\n\n\n\n
Y-axis.<\/h2>\n\n\n\n
It All Began with This Specific Y-Axis Component:<\/p>\n\n\n\n This part includes 16mm guide rails with CS16UU bearings, frame mounts, a heated bed, and a motor with a pulley that moves the bed along the rails.<\/p>\n\n\n\n The bed itself isn\u2019t just a board on wheels. It\u2019s a kind of “layered” structure consisting of a base plate that holds the bearings and the bed itself, mounted onto the base plate through corner springs. These springs allow for horizontal adjustment across all planes. This base plate under the bed was where the entire project started:<\/p>\n\n\n\n In my dreams, this was supposed to be a solid quarter-inch thick slab. Alas\u2026 Real life imposes quite a few restrictions on flights of fancy.<\/p>\n\n\n\n For instance, you could just go to the nearest hardware store and grab some aluminum\u2026 Sure, that\u2019s an option\u2026 But what you\u2019ll get is terrible quality aluminum. Thin-walled profiles and plates barely thicker than foil. And the cost of this flimsy junk? Comparable to an equivalent amount of adamantium! Finding a solid aluminum bar in an ordinary store? Practically impossible.<\/p>\n\n\n\n Thankfully, a friend directed me to a small shop in the neighboring town\u2026 “Shop” might be an overstatement. It felt more like a makeshift den in a shed for hardcore metal enthusiasts\u2026 But that doesn\u2019t matter. What matters is that I found almost everything I needed there, and at very reasonable prices. Specifically, real 6061 aluminum with official factory stamps marked Made in U.S.A.<\/em>.<\/p>\n\n\n\n The only downside was their limited selection of sizes and shapes. For example, the only wide panel of a suitable size they had was just 1\/8 inch thick. But hey, beggars can\u2019t be choosers! Plus, they cut it to size for me right on the spot:<\/p>\n\n\n\n At the price they quoted me, I didn\u2019t hesitate for a second and bought the entire sheet. Both the pieces they cut to size for specific parts and the leftover scraps. I\u2019d have taken the shavings too if their cutting machine left any\u2026 This aluminum was just that good. After dealing with all the flimsy materials I\u2019d been forced to use recently (like the frame for the mechanical dog), it felt like a breath of fresh air. It was satisfying to hold in my hands.<\/p>\n<\/blockquote>\n\n\n\n Of course, not everything could be cut precisely to size right there in the shop. Many parts had to be cut or finished at home. However, for the bed\u2019s base plate, all that remained was drilling some holes.<\/p>\n\n\n\n For the first time in a long while, I ran into issues with measurement systems. Over the past decade, I\u2019d thoroughly adapted to working with the imperial system. These millimeters? I can barely see them on a ruler anymore\u2026 Just a mess of tiny lines\u2026 And way too many of them!<\/p>\n\n\n\n Here, everything in the stores is sold in feet, inches, and their fractions. All the measuring tools default to those units. In fact, even the robots in our workshop calculate their movements using the imperial system, including the laser engravers. Even the ultra-modern Swiss machine from Mitsubishi operates in inches (well, thousandths of an inch). Everyone\u2019s used to it, I\u2019m used to it, and everything was fine\u2026<\/p>\n\n\n\n An inch is simple, convenient, and intuitive. Unlike these millimeters tied to the wavelength of some unmentionable beam in a vacuum. I was perfectly happy \u2014 until this project with the damned printer came along!<\/p>\n<\/blockquote>\n\n\n\n So, all the raw materials, as I mentioned, were bought in inches. Most of the fasteners too. All my modeling software is set up to work in inches. But the electronic components I ordered from Amazon, Alibaba, and other platforms predominantly come in metric sizes. Or even better: for example, mounting holes in millimeters but overall dimensions in inches. A complete mess\u2026<\/p>\n\n\n\n Honestly, I don\u2019t care what numbers I type into the fields in my modeling software. It translates everything back and forth depending on the postfix I add after the number. Write “10 mm,” and the program will standardize everything into the units specified for the document. I can then feed this model to a robot, and it will sort everything out on its own, converting whatever units it receives into its motor steps.<\/p>\n\n\n\n The problems begin when I have to mark something manually with calipers. For instance, a bunch of holes on this panel. The mounting holes for the heated bed are spaced in millimeters, while the ones for the bearings are in inches. Pretty quickly, I got tired of switching the calipers back and forth a million times or dealing with absurd fractions of millimeters or inches.