Hi, recently got a flsun kossel and apart from a couple issues it’s. Working perfectly. One of those issues is the top and bottom layers don’t seem to be joined together properly (spaces between the lines). The bottom layer is the main issues, but the top has issues as well. If anyone has some suggestions that would be great. If you need any details about settings let me know. Thanks



1 your extruder gear is not gripping the filament properly, clean the gear and make sure the bearing has higher pressure on the filament

2 the filament diameter is varying to much, measure it

3 the extruder motor is skipping steps

4 calibrate your extruder again to see if you extrude 100mm it is really extrudes that much

Check these and see if its helps.

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Thanks for that, will try it when I get home. Thinking the bearing might not be tight enough. How would you measure how much has been extruded? Do I put a mark on the filament 100mm from the extruder entry and make sure they match in the end?

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This page specifically has settings with illustrations that might help.


My guess is you need: More infill, and more top and bottom layers.

On the top, your infill is sagging downward, on the bottom, your bed is not perfectly level.

Thanks, I’ve got it at 20% hex fill. How much would you go up from there?

For proper calibration, I suggest to mark the filament before the extruder(50-100mm) . Heat up the nozzle and slowly extrude the filament, than measure the distance again between the extruder and you mark. Than calculate the new steps/mm value:

(Requested amount / measured amount) X current steps/mm value.

Example: You requested 100mm to extrude, you measured 96mm movement on the filament your current steps/mm value is 150 steps/mm.

The new value will be: 100/90 = 1.1111, 150 x 1.1111 = 166.667 steps/mm

Modify this value in your Firmware and re upload it, than test is again.

You can modify this value on the fly with “M92 E166.667” command so you don’t have to upload the FW after every measurement.



Thanks for that. Hopefully that should fix the issue. Though instead of setting it the firmware, is it possible to just set it in the software? Or is better to do it via firmware? Thanks again :slight_smile:

I would fix it in the firmware, than you can tweak it afterwards in the slicer program modifying the flow rate value.

Also you can put the M92 Exxxx -value into your slicers start gcode so it will use this value for every print, attached a picture from my cura setting and the gcode it makes

Sorry to ask some many questions (very new to the 3d printing game). But at moment I’m using slic3r, if I was to switch to cura (had it suggested as being the better option). Do you know of any good tutorials in flashing the firmware and set up. Thanks again :slight_smile:

No problem, just ask we are here to help.


First watch this video to understand how it can be done:

Thomas Sanladerer 's : How to set up the Marlin firmware


Do you have your original firmware in and editable way you will see on the video?

Personally I prefer Cura, but use the older version 15.04.06 the new one is terrible.



Don’t believe I’ve got the source code for the firmware (chasing the seller for that now). Though it seems to working as is. Only issue so far, is that when it starts it takes forever for the head to reach the plate. A quick google and seems that cura might not be picking up the max speed from the firmware and needs to be set via gcode, though they didn’t go into how to do that. Any ideas? Also, tightening the extruder seems to have fixed the layering issue. Was inconsistently feeding, so cleaned and tighter and pulling exactly now. Thanks heaps

Got Cura up and running and so far looking good.

I’ll put up some pic once I got something decent to show.

hanks for all the help


Good to hear the extruder problem is solved.

Regarding the firmware its not a big problem. If you can send all the info about the printer, exact order page link, and even a picture from the printer I can identify it and search the firmware for it. Then migrate the settings into a new Marlin FW. (10 minutes work if we have the old printers setting).

Regarding the slow movement when print starts, please export you cura settings (File menu- save profile) and upload it to here so i can take a look. But it will be a travel speed problem in your start code for sure.

Here’s where I got it from. https://www.3dprintersbay.com/flsun-autolevelling-kossel-diy-kit

Got the speed issue sorted, it was using the manual adjustment speed not the travel speed in the startup gCode. Forgot to export the settings, but will do that this afternoon.

Think the only issues I got now:

  • The first 2 layers seem to thin out to nothing at points on the bed. Think it’s from the bed not being 100% level once it’s got the masking tape on it, but not sure if it’s just crap tape or a bigger problem
  • When I print a raft (to fix the above issue), it prints in a way that’s impossible to remove

Again, thanks for all the help :slight_smile: