Should you be able to see retraction?

[levelhead 0]

Hi, I recently bought an Ultimaker 2+ and am getting it tuned in. When I first was experimenting with retraction I was sure I could see the filament retracting in the Bowden tube above the print head. Today I noticed that I was not seeing the filament move there anymore. The extruder is retracting as I can feel it when gently holding the filament as it enters the extruder. For extraction to be working properly, should I be able to see the filament move at the head? My retraction setting are at the default speed and distance.

Thanks!

[gr5 2,230]

It should not move at the head but if you look at the top of the arch of the bowden it should move from pushing hard on the "ceiling" of the bowden to gently resting on the "floor" at the top of that arch. In other words the pressure should be removed at the head but no actual visible retraction. If air gets in the nozzle then you get other problems.

[levelhead 0]

Thanks , that is what I am seeing now so I guess I had a bit of over-retraction at some point when I saw the filament moving near the nozzle.

Edited May 15, 2017 by Guest

[levelhead 0]

A quick follow-up - I have noticed my bowden tube end at the extruder is moving up and down a few mm on retraction. I know the bowden should not move at the print head but is the extruder end movement something I need to fix?

[gr5 2,230]

Yes. It's not mandatory. In fact if you measure how much it is moving up and down add that amount to 4.5mm and that should be your normal retraction. But it's better to just fix it. If you are lucky it will take all of 10 seconds. Remove the clip. Push down on the collet (the ring) and remove the bowden. Then while pushing down on the collet push the bowden back in and then lift firmly on the collet while pushing down (I found needle nose pliers help with this step) and then keep holding the bowden up and put the clip back on.

If this doesn't work cut off 3mm off the end of the bowden and try again.