I'm looking for pictures for my article,

I’m looking for pictures for my article, and I need one that clearly demonstrates Z wobble. You would think this would be easy to find, but people tend to share good prints, and most of the bad ones I’ve turned up have other issues that muddy the waters. Does anyone have a good “before” picture that demonstrates it well? Ideally, I need a picture of a relatively thin tower so that you can see that the ridges run parallel on both sides. One that matched the wobble up to the threads of the Z screw would be best of all. Send me all your best worst print pictures!

How are these: missing/deleted image from Google+

the wobble is pretty visible in the third pic, but that’s a hideous print in general, so probably no better than what you’ve seen.

Yeah, there appears to be some genuine Z wobble in there, but it’s hard to be sure with all of the other Z issues. Maybe everyone who has actual Z wobble fixes it before their print quality is otherwise good enough to clearly demonstrate Z wobble… but there must be some from all the bearing-encumbered prusas out there…

https://lh4.googleusercontent.com/-7ZBS67gJpSc/UP08gHjN-HI/AAAAAAAAPSc/uUOjxoIH0vI/s700/0_cdd95_78d536e6_orig.jpg is this one good enought? picture with two towers…how about that one? https://lh4.googleusercontent.com/-LbxW8zfB_Eg/UEINn95aeWI/AAAAAAAAL28/BKtQHGEpQGU/s804/CameraZOOM-20120807113229552.jpg

There’s definitely something going on there, but from that angle I can’t be sure if it’s Z wobble or Z ribbing, and there are also some irregular artifacts muddying the water.

think thats was z- wobbling. lines go all around print.

If they form rings going all the way around, it’s Z ribbing. If they’re one continuous line going around the print like a screw thread, it’s Z wobble. Regardless, the fact that I can’t tell with certainty which it is from the picture means that it’s not suitable for my needs, as I’m looking for something to contrast the two.

wobbles going to show as an small offset isn’t it? ie one side will be in slightly, the other out slightly. ie you’d get the same affect if you skipped some x,y steps one a couple of z layers then made them back a few layers later, but repeatedly.

ribbing will be a consistent ring.

Basically, yes, though it will be smoother than that, approximating a sinusoidal wave.

this is true. I’m wondering if it’s going to be easier to draw this rather than get a picture. I’m not sure how you’d get a wobble without bending rods. maybe print an offset zmotor zrod coupler?

@Jonathan_se5a_Sorens That’s a good idea. I’ll have to lock down the other end and find something with less stiff Z guides than my bukobot to do it… I bet I could retrofit Wallace for the job, though I might have to make new X ends as well so that the wobble doesn’t just make it bind.

drawing pictures would be better for principles explanation )
pictures always makes u think - oh not, thats not mine problem )

@Whosa_whatsis about retrofit. thats not a problem - jast fix lower nuts in holes and add upper one )

I think that whatever else, for something like this you need both a schematic, exaggerated diagram (2D projection will do) as well as a photo. You can’t really do it with just one of the two.

But you could have a photo demonstrating simply “Z axis is funky” and then have two diagrams (one showing the < < nature of wobbly, and one showing the < > nature of wobbly) to show how you distinguish between the two types of funky, if it’s that hard to photograph the difference anyway.

How’s this? http://www.flickr.com/photos/jabella/5545118221/

Actually, that might have been a PID problem. Let me dig more.

@John_Abella I agree, looks like a pid problem.

This might be a better example: http://www.flickr.com/photos/jabella/5642459912/in/set-72157623829152993/

I have some Z wobble going on that I was just about to take steps to try and mitigate. I can print some before and after items, and get some pictures but probably not for a couple of days.

@John_Abella Looking through John’s photos: how about http://www.flickr.com/photos/jabella/4613127856/in/photostream