Using DC motors to replace steppers on x and y axis

Here is a new project of running a 3d printer with cheap DC servo motors. It was developed by misan from Spain and he used it successfully on x and y axis of his Prusa I3. Dc motors are controlled by Arduino Uno and the project is based on "servostrap" project. DC motors are cheap and can be found and salvaged in recyclable or scrap electronic device such as paper printers and others.

He made the code and bracket designs available. Thnx misan!

DC servo motor powering y axis of Prusa I3

You can find all the files and code here:

https://www.youmagine.com/designs/dc-motor-closed-loop-control-software

http://www.thingiverse.com/thing:618042

Here are the files for y-axis DC motor drive:

http://www.thingiverse.com/thing:620183


Here is video of stepper motor and servo running together:




Here is a video of DC servo motor powering the x-axis:



Here is a video of DC servo motors powering the x- and y-axis:



Project description:

This program uses an Arduino for a closed-loop control of a DC-motor.

• Motor motion is detected by a quadrature encoder.

• Two inputs named STEP and DIR allow changing the target position.

• Serial port prints current position and target position every second.

• Serial input can be used to feed a new location for the servo (no CR LF).

Pins used:

• Digital inputs 2 & 8 are connected to the two encoder signals (AB).

• Digital input 3 is the STEP input.

• Analog input 0 is the DIR input.

• Digital outputs 5 & 6 control the PWM outputs for the motor (I am using half L298 here).

• Please note PID gains kp, ki, kd need to be tuned to each different setup.

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ServoStock Delta 3d printer powered by servos and Bowler protocol

This Delta is heavily modified Kossel derivative which uses DC motor powered servos instead of stepper motors developed by team led by mad.hephaestus.

On each axis is a small board containing a magnetic encoder, and a continuous rotation servo. With this setup, the makers are able to get 4096 steps per revolution with closed loop control that can drive the servo to with ±2 ticks.
The electronics and firmware are fully redesigned configuration when compared to the usual 3D printers. The motherboard uses a Pic32 running at 80MHz. In parallel with hardware, the communication between the host and printer has been completely redesigned, instead of g-code, the team is using the Bowler protocol for sending packets over serial, TCP/IP, or just about any other communications protocol you can think of.

The final aim is to create much cheaper powerful 3d printer that would cost in 200 - 300 USD range.

Project on hackaday.io:

http://hackaday.io/project/962

GitHub repository:

https://github.com/Technocopia/ServoStock

There is lot of discussion on the project page and on hackaday about viability of this technology. I don't know much about all the stuff they use, so it will be lot of new stuff to learn. Maybe it will be the standard in the future.

Here is a video about closed vs. open control systems:



Here is a link about differences of DC vs. servo vs. stepper motors:

https://www.modmypi.com/blog/whats-the-difference-between-dc-servo-stepper-motors

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