The first installment of converting my six year old Optimum MH28V manual benchtop mill to 5 axis CNC with full enclosure and flood coolant.
After losing my apprenticeship at a leading Australian racing team due to COVID and deciding to move to Brisbane with friends and family (a tonne of us were moving at the same time), I had arranged to store my big custom 5 axis CNC router at a mate's shop indefinitely. I'd also just started organising the sale of my Optimum MH28V benchtop mill along with all the tooling and workholding that I'd acquired for it. I was half expecting to do the obvious thing and continue my apprenticeship in Brisbane with another company, but I've had a strong entrepreneurial spirit in me for a long time now, I always have to have some project of my own going. Just working for someone else doesn't come so naturally to me, though I'm a good, honest worker when I do have a job.
I LOVE to live in my head, planning out machine ideas... it's an obsession, actually.
Laying in bed, late at night while temporarily living at my parents' house while I waiting to move up to Brisbane, the idea suddenly dawned on me: why don't I take the rotary axes of the 5 axis router and stick them on the benchtop mill? I could offer affordable 5 axis machining services from my garage in Brisbane! I love and hate having these exciting thoughts in bed, because I can't stop thinking about it, I lose sleep over it. I LOVE to live in my head, planning out machine ideas... it's an obsession, actually. The only thing that stops me is when I hit the limit of what I know.
So the next day I changed my plans, I started stripping the electronics and the rotary axes from the 5 axis router, leaving only the frame and the linear motion guide rails and ballscrews. I intended to use the stepper motors and all the associated electronics on the new mill project to save money, but after realising that I'll want a more professional machine for professional work, I ended up buying all new closed loop steppers and drivers along with a conversion kit (more about that kit in a future YouTube video and article). I will definitely find a use for those old steppers and drivers, I've already got a few ideas in mind 🤔. I had to cancel the sale of the MH28V too, thankfully the bloke was really nice about it.
Getting a machine like that sent on a boat to Tasmania was a little daunting of a thought, epecially in the middle of trying to pack up the family house of 20 years, but fortunately it all went pretty smoothly.
Eventually I made it up to Brisbane, and eventually after that, so did the MH28V. It wasn't until a month or two after that where I started thinking about creating a YouTube channel. Another late-night bed thought, truthfully. 😅
The mission for this machine is to create a versatile, high performing hobby/pro-sumer grade 5 axis CNC vertical mill that's well suited to creating video content with. At the same time, this machine will act as a test bench and learning experience for more complex future machines. This project has many criteria, here I'll cover the interesting and the relevant ones for this article.
The initial plan was to build this machine into a ~$15,000 5 axis CNC mill with decent but not amazing quality components for the most part. Good enough to make some money machining complex parts in small runs that many other shops in the area might shy away from or simply find too expensive to machine for customers. Afterall, I've got the advantage of not paying rent for a shop, I'm paying little in home living expenses, and I already have many of the resources and experience to build this machine. I still would like to reach something close to the requirements listed above, though there's less emphasis on professional job shop work and more on making good YouTube videos and manufacturing products for sale - that's where my passion really lives. This means that cutting aluminium and steel in three axes is important while cutting steel in 5 axes is a hope, but not a strong expectation. I think light cuts should be possible.
After working with machines that run high pressure, through-spindle, flood coolant using Capto C6 spindle interfaces, I learned the value of a good flood coolant and enclosure. It's a requirement that this machine has a full enclosure to contain the chips and all the splashy coolant, as well as an effective method of filtering the coolant for recirculation and capture of chips for recycling. I haven't yet figured out exactly how the coolant system will work in terms of which pump to use and how much pressure the system should run on, I'll sort that out when I need to.
I have, however, mostly figured out the filtering and return of the coolant because that was part of the stand design.
The enclosure is designed to have the coolant and chips funnel back towards the center and fall down into a big tub. The bottom of this tub will have small holes to allow coolant to quickly filter through.
Below that is a screen for filtering out finer chips. I don't know what the screen will be made from yet, but again, I'll sort that out when I have to.
Next is a drip pan to catch the filtered coolant and direct it back to the coolant storage tank for reuse.
As already mentioned, the enclosure needs to be able to contain chips and coolant, but I've also tried to design it to be as camera friendly as I can think to make it. Cameras need light, so the front and top panels are going to be clear polycarbonate for maximum lighting potential. I'm told there might be issues with the coolant damaging the polycarbonate, so I may try to find a way around this, or I may just wing it and see how bad it is after a while. 😁
The inside of the left and right panels will be white to maximise brightness while the back panel will be a dark gray because I think it will make for the most beautiful background for lighting the workpiece to make it pop while in the machine.
I also want to make it easy to attach lights and cameras to the inside so I have easy flexibility to adjust lighting and angles for all scenarios.
As with many other things, I'll be covering the manufacture of the upper enclosure in a future video and blog article.
This is what this article is mainly about: the stand. The stand is the backbone upon which everything else depends. The machine lives on top of it and depends on it being sturdy and rigid. A CNC machine like this can accelerate quite a lot of mass very quickly, if the stand is not sturdy, the whole machine will wobble around, which WILL show up in the surface finish and accuracy of your parts.
The stand is made mostly from 75mm x 75mm square hollow section steel with 3mm wall thickness. The angle iron used for supporting the slide-out filtering elements is 20mm x 20mm angle, also with 3mm thick walls.
Knowing that the machine would bear much of its weight towards the center of the stand, and wanting to get as much triangulation into the stucture as practical, I opted for the large truss pieces on the left and right to provide enormous rigidity to stop having the machine wobble front to back (in the direction of the Y axis), as well as providing plenty of support around the center area to bear the weight of the machine better.
There's also some triangulation at the back (picture below) to do what I practically could to prevent wobbling left to right (in the direction of the X axis). I couldn't do the same at the front because there needs to be a clear opening for all of the filtering elements to slide in and out.
Further than that, the two long top sections were capped off by welding in 5mm thick plates to help increase the rigidity, and also it makes the stand look super professional. 👌
The big 5 axis router had several sections of the frame filled with sand to help with dampening vibrations, this improves performance and also helps to reduce the noise being emitted from the structure. I haven't filled this frame yet, but I'm thinking I might do that in the future.
All this talk about studiness, rigidity, and stopping wobbling, then I accidentally bought plastic leveling feet! 🙄 I'll keep them on for now, but they look suspicious to me.
That's all for now, how much can I say about a simple stand?
By the way, try to ignore my stupid big mug on the thumnail of the video, whenever I do that, I'm just trying to optimise for the monkey brain YouTube thumbnail game. 😅
