Extrusion problems

[sean-stein 1]

After using an ultimaker ² for over a year, I still having problems getting reliable prints in good quality.

It seems this is mostly related to the extruder setup.

It has a new nozzle, the extruder spring is set to least tension. Frimware has been updated regularly.

I suspect something on the board is wrong, maybe stepperdriver jumpered wrong, resulting in less microstepping?

With the default settings it extrudes way too much material, putting too much stress on the extruder. A callibration box comes out with 1.1mm walls, when they should be 0.4. As a result I tuned down the material flow to 37% to achieve 0.4mm, as seen here:

This resulted in prints coming out nice, yet it still tends to start underextruding on longer prints.

Since the flow is off with the dafault settings I suspect something wrong in firmware/electronics.

Has anybody experienced similar issues or has suggestions/tips to this?

[nallath 1,117]

Sounds like your teflon part (its the white part in your hotend). Have you replaced that since buying?

[sean-stein 1]

Thanks for your reply.

Yes, the teflon part was replaced along with the nozzle.

I see how a worn down teflon bit can cause extrusion problems, but it doesn't explain why the printers material flow is so off in the default setup?

[nallath 1,117]

If i recall correctly (im not an electronics guy, so i'm not quite sure) the older electronics have a jumper that can set the extrusion to 8x or 16x microstepping.

[sean-stein 1]

hm, still having the issue with multiplier down to 0.4 for best result.

There is no apparent way to change microstepping on the board individually, it seems there is an over-all jumper between 8x and 16x. In my case only the extruder seems affected, so that doesn't lead anywhere?

One way to reduce jamming was turning the cooling fans off, it seemed the sheet-metall is bent so some of the air gets pumped towards the heater. We bent the metal a little, since it was crashing into the main frame when homing.

Guess its the problems that come with owning probably one of the first production batch machines, but still utterly annoying considering all the time and money going in adjustments/nozzle exchanges when I've seen and worked with other machines doing quite fine.

Anyhow, I'd be glad to find any hints in making this machine more predictable.