So overall, it’s a dual delta design, possibly combining all the disadvantages of a moving platform and moving head. It does allow you to accelerate and move twice as fast, but will not reduce mechanical overswings/ripples or allow you to tilt the bed.
@Rene_Jurack if you look closely, you’ll notice that the hotend has neither a fan nor a thermistor or heater, there’s not filament in the extruder and the print is off-center - hence, the printer was not in a functional state when the picture was taken.
I would think the build area would be very small at the surface, but get larger as the build height increases. It builds from the center point (vertically) and at the extents of the arms in those positions, simply would have very little travel.
I bet that is why the bottom is rotated 180 degrees from the top. A couple of other things. For multi degrees if freedom you’d want six steppers on one side, top or bottom, each one driving one of the six struts, like one of those big flight simulators. Put that on the bottom, only, to remove gravity from the support problem añd you might have something. The tool path generator will be interesting. A slicer would no longer be sufficient.
I think the motors are being driven in pairs, like the Z motors on a Prusa-style design. Each top motor is wired in parallel with the bottom motor in the position 180 degrees from it. This would explain how they’re driving 6 motors off of a standard RAMPS, as well as why only the top motors have endstops. Mathematically, this should just double the distance moved in any direction for any movement of the motors, the same as if you just made all the parts twice as big.
Perhaps what is most curious about the
motors is that they drive the ends of each rods in an arc, not a straight line. That would need a new set of equations to govern the positioning.
If you look closely at the bottom motors, there appears to be a gearbox, then a blue plastic shaft that spins, with the metal rod attached to the end.
The gearbox maybe needed to get greater resolution out of the stepper’s position.
This is not an arrangement typical of a delta printer, which drives the end of the rods straight up and and down, constrained along a vertical line.
I would love to see a video of this machine in action, and also to ask the designers why they chose such an unusual configuration.
@Paul_Gross Linear deltas are more common for printers, but for other applications, angular deltabots like this one are more common. And yes, they require gearing to get sufficient angular resolution because their entire range of travel is less than one full revolution of the output shaft.
Wow guys, c’mon. It’s just two Clavel (rotary-arm) deltas controlled in sync to move opposite each other. The rotating-arm design pre-dates the linear delta we use by about 30 years. They’re incredibly common for pick-and-place applications. Google image search “delta robot” and that’s most of what comes up.
There are already rotary-arm delta variants for many popular 3DP firmwares and many open-source versions. Nothing fancy is required to control it.
There are two delta mechanisms in this mirror arrangement because it doubles the height and diameter of the working volume. (Work space limits are the main reason why rotary-arm deltas aren’t popular for 3DP.) Also doubles the speed and halves the resolution, which is problematic because you then need even finer angular resolution for the arms than usual.
It’s still 3-DOF and any vanilla Delta firmware can run it by doubling up the motors, like @Whosa_whatsis mentioned.
This is definitely interesting and I think we can all agree on that but it seems like due to the extra steppers it would cost more without any added benefit of speed or quality.
I think that the gearboxes are the biggest negative. The backlash and hysteresis from those gears means that the theoretically precise positioning will not be obtained in reality. This will likely be sloppy compared to a delta machine that uses linear vertical rails.
Gearing-down the steppers will slow down the machine much more compared to using linear rails.
Then there is the headache of calibrating two sets of delta machines that must work precisely in concert to realise any theoretical gains.
So doubling the expense in motors and gears for a doubling of volume, speed and resolution will still not likely make it desirable compared to more common designs. Doesn’t seem like its worth all the expense and effort to me.