<\/p>\n\n\n\n So, I simply printed out a template on adhesive paper, exporting it directly from the 1:1 model:<\/p>\n\n\n\n Using the template, I marked and drilled the holes:<\/p>\n\n\n\n This turned out to be faster and more accurate than crawling all over the surface with a ruler, square, and calipers, transferring all those millimeters, inches, parrots, parsecs, and other astronomical units. Print, slap it on, punch, drill \u2014 and done. I stuck to this method for all other similar parts moving forward.<\/p>\n\n\n\n The first piece is done\u2026 Only a godzillion more to go\u2026<\/p>\n\n\n\n It was time to tackle the kinematics. And, as we all know, you can\u2019t just go out, buy a couple of steel rods and a few bearing blocks, throw it all together, and expect a miracle. Unfortunately\u2026<\/p>\n\n\n\n Every bearing needed to be disassembled, thoroughly cleaned of factory preservatives and metal shavings (!!!), packed with high-quality lithium grease, and reassembled \u2014 all while trying not to lose too many of the tiny balls in the process.<\/p>\n\n\n\n However, even this doesn\u2019t guarantee the desired result\u2026<\/p>\n\n\n\n Knowing what to expect, I bought two extra bearings for each axis. For the Y-axis, for instance, one bearing predictably ended up being scrapped \u2014 it jammed and crunched no matter what I did with it. On the bright side, it became a donor for a couple of missing balls in two other bearings.<\/p>\n\n\n\n Well, not exactly scrapped \u2014 it went into storage with a black mark labeled \u201cCruncher\u201d on the side, just in case it could be useful for something less critical in the future.<\/p>\n<\/blockquote>\n\n\n\n The key element of this part of the design is the rail mounting.<\/p>\n\n\n\n A bearing system of this type is highly sensitive to misalignments, twisting of the rails, and similar issues. Consequently, I never even considered using the standard mounting brackets that come with the rails. You can see them in the photo above \u2014 they were only used as temporary stands while I was fine-tuning the bearings.<\/p>\n\n\n\n Using such brackets would require aligning everything across four independent points in all planes. Not only is this a major headache, but in the future, once those four brackets are integrated into the main frame, even the slightest deformation of the frame would throw everything off again!<\/p>\n\n\n\n Therefore, I decided to make mounts that would eliminate any potential misalignments not only during assembly but also in the future. The rails would be mounted onto two massive blocks made from solid aluminum:<\/p>\n\n\n\n The equal spacing and parallel alignment of the rail mounting holes are ensured by the CNC milling machine itself. All of our machines are certified (with an official document updated every six months) to operate with an accuracy of up to 0.0001 inches (two-thousandths of a millimeter).<\/p>\n\n\n\n Of course, this is far from the pinnacle of global precision standards, but for gunsmithing tasks, it\u2019s more than sufficient. Generally, tolerances here range from 0.01 to 0.001 inches. I honestly can\u2019t remember ever having to deal with tolerances beyond four decimal places.<\/p>\n\n\n\n And let\u2019s not forget we\u2019re talking about a machine the size of a small room. Personally, I can quite literally step into the machine, get comfortable, and even take a nap on its worktable \u2014 and it would cradle my couple of hundred pounds with two-thousandths-of-a-millimeter precision.<\/p>\n<\/blockquote>\n\n\n\n In short, there are no issues with the parallelism or spacing of the rails. The machine will cut exactly what\u2019s drawn in the model. The remaining concern is the accuracy of the hole diameters for the guide rails. And here, not everything depends on the machine.<\/p>\n\n\n\n Formally, these guide rails are supposed to have a diameter of exactly 16 mm. But the manufacturing facility where they were produced has its own tolerances and standards. The bearing, in turn, is designed to:<\/p>\n\n\n\n But for the mounts, this precision is crucial! The more accurate the mounting holes are, the less play the rails will have, and the higher the parallelism of the rails will be across all planes.<\/p>\n\n\n\n After a few experiments with hole diameters (the rails were actually not precisely 16 mm but somewhere around 16.01\u201316.015 mm), I achieved my \u201cperfect\u201d mounts:<\/p>\n\n\n\n I messed up in just one spot. I should have drilled the holes for the set screws and threaded them first, and only then bored out the guide rail holes. I botched this in the most embarrassing way, and as you can see in the photo, I ended up with a \u201ccrown\u201d inside the rail hole around the thread for the set screw\u2026 I had to carefully trim it away with a scalpel.