This is my current project, a three stepper motor XYZ machine. The rods are about 250 mm long and made from aluminium. The flat surfaces are laser cut acrylic and the remaining parts are 3d printed ABS.
So far I have the driver board working for one stepper motor (I'm expecting the other two tomorrow) under control of a Particle Photon, and I've requested a quote for the acrylic parts. I've also purchased the rod, the tube, the bolts to hold it all together (not shown). The design of the other parts appear printable to me.
Laser cut parts ordered. $41 pickup.
Picked up the laser cut parts today (4 Dec) and John soldered the other two sets of stepper motor and driver boards.
Wire cutting 10mm tube and 6.3mm rod using my poor man's lathe.
I found extra-virgin olive oil works better than canola spray :)
Putting it together without the 3d printed parts proved difficult. It was informative though. First redesign:
Today I finished the assembly and did some programming. At first I was less than impressed with the mechanics of the sliding motions but I managed to get a simpler slide part to work and it's quite stable while still being stiff. The cutting tool is mounted and seems to cut ABS easily enough.
As you can see from the video, the sliding mechanism is still quite poor. The square being cut is 2500x2500 steps. The top stepper motor isn't connected yet. Third slide design:
I added rollers, which solved the friction problem, while maintaining the stiffness.
I mounted my dremel (a Ryobi rotary tool). Tomorrow, hopefully, I'll wire up the Z-stepper and do some programming.
I got it cutting:
I've experimented with lifting and lowering the cutting tool between every 100th step of the platform. This "pulse" mode seems to produce better results than using the steppers to push the platform into the cutting tool. Either way the results are pretty terrible.
I got my own 3d printer yesterday, the white components are printed with PLA and seem sturdy enough. I'm back to scraping using the tungsten cutting tool. At 1/10th speed I get about 100 micron repeatability. At 1/100th speed I get much better repeatability - perhaps even one micron. So far I'm just drawing a square, and it cuts better in one direction than the other.
This is the result of my hunt for platform stability. The steppers are now 3/4 enclosed (neither open in the direction of travel), bolted onto the frame. The sliders are now externally guided, with rollers that are mounted on bolts. It seems pretty stable, but the X direction (left to right in this picture) is a bit too loose, I think.
This is the final version of the slider - two rollers on top, one on the bottom - centers the stepper rod in the acrylic slots and prevents rotation. The high stiffness makes the repeatability exquisite.
This is probably a terrible idea, but let's see how cheap of a DC motor I can use with an engraving cutter.
As expected, the stiffness of this ZDriller is pretty horrid, which results in very wild cutting. Considering that the bit is not even properly centered on the motor shaft, it's amazing it works at all.
Some improved stability.
I had an amusing incident where I couldn't get my pliers into a small area to hold a 6mm nut and found myself thinking "if only I had a tool that could reach around this bracket". Well, I have a 3d printer...
In any case, I dropped a complicated design that was three parts bolted together, with superfluous wheels and came up with this single part:
By adjusting the shims between the inverted pyramid and the ZDriller, I was able to find the sweet spot where the dremel bit is held in contact with the motor gear and doesn't have too much friction pushing it into the holder. It makes sense:
Now that I have a stable cutting tool, the rock and roll of the platform is even more obvious, though.
