My experience designing and making a building DIY 3D printer
Using threaded inserts was new to me. I was introduced to the idea in one of CNC Kitchens videos where he tested various styles of threaded inserts. Check out his video to learn how useful threaded inserts can be. https://youtu.be/G-UF4tv3Hvc.
I had various ideas in mind as to how I could assemble the printer. Screws in inserts, screws in plastic, screws and nuts and cable ties. My previous printer used cable ties quite extensively. Cable ties are alright but are not the strongest, neatest, or most maintainable. Screws in plastic are neat but aren’t very strong. They also tend to be easy to strip so maintenance on the printer is limited. Once you install and remove a screw once or twice it generally strips. Screws and nuts work well but nuts aren’t as convenient as inserts. Inserts are clean, convenient, strong and allow for multiple assemblies and disassemblies.
The main frame plates on the printer were made from 6mm steel plate. I laser cut steel because I hoped it would be strong, accurate, cheap and quiet.
The strength of the frame is excessive. The steel frame has far more strength than a printer should ever need. The Prusa Mk3 printers use aluminium frames (I presume this may be to keep weight low for shipping?). Aluminium is great but doesn’t work for my design. I don’t have the skills or tools to weld aluminium, my design has a spot-welded frame.
Laser cutting was used to ensure that the finished frame was square and accurate. I had all the sheet metal parts laser cut and etched. Small 3mm holes cannot be cut by a laser cutter. In these situations, centre marks were etched to once again ensure accuracy. I decided laser cutting was an affordable to outsource accuracy so to speak. I could cut a frame myself however it was easier to use an already accurate machine to do all the precision work for me.
I hoped steel would also make a quieter frame than my previous printers wooden frame. I thought that denser, smaller sections of frame may produce less noise than large wooden plates. I have no real numbers or evidence to support this theory, it was merely based on personal observations and guesses. The finished printer was much quieter than my previous wooden design, whether this was due to the frame or not I cannot really say.
Price, steel seemed to be cheaper than aluminium. The pricing on the laser cutting seemed to suggest that the steel was going to be cheaper overall. The bed carriage cost around 40 - 50 dollars to cut one piece. The rest of the steel frame cost the remaining 20 dollars or so.
As previously mentioned, aluminium was used for the bed carriage. This was simply to reduce the mass of the moving bed carriage. Less mass on an axis is a good thing, it reduces ghosting, skipped steps and allows for faster printing.
The 3030 aluminium was chosen because it is fairly common and cheap. I really just used it because Prusa printers use it.
Printed parts were used as part of the frame. This was because its easy, cheap and popular. Other printers use printed parts with great success, it doesn’t seem to be a limitation. ABS was used for all printed parts. This was to ensure that parts remained strong even when near the hotend or heated bed. All the plastics together used less than one kilogram of ABS, this fit with the goal of being affordable.
When designing my new 3D printer there were a few design goals I had in mind. Some of these goals were different to my last printer and some were just carried through from my last design. My new goals were to make the printer as quiet as possible, make it good value and a clean design. Some goals that were inherited from the last design included high accuracy, reliability, and ease of use.
I basically copied everything from the last printer that worked well and changed whatever did not.
Silence was the key goal for my new printer. My previous printer was about as loud as a 3D printer could be. The bearings rattled, steppers whined, and fans buzzed. This limited my effective printing time to times when I was not going to be bothered by it. I could not print while studying or sleeping. The new design had to be quiet enough to study and sleep through. This would expand my printing production significantly.
Accuracy was another key requirement. The accuracy had to match that of a Prusa printer or similar production printer. The previous design did not even produce prints that were square. A large print would be clearly out of square. Since I offer printing to people on Gumtree, I needed to be able to guarantee a degree of accuracy.
My old printer was designed to be extremely strong and powerful. After having realised that this did not result in prints that were any better than other printers, I changed my mindset. This new printer was going to be more optimised. I would not pay for a part that would not provide better printing results
My previous printer was easy to use and it worked nearly all the time. My new printer would inherit a lot of the same features. My goal was to minimise the amount of effort that needed to go into printing a part. This would make printing for others a lot easier and more enjoyable.
My old printer was not the best-looking machine. Since I was making a new one, I decided I may as well make it look half decent. I wanted to machine to have a clean design, similar to a Prusa Mk3.
Being an engineering student gives me a good excuse to waste months on building stuff that I could easily buy online. I fully admit that buying a Prusa mk3 would have been a far better option than buying a printer. This will not stop me from going on and justifying it anyway.
As a student, any experience I can get in engineering is beneficial to me. This means that I try to attempt building things rather than buying them. Another advantage of being a student is the long holidays we get. I have the time to waste on designing and building a printer that is almost an exact copy of an existing printer.
It was going to be fairly expensive to import a Prusa Mk3 into Australia. At the time of building it was going to cost around 1400AUD. The printer I built (minus enclosure) cost around 700AUD or there abouts.
The previous printer I built and designed was getting old and ugly. It was time for an upgrade. In my spare time I offer a printing service on Gumtree. This old printer was starting to frustrate me and give me problems. This made it hard to continue my small business.
It is clear from the list of pros and cons that my old printer was limited. The only reason I kept it for so long was that it did give pretty good results. It was a good first attempt a building a 3D printer. The lack of accuracy and loud operation killed it in the end. It was time for a new model.