Make:

What voltage are you running the Easydriver at?
You should be able to run 12Volts with the stepper you have,
and you can probably go higher to get more torque out of the motor
if it doesn't get too hot.

What do you have the current-controls setup for? (R6)
That stepper should be able to handle 350 milliAmps.
If you've got the EasyDriver set to 150 mA, you'll get a lot less torque.

How are you connecting the motor to the trolley?
These motors are fairly beefy, so let's look around a little
before using a larger motor.

(You might be 100% right, but if you don't need to
spend money, that would be great.)

Thanks for the quick response alakilian

<i>What voltage are you running the Easydriver at?</i>
Right at 12 volts, well close any ways, 12.1 according to my meter.

<i>What do you have the current-controls setup for? (R6)</i>
While its trying to move, it seems to be hovering at .2 and when its stops, it goes up to .4. The holding torque has no problem holding the trolly in place, only moving.

<i>How are you connecting the motor to the trolley?</i>
I stuck some pictures of the spine only ,which is were I'm having all the problems, here: http://picasaweb.google.com/f15cspec/DVDBot?feat=directlink

I have a second motor of the same type here, I might put it in to see if it does any better.

Something you can try is to increase the voltage. (You can easily go up to 15 volts, and you may even get up to 20). More voltage = more power. (But it will also require more wattage).

Otherwise, you can get a bigger motor.

Ah, i see.

Clamp a large weight to the other side of the toothed belt to counteract the
weight of the carriage and things will get a lot better.

Or add a pulley to the top of the rig, run a cable up and over the pulley,
attach one end of the cable to the trolley and add a weight to the other end
to balance out the weight of the trolley.

Scavenge a stepper from an old laserjet printer ( II or III series) -- I use them on my CNC machine and they are quite powerful. Or a scanner or something like that.

After 2 days, I was able to sit down and work with it. I was able to get the trolly moving... sort of. I ended up strapping on a counterweight, but that alone didn't do it. After I also increased the voltage to 16V at .5 amps, the trolley seemed to move decently.

Now I am left with a decision. I don't like running a 12 volt motor at 16 volts for an extended period of time. Also the tolly is not yet complete, I still have to add an actuating arm, which is going to add some more weight, which means a larger counterweight, which of course means even more mass for the motor to move.

I think I might be back at the beginning, needing a bigger motor. Perhaps a 24volt stepper would be the answer?

You will probably have to go with a NEMA 23 type stepper, one with about 80oz/in torque, and go with a 24 volt setup. From what I see in your pics, once you get the rest of the parts on there, your motor will be working very hard. Or you can try putting the motor at the bottom and the pulley on top, so all the weight of the carriage is not resting on the motor shaft, which would require the motor to overcome the weight tension in order to move freely.

Small scanner's or printers will not have the right motors, it would have to be a large industrial scanner/Printer in order for it to have NEMA23 rated motors.

Have you thought about using a 12VDC Gear Motor instead of a stepper motor?? (Use a quadrature encoder to count steps and direction of motor)

Or what about using drawer slide rails, the kind with bearing slides (You can get a pair for around 14.00 at Home Depot) it would reduce the weight of your carriage.

My .02

<i>Have you thought about using a 12VDC Gear Motor instead of a stepper motor?? (Use a quadrature encoder to count steps and direction of motor)</i>

I was thinking about this, and I do have some experience with pot and encoder combination's. Though I have never programmed an Arduino to read them.

In theory it shouldn't be too hard though. My biggest problem is finding out where to buy the components. I would like the motor and encoder to be one unit if possible, or at least be able to have the encoder mount to the motor somehow.

If you are using an Arduino, check out www.OOPIC.com, the OOPIC S seems to fit what you want to do, it has built in objects to control all kinds of things from H-Bridges to quadrature encoders... also for different LCD's available in the market and for 4x4 matrix keypads (I'm sure you are planning on using a keypad for input on video selection?), even a text overlay board for Televisions (that would be cool to display users selection data on the TV)..... just give it a once over and see what you think.....

For h-bridges use the LMD18201T (http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=LMD18201T&x=0&y=0) very reliable and can handle voltages up to 55 volts DC up to 6 amps(max).

any encoder with a quadrant style output would work with the OOPIC's oQEncode object. Easy to make all you would need are a couple of IR phototransistors and some IR LED's, a plastic disc (anything flat and round would do, about any size you want as long as you can drill plenty of holes around the circumference of it for better resolution)

here is a sample listing of how to use the oQencode object in the oopic (This sample is in basic, the oopic can also be programmed in C and Java.

