At least smaller than what I imagined possible and I was printing small stuff before I got a Zero. I’ve been refining my processes printing small fasteners as they are challenging to print well and in use they give feedback of qualities achieved in smoothness of operation and holding power. The Zero has been great for rapid iterative testing and refinement. It’s also pretty good at precise repeatable motion although I suspect even the cheapest Ender 3 clone could achieve impressive results with the approach I’m developing.
Here’s a print done on my essentially stock Zero with an 0.4 mm nozzle. The thread pitch is 0.4 mm. This has good usable strength despite being printed vertically. It was printed hot for PLA, 230 C, and the layer adhesion is great. I need to set up a testing rig to quantify strength and see what further optimization possible. These were sliced in vase mode with an extrusion width of 0.20 mm and over extrusion to fuse adjacent extrusions and minimize seams. The trick to getting strong parts with vase mode is putting micro cuts in the model to create a convoluted perimeter instead of just getting a simple loop around the apparent perimeter as shown in the bottom image from the slicer. The power of this technique has me thinking about setting up a dev environment for Orca or Prusa slicers and seeing if I can add a hybridized conventional and vase mode slicing option with parametized zig zagged paths especially with respect to overhangs, interior holes and other features that might benefit from this approach.
Typically mine are hollow although asymmetric cut patterns can be used to drive one or more extrusions to the core. The flow rate can also be dialed up to get a more complete fill but that must be balanced with the tolerance modeled between male and female threads as increased flow thickens everything. I have thought about using a script to modify the sliced gcode and every nth layer add a move to the center from the nearest point and then extrude the expected needed volume to fill the core.
I’d be surprised if any of my slicing parameters are stock. I think I have the speed of external perimeters set to 150 or maybe 200 but it is irrelevant as the motions are so tiny the speed is controlled by accelerations never approaching the speed limit. I think my acceleration for that print was 10k and the nut and bolt together print in about 110 seconds at a 0.05 mm layer height.
0.4 mm thread pitch is very impressive with a 0.4 mm nozzle, but so is printing a fastener that’s almost the diameter of the 1.75 mm filament. I love seeing people using 3D printers to do creative things, but I particularly love seeing people 3D printing creative and cutting edge mechanical parts and other functional stuff. Engineering is how I express my creativity, and there is definitely an art to it. Well done. Thanks for sharing.
Printing horizontally also has drawbacks. Print resolution is better in Z than the XY plane typically by a factor of 2 or more so printing horizontally requires a larger tolerance between male and female threads which reduces thread engagement which reduces the amount of torque the threads can take. The threads at the top in Z are printed as isolated islands which makes their quality and strength worse. Max torque is further impacted when the bolt is clipped to eliminate the need for support by the fraction of the bolt clipped off the bottom. Also clipping the head of the bolt decreases the functionality of hex head bolts and wrecks some types such as socket heads. Resistance to cross threading is also impacted by horizontal printing.
My approach should work great for larger fasteners. I first started doing fasteners in the range of 4 to 7 mm where it worked quite well before pushing it smaller. I haven’t yet tried but expect the quality will improve as size increases. I’ve made further improvements and will post new photos in another day or two.
I was very impressed with your method that has a continuously printed helical thread. That’s going to be very strong and uniformly so, as well as accurate, but seems more applicable to small fasteners. I did consider that horizontally printed larger fasteners would have little dots of plastic at the top of each thread peak which would not print well and would have poor layer adhesion, but that seemed less of a problem than slicing 20% off the diameter of the thread on one side so it could lay flat on the build plate. In my comment under the video, I stated that I’d leave the bolt head intact and would design rectangular print-in-place support for the flat side of the removed side of the threads.
Vase mode is going to be best for small fasteners, without question. I can see pros and cons of horizontally printed larger fasteners.
Apologies if you consider this a thread hijack. If so, let me know and I’ll gladly delete my comments.
In my comment under the video, I stated that I’d leave the bolt head intact and would design rectangular print-in-place support for the flat side of the removed side of the threads.