What does jumper JP3 (8/16 step) on Ultimaker 2 main board v2.1.4 do?

[umagi 8]

Hi,

On the Ultimaker 2 main board is a jumper JP3 "8/16 step".

What does this do?

If this sets the microstepping mode, why is there only 1 jumper and not one for each stepper motor?

If it is used, does the open state (no jumper installed) mean 8 or 16?

Thanks!

[tinkergnome 927]

https://ultimaker.com/en/community/4878-ultimaker-2-strange-noise-on-z-axis-during-slow-movement#reply-75880

It sets the microstepping for the z-axis, open=8 (default), closed=16.

AFAIK all other axis are already on 16 microsteps.

If you close it with a jumper don't forget to double the steps/mm for the z-axis (from 200 to 400). The sound is a bit different afterwards, but besides that i noticed neither benefits nor drawbacks...

[umagi 8]

Exactly what I needed to know.

In the link you provided above, it seems that changing to 16 steps may reduce some of the Z axis noise, so I will give it a try.

Some people in that post speak of resonance effects, and I believe my custom UM2 build may suffer from it as well, especially since it is even taller than the UM2 extended. My construction is build around an 20x20 aluminum extrusion frame and covered with 4mm composite alu panels. The Z max is 435mm now, and to stabilize the bed somewhat, I have attached flange bearings also below the bed. These bottom bearings also serve as support for the two bed support arms I have mounted as well below the bed. I hope the pictures of my (unfinished but yet functional build) will make this clear.

To compensate for the weight of the supporting arms, I even cut away the same mass from the build plate. The weight of the build platform has thus increased only by the weight of the extra bearings.

I hope that increasing the number of microsteps will alleviate some of the (resonance?) noise I am experiencing when the Z stage is moving down during homing, but possibly, the Z is just too high with respect to the various shaft diameters involved to avoid resonance. Maybe I need to find other ways to dampen those vibrations...

Thanks tinkergnome!

Edited March 9, 2016 by Guest

[umagi 8]

Changed to 16 steps for the Z by installing the jumper on JP3, and the "resonant" noise when the Z shaft moves up and down (homing and to Z=0) have basically gone.

However, my Ulticontroller board has again failed, and again, it's the U3 chip that has blown with a very visible burnout hump on the chip.

I really start to believe this Ulticontroller design is flawed big time!

Edited March 10, 2016 by Guest

[umagi 8]

....

Edited March 9, 2016 by Guest

[lars86 42]

Cool build umagi. Did you get it finished up?

[umagi 8]

Hi Lars. Thanks. Yes, I finished it! It works fine, but the whole 3D printing process is too slow for my liking (and I get bored quickly). So, for the moment, I am focusing on other stuff.