Solidoodle 3 & similar Z-axis antiwobble nut cage V1

thingiverse

I've seen many other people’s setup to eliminate Z-wobble, but it just seemed like it could be better. I’ve devised a “cage” for a 5/16”-18 hex nut that has 4 degrees of freedom (X/Y translational, X/Y rotational) to compensate for Z-wobble and a locker for backlash. This is done by 2 different methods. The first is the actual holder for the nut. It is curved to allow the nut to swivel in the X/Y axis while not rotating on the Z axis. It rests on 2 other layers that give it independent X/Y translation. If only 1 layer was used for both, it would have excess clearance to rotate on the Z axis so translation distance would have to be small or the rotational freedom would be too great and layer height would be inconsistent. The second is with the nut locker. This setup does not require any springs since the nut locker applies pressure against the nut to prevent backlash and unwanted Z axis translation. It does this by exploiting the flexible property of thin wall materials. Update: I'm researching some new ideas and will post another version of this that will work better. I don't have an estimate of when this will be done. Update: So what I plan to do is use something similar to a CV joint. I will probably use unlubricated stainless steel bearings. A nylon filament will be recommended for it's low friction coefficient. Update: I ended up replacing the stock 5/16"-18 rod with an M5 rod from ebay. I suggest doing the same and using my anti-backlash setup. Works incredibly well. Instructions No supports are needed. It’s a good idea to get a >50mm bolt (so you don’t burn yourself. You can use your Z axis screw, but I would suggest getting a separate bolt). I recommend printing at a layer height of 0.1mm-0.2mm. I actually had a lot less mess with the 0.2mm height. I used PLA to start with, but PLA, ABS, or Nylon should work. Nylon would probably be the best considering its high deforming temp, elasticity, and low friction coefficient. Once the parts are printed, the edges that will ride against each other will need to be straightened even more to get them to fit because of tight clearances and seeing how the bottom layer always spreads out more and the corners flare out just a little. 1 of 2 things can achieve this. The first, which is what I recommend and used myself, is use a flat and straight piece of metal that you can heat up with a torch or some type of heat source that will heat the metal up enough to melt the material. Heat the metal up and smooth the sides that slide on other surfaces by sliding it across (don’t keep it still). It shouldn’t take many passes, just take your time and don’t burn yourself! Also be careful because the thin walls will deform easy when they are heated up. Secondly you can just using a file or something similar to clean up the sides, but it’s going to take longer and probably won’t yield as good of results. For the last part you will need a heat source. Heat the nut up on the bolt or z axis rod and put it in the nut holder and swivel it around. Don’t leave it in there too long and repeat the process a few times. This will allow the nut to swivel easier and it will flare some material out at the bottom. Leave it there. The layer underneath it has clearance for this. After that’s all done, fit check all your parts if you haven’t already and make sure your screws go through the holes with little resistance. If you are happy with the fitment, remove the bed and press out the old nut (I used a big pair of channel locks with that 50mm bolt and a socket that just fits over the nut). The nut locker can retain the screws for easier installation. The screws are installed upside down because there is not enough clearance with the nuts. On later versions I will refine that part a little more just to hold the screws better before installation. The nut with nut holder can be installed on the rod at this point. Add the other 2 layers and you can then slide the bed on. Slide the nut locker over the other piece and align them and push the screws through. Spin on the small nuts and check to make sure all the parts are in there place. Finger tighten the nuts and check for proper movement then tighten them a little more with a socket or whatever works. Move the threaded rod around to verify it’s working. You may need to set the surface inset if the clearances are still too small or large.Update: Looks like this part needs a break in before use for better results, not that just having it in there should eventually break it in. It works fine without it, but still has some banding. I've been playing with the bolt setup in the picture and it's getting easier to move it around so basically that would be how you would go about breaking it in. Also just as a guesstimate but it appears (print dependent) that the z rotational free-play is roughly 10 degrees which is a 0.039mm vertical deviation. This primarily only effects the first layer z offset since the bed only travels down for the print.