'This program reads an oQencode Object
'and outputs the value on I/O lines 8 - 15.

Dim A As New oQencode
Dim B As New oDio8

Sub Main()
oopic.pullup = 1
A.IOLine1 = 8
A.IOLine2 = 10
A.Operate = cvTrue
B.iogroup = 3
B.direction = cvoutput
Do
B=A
Loop
End Sub

Here is a listing for the oDCMotor object connected to an LMD18201T HBridge:
' This program ramps a DC Motor's speed
' up and down / forwards and backwards.

Dim A As New oDCMotor

Sub Main()
A.IOLineP = 17 'PWM IOLine
A.IOLineD = 27 'Direction IOLine
A.IOLineB = 25 'Brake IOLine
A.Operate = 1
A.Brake = cvOff
Do
For A = -100 To 100
OOPic.Delay = 2
Next A
For A = 100 To -100 step -1
OOPic.Delay = 2
Next A
Loop
End Sub

Here's one for the L293 Motor Driver:
Dim A As New oDCMotor2

Sub Main()
A.IOLineP = 17
A.IOLine1 = 27
A.IOLine2 = 25
A.Operate = 1
A.Brake = cvOff
Do
For A = -100 To 100
OOPic.Delay = 2
Next A
For A = 100 To -100 step -1
OOPic.Delay = 2
Next A
Loop
End Sub

This is a great learning tool for newbies too, and it is PIC Based!.


My .02

Anyone think what kind of DC motor would be best here.

Also a good reputable store, been poking around spark fun, but I don't see what I need their.

Double Post

try these motors here >> http://www.mcmaster.com/#6409k18/=3xnbh4

McMaster to me is like ACME was to wiley coyote....

There are a lot of surplus sellers that often have good deals on motors. There are some I use:
http://goldmine-elec.com/
http://allelectronics.com/
http://www.mpja.com/


@BMorse: The platform really doesn't seem to be the issue... I don't want to fuel an AVR vs. PIC religious war, but there are libraries for the Arduino to do everything you describe. Plus, it's all open source and the tools are available for several operating systems.

Stokes, I dont want to start any feuding about uc's either (sorry if I stepped on anyones foot!)..... the oopic is open source also under GPLv3..... I was just mentioning this to him to give him some other options......

CaptRR -I also have a similar project, but my setup is horizontal, not vertical like yours, so my motors do not need to be really strong and I am using some micro gear motors to move the carriage and using RC servos to load and unload the discs. The only thing holding me up from finishing it is the holder for the discs.

I think I will go ahead and get the motor from mcmaster that BMore Recommended (after all 10lbs of force should have no problem lifting the carriage). I did notice however that the motor does not have an encoder. So I will have to get one from somewhere.

I been poking around, and it seems finding an encoder (non industrial anyways) is allot harder than I thought. Sparkfun didn't have one either, anyone know where else I can look to get an encoder?

digikey.com has hundreds of optical encoders.

here is a Makezine project on how to make your own... http://blog.makezine.com/archive/2009/02/how_to_diy_quadrature_encoder.html

You could also make one with 2 IR LED's and 2 IR Photo transistors, use a solid disc (so IR light does not go through) and drill holes around the circumference of the disc, place the IR LED /Photo transistor pair 90 degrees offset from each other...
The more holes around the circumference of the disc, the higher the resolution...

I used a hacked PS/2 'ball' mouse to create encoders for the left and right wheels of a little robot. You could do the same but use only one axis. There are PS/2 libraries for most microcontrollers; personally, I've used them for Arduino and Propeller.

Well after messing around with motors and encoders, a big ass stepping motor was dropped into my lap last weekend. Since it was free, I would like to use it.

The problem is that the stepper is a 4.2V 3Amps monster, my easy driver only supports max .8. If possible i would like to use my easy driver, since it makes interfacing and moving a snap. Anyone have any recommendations on interfacing them.

I was thinking of trying to find some transistors that would support the current, and powering the motor off a separate power supply, am I on the right track?

Thanks for everyone's help.

Amazing what a little googleing will get you. From what I can tell these type of motors seem to be used in CNC products allot. And they have driver board kits already. Rather than reinventing the wheel I am thinking of getting one of these kits, and just using the aurduono to send the control signals to the driver itself..

Here is the driver I am looking at using.
http://www.hobbycnc.com/products/hobbycnc-ez-driver-board-kit/

I have been sorely tempted to buy from those guys. I tried asking around here if anyone had used their stuff and how successful they were and all I got back was silence. Their stuff looks really good though.