed that your Airwolf nozzle has two black-oxide cap screws that ride just above the print surface - these are going to radiate a lot of extra heat into the material as well.

Cooling is also crucial. I started off with a ducted fan, but after looking at a Makerbot Replicator, I switched to a ducted blower (an actual blower rather than a blower-fan) which can produce a much higher velocity airflow. It nearly whistles as it moves across the print.

My test print has been a single, hollow 12mm ball with no supports, raft or brim. Any curling of the overhang will cause the print to dislodge, which makes for a pretty good acid test. It's also easy to measure the final print to look for irregularities - particularly in the steep overhang on the lower part of the ball.
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