Jump to content
jlegitt73

Over Extrusion First 8 Layers

Recommended Posts

Posted · Over Extrusion First 8 Layers

This just started happening a couple days ago. Nothing about the printer has changed intentionally. The same GCODE printed perfectly 20 times before. Now it's over extruding like mad for the first 8 layers, then it prints perfectly fine for the remainder of the print. It does this on every single print now - old GCODE and new. I've seen a dozen posts around the internet with the exact same problem, but nobody seems to be able to offer a solution that works. The printer is essentially useless until I fix this.

 

Possible problems:

 

- The first 8 layers are over extruding, which is causing a build up of plastic that the nozzle starts dragging around with it. The outer layer bulges out frequently to cause the problem shown in the photo.

OR

- The first 8 layers are not the proper Z height. Layer height is set to .2 mm, but if the Z shift is less than that in those first 8 layers it might just seem like over extrusion.

 

Solutions suggested:

 

- Adjust Z rods and wheels.

- - Adjusted everything and it seems fine.

 

- Turn down bed temperature.

- - Have tried printing with the bed between room temp and 60c. No change.

 

- Adjust Initial Layer settings in  Cura.

- - Have tried this with no success. Reducing Initial Layer Width, Speed and Fan have only changed the problem.

 

- Something wrong with Z Screws in that range.

- - Have raised the bed about 5mm. If the Z Screws were faulty in that area, it should have fixed the problem. It still does it for 8 layers.

 

I think that about covers it. Anyone have any insights?

Over_Extrusion.jpg

Share this post


Link to post
Share on other sites
Posted · Over Extrusion First 8 Layers

Your first layer is too close to the bed (clearly visible on how that brims shows transparency). That makes the filament buildup and it fixes as soon there’s room for the excess to crawl (non solid layers).

 

make a first proper layer and it should fix itself

Share this post


Link to post
Share on other sites
Posted · Over Extrusion First 8 Layers
5 hours ago, neotko said:

Your first layer is too close to the bed (clearly visible on how that brims shows transparency). That makes the filament buildup and it fixes as soon there’s room for the excess to crawl (non solid layers).

 

make a first proper layer and it should fix itself

 

I've printed at multiple heights from the bed attempting to solve the problem. All have the same results. This one wasn't actually too close either. It was set with the .2 mm feeler gauge and the first layer was perfect other than a tiny blob where the layer started. What looks like a thin line on the skirt is actually a bit of left over clear filament mixing with the black.

Share this post


Link to post
Share on other sites
Posted · Over Extrusion First 8 Layers

@neotko is smarter and more experienced than me so I hate to disagree but I think "first layer too close" wouldn't affect so many layers - just the bottom 2 or so.

 

Your analysis of "screw" issues is what I thought of at first also.  Also heat.  I know you said you changed bed temp to room temp but this looks so much like a heat issue.

 

What are the internal infill layers like?  I guess it's important to decide if this is really overextrusion.  Speed changes can also cause this kind of overextrusion when it goes from printing fast infill to slow outer edge but it wouldn't likely go *all* the wway around the part (does it go all the way around?).

 

I'm really not sure what the issue is.  Note also that it probably is printing slower on those lower levels.

  • Like 1

Share this post


Link to post
Share on other sites
Posted · Over Extrusion First 8 Layers

If it was a screw issue it should do this on everything you print on the bottom "8 layers".  Not just this print.

 

I would try resetting cura settings back to defaults as well.

Share this post


Link to post
Share on other sites
Posted · Over Extrusion First 8 Layers
1 hour ago, gr5 said:

If it was a screw issue it should do this on everything you print on the bottom "8 layers".  Not just this print.

 

I would try resetting cura settings back to defaults as well.

 

It did it on every print. I actually found the solution, however. I posted for advice before taking the entire thing apart for a thorough cleaning, just in case I needed to replace something while it was apart. During disassembly, I noticed a couple of things.

 

1. The Z rods had a bit of dirty build up in the recesses. Took them to the wire wheel and scrubbed them with alcohol.

 

2. The top carriage that loosely holds the Z rod in place wasn't centered. It's designed to allow plenty of front to back movement, but not enough left to right movement. With the nozzle close to the bed, I loosened the carriage at the top of the Z rod and allowed it to center itself before re-tightening.

 

Put it all back together and first two prints are now perfect.

  • Like 2

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×
×
  • Create New...

Important Information

Welcome to the Ultimaker Community of 3D printing experts. Visit the following links to read more about our Terms of Use or our Privacy Policy. Thank you!