I've got an idea for a project but I'm not sure if it's possible with arduino.
What I need to do:
I need to build a paper take up system for my Epson 9880 so it rolls the paper exiting the printer onto a blank tube.
How I need it to work:
I have two stepper motors which need to turn in sync, at a set amount each turn. Is this possible?
I need the motors to turn in sync with the printer as it ejects the paper so there is the right amount of tension on the paper. To soon and the ejected paper will be to tight and to late the paper will be to lose. I will need to measure the amount the paper ejects with each pass and tell the motors to turn this amount. Is that possible?
My idea for this was to have some markings on the bar that grips and drives the paper out of the printer and a sensor to read the marks. Is this possible? Is there a sensor to do this? Is it possible to sync the sensor with the motors so the sensor activates the motors to turn once it's seen the marks?
Hope all that makes sense?
As you can tell I'm new to arduino and don't currently own one. If this is possible, what would I need to make it happen?
I'm glad it's possible. Would you have any advice on what's needed to do this project? How would I control the motors? What sensor would work? Would I need a separate power supply to run the motors? The paper is 44" wide so can be a bit heavy.
Good to see you got the point.
Don't ask so called closed questions (those where you only allow for certain answers), unless that is absolutely what you want.
Most of the times steppers aren't used in pairs.
Instead belts, gears and axles are used.
If you need this, you can do that by wiring a stepper controller a bit different.
You can't set 2 pins the same at the exact same time.
But steppers are usually controlled by multiple pins.
A lot of these controllers have a pin that sets the direction, and another that enables a single step.
If you first set direction for both motors, and then set the enable pin, which would be connected to both motor's controller, you would be as close as you can get to simultaneous movement of those motors.
So have a look into how to control stepper motors.
You can find loads of info on that right here on this forum.
Using separate motors is really a must, so yes.
Your printer uses optical and mechanical switches to see the paper being loaded (or not).
If that's good enough for the printer, it should be good enough for your contraption too.
Study a few salvage printers to see how that is handled, if you've got the time.
Use the paper's weight to your advantage.
Once you've picked up the paper and fixed it to the roll (something to think over too), see or feel the paper sagging.
Now tighten it by turning your motors a set number of steps.
You need to do something with these steps, because the more paper you have on your roll, the lesser steps need to be made to get the same result (the diameter of the roll gets larger).
Ok thanks for the advice. What is the best controller for the stepper motors? There seems to be a lot of different options. Could you advice me on the correct arduino board to buy? Like I said, I'm completely new to this so any advice is greatly appreciated.
Find an old printer (well, less than 30 years old) and pull it apart. Inkjet, laserjet, doesn't matter. There will be heaps of components in there useful to your project:
Optical paper sensors - senses when the paper goes through a slot in the sensor. Usually you can give these 5V power and the output will go straight to an Arduino pin.
Shaft encoders - often optical too, but they measure the rotation of a shaft with a slotted or printed disc.
Motors - stepper motors usually.
Motor drivers - The smart chip that takes direction from the Arduino and pumps out the power the motor needs to move. I have cut around such a chip with a hacksaw and used it while still attached to a fragment of PCB.
Switches - you always need switches.
Rubber rollers and other paper handling gadgets.
For your project, I see two ways to manage the paper tension: 1 have a bend or 'loop' in the paper that you can measure (like with a feeler switch running on the paper) and drive your takeup to always keep this loop within limits or 2 use a DC motor driven by PWM that can just apply a constant tension, controllable by the Arduino.
Thats some good ideas, I've got an old laser printer knocking about. I've attached a photo of what I'd like to achieve, on a more diy level.
With option 2, what is PWM? Would the constant tension be enough to turn the paper on the roll? It can't be to tight as it may effect the print coming out the printer.
PWM is Pulse Width Modulation.
You can set current in 256 steps (that includes zero, so none at all).
It typically sets motorspeed.
PWM is a digital control, but it seems that that is a bit hard to grasp as lots of people mistake it for an analog output (they are even referenced as such quite often).
One reason for that might be that when you connect an analog or digital multimeter (which are all averaging test instruments), you will see an analog indication that correlates with the set value, as long as there is a load connected.
