nono he using 8mm threaded rod. which is 1.25mm pitch. 5120 is the nominal s/mm.

yup your value is right.

So over the weekend my Z axis motor bracket cracked and failed. So the problem is I can't print a new one until I get my existing bracket fixed, so I had no choice but to use epoxy glue to glue it together to print the replacement.



The epoxy glue process isn't perfect and the bracket no longer is 90 degree to the frame.
That caused some wobble in the Z axis and it caused the Z banding that you see in the picture.
This is the first time I've seen it.




So if you see Z banding, check your screw, alignment, wobbling, crack in Z axis mount etc to see whether it is the problem.

So i use izzudinhafiz value and get 9.8 when i print 15x15x10 cube and i adjust it and get actually 10mm on the z height with this is my current value 5278s/mm

can anyone explain why my value before i change just now and my value after i change right now is still gave the same z height?

my mount seem ok because it acrylic and if it crack i can see it clearly, and i just allign the stepper motor lead and threaded rods last week and it seem fix a little of my banding problem and after i tighten my extruder screw the banding almost gone and right now i still figure out why it only happened on the area that i show on the pictures that i attach on few post back.

Is it consider to be banding or something else, i think i didnt has wobble problem on my printer cause i dont know how many calibration cube i print these past days and didnt see any wobble on any of them

errors in layer height extrusion + errors/tolerance in screw pitch + errors/tolerance in nut + bed height error/tolerance + backlash error/tolerance + microstepping error/tolerance. It adds up.

The problem with calibrating it like this is that the errors might be different for different heights.

what if you print 10mm you get 9.8mm and if you print 30mm you get 29.7mm. Notice that the error is not linear.
So if you compensate for 1 you might make another height overcompensated for example.

Also you also make your layer height no longer multiples of the stepper motor core resolution.

can you print a shape that has multiple height step? Like a staircase. Check the height for each level.

http://3.bp.blogspot.com/-wAVXLAcqFQA/UaGH...00/DSCN2810.JPG

We're looking for systematic error to fix. random error caused by poor tolerance is out of our hand.

I think the best solution is to change out your threaded rods with proper lead nuts and lead screws if you want to improve overall accuracy.

Threaded rods are not designed to allow smooth moment and they tend to wear against the threaded nuts each time there is movement. They are designed to lock in place and prevent any loosening.

Lead screws on the other hand are designed to move freely and have higher quality standards.

Heh. they're not as cheap tho. I've gotten pretty good accuracy with my threaded rod + Anti-backlash nut. but i do second the high wear. I change the nut every few hundred hours of printing

So here is my final value after printing this 5mm calibration step 5113.49s/mm

first step = 5mm
second step = 10mm
third step =15.1mm
forth step = 20mm
fifth step 25mm

the way i measure is like this, press the caliper hard enough again the model and release to check the measurement so all the measurement is like above result

This is what im using for anti z wobble and backlash

That's is a lot of nuts to change

If not mistaken, I bought mine for about RM 25 per 30cm leads so to me it's quite reasonably priced. I got them through another person who ordered from china.

Looks like the Z-axis bracket is quite thin. Have you observe any flexing on the bracket each time there is a change in height?

This post has been edited by altan: Mar 28 2016, 07:47 PM

which bracket do you mean

hmm. your printer is printing correctly for 4/5 heights. 2 on the lowest one and 2 of the highest ones. nothing much wrong with z-axis.

altan is referring to your motor mounts for the z-axis.

the anti backlash system is similar to mine

Sorry for the late reply, it's the top part that the anti backlash nuts are pressed against. Also, check the motor mounts for flexing too...

Oh ok, it 8mm thick acrylic and i didnt see any movement on it when z axis go high or low.

So i ask similar question on reprap forum and someone answer maybe it cause by slicer setting

i didnt noticed any flex on the mount, maybe i should design new one

where do you get the springs? i've been trying to find spring shops

i found the spring inside my tools box and can't remember where i got them and i sure i never buy a spring before

just order more stuff that i need for my next build just now on aliexpress with the point i collect in this past week i got $8 discount aliexpress got anniversary sale right now