Help with Selecting a Stepper Motor Controller

Check out the Animatics Smart Servo Motors. They have all the electronics built in. They have their own internal encoders for position feed back so you don't need steppers. They have excellent position, speed, torque and acceleration control and are easy to program.

What is the thickness of the cards? The old computer cards with the square holes were about 7 thousandths and could be picked at 1000 per minute or any number up to that. They did not use the spinning picker as you describe. There are several ways to pick or grab a card but the thickness and flexibility of card stock comes into the solution. Some pickers were vacuum fingers that sucked the card against a spinning drum to start the card moving. Others used a blunt knife edge thinner than the card stock and sliding on a rail to allow knife to card contact to be complete, square and remain in contact until the card has been moved far enough to be grasped by the next control pinch roller or belts what ever.

the cards will be 2-3mm thick.

i saw a video for the vacuum fingers, i am not sure if it is cheap and simple enough to be used in my case?

can you give me links or names of machines that use different types of mechanisms for picking the cards.. the generic search on google isn't helping a lot.

i was myself thinking of implementing the paper feeding method used in printers, where instead of the bottom the top most paper is sent into the machine for printing...lets see if i can find a detailed video for that

I have searched for some photos or drawings and I cannot find anything. The equipment I am referencing was made by computer vendors for handling what was called IBM cards or TAB cards. They had 80 columns that would have square or round holes (some had 90 columns) later in the tab card life they used a downsized card with 96 columns of very small round holes. There were machines that could read the larger and the smaller cards by installing a guide fence in the input hopper.

Things you will have to address will be the picking or selecting only one card and rejecting or stopping the next in line card from following because of "sticktion". Adjoining cards tend to slide together; they often are cut with residual edge curl that matched the card next to it. The weight of the stack in the input causes the pressure on the next card to follow. Many of the machines had a throat that the card would have to pass through that was only a thousandth or two larger than the card. Consider the problem of having two cards fed through your process and the corrective steps needed if it happens to help determine how much effort you put into the card pick and select accuracy. If no harm done by having two selected occasionally, don't worry about it as the card supply is probably pretty cheap. Now if the individual cards are getting sequential numbering or other unique information, you will want to spend lots of time making sure only one card is selected or that you have a downstream reject or second selection. There are check processing machines that pass 2000 checks per minute with minimal erring and they have reject hoppers for second chance items.

The next concern will be stopping, positioning the card for your processing step or maybe you will process while moving but it still needs to be square and level in some fashion.

Finally exit and final stacking, packaging, sorting for the user.

Check out computer card reader designs from the 60's 70's and 80's. They used solenoids to push the cards out from under the stack, and they were often then grabbed by belts to transport them away. the solenoid was pulling a lever which operated a sliding plate and the card when ejected was forced into contact with the belt.

Automation Direct makes a small PLC DL05 that has pulse output/dir for around $120 and software is free. They also include examples that work for basic stepper controls. Great way to learn and cheap

thanks for the options but i couldnt find a motor which suits my requirements besides even if i come down on the motor torque(i have calculated it for 2.5 times my actual requirement) i think these will be quiet expensive as they have there software and all

i personally am thinking for a solution that keeps my electronics including the motor under 100$.

One of the problems I've had using stepper motors at high speed is 'stalling', where the motor stops and the step rate needs to be reduced to get it to pick up again...I'd recommend you check out the 'arduino'(about $40 ( atmel based micro) with open source software examples for motor control and a motor driver chip on a 'shield' that piggybacks on the arduino for pwm or step control( about $15) ...available online or at Radio Shack. Lots of examples available online.

are u sure about the stalling issue. i am using a 44rpm motor and will be using it below that speed, shall i still worry about the stalling issue?