This has been awesome constructing it. Here’s my 25mm build:
Work area about 420 by 620 by 80 mm (about 16 by 24 by 3 inch)
25x2mm stainless steel tubing.
Kress FME800 spindle
Arduino Uno clone + CNCShield
Grbl 1.1 & bCNC
Just before Christmas I ordered most of the metal bits and started printing all the plastic parts. That was done around Christmas, but sadly my bearings took almost 3 weeks to be delivered (normally it's 3 days, tops) so I wasn't able to start building. I ordered the tubing online, cut to size. All I had to do was de-burr. Because they were factory pre-cut they turned out to be remarkably similar in length, about a tenth of a mm. This, combined with the nice prints from the Prusa i3 MK3 made squaring up a breeze. It's probably not perfect, but it is very good out of the box.
My initial electronics setup consists of a Chinese Arduino Uno clone with a CNC Shield with Stepstick DRV8825 running Grbl 1.1. They’re driving NEMA17 steppers of very similar specs as sold in the v1 shop. Taking small steps, using parts from my old Anet A8, I tested the electronics until I was happy I wouldn’t trash my build the first time I powered it up. That didn’t even end up taking all that much time with the very satisfying end result of a machine moving under its own power.
I wanted to use Grbl because… just because. I know Marlin from, time for something new and made especially for CNC. Using bCNC on my Macbook to control and configure Grbl steps per mm, maximum feeds and accelerations. And I hooked up an e-stop button, which saved my machine a couple of times while dialling things in.
Making bCNC do the right thing and draw a reasonably sized Crown was a bit trial and error, not helped by the lack of progress bars in bCNC for operations which take a long time.
And then it was just mesmerising to watch it move. And draw.
So here is it, the Crown, drawn on 5mm grid paper.
Ah yeah, I’m not feeling the love for bCNC, I’ll give CNCjs a go, thanks.
I’m still building the electronic, it’s currently on my desk - visible just behind the rear x rail. The MBP is a very temporary situation, I want something a little easier to fix near a messy CNC machine. Not sure where I’m heading, but I like my RaspberryPis - I use them in various other projects. I would like local control, a keyboard or other directly connected to the CNC controls - either via Grbl or the Pi. And maybe a little joystick to control the XY position.
I think we’d all want that :). CNC.js has some plugins you can play with to control it via a shop tablet, which can by anything with a web browser and a touch screen. Or there is a plugin for a PS3 controller, which would be pretty nice, but it’s a little hard to find. You can always attach a monitor and keyboard/mouse to the pi, and connect via it’s browser. At that point, I wouldn’t recommend using a pi zero, because the X can take a lot of resources and you don’t want to starve the gcode sending.
I really need to look at converting that PS3 code into generic joystick mappings… I think it would be a great solution to buy any USB gamepad and connect it to the pi.
Marlin has a big advantage here, with the many LCD options. They are great at playing files from the SD, and pretty decent at machine setup. You just have to get good at ignoring everything related to printing.
I personally bring my laptop out with me. It’s still helpful to not have it attached. I bring it to the table when I’m setting up, and then I move it across the room when I’m cutting. After the initial awe of seeing it work, I like to have my computer there to work on CAD, CAM, or just watch videos. I’ve used my phone once or twice in a pinch.
You’re shitting me right? Most everyone’s crown should look like this? Slightly sloppy the first time perhaps because they hadn’t tightened the belts enough? All I did was follow the instructions (carefully). Technically this is the third time I’d drawn the crown, the first was a 5 cm one (couldn’t find the scaling option, but damn it, I wanted it to move on its own), the next was the same as on the 5mm grid paper, but on the brown paper you see below.
I did assemble an Anet A8 and Prusa Mk3 in the last 18 months, so I had some practice.
After I’d done the crown, I tried some HD foam engraving, but the only cutter I have is the 3mm Dremel ball engraver, which doesn’t have a nice shape for engraving. Looked nice anyway. Good thing it was in foam, because that took several attempts before I got the DOC right. First time it dove right in so I slammed my big red button. Then bCNC was just hard to use, so I tried with text in Fusion 360 and engraving with that. Lovely
I should have some proper engraving bits, a small ball nose and a 6 mm straight cutter tomorrow. Do another project in foam and then I’ll try some soft wood.
That would be rad. Use the various button for enable (need to pull trigger to move gantry, another button to move Z). Haven’t looked at Node.js code in ages, but there must be ways to access the system game controllers…?
I’m sure there are, but even there weren’t, linix makes it very easy. The difficult part is that different controllers have different capabilities, so I’d either meed to pick one (logitech 710 or something) or I’d need to come up with a way to make the map that people could follow. Doing all that in the gui would be great, but that would definitely stretch my skills.
I was thinking of using one of these aliexpress cheap ones because I have a few and they’re small and cheap and easy to use. They use two or three analog pins on the Arduino, not sure if the Rambo boards have those exposed and available. But I’ll find a way.
Interesting build especially the electronics side. Question about the CNC shield. Is it one of the Chinese ones or the original from Australia? I have the Chinese one but thought it was only compatible with older Grbl due to pin mappins - seems I might be wrong?
Thanks. I thought I’d learn more by doing it this way, and I can confirm this is true.
I’m 99% sure it is a clone. I got it from a Dutch store, but it has all the build quality hallmarks of cheap clone.
The only pins that have been changed from original to 1.1 is are the z-limit and spindle enable. So I just swapped the cables from one to the other. Although it took me an hour to figure out why it wasn’t responding to my Z limit switch for homing.
Now the CNC Shield has filtering on the limit switch pins. This is easy to add for the Z limit switch, just a capacitor and a resistor. But now the spindle enable, living on the Z limit switch pins on the shield, has a fairly high pull up - that doesn’t bother my circuit as I’m only doing on/off for now, but I’ll be sure to remove the resistor and capacitor from the board should I want to do spindle speed (which would require modding my AMB/Kress 800, which I’ll hold off on for now)
Anyway - for now I’m happy with Grbl. It seems to be doing sensible things and I don’t think I’ll need the dual end stop soon.
A word of caution: the high pull-up on the Z-limit on the shield may cause unsafe situations where the shield powers up before the Arduino and enables the spindle very briefly. I haven’t hooked mine up yet, but I will remove the pull up before I add spindle control to Grbl.