Discussion in 'Hobby Engineering' started by PheonixV2, Apr 1, 2020.
Nice work! I am also helping a friend build his steel framed fixed gantry machine
And thus began a long weekend of small tasks and reading a lot, and I mean a lot, of datasheets
I had my replacement pulleys arrive which were all spotted with a pilot hole from the supplier, which is useful because it means I can drill them out to fit any sized shaft I'd like.
It's also a pain because it means I have to drill it exactly in the center, which is not easy when you're aligning it by eye
First attempt was in the drill press, I got pretty close, must've been <0.2mm off centre but you could see I had missed, and thus scraps one pulley until I re-bore it properly, luckily I bought spares
One benefit to the relaxed quarantine restrictions was that I was able to borrow a friends lathe for the morning to bore them out quickly. Drill a 5mm pilot hole and followed it through with a 12mm drill bit.
It was during this as well I discovered the flanges are not concentric to the pulley shaft and so had to align them by eye in the chuck which worked out surprisingly well, like pretty much perfectly, had 0.01mm runout
Drilling and tapping holes for grub screws, unfortunately I broke my friends tap on the last damn hole. Also, did you know bunnings only sells grub screws from M5 to M8? Very inconvenient sizes, and my usual bolt supplier is closed on the weekends, unless you get up stupidly early on a saturday
Drilled out mounting holes for the spindle bracket. The cast piece was fun to drill, small chips everywhere!
I also discovered that the mounting block is spectacularly not square to anything, so I drilled oversized M8 clearance holes to get a lot of adjustment in. I'll have to go in with the dial indicator and measure up against the spindle itself
Testing out the spindle. I've got a YL620 Variable Frequency Drive and a BST2.2C-80-24K G-Penny spindle (water cooled).
Chinglish documentation is my favourite, and all the settings are wildly unclear about what they do. I had to do a lot of googling to get a proper picture of how to set it up. I'll post a full wiring diagram with explanations later on if people would like - save themselves an afternoon of pounding their head against a wall
To test with I was just playing with it manually, using the potentiometer on the vfd to control speed (in Hz because rpm is a terrible unit according to the manufacturers haha) 50 - 400Hz (3000 - 24000rpm) is very nerve wracking, especially when you've got your laptop and a work oscilloscope sitting on the bench next to it because I r smrt. Was nervous about something deciding to let go haha
I had to make my own 4 core power cable, which went very smoothly. And I've got the wiring set up to do the external control for Mach3, just haven't gone in a matched the pinouts to the C41 pwm board yet
Everything mounted and ready to go! Just have to connect mach3 to the vfd and it'll be ready to start cutting
I'll be camping this weekend, but hopefully on monday I can cut my first chips (yay for public holidays)
How's it going? We're a few months down the track now.
Due to popular demand I'm back with an update and more poorly rotated pictures. Genuinely, I am glad people are interested in my project, gives me a warm feeling inside that you want to find out more after me being absent for a few months!
The CNC Mill build got put on the backburner for a while because I went up to Sydney for work and got stranded there for a month with the border closures, which gave me plenty of time to plan and prepare my next steps. Who am I kidding, I procrastinated the entire time I was there (when I wasn't working). Before I left my first order (notice I said first, this becomes important later) of end mills arrived, I got a whole variety to test out the capabilities of the mill. I got a dovetail and T-slot cutter along with a range of end mills, 2 flute and 4 flute, centre cutting and non centre cutting (don't get non-centre cutting, no idea why're they're a thing and I don't have a machinist to ask), ball mills and some chamfer mills.
After powering up the machine and plugging in some standard G-Code I was rapidly reminded of the world of work-offsets, I had previous experience manually coding machines and it completely slipped my mind that the computer wouldn't do things the sensible way. So naturally I had a chamfer mill plunge directly into one of my clamps and astonishingly, nothing broke! It carved through the clamp like butter!
All these first few tests were done using MDF (I would add some pictures of the squares, C-spanners, and circles I had it profile, but there's a 10 image limit per post) and it was then that I vowed to never again machine MDF without a vacuum running. Preferably a vacuum plugged directly into a black hole. I spent hours wiping the machine down, removing MDF dust from the linear rails and other places on the machine I never knew existed. These tests were all done in the weekend or so after my previous post, at which point I got launched into Sydney.
After returning a month later I started finalising the whole machine to get it into a permanently working order. This included properly lubricating all the bearings, i.e. packing the bearing blocks with grease as they do not have external greasing ports. Doing a final alignment on the rails as well as filling in any welds I had previously missed. It was quite astonishing that the entire machine, which has taken several months to make and assemble, came apart in 30 minutes. All the mechanical parts except the rails were stacked neatly on the table and I honestly wondered why drilling 400 holes took so damn long.
