Most inexpensive 3D printers use a type of lead screw to move some part of the printer in the vertical direction. A motor turns a threaded rod and that causes a nut to go up or down. The printer part rides on the nut. This works well, but it is slower than other drive mechanisms (which is why you don’t often see them on the horizontal parts of a printer). Some cheap printers use common threaded rod, which is convenient, but prone to bad behavior since the rods are not always straight, the threads are subject to backlash, and the tolerances are not always the best.
More sophisticated printers use ACME threaded rod or trapezoidal threaded rods. These are made for this type of service and have thread designs that minimize things like backlash. They typically are made to more exacting standards, too. Making the nut softer than the rod (for example, brass or Delrin) is another common optimization.
However, when lead screws aren’t good enough, mechanical designers turn to ball screws. In principle, these are very similar to lead screws but instead of a nut, there is a race containing ball bearings that moves up and down the screw. The ball bearings lead to less friction.
Misumi recently posted a few blog articles about ball screws. Some of the information is basic, but it also covers preloading and friction. Plus they are promising future articles to expand on the topic. If you prefer to watch a video, you might enjoy the one below.
Continue reading “Mastering Ball Screws”
Misumi is doing something pretty interesting with their huge catalog of aluminum extrusions, rods, bolts, and nuts. They’re putting up BOMs for 3D printers. If you’ve ever built a printer with instructions you’ve somehow found on the RepRap wiki, you know how much of a pain it is to go through McMaster or Misumi to find the right parts. Right now they have three builds, one with linear guides, one with a linear shaft, and one with V-wheels.
So you’re finally looking at those fancy SLA or powder printers. If you’re printing an objet d’arte like the Stanford bunny or the Utah teapot and don’t want to waste material, you’re obviously going to print a thin shell of material. That thin shell isn’t very strong, so how do you infill it? Spheres, of course. By importing an object into Meshmixer, you can build a 3D honeycomb inside a printed object. Just be sure to put a hole in the bottom to let the extra resin or powder out.
Remember that episode of The Simpsons where Homer invented an automatic hammer? It’s been reinvented using a custom aluminum linkage, a freaking huge battery, and a solenoid. Next up is the makeup shotgun, and a reclining toilet.
[Jan] built a digitally controlled analog synth. We’ve seen a few of his
FM synths VA synths built from an LPC-810 ARM chip before, but this is the first one that could reasonably be called an analog synth. He’s using a digital filter based on the Cypress PSoC-4.
The hip thing to do with 3D printers is low-poly Pokemon. I don’t know how it started, it’s just what the kids are doing these days. Those of us who were around for Gen 1 the first time it was released should notice a huge oversight by the entire 3D printing and Pokemon communities when it comes to low-poly Pokemon. I have corrected this oversight. I’ll work on a pure OpenSCAD model (thus ‘made completely out of programming code’) when I’m sufficiently bored.
*cough**bullshit* A camera that can see through walls *cough**bullshit* Seriously, what do you make of this?
Thinking about starting a CNC machine, 3D printer, or laser cutter project? Misumi has you covered. They’re offering up $150 worth of free stuff with a coupon code. [CharlieX] is putting together a BuildLog laser cutter, a whole bunch of people on reddit are building 3D printers, and I have most of the rods for an i3 build. Just use the promotion code First150 on your order. Actually, read the terms and conditions, but rest assured – this is legit.
A few months ago, we saw this Enigma cypher machine that combines the classic late-30s aesthetic of the original with modern hardware – including a few 16-segment displays. Now there’s a Kickstarter for the Open Source Enigma replica, and it looks like it’s going to end up being pretty popular. Here’s the site with all the deets. Check out that QWERTZ keyboard.
[Jason] has a love of LEGO and a terrible keyboard. Combine the two and he came up with a functional LEGO keyboard. The electronics are, sadly, an old PS/2 membrane keyboard, but the mechanicals are a work of art – all the keys are mounted on a grid of Technic parts that can be positioned over each of the membrane buttons.
Want a really cool look for your next enclosure? How about LED pipes? They’re those clear plastic bits that direct the light from LEDs around corners and can make any enclosure looks like a Star Trek set piece. You can cut these things with a laser cutter like the Alima team did with their indoor air quality meter. Looks pretty cool.