Help with missed layers

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Kay
Posts: 3
Joined: Tue Aug 08, 2017 4:36 pm

Help with missed layers

Postby Kay » Tue Aug 08, 2017 4:47 pm

Hello to all. My name is Kay. I am new in 3D Printing and i prefer Idea Maker as slicer software, because i get the best results with it. I am still tweaking the settings, but i have some problems with "missed" layers. First, i had issues with the first layer:

bad_adhesion.jpg


With reducing the First Layer Flowrate to 98% the first layer was nearly perfect.

And im also impressed with the top layer:

good.jpg



But then i got problems with above layers as you can see here:

problem.jpg


Can someone give me a hint, where i can adjust to get it with better results?

Thanks in advance
Kay

Jetguy
Posts: 1773
Joined: Tue Mar 22, 2016 1:40 am

Re: Help with missed layers

Postby Jetguy » Wed Aug 09, 2017 2:40 am

That's not an adjustment. That is your printer failing to follow the very gcode commanded.
You cannot magically solve this with a setting.
Your extruder is either skipping steps or slipping and not gripping the filament. You need to solve that mechanical issue first.

Jetguy
Posts: 1773
Joined: Tue Mar 22, 2016 1:40 am

Re: Help with missed layers

Postby Jetguy » Wed Aug 09, 2017 2:42 am

Please provide the details of your printer (model) so that we can maybe have a chance of telling you more detailed instructions. Again, this is not something you can fix in software. Your extruder skipped steps or slipped and did not push the raw filament into the hot nozzle as commanded- that's why you are missing layers. This is again, a hardware issue at the printer.

Jetguy
Posts: 1773
Joined: Tue Mar 22, 2016 1:40 am

Re: Help with missed layers

Postby Jetguy » Wed Aug 09, 2017 3:09 am

http://3dprinterwiki.info/extruder-troubleshooting-101/

While that was written for a specific brand in mind in some of the comments, it's pretty much universally true.
Most extruders fail at the feeder long before they have a problem at the nozzle. If the feeder cannot transfer the motor force to the filament (slipping or grinding) then it digs a divot in the filament and even less force is transfered to try to push past the jam in most systems.
Hence why during that test, the goal is to see the extruder motor skip steps, but not lose grip. You don't want skipping steps during a print and should listen and know what that sounds like. But the alternative is slipping and grinding which you don't hear skipped steps and just get bad extrusion- your pictures are a shining example of what that can look like.

Kay
Posts: 3
Joined: Tue Aug 08, 2017 4:36 pm

Re: Help with missed layers

Postby Kay » Wed Aug 09, 2017 9:41 am

Jetguy wrote:That's not an adjustment. That is your printer failing to follow the very gcode commanded.
You cannot magically solve this with a setting.
Your extruder is either skipping steps or slipping and not gripping the filament. You need to solve that mechanical issue first.


Thank you for your reply. It is a Creality CR-10 with Bowden Extruder. So i will check hardware first.

Kay

Jetguy
Posts: 1773
Joined: Tue Mar 22, 2016 1:40 am

Re: Help with missed layers

Postby Jetguy » Wed Aug 09, 2017 11:50 am

OK, that says a lot about the "why".
A Bowden extruder (for those in this group that do not know) has the feeder and motor section typically bolted stationary on the frame of the printer and is connected to the hot end and nozzle via a long PTFE (because Teflon is a brand name) tube.
I was only vaguely familiar with this printer but in less than 1 minute of research I found the picture I was looking for.
DHL-Free-2017-Newest-Top-Quality-Extruder-Desktop-3D-Printer-Creality-CR-10-3D-Printer-Kit.jpg


The are using the brass drive gear style feeder and at least a piece of the problem is that drive gear IMO and experience. The reason is several factors about the specifics of that gear, with everything from the shape of the teeth to the very brass material in the first place. It simply does not bite well into the filament and is most likely slipping and grinding the filament. You would see filament dust all around it if that was happening and if you unload the filament, see evidence of grinding on the filament probably the entire length that had been pushed inside the Bowden tube.
There are actually a couple of drive gears I recommend as an upgrade and please, do not substitute one that you think "looks like" the ones I am linking. I'm doing this to help you print better an trust me, I have seen hundreds of people buy "upgrade gears" from the wrong vendor and throw money this and not solve the problem and/or make it worse. I'm not saying these are the only ones, but again, have seen many folks folk into the trap and buy what they thought was a similar looking but did not perform the same gear.
$3 from Monoprice. https://www.monoprice.com/product?p_id=12638
The key advantages of this gear are even though some call it the aluminum gear because they paint it with silver aluminum paint, it's actually steel gear with very hard teeth. The 2 metal rings or grooves help ensure the filament runs straight on the teeth of the gear. I have about 5 of these on various printers of my own. Note, because this gear has a groove, the other side of the extruder called the idler bearing pressing the filament should be a flat surface bearing- not a V groove bearing. I could not find pictures of what you had exactly stock on a CR-10, only the motor gear picture.
This gear is one of my favorite all time gears and is recommended here in this forum for those with a stock Raise 3D extruder feeder wanting more grip https://www.3dp2go.com/38-teeth-steel-e ... p-450.html. This is a super sharp hard steel gear. These are hands down the best I know of. Works best with a V-groove bearing on the older side though since this cannot guide the filament straight.
Just found this set of gears (more than you need set of 4) but they are worth every penny and like the above listed 38 tooth gear. https://www.amazon.com/Wangdd22-Accesso ... B06ZYG5Z47

In my experience, these gears are not as good as anything listed above.
https://www.amazon.com/Witbot-Extruder- ... B06XNP8X5C
definitely not these
https://www.amazon.com/Signswise-Extrud ... B00ZZRI0DC
Same brass junk gear you have now
https://www.amazon.com/CTYRZCH-Pieces-P ... B016Q7YJAM

Changing to a super sharp tooth gear should solve the gripping and 100% ensure your feeder is putting as much motor force as possible into the filament and even if the motor does skip steps- at least now you know the next step to tackle is the hot end.

Just follow my logic on this. Many people immediately go first to the hot end and try to fix it or upgrade.
Both sides of the system have to work and both can cause the problems of under extrusion.
That said, even a good nozzle with a shoddy feeder is a bad extruder. A good feeder with a bad nozzle might jam, but it will attempt to recover and print good if the nozzle is cleared.

Hope this helps you out.

Kay
Posts: 3
Joined: Tue Aug 08, 2017 4:36 pm

Re: Help with missed layers

Postby Kay » Wed Aug 09, 2017 12:07 pm

Hi Jetguy,

wow ... this helps me a lot. I will look at the gear when i am back home.

Thanks
Kay


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