Another anti Z wobble device

Like piercet, I have some Z-wobble in my parts and I want to have a solution for this. You can find his solution here. First, I wanted to use his version, but I run into some problems: He uses additional hardware in Inches which is not available in Europe and other things like the bushes I can’t order here.
So I started thinking how such a device can be built in a more easy way, and maybe also smaller… And I got it!

My first attempt was something like a cardanic joint with the possibility of side movement (same principle as piercet, but all axes in “one” part). A great device, but not enough space on the TAZ…

Now I’m using a spiral to allow the z-nut to flex a little bit. All hardware necessary is 6x M5 nuts and 8 M3 nuts. Not perfect, but a hughe improvement and simple solution :slight_smile: See pics attachet for comparison. I think I can make it even better in the future, but as for now am satisfied.

Of course there is a small drawback. With original mounts, I measured 0.01mm Z backlash. Now, I have 0.02mm. But thats only important if you use Z-hop on retract which is always a bad idea (in my opinion) so no real problem…
Nut Holder_v3.stl (2.93 MB)



Neat solution! I like the compactness of it

Nice, seems pretty simple. I am in the process of swapping out my rods for hardened steel rods and linear ball bearings along with dampeners, I was wondering if I should add this to my printer while I’m at it.

What type of filament did you use?

Scott

I’m using pla, but you want it to flex so abs should work even better.

Looks like a good idea, i have the. Z-axis for the first taz models(which is a m6 rod) and it uses the same flexing principle. I have been wondering why they changed it since that it seems that the wobble is a problem. I guess the rods got alot straighter and it is thought as not needed? Or maybe there is something more than backlash sacrificing?

I bet that’s the reason. Maybe they are satisfied with the small rest of Z-wobble?
I’m currently working on the next version, curently printing. Maybe it flexes a little better without torquing around x-axis…

The main issues with printed springs are breakage, and Z axis up and down deflection, which shows up essentially as backlash. I suspect the former is why you don’t see them on the TAZ design anymore.

You have to have a really rigid spring section in the Z axis, but really flexible in X, or X and Y depending on the design. In this particular case with the rods in the bottom section, if they are moving fluidly enough you shouldn’t technically need the spring section as well, since they are both basically serving the same function. I moved away from spring sections because they also exert a centering force. Though small, it basically forces the carriage to align to the leadscrew again, where a pin only section will just sit wherever the leadscrew wants to be without exerting a side force.

I wonder if the new TCTPE or some other nylon filament would be good for this?

I replaced my spring-type parts with a slider version. It’s a kind of merged together Z-Nut bracket and the cardanic joint I wanted to use in the beginning. Still not perfect, I’m thinking about version 7…
But at least it looks cool :laughing:


Slider.stl (1.2 MB)
Nut Holder_v6_Zanschl.stl (1.24 MB)
Nut Holder_v6_Base.stl (1.28 MB)

On the latest prototypes we are putting a thin ninjaflex disc that goes between the lead screw nut and printed part. It should be here, but I don’t see it at the moment, idk. The drawing will likely appear:

http://devel.lulzbot.com/TAZ/nutmeg/production_parts/printed_parts/

How well does that seem to be working so far?

Try in the test parts:

https://devel.lulzbot.com/TAZ/nutmeg/production_parts/test_parts/flexywasher.stl

So what exactly do I need for this to work, I’ve noticed moderate Z-Wobble on my taz. and this could be the solution, I noticed in your updated version, there were pieces which looked like white spacers, will I need to find those, if so, what are they, and what size are they so that I may easily create this lovely item.

You need 6 M5 nuts, 8 M3 nuts and a rod of 4mm diameter (thats what you see white in my pictures). I used a GRP rod because it slides quite well, normal steel should be also OK.
But I think you also have to exchange the bearing at last on the Z axis. The best anti wobble device can’t do anything if you bearings have play as the originals have due to bad bearing holders.
I’m using my yellow version with Igus RJUM-01-10 bearings with good results :slight_smile:

I was able to grab the metric nuts in 10 mins at my local hardware store, couldn’t find any 4mm rod, so I’m settling on your v3 for now, quick question though, for the v7 do the rods make contact with the threaded z-axis screw, or are they there for support, thanks alot by the way, judging from the pictures it looked to do quite the change, even in the v3 phase. I’ll order some 4mm rod online, but a quick test fix using v3 should be very telling on the true nature of my issues.

Nothing should have contact to the z screw. The 4mm rod is only a sliding connection. You have to bore out the holes carefully: the two rod pointing along the x axis should stick inside the holes of the bracket mounted on the x axis but slide in the holes of the slider part.
The two rods pointing along the y axis should stick inside the holes of the slider part and move nicely inside the bracket mounted to the z nut.

I just made this mod over the weekend and it seems to have worked out great. In the end the only rods I could find in the correct size were brass, but they seem to be doing the job just fine.
20160314_093630.jpg
Here are the results of just this mod alone:
20160314_093808.jpg
Without upgrading the bearings, or doing an openbuilds axis mod, there is still some slight banding, but it’s a huge improvement over the stock print. Thanks for the design! It was pretty simple and very compact.

Hi

I installed the first version, but it didn’t change anything unfortunately. I’ll try the second version now :slight_smile:

Where did you buy the Igus bearings, if I may ask? I can’t seem to find them in Europe

The metal IGUS bushings are very hard to get, that’s right. The only source inside the EU I have found (and which is also shipping to private persons) is: http://www.rs-online-privat.de/

But think twice before you buy them: I wouldn’t go that route again. The Openrail Mod is less expensive and much, much! better compared to the bushings. It’s a little bit more work, but realy worth it. The RJUM things are OK for the Z axis, I’m still using them in there. X and Y are Openrail now.

If you want them, I would sell my ones left from the X and Y axis (=up to 7 pieces). Only very short time used, if you are also inside the EU shipping shouldn’t be too bad :slight_smile: