Hi all! This video should hopefully give you a rough idea of the things I’ve been working on, but I also wanted to write a bit more about the technical details of each machine in case you were interested, so I’ll go through them each below in reverse chronological order. Of course, you’re probably pretty busy, so no worries if you don’t have the time to read it!
PlyBot: This is my most recent build and the foundation of my company! I began this about 18 months ago, and have gone through 8 iterations, making it by far my most time-consuming project. I’ve long been on a search for the “Holy Grail” of desktop 3D printing: a simple, cheap design that would make it a household item. There are many great 3D printers, but they’re all simply too expensive, so I aimed to make one as cheap as possible by removing the expensive linear rails and using a SCARA arm mechanism instead. I found a few projects online that attempted to implement a SCARA arm mechanism into 3D printing, but all of them were abandoned in the early days of 3D printing (2013/2014). They had a lot of problems, so I designed my own novel arm system to circumnavigate these issues, and after working on my first iteration through the summer I finally got it working in November 2017.
I saw this as a potential commercial project from the beginning, so this wasn’t just an engineering project, but a product design project. Once the arms were successfully implemented on the first machine, I spent the next seven iterations (with an eighth in the works as I type!) attempting to convert it from a school project to a commercial product. This began with making it look clean and simple, such as implementing a fishing line-drive Z axis, meaning there’s no visible drive system (like a leadscrew) that would obscure the logo, making no wires visible, and making it all self-contained with nothing exposed that doesn’t need to be. I made machines of all shapes and sizes in order to determine the optimal height/width ratios etc, and settled on the one that looked the best. Most of my time was spent making everything snap-together, and shortening the assembly time as much as possible. Everything from the hooks that are used to snap-assemble it to the radius of the fillets were experimented with and carefully selected. I was basically attempting to make the Google Cardboard of 3D printers – flatpack, simple and easy to use.
For a person with access to a laser cutter, the MDF version of the machine costs £49.22 to build (using Aliexpress parts – free shipping), making it by far cheaper than any other 3D printer. The cheapest on the market at the time of making the machine was £99, and this was with no profit – I spoke to the retailers in their London store, it’s just to get initial customers so they come back and buy a more expensive machine. This means that my machine costs around half as much as the other machines, even without manufacturing in bulk. This is mainly due to the implementation of the SCARA arm system, which subsequently results in a very low part count: Of the £49.22 one-off manufacturing cost, 74% (£37) of it is electronics, meaning that for a cheaper machine to be made without sacrificing speed (cheaper electronics would sacrifice speed), the mechanical assembly would have to be made for less than £13. As this is pretty difficult, I think I’ve made it pretty much as cheap as I can!
With this project I won the title of UK Young Engineer of the Year, and that’s when I met my business partner, Ian, and we began to change the design for the new company direction. Whilst I’d initially aimed to target this to techies and 3D printer enthusiasts, with Ian on board (and some investment!) we now had the power to aim for regular consumers, so the aim of PlyBot shifted from a simple, flatpack kit for 3D printer enthusiasts to a fully-assembled, WiFi-enabled, smartphone-controlled desktop consumer product.
I naively thought that the initial size (30x30x50cm) was a good size, but looking back I have no clue what I was thinking! I shrank the design to about 60% size and then 60% size again, determining that the middle size was closest to the optimum size, aesthetically and performance-wise. After this, we decided to shift away from plywood, and design it to be injection-moulded instead. This brings us to the current day, where I’m working with Brook (explained in my additional info section – he’s the guy that founded the big consumer 3D printing company!) to develop the machine to be mass-manufactured at a low price. The main difference with the new design is that it’s mainly plastic and the arms raise up on rods with a static bed, rather than the arms being in a fixed position with a lowering bed.
We’re also seemingly (emphasis on “seemingly”!) close to raising a round of funding over the next few weeks, which will give us much more money to develop before the impending Kickstarter, as well as trigger my move to California, which I’m extremely excited about!
DesktopWorkshop: This is a combined 3D printer and milling machine. The glaring difference between milling and 3D printing is the speed and torque, with 3D printing being fast and low-torque, whereas milling has to be slow and high-torque. For this, I used a rack and pinion drive for the XY axis with a switchable gear ratio, enabling the milling to run about 3x slower than the printing. I experimented with many different methods for switching the gear ratio, but all of them either had backlash issues or were unreliable. Eventually, I moved back to the original design – bearings pressed against the bottom of the rack can be loosened, the larger/smaller pinion placed on the rack, and the bearings retensioned. This wasn’t the most elegant solution, but it did the job! I also ensured that it was rigid, with the Z-axis sliding directly onto the four cornerposts of thick angle iron, meaning that any flex in the frame won’t affect it nearly as much as if they were on separate linear rails. I also used four lengths of threaded rod as leadscrews for the Z axis, all connected to the driving stepper motor using timing belts, ensuring they’re all completely in sync. The electronics and power supply were contained in the bottom base (made of slot-together MDF milled on my CNC router), and I aimed for the Z axis to be in there too, but it was pretty difficult without making the base double the height! The main advantage of this was the price, at under 200 dollars to make, and I did plan on publishing the files open-source online, but to be perfectly honest it’s nowhere near finished enough. I took a few shortcuts with the build that I never fully sorted out, leaving it with a few niggling issues, but all in all it was a decent machine!
CNC Router: I wanted a CNC router at the time, but they typically used expensive electronics and custom-extruded aluminium for the rails, meaning the machines cost a few thousand pounds. Instead of using extruded aluminium, I came up with a design using skateboard bearings riding on steel tubing, which cut the cost of the rails a lot. The electronics were the other major cost, due to the expensive drivers (50 USD per axis), and motors (40 USD per axis). The thing about CNC routers is they’re extremely slow, so they need high-torque, but low speed, meaning the sensible option was just to use smaller motors/drivers and a reduction gear. It sounds obvious, but it hadn’t been implemented yet, and with the declining price of these parts due to the increasing popularity of consumer 3D printers, these smaller motors/drivers were extremely cheap, making it a very sensible option. The plan was to manufacture a kit for this machine, with the customers sourcing the larger parts, the steel rails and the wood frame, for themselves. It would perform just as good as the £3000 machines, but only cost about £300. I still think this is a good opportunity, and definitely fills a gap in the market for a really low-cost CNC router.
Third 3D Printer: After the second machine, I wanted a really fast performance printer. There was a really interesting machine I saw on the internet, and I based my design on it. I started off using the same frame dimensions as it, and then using the same printed parts, and then everything else… So the end product was basically his machine – he designed it so well I couldn’t think of any improvements, so not much to see here from me!
Second 3D Printer: Whilst building my first printer, I saw many of the parts used could be replaced by much cheaper options, and built this machine to test those out. I mainly focused on the linear rails and the drive systems, as this is where the main cost savings could be made.
Linear rails:
On the Y axis, I tested steel rulers, which performed well but had a bit too much wear to be used anything past a bedroom project.
On the X axis, I used mild steel rods with V-groove bearings. I ran a program to move the carriage from one end of the rods to the other for a few days, meaning it would wear a consistent groove in the rods, and as there was a much larger surface area then it wouldn’t wear much more. Once I did this for a few days, it worked absolutely perfectly – success!
On the Z axis, I used aluminium L-channel. As the Z axis moves very little in comparison to the other axis, the aluminium worked absolutely fine, and didn’t really wear – success!
Control/Drive Systems:
On the Y axis, I used a rack and pinion. Although this is, of course, a standard method, it was such early days for the industry that I think I was one of the first, if not the first to use it on a 3D printer. This worked great, and there were no issues at all – success!
On the X axis, I used fishing line. I had a fair few issues with this. First off, it’s incredibly slippery, so I had to experiment with many pulleys, determining a simple M8 bolt to be the best! This wasn’t perfect though, and over time the line “creeped” in one direction, meaning that the print came out slanted. I fixed this by making it home the axis (recalibrate where it is by triggering the endstops) after every layer, but it was still a bodge job and I wouldn’t do it again!
On the Z axis, I used standard threaded rod, so nothing to see in that aspect!
First 3D Printer: As I explained in the video, this was my first machine, and being quite young I had no money. I salvaged everything from old paper printers and made a deal with my dad that if I could get it to a state that looks like it would work then he’d buy the electronics and extruder for me (~130 USD at the time). Most of my research was online forums, YouTube and Google Images, to be perfectly honest! I made a lot of mistakes and worked through three prototypes before finally getting this one working. I still regard this as my proudest achievement, as it was such a big jump from all of the other projects I’d been doing, and it seemed so impossible at the time.
Thanks for reading this description of my projects, although I’m conscious you’ve got a lot of applications to go through so no worries if you skipped to the end! On the off chance you want to see more about these machines, I wrote some detailed posts with photos/videos a year ago just beneath this post, so have a scroll down if you’re interested! The PlyBot is still very much a work in progress so this is changing every week, but I’ll email the admissions department when the Kickstarter launches. Lastly, after watching the video I’ve realised I come off as pretty dull – it was tricky to remember what to say, so I hope I’m less boring in real life!
Thanks again!
Josh