If you're looking for a how-to article on building a 3D printer for $300, you can find all sorts of them with a quick web search. This Instructable is definitely NOT for you.
If you're looking for a how-to on building a machine that prints at 1000 mm/sec, this Instructable is NOT for you. SoM, like MegaMax before him, was built with an emphasis on print quality, not speed. I haven't tested maximum print speed, but SoM was designed to print at about 50 mm/sec and does so beautifully.
If you need a complete bill of materials with prices and suppliers listed, and illustrated, step by step assembly instructions, this Instructable is NOT for you. There will be plenty of pictures showing how I built my machine, and I’ll describe some things in detail, but you’ll have to get a lot of info from the photos, by reading the references I’ll link, and by asking questions.
This Instructable IS for people who don't want “cheap” to be the only positive (?) thing they can say about their printer. It's about how to build a printer the right way. It definitely isn't the ONLY right way, and it definitely isn't the cheapest way. SoM cost me about $1100 to build, and included a lot of used and free parts.
Here’s how things usually go when I want to make a print: I put the gcode file on an SD card, plug it into the machine, wipe the bed with acetone, and print. There’s no bed leveling, zeroing, no tweaking settings or other baby-sitting during the print. I come back when it’s done and remove the finished print from the bed. I can do that over and over, and I can put the machine in my car, laying on its side, drive it across town, take it out, stand it up, and do it all again without making any adjustments.
If that sort of reliability sounds like what you want, and you're willing to pay a little more and expend some effort to get it, this Instructable IS for you. Almost reliable? Of course, there are still plenty of things that can and do go wrong, so I still have occasional print failures. That's why I call it an "almost reliable" printer.
I built my first 3D printer, MegaMax, using surplus machine parts over a period of about 2 years. I built it myself because when I started the project, the biggest build envelope you could get in a reasonably priced machine was about 5" x 5" x 5" or so and I wanted to make bigger prints- full sized human skulls using data extracted from CT scans, for example. I decided to build for a 12" x 12" x 12" print envelope. MegaMax produced high quality prints, but as I worked on him and solved many problems problems over a couple years I got some ideas for improvements and decided it was time for a rebuild using everything I had learned.
This Instructable is about the rebuild, and though you probably won't be able to duplicate my machine exactly, I hope it will provide some ideas you can use in your machine. I wanted the new machine to be self-contained, smaller, and the electronics isolated from the warm print chamber. I also wanted the print quality and reliability pushed to maximum. SoM is the result. I already had a large investment in time, effort, money, and materials in MegaMax, so SoM was built in the same configuration (bed moving in the Y-axis, X-axis lifted by Z-axis screws), reusing many of the parts. If I were building a machine with the same print envelope from scratch today, I would probably use a coreXY design so that the relatively heavy print bed moves only in the Z axis.
SoM is a cartesian printer with the print bed moving in the Y axis, but most of the ideas presented will apply to other architectures.
SoM basic specs:
A lot of people have 3D printers that came as kits or were fully assembled and cost $300-1000. If you look at the user groups and internet forums you see the same problems reported over and over.
What causes prints to fail to finish?
What causes print quality problems?
poor filament quality
A lot of these problems are related to each other. Most of these problems are a direct result of the primary design principle: how cheaply can a 3D printer be made?
If your printer's bed moves noticeably when removing a print, and/or requires re-leveling with almost every print, or comes with auto leveling (aka auto-tramming), or uses two or more motors to drive Z-axis screws, uses hardware store threaded rods in place of lead screws, or has any moving parts cantilevered more than a few cm, the machine is not built for precision, accuracy, and reliability.
That doesn’t mean you won’t be able to get good prints from it- obviously many people have such printers and use them every day, and many are able to get decent quality prints from them. But building the printer a little better goes a long way toward fixing most of the problems that plague the low to ultra low cost printers and reduces the effort required to get a decent print.
If you’re contemplating buying a $300 printer kit, you should know that every dollar the kit maker takes out of the price is going to add many hours of work that you’ll be doing to get that machine to produce an acceptable quality print, and it may never give you the quality you desire. Sometimes you get what you pay for, but you absolutely NEVER get what you don’t pay for, especially in the world of 3D printing.
If you've got one of those $300 printers and are dissatisfied with the quality of the prints it produces, or are tired of all the screwing around required to get it to produce an acceptable quality print, or you value your time more than the kit maker does, this Instructable is for you. Even if you choose to buy a printer instead of build one or upgrade the one you already have, this Instructable will help you know what to look for and what to avoid.
Some may say that building a printer like I did takes a lot of time, so what difference does it make whether you spend the time building a good machine or tweaking a cheap printer before every print? The difference is where you end up. Building a machine like I did is a learning experience. You acquire useful skills along the way, learn a lot, and end up with a high quality, almost reliable printer that produces good quality prints with a minimum of messing around. If you choose the other path, you will mostly learn how frustrating and difficult it can be to get a $300 printer to produce a good print and in the end you'll still have a $300 printer. On the brighter side, after you learn about all the things that are wrong you'll be more knowledgeable when it comes time to get your next printer.
My design philosophy is simple: learn from and avoid the mistakes/compromises made to minimize cost. If you want to build a high performance car, you don't emulate the Yugos. You learn what not to do from them. Then you look at the Ferraris and Porsches and emulate them. Likewise, when you want to build a high performance printer, study the $300 machines to understand the mistakes. Look at industrial machines to learn how to do things the right way.
You can build a 3D printer that is accurate, precise, and even almost reliable. Step 1 is adjusting your approach. Forget about searching for the cheapest possible way to do everything. How often is the cheapest way to do anything the best way? Instead, seek the best way and understand why it's better. Then start looking for the way to either get the parts needed for that best way, or come as close as you can with the funds available. Be prepared to spend some time looking for quality parts at bargain prices and don't be afraid to spend a little more money to get them.
Precision parts don’t have to be too expensive if you get creative when searching for them. Local scrap yards and eBay are full of scrapped machines and precision parts that can be purchased for a fraction of their brand new prices. You have to be persistent in your searches and patient enough to wait for the right parts at the right price. Find and join your local makerspace or hackerspace. Those places have a lot of tools, materials, and people who can help you find your way. I would not have been able to build my machine without all the help I received from the brilliant people, and access to tools and materials at the Milwaukee Makerspace.