z-axis moving too much?

[mgg942 0]

Made a couple of things this morning - no problem. Then a problem that has me baffled.

The print starts off fine but something goes wrong as the number of layers mount.

To my inexperienced eye it looks like the z steps are too great.

The photo is of a whistle that I've made successfully several times using the same material (PLA/PHA). Settings are Cura beta 2 defaults, layer height 0.1mm, filament diameter 2.85mm, fill density 20%.

Z motor coupling grub screws are tight (all 4).

I increased the pressure on the extruder feed.

No better.

Hopefully someone can take a look at the photo and identify the problem!

 

[IRobertI 516]

Maybe take a look at the jumpers for the z-driver on the PCB. Maybe a jumper has shaken loose causing the number of steps to change:

http://reprap.org/wiki/Ultimaker%27s_v1.1_PCB#Step_14_Place_Jumpers

 

[mgg942 0]

Thanks - I'll check that tomorrow as it's 1030pm here.

 

[gr5 2,069]

Test Z only. Using crua or pronterface move the Z up and down in known amounts - for example 10mm or 100mm. Measure the distance moved. See if the two directions move different amounts. I would measure against the wood near either of the back 2 corners with a ruler or paper or calipers. Your Z error looks very high - more than 10%. If you have an ulticontroller ask it what steps/mm for Z are. Maybe it got corrupted and power cycling will fix.

FYI your very first printed layer (skirt) isn't quite flat (squished) enough - when leveling your bed use a piece of paper and make sure there is slight tension between the paper and bed. Then move the bed even closer to the nozzle by 1/8 turn on each screw.

This isn't your current problem but it will cause problems in the future (e.g. part not sticking well to bed, bottom layer has gaps, bottom layer doesn't look as good as top layer).

 

[mgg942 0]

Well, I dunno....

Checked Ulticontroller - z-axis steps/mm 533

I used the Ulticontroller to Auto Home, measured as shown below. Used Ulticontroller to move down 50mm, Measured. Then back up 50mm measured. Did this twice.

50mm down measured 49.67, 49.79

Return to zero measured 0.13, 0.27

Before checking the jumpers, I uninstalled Cura 13.04 and closed_beta_2. Then installed Cura 13.05. Made new gcode and all seems well!!!!

I've been confusing myself with the several Cura versions so I'll now have only 13.05 - for a while at least.

Re z setting. I don't know if the photo was misleading or not, but I've no issue with adhesion. Possibly through scrupulous use of Isopropyl alcohol. Nonetheless I'll move in the direction that you've recommended.

Thank you both for your help.

Here's how I measured - a couple of pieces of wood on the patform and a digital vernier.