https://www.reddit.com/r/3Dprinting/comments/4u2eid/linear_magnetic_encoder_modules_print_error/
A magnetic strip on each axis and a sensor for closed loop printing. No more layer shifting!
Interesting. I wonder what is the delay. At 0.48um resolution, why would you use steppers at 12um? with that resolution, you can run high RPM brushless DC motors on a closed loop and have far better results for less cost. The delay would limit the maximum travel speed.
3D printers suffer from vibration the higher the movement speed of the head as you print. This at the point when you change direction so at a 90 Degree corner you see it as a slight wave on the poor quality printers.
By using steppers motors you get that built in dampening caused by the dead stop the way steppers work. DC motors would have to be designed to reverse at the end to counter the movement first then change direction.
This vibration is always there, just have to do what you can to limit it. One reason why designs try to make the head as light as possible like my bowden extruder, which can print faster then all the other types of heads.
With BLDC motors in a tight closed feedback loop, you can have marvelous decceleration and acceleration curves to keep the energy dissipation within the realm of the motor capabilities, avoiding such energy from being transfered to the chassis.
Yeah the firmware already has that built in as even steppers need to slow down. Its still not enough to counter all vibration because as you decelerate you also have to slow down the extrusion motor to compensate but the back pressure on the filament causes over extrusion so you have to balance it. And that atm is still a crap shoot with corners as back pressure is still sort of guess work. depends so much on filament width, flexibility, nozzle size, etc. The shorter the distance between the extrusion motor and the nozzle is a big way to counter that but then your back to extra weight on the head.
Lot of this could be reduced except most 3d printers have a total lack of any kind of active sensor feedback to the controller. One of the things I feel still keep them out of the hands of the home user.
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Are the magnetic strips they’re using just cheap craft sticky magnets, very similar to fridge magnets? That’s what it looks like. That’s certainly cheaper than using the capacitive sensing in digital calipers for absolute positioning.
Yes, it is very likely the same material as fridge magnets. However, I wonder if they are using specially manufactured ones for better tolerances, or if their design can tolerate the low resolution of a plain flexible strip.
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