<\/p>\n\n\n\n The guide rails for the bearings fit snugly into place without the slightest play. In fact, the set screws in the design are merely a formality. The whole setup holds itself perfectly still, absolutely level, and perfectly perpendicular without any additional fasteners:<\/p>\n\n\n\n Of course, the set screws are mandatory. The setup holds itself reliably only as long as it remains static. Once the bearings start sliding and moving along the rails with a heavy platform on top\u2026<\/p>\n<\/blockquote>\n\n\n\n So far, everything is going beautifully and exactly according to plan. It\u2019s time to see how well it all moves.<\/p>\n\n\n\n To get this printer axis moving, a motor needs to be attached. For this purpose, the rear mount has threaded holes for securing the motor platform:<\/p>\n\n\n\n In fact, both mounts for the guide rails are completely identical \u2014 this made the design and manufacturing process simpler and faster. As a result, the mounting holes for the motor platform are present not only on the rear mount of the axis but also on the front, where they aren\u2019t really needed. But don\u2019t worry, those holes will find their use eventually\u2026<\/p>\n<\/blockquote>\n\n\n\n The motor mount was made from a quarter-inch-thick plate.<\/p>\n\n\n\n I found this material in the metal enthusiast’s den. A grim-looking shaggy fellow \u2014 reminiscent of Leontiev circa 1980 \u2014 dug around in a corner of the shed and pulled out a quarter-inch strip of material, slightly chewed up along the edges by some wild cutters and covered in a layer of dust about a finger thick. It wasn\u2019t a particularly long strip, but it was enough to cut out the motor mounts:<\/p>\n\n\n\n Of course, the holes in the plate weren\u2019t drilled at home on a drill press \u2014 they were made using the same CNC mill at work. And the result looks quite professional.<\/p>\n\n\n\n Another crucial element needed to be added to the design before attempting any movement. This part is almost invisible in renders and photos, but it\u2019s there \u2014 and it\u2019s exceptionally important. Without it, nothing would move properly.<\/p>\n\n\n\n The tensioner pulley for the drive belt. You can see it tucked away in the dedicated mounting niche:<\/p>\n\n\n\n It\u2019s not as simple as it seems. And it\u2019s definitely not as simple as how 99% of DIY makers and even Chinese manufacturers build it into their printers. Typically, they take a standard 2GT belt pulley and bolt it directly onto the frame. That\u2019s exactly how it was on my Black Widow printer\u2026 For added frustration, the pulley height is often adjusted using a sandwich of nuts and lock nuts.<\/p>\n\n\n\n Maybe I\u2019m being overly picky, but seeing those nuts and the inner bearing sleeve grinding directly against the cheap screw\u2019s threads makes my blood boil. Especially since the screw diameter almost never matches the bearing diameter exactly. To keep the pulley from wobbling, they tighten it with another nut \u2014 which usually ends up locking the bearing. So, the belt just slides over a jammed pulley\u2026 Bar-bar-ians! I hate it!<\/p>\n<\/blockquote>\n\n\n\n First, the pulley mount is designed so that it\u2019s always vertically aligned with the center of the guide rails. This completely eliminates the need to adjust it for the belt to run parallel to the axis. It simply has no other option.<\/p>\n\n\n\n Second, the pulley\u2019s mounting axis is secured both from the top and the bottom. A threaded hole goes entirely through the niche, which eliminates any vertical misalignment of the pulley (a common issue that leads to loosening and slipping of the belt).<\/p>\n\n\n\n Third, the pulley\u2019s mounting screw doesn\u2019t interact directly with the bearing at all. Instead, special inserts are placed between them. The outer diameter of these inserts matches the inner diameter of the bearing sleeve perfectly, while their inner diameter matches the screw diameter precisely.<\/p>\n\n\n\n No adjustments are required, no undue pressure is applied, nothing tilts, and everything rotates smoothly and freely:<\/p>\n\n\n\n The faces of the inserts were intentionally left unfinished at first. During installation, I sanded them down with fine-grit sandpaper to ensure there was no gap between them and the mounting niche:<\/p>\n\n\n\n Everything is almost ready for the big move. All that\u2019s left is to add the drive belt.<\/p>\n\n\n\n To avoid fiddling with clamping plates and “ties” constantly, I \u201cinvented\u201d special locks for securing and tensioning the belt ends:<\/p>\n\n\n\n Essentially, the belt grips itself by meshing its own teeth together. The locks simply prevent the belt tails from splaying apart. It\u2019s like a rough approximation of a zipper. Reliable, easy to secure, and just as easy to remove:<\/p>\n\n\n\n That\u2019s it. Time to make it move.<\/p>\n\n\n\n Here\u2019s the very first almost-independent motion this device made:<\/p>\n\n\n\n![\"\"](\"https:\/\/jimsghost.place\/wp-content\/uploads\/2021\/08\/2021-16-08_007-640x323.jpg\")
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