Those rose-tinted lenses make hours of work and filing look like it should've been a minute each!
Once stripped it was painting time. I've never painted a machine before and in hindsight spraypaint probably wasn't the way to go. I ended up painting more of the floor than the frame.
I decided to go with a rust-proof white paint which I think looks rather sharp. The other options were Classic-machine-green, and what-I-should-have-made-the-weld-cart-grey.
The re-assembly took about 45 minutes and I was thoroughly pleased with how everything went back together. All the grease made everything glide so smoothly and there was no binding at any points. (I did discover the floating bearing for the x-axis ballscrew is not exactly level, but hey, a lopsided bearing block adds some character, no?
I named my mill Ghost.
It was quite an experience learning how to use CAM properly. I spent an entire afternoon inputting machine settings and building a tool library. An accurate tool library is so insanely useful, and I rapidly learned very important if you don't want to accidentally carve through the jaws on your vise. My mill has a fair bit of oomph to it, able to run a 10mm end mill at 10mm DoC and 4mm step over pretty comfortably (my pucker factor was quite high). I'm now quite confident with my CAM abilities and can whip most things up fairly quickly. I'm still mastering the art of fixturing and multiple set-ups.
Learning to accurately set z-offsets was also an experience, and have lost a few end mills that way, enter my now multiple orders for end mills. After the second order I just decided to order 5 of each of the small sizes and hope I don't burn through them too quickly.
Up to here it might have sounded like running the mill has just been one disaster after another, when in truth its actually been a dream. My first attempt at machining the test geometry for a cycloidal gearbox came out absolutely perfectly. As well I've been commissioned for aluminium T-nuts which came out perfectly and the end user has thoroughly enjoyed them.
This gear has quickly become one of my favourite desk toys. I've been working on designing a full gearbox for it (18:1 reduction) and am just waiting on some smaller end mills to arrive. As well I've now got an automatic tool height gauge so once that's programmed my tool changes are going to be perfect.
The above pic is while figuring out the feeds and speeds of the machine, it just kept being able to go harder and faster without giving up.
As well I had to learn to set up Mach3 so that it matched my CAM outputs otherwise you get interesting arcs like the one below instead of a small hole (the difference is incremental vs absolute arcs)
If you've ever played with glitter before, whether it be with kids or on a night out, you know it never goes away. I recently discovered the same thing with the high-speed aluminium chips. I've been finding it in the carpets, in the grass in the garden, somehow found it in a pocket 3 weeks later, that stuff gets around. And so I've now embarked on adding an enclosure for the mill as well as a chip tray. I've had a friend take order of several 1.6mm aluminium sheets and once restrictions allow, I'll head over and we can whip it up! This design will have acrylic doors and an open top, I haven't ruled out the option of me building a 6 axis arm for automatic parts loading just yet.
This section of the project has been a blast and a grind, it's going from the 20% of the work that gets the machine working and functional, to doing the remaining 80% of making it perfect and user friendly.
I'm currently waiting on more end mills and bearings to arrive so I can perfect my gearbox and then who knows what I'll work on next!
I had an idea for some hangboards to sell but I might need to buy a shopvac before I sacrifice my mill to the wood gods haha
looking sweet as
I'm really a novice observer of this magical witchery, and it looks superb and something to be proud of.
My question is, I've seen some of these multi axis cnc machines, and a lot of them have this white milky gross looking coolant or lubricantspewing everywhere while the tools are cutting. Now, I'm not sure if that is absolutely necessary, but is it something you'll consider.. and is it worthwhile building a drainage system into your case in advance -- even if only a 'just in case' step for now?
Thanks! It's honestly great to have actually built it and not have it on the horizon anymore
The coolant they use is primarily for keeping the material cool to prevent heat expansion and geometric accuracy, as well as flushing chips and swarf out of the cutting area (Flood cooling) to prevent recutting and clogging/chip welding of the cutter (this happens a lot with aluminium). At the moment I've been using copious amounts of WD40 as a coolant and to flush chips away but that hasn't worked too well. Ideally I'd have an air blast from a compressor to clear chips and maybe even mist cooling (which is just injecting small amounts of cooling fluid into the air blast line).
I doubt I will require flood cooling, as well the added cost of a coolant pump, and sump tanks kinda turns me off the idea.
The removable chip tray at the bottom will likely be configured in a way to include drainage to a smaller sump that can be periodically emptied and I can recollect the chips through a sieve or similar. I'll definitely leave room to allow the modifications in future.
As well I kinda designed this mill to be a bench top mill with the legs only being 100mm high, which doesn't leave me a lot of room for a proper drainage system and chip collection.
Swarf and fluid also tends to get EVERYWHERE and leaves a grimy film all over the shop. Does give your work area that nice metallic tooling aroma though
Awesome build! Looks great in white too. Post a vid