UM1-Z axis is 1/2 of original height - SOLVED

[stewe 0]

Hello guys. Today I finished my Ultimaker Original build. What a machine. I was impressed by the quality of the components during the build.

After about hour of messing with bed leveling I made my first print. It was the Ultimaker robot which was loaded in Cura 14.01. I choose the quick settings in the simple version of settings and clicked print. The final product wasnt bad, but it is only 1/2 of the original height.(I got about 1,7cm instead of 3,3cm) I printed with PLA/PHA from ColorFABB on 203°C, blue tape, Cura 14.01 via USB. I also have Ulticontroller connected, but didn't used it. The second print was on expert settings, 0,1mm layer, set raft on, temperature 200°C, speed 50mm/s, travel 150mm/s, retraction on, printed 36min. But again, the layer thickness is about 1/2 height of the original. If I click to move bed in Z axis, it moves without problem and when I move it with my hand(machine disconnected from power) it is the smoothest movement of all my axes.

Can somebody suggest me what could be the problem? Thank you for any suggestions and help

 

 

[illuminarti 18]

Well, it could be that it's skipping steps during the moves, or the coupling could be slipping. So the simplest thing to check is that the coupler between the z-motor and the lead screw is connected tightly. Skipping steps is probably not the case, if you say it moves smoothly by hand.

So, next check the steps per mm in your ulticontroller... go into the Control -> Motion section, and check that the z axis steps/mm is 533.33. That's what it should be for the UM1 - 200 steps of the motor turns it rounds once, but with 8x microstepping that looks like 1600 steps per revolution. And one turn of the lead screw is raises the platform 3mm. So 1600 steps/3mm = 533.33333 steps/mm.

It's unlikely that is wrong; most likely if it's exactly half the height, then the microstepping setting is wrong, so the motors are expecting twice as many step pulses per mm of movement.

The Z-axis is supposed to be stepped at 8 x Microstepping. The others are 16x. I can't find a photo of what it's supposed to look like... but if you look here...

http://wiki.ultimaker.com/Electronics_build_guide

... it points out that the MS3 jumper for the z-axis should not be connected - so you might check for that. The steppers are under the little stepper driver boards, I think (the small raised boards with heatsinks). You'll need to carefully remove the board for the z-axis by rocking it end to end while pulling gently. That should reveal the jumpers underneath. Two of them should be connected, but the MS3 one should not be.

 

[illuminarti 18]

Oh, and welcome, by the way!! I'm sure you'll get a lot of great use out of your printer, once we get these initial gremlins sorted!

 

[stewe 0]

Thank you! I spent a lot of thenths of hours reading this forum before ordering my own. I was prepared to fight X/Y skipping and other common prodblems, but I was paying attention to these things during the build, so the common problems are fixed. Only this Z axis thing... I hope that the problem is underscrewed coupling between stepper and screw. I will try to screw it properlly tomorrow and print something. Or could it be the updated firmware? I installed Cura 14.01 and it asked me to update firmware, so I did it.

 

[illuminarti 18]

No, I don't think it's firmware-related.

Most likely either a loose screw, or a the microstepping jumpers.

 

[illuminarti 18]

One way to tell would be to connect to the printer over USB, and move the bed up and down using Cura, or pronterface. Try moving it fairly slowly (600mm/min), 10cm at a time. Stick some blue tape on the inside back wall of the printer, and mark the position of the bed at each extreme. Run it up and down a few times and see if it always ends up in the same place.

If the positions are different each time, it's probable a loose screw, unless you hear odd noises as it moves and/or it stutters - in which case it's skipped steps.

If the positions are always spot on, but the extremes are 5cm apart, instead of 10, then it's probably the microstepping jumpers.

[stewe 0]

Thank you for help, the problem was in jumper on Z axis stepper, there were 3 jumpers instead of 2, so it wasn't stepping 1/8 as it should. Thank you again for your help

 

[gr5 2,167]

For anyone else who has this problem - the red circled area is how the z jumpers are supposed to be (right most one removed or postitioned as shown so that it does nothing). As usual, click image to see it larger.

 

[davinci 0]

Hi there....

maybe I ve a similar problem...

My UltiControler (UM1) shows the z-print-values while printing in a curious way (to my mind).

e.g. : "Layer hight" setting at 0,1mm

a. "Initiallayer" : 0,3mm (z-value indicates only 0,29mm)

b. first printlayer: plus 0,1mm --> so z= 0,4mm, but indicates only z= 0,39mm

c. second printlayer: plus 0,1mm, --> so z= 0,5mm, indicates z= 0,5 mm

d. thrd printlayer: plus 0,1mm, --> so z= 0,6mm, indicates only z= 0,59mm

e. z= 0,7 mm

f. z= 0,69 mm

etc.

My conclusion:

one layer prints correctly at 0,1mm and the next layer only at 0,09mm, next 'compensate' it with 0,11mm ...

With a "layer hight" at 0,1mm would be the printing result ok, but printing with a "layer hight" at 0,06mm this "misstep" would be added and results in an uneven surface ...?

What would you think...?

 

 

[IRobertI 520]

That's just a rounding error when displaying the value on the display IIRC.

 

[davinci 0]

thx for answer!

hm ... but what do the controller has to "round", if there are allways full values... just has to add "0.1" ...?!

...maybe an intern calculating thing...

 

[gr5 2,167]

Computers don't store numbers in base 10. They use binary or base 2. For example the number five is 101.

The number half is 0.1 One quarter is 0.01 and one eighth is 0.001.

But numbers like 0.1 (base 10) are much more complicated and go on "forever" and you have to round at some point. In fact 1/10 (decimal) converted to binary is 0.0001100110011001100110011001100110011...

More info here:

http://www.exploringbinary.com/why-0-point-1-does-not-exist-in-floating-point/

 

[davinci 0]

:huh: ... thx !

 

[trint 8]

Hello

I had a very interesting problem today.

My old printer Ultimaker Original try has updated its firmware. After the update is received similar to your problem.

Printer launched Z-axis to print 2 times lower.

illuminarti Thanks for decision.

I changed Zaxes_mm of 533.3 and now everything is OK.

[jeanpaul.maley 0]

It's been a while since i ran my umo and i seem to be running into the issue that my z steps per mm is set to 200 instead of 533.3. is there a reason for this?