As a community we owe perhaps more than we realise to the RepRap project. From it we get not only a set of open-source printer designs, but that 3D printing at our level has never become dominated by proprietary manufacturers in the way that for example paper printing is. The idea of a printer that can reproduce itself has never quite been fully realised though, because of what the RepRap community refer to as “vitamins“.
These are the mass-produced parts such as nuts, bolts, screws, and other parts which a RepRap printer can’t (yet) create for itself. It’s become a convenience among some of my friends to use this term in general for small pieces of hardware, which leads me to last week. I had a freshly printed prototype of one of my projects, and my hackerspace lacked the tiny self-tapping screws necessary for me to assemble it. Where oh where, was my plaintive cry, are the vitamins!
So my hackerspace is long on woodscrews for some reason, and short on machine screws and self-tappers. And threaded inserts for that matter, but for some reason it’s got a kit of springs. I’m going to have to make an AliExpress order to fix this, so the maybe I need you lot to help me. Just what vitamins does a a lone hardware hacker or a hackerspace need? Continue reading “3D Printering: Can You Ever Have Enough Vitamins?”→
We’ve all been there – that last stubborn screw, the one thing between you and some real progress on a repair or restoration. It’s stuck tight with thread-locking fluid, and using more torque threatens to strip the head. Frustration mounting, drilling that sucker out is starting to seem pretty tempting. But wait! [Daniel] offers a potential solution using nothing but a soldering iron.
This tool hack is pretty simple, but all the great ones tend to be straightforward. In the video, [Daniel] is faced with a titanium Torx screw that refuses to come loose due to threadlocker, an adhesive that is applied to screws and other fasteners to prevent them coming loose. Available in a variety of strengths, thread-locking fluid is great at keeping screws where they need to be, but too much (or the wrong kind) can seize a screw permanently.
Instead of drilling out the offending screw, [Daniel] reaches for his soldering iron. By applying a significant amount of heat to the screw head, the adhesive starts to give. After heating, working the screw back and forth breaks the threadlocker, thus freeing the screw. The whole process takes just a couple of minutes, and potentially saves the repairer from destroying a screw.
The chemistry behind thermoset adhesives makes for some great bedtime reading, however the main takeaway is that threadlock fluid, while somewhat resistant to heat, will eventually become brittle enough for the screw to come loose. Unlike most adhesives, which melt under high temperature (think glue sticks), thermoset materials tend to initially harden with the application of heat, before turning brittle and breaking. While high-temperature threadlocker derivatives exist, typical Loctite-branded threadlocker (and similar products) would not appear to be able to stand the heat of a typical soldering iron.
MDF is the cheapest and flattest wood you can buy at local hardware stores. It’s uniform in thickness, and easy to work with. It’s no wonder that it shows up in a lot of projects. MDF stands for Medium Density Fiberboard. It’s made by pressing materials together along with some steam, typically wood, fibers and glue. This bonds the fibers very tightly. Sometimes MDF is constructed much like plywood. Thinner layers of MDF will be made. Then those layers will be laminated together under glue and steam.The laminated MDF is not as good as the monolithic kind. It tends to tear and break out along the layers, but it’s hard to tell which kind you will get.
MDF is great, but it has a few properties to watch for. First, MDF is very weak in bending and tension. It has a Modulus of Elasticity that’s about half of plywood. Due to its structure, short interlocking fibers bound together by glue and pressure, it doesn’t take a lot to cause a crack, and then, quickly, a break. If you’d like to test this, take a sheet of MDF, cut it with a knife, flip it over, and hit the sheet right behind your cut. Chances are the MDF will split surprisingly easily right at that point.
Because of the way MDF is constructed, fasteners tend to pull out of it easily. This means that you must always make sure a fastener that sees dynamic loads (say a bearing mount) goes through the MDF to the other side into a washer and bolt. MDF also tends to compress locally after a time, so even with a washer and bolt it is possible that you will see some ovaling of the holes. If you’re going to use screws, make sure they don’t experience a lot of force, also choose ones with very large threads instead of a finer pitch. Lastly, always use a pilot hole in MDF. Any particle board can split in alarming ways. For example, if you just drive a screw into MDF, it may appear to go well at first. Then it will suddenly jump back against you. This happened because the screw is compressing the fibers in front of it, causing an upward force. The only thing pressing against that force is the top layer of laminate contacting the threads. The screw then jumps out, tearing the top layer of particle board apart.
So you’re looking to buy your first 3D printer, and your index finger is quivering over that 300 US Dollar printer on Amazon.com. Stop! You’re about to have a bad time. 3D printing has come a long way, but most 3D printers are designed through witchcraft, legends, and tall tales rather than any rigorous engineering process. I would say most 3D printer designs are either just plain bad, or designed by a team of Chinese engineers applying all their ingenuity to cost cutting. There are a few that are well designed, and there is a comparatively higher price tag attached.
I’ll start by going through some of the myths and legends that show up in 3D printers. After that I’ll go through some of the common, mostly gimmick, features that typically hinder your printer’s ability, rather than adding any useful function. Next I’ll go onto the things that will actually make your printer better. Finally, I’ll add some special consideration if you’re a beginner buying your first printer.
For those unaware, the little acronym above stands for Do-It-Yourself-Direct-To-Garment printing. In layman’s terms, printing your own shirts and designs. Commercial DTGs can cost anywhere from $5,000 to $10,000 which for the hobbyist who only wants a few shirts is ridiculous. So you would think this field of technology would be hacked to no end, but we’ve actually only seen one other fully finished and working DIYDTG. So we took it upon ourselves to build a DIYDTG as cheaply and as successfully as possible. Continue reading “How-to: DIYDTG”→