PWM is also often used in current control for stepper motors.
hi, an arduino uno r3 should work fine.
look into getting a stepper motor driver and/or a motor shield.
sites like adafruit or ebay should sell them separately
they are also sold as kits with an arduino r3
my post regarding solar tracking is right after yours on the forum as of 5.23.15.
it discusses the use of a stepper motor with a driver and the arduino board.
i've listed out as many details as i thought of with respect to the part numbers and how the
motor, driver, board functions with the code.
board: arduino uno r3
motor driver: ULN2003 (PART NO. ZC-A0591)
motor: 28BYJ-48 Stepper Motor
note you can also use a simple dc motor and hook it up to a motor shield from adafruit or funduino, etc but I don't know how well you can control it with PWM (pulse witdth modulation) for your application.
That geared stepper is not going to keep up with the printer.
You will need something more robust, and that includes the hardware driver.
If you keep the idea of a 2 motor-on-1-axle setup, look for a or shield that can handle these 2.
Or two of the same that can be set to use different pins.
The image attached is a paper pick up from China, the problem with it is it will continue to run even if the printer stops. Will I need a driver or an add on to the arduino board to control the sensor?
Does the printer cut the paper, or does it just stop feeding it ?
If it cuts the paper or the paper has a fixed length and will run out of that printer, you can detect that too.
If you use the techniques discussed by MorganS and me, where you detect the paper to drop below a certain level, then the device will still wait for the paper to drop that far after the printer has stopped feeding the paper.
You will be at risk rolling multiple prints on a single roll that way.
You need to know exact what sensor you will be using before you can tell whether it needs external hardware.
But most optical sensors need no difficult hardware, perhaps a resistor to limit current through the LED.
And a plain switch doesn't need external hardware, just a correct setting to the input.
The printer won't be cutting the paper, I'll turn that feature off. We print onto fabric so I need to print long runs. I need the printed media rolled back up so I can then transfer it to my rotary heat press.
Sometimes when printing the printer will stop for 30 seconds during a print, maybe to check page alignment, then it will start again. I need to make sure I can control my contraption to stop with the printer.
OK, the fabric explains why you don't want the contraption to pull too strong (the fabric might expand that way, more than paper would).
You were already offered a few suggestions on how to do that.
I'll be printing on the paper first then it will be run through the heatpress with the fabric. I'm trying to make sure I can do it and understand what's involved, I've only had a little of experience arduino with my 3d printer. I don't want to by the bit needed and its out of my league.
You may want to print "tick marks" on the edge of the paper. Then a opto-interrupter can read the marks and if it senses a change the arduino will move the stepper to take up the slack. Just a wild and crazy idea!
The real problem is the mechanics. Once you've got that worked out then it should only be a few hours to write the code.
2 motors on one shaft sounds like a bad idea. You are thinking that this will be one long shaft, longer than the width of your paper/fabric? That's not long. Both ends of the shaft will rotate at the same speed, with a motor at one end. Now if there was some reason that you had to wind both edges of the paper separately and couldn't put a long shaft down the middle to synchronise both sides then steppers are definitely required. I'd still try to run a long shaft or toothed "timing belt" around the outside of the machine instead of using 2 motors.
The big printer almost certainly has some kind of encoder on the output shaft that you could attach to your Arduino, without disturbing the printer's system. You do need to know what you're doing. Yes, you could put your own encoder on the relevant output rollers - maybe a dab of reflective tape and an optical sensor. But I think you would be better off controlling the tension with a feedback system - a feeler that touches the back side of the paper and lets you know when the loop is too big or too small.
If you open up a printer, there are many different encoders. I guess you could use one of them, but it's hard to get into a printer without destroying it. I have taken apart 3 different printers and destroyed every one
If you can print on some spare surface the you do not need on the fabric, then isaac96's idea is a good one.
There's also some tricks you can do with printing these ticks in different colors if you need it.
One of these would be a marker for the end of the print, telling to stop the rolling (in x turns/steps).
Oh, and isaac96:
There's better ways to get into a device than hammers, hacksaws and crowbars.
