After returning from the Swiss Talent Forum I was set on launching a startup and identified low-cost 3D printing as my best bet. It was the obvious choice, as I had been building low-cost 3D printers for years and the only thing driving the cost down was Chinese manufacturing, with almost no change or innovation to the design of the printers.
After running through BOMs of common 3D printers I came to the conclusion that the costs of the vitamins (linear rails, belts, motors, electronics) alone were way higher than I was aiming for, therefore these would have to be compromised. I could either compromise the electronics (opt for slow, cheap steppers) or change the mechanical system to eliminate the linear rails. Using cheap steppers wasn’t an option for me as they created a terrible printer (with a max speed of 10mm/s), so I opted to eliminate the linear rails. After countless hours researching online and emailing creators of different machines, I was set on using a SCARA XY axis, however, all of the ones that had been used before had at least one fatal flaw that made them unusable for a 3D printer, with most attempts being abandoned by the creator. After experimenting with a few approaches I settled on the one I use now, which works great. All the parts were then designed in LibreCAD and either milled on my CNC Router or laser cut.
The Plybot had 4 main goals:
- Cheapest 3D printer ever.
- Pack flat in order to ship easily.
- Use only off-the-shelf parts and CNC milled plywood.
- Easy to assemble.
Cost: The design satisfied all of these aspects, with a BOM for a one-off coming to £52.04, and at larger quantities, it is expected to be less than £40. The only printer with a cost close to it is the ‘Cherry 3D printer’ at £52.64, however, this uses extremely cheap stepper motors that run extremely slowly (10mm/s) and break frequently to reduce the cost, and if I was to use them my cost of a one-off would be £34.77. The cheapest commercial printer costs about £90 to produce in bulk (I spoke to the resellers of it), so if mine was produced commercially it would still be quite profitable to price it below this printer.
FlatPack: The printer packs into a 320x320x60mm box (about the size of two twelve inch pizza boxes stacked on top of each other), so is extremely compact and therefore cheap and easy to ship/transport.
Parts: The PlyBot is completely made out of off-the-shelf parts and CNC milled 6mm and 12mm plywood (aside from the acrylic bearing holders, I couldn’t for the life of me get plywood to work).
Assembly: The frame takes about 20 seconds to assemble and is completely snap-together with no hardware used. In all, it takes probably less than 10 minutes (I put a lot of effort into minimising the number of screws and part count in general).
Speed: The printer has very little moving mass, and therefore the motors can accelerate the print head much faster, achieving higher print speeds and therefore faster prints. I didn’t anticipate or plan too much for the print speeds, as price and aesthetics took priority over it, however, I was pleasantly surprised when I bumped the settings up and the printer kept up. My current settings are Jerk:30mm/s, Acceleration:9000mm/s^2 and Max Speed for Rapids:300mm/s. This makes it one of the fastest printers out there, and therefore the bottleneck of printing would be the extruder, not the speed at which the machine can move.
Other: The printer has a build area of 190x190x165mm (although for the next iteration it should have 200x200x200mm), uses 1.75mm PLA filament, runs off a 12V 5A power supply and print quality is comparable to most commercial printers, with there being no visible differences between the PlyBot and my school’s Makerbot (at 50x the price).
I struggled a lot with many issues, including the snap-fit frame, snap fit bearing holders and extruder, having nothing obscuring the PlyBot logo, stopping the arms sagging, making an ‘invisible’ Z-axis drive, working out the inverse and forward machine kinematics and integrating them into the preexisting firmware, using only plywood (no other custom parts whatsoever), reducing visible screws, cable management and most annoying of all getting my £4 knockoff hot end to stop jamming.
One of the main aspects that I focused on was the aesthetics and user experience. When customers buy the cheapest product on the market they’re not expecting a sleek, beautiful product, therefore I couldn’t make the product aesthetically pleasing by using high-quality products and expensive production techniques. I opted for a raw, no-frills, functional aesthetic that above all else was clean. By minimising non-essential parts, using some unconventional design and taking great care to only place parts in certain places I personally believe that I achieved this. Some examples are:
Using fishing line with the motor mounted on the Z-axis, routing it in the same place as the Z-axis rails in order to declutter the front:
Attaching the extruder mount behind the arm mounts, making it invisible from most angles:
Routing all cables around the backboard using zip-ties resulting in pretty much no wiring being visible from the front, and also very tidy at the back:
Mounting the spool holder on the base, using a Teflon tube to route it into the extruder, which also results in minimal exposure to air, meaning that it is less likely to pick up debris which can clog the hotend:
Using a completely snap-together frame, resulting in no fasteners being used.
Using as little bolts as possible (25 in total) by having multiple uses for most of them and using alternative methods for as many fastenings as possible.
Using a power-brick style power supply instead of a traditional power supply, which also gets rid of the issue of live mains leads and also certification as they are certified by the manufacturer.
Getting rid of endstops. Endstops are a luxury, and I argue that they do more harm than good for a beginner. They were frequently an issue in almost all of my printers, (both mechanical and opto-endstops) and can be removed by simply positioning the machine to a certain place and clicking a button. This ties into my belief that a simpler machine is better for the user. Many users aren’t techies and struggle with all of the bells and whistles of a complicated printer (LCD’s, WiFi, auto-calibration, SD cards, etc), so it made sense to eliminate them in favour of usability, and an extra minute of setup before a print is much better than hours of trawling through forums (and leaving negative reviews) trying to fix issues. I also would have to either use mechanical endstops with very visible wiring or optical endstops which are quite expensive and as price and aesthetics are my main focuses on this machine I decided against it.
It’s hard to think of other methods I used to achieve this as they gradually became integrated into the design as I reiterated, but I gave almost all aspects of the design significant thought in order to declutter it and overcome many unsatisfying features. To put it in perspective a quick google of cheap 3D printers bring up many massively cluttered machines showing how much of a focus aesthetics was to me.
What Now?
I currently have two fully working machines, with the newest one tailored towards being manufacturable. My Father (an accountant) and I have run through the financial aspect of producing the machines commercially and came to the conclusion that it is definitely worth pursuing. I have run the idea and business model through as many people as I can (including two people who have run Kickstarter campaigns) in order to gain advice for what is to come, and plan to possibly launch a Kickstarter this year with 3 of my classmates. I already know the financial side should work out, and that it should be fairly profitable if I can get the sales. My plan now is to try and drum up as much attention/followers/fans as possible, and then further investigate if people would buy it based on the attention gained. If it is a positive experience and I conclude that it is worth doing then we will pursue it, however, if not then I will probably move onto my hotend concepts and experiment with them.
Future:
I have a couple concepts for changes to the hotend of the 3D printer, both of which could be extremely disruptive and profitable if they work in my opinion. I’m beginning to experiment with them now, however, most of the development of these ideas will likely be at university, hopefully in an advanced hackerspace somewhere.