Please Help With Stepper Motor Control

Question

Hello I am very new to this site and building computerized projects in general! but always wanted to learn and this site is by far the best i have found! Now im trying to build a mini cnc machine andin which for starters i wanted to use the small stepper motors out of some old 2000's printers! I ended up salvaging about 7 good ones. Now from watching Ben Heck show i have now leaned that the stepper motors need a motor control to run but my main question right now is..." Do printers have built in motor controls? cause im just confused why i couldnt reuse the printer board as a motor control board if it did that for the printer! Now as i have said i am really new to all this! so if u have an answer for me try and explain it as u would a child! haha im learning a lot fast but certain terms and stuff i have no idea what they mean! im sorry if this is a dumb question just a 26 year old tryin to make a change! Thanks for any help you can provide!

Robert Peter Oakes · Answer

With salvaged parts from printers and the like, you will get a varied number and type of motors, probably 2 stepper motors and 2 or three regular DC motors (Three all technically DC motors). The steppers will have 4 or 6 or 8 wires going into them, the regular motors typically just the two. if you rotate the shaft of a stepper you will also "feel" the steps compared to a simple motor. The printer DOES include stepper drivers on board but the work to remove or isolate them is probably beyond a beginner skill level, better off getting a motor control board for an Arduino or something, there are many to choose from. If the stepper has only 4 wires then you will need a FULL H Bridge capable controller If the stepper has 6 wires then you have a choice between the full H Bride or the simpler ULN2003 type control (If the motor is low powered then this would be ok, if not, again there are loads of boards available for this. If the motor has 8 wires then you have many options, including all of the above. Basically there are two ways to drive a stepper. Bi-Polar where you use an H Bridge, and Unipolar where you simply ground each leg of the coils in a sequence. BiPolar is more complex but provide for more torque at low end of speed. If your printer is a typical desktop home style then there will be limited power available for a CNC (With router type cutting involved) so even if it worked it would quickly prove to be needing upgrading. As an educational process this is perfectly ok. If you building a 3D printer style CNC then the steppers should be ok for most common sizes. To clarify my use of the term CNC. CNC means "Computer Numeric Control", a Robot Arm, 3D printer, A CNC Router, A Laser Cutter, A XY Plotter, A Laser Etching machine are all specific examples of CNC machines, these days though, people automatically think of a CNC as being the CNC Router (Rotary Cutter) type of machine. It really only refers to any process where is numeric control using a computer is used.

Robert Peter Oakes · Answer

I have done a few myself and I tend to find two steppers and two simple DC motors. The steppers seem to be used for the ink sucker and the paper load(I think), the regular motors seem to be for the head feed. and subsequent paper feeding (These both have optical encoders with them as Kas mentioned) The steppers are typically square but the other motors are round. See this video for one of my experiences...

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koudelad · Answer

Hello,

a few links to start with, just to get the idea about the inner workings, quick start and circuits that accompany motors. All the materials were made by semiconductor manufacturers or a distributor, but the most important is the general stuff.

PSoC 3 Stepper Motor Control with Precision Microstepping

Sparkfun Stepper Motor tutorial

Texas Instruments Motor Drive and Control Solutions

kas.lewis · Answer

Are you sure they are stepper motors ? I ask because of all the printers I have taken apart (which is quite a bit) I don't recall seeing stepper motors inside. They generally have some form of sensor feedback (at least the ones I ripped apart). An optical sensor with a wheel/rippon with very fine lines on it to let the system know what the motor position currently is. I can only assume this is cheaper or easier to implement than a stepper solution. Otherwise if it is the advice given above is a great place to start. Kas

koudelad · Answer

You can find different motors in printers - a DC motor and/or a stepper motor. All the motors need some switching circuitry driver as the current needed to move them is much higher than a microcontroller CPU pin can provide You can built them yourself or search on eBay for"h-bridge for controlling a DC motor(both directions and"stepper motor driver which usually contain ULN2003A ULN2003A integrated circuit Or try to find them on PCBs in the printer Good thing about motors from printers is that you can usually find a datasheet with all important parameters that are required to drive the motor.

Please Help With Stepper Motor Control

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