I recently acquired 3 small $5 servo's and stuck them together in an arm fashion. I have a small dc motor and I'd like to use it to create a gripper or hand for the small robotic arm.
If you have any ideas please let me know.
I'm intrigued about what you mean that you stuck the servos together in an arm fashion!
Can you post a photo please?
Here is photo. http://i.imgur.com/ibNfj.jpg
Please keep in mind that I stuck this together in 10 minutes and used only parts I had lying around. Also it's missing one wooden arm where the 3rd servo is and it's very small.
Stuck on the gripper part.
It's a good thing you lots of spare rubber bands lying around!
I can't think how a dc motor would operate the gripper- I think that would need a servo too? Perhaps one side of the gripper static and the other side hinged and moved by a cam or a linkage from the stepper...
(I'm new to this too by the way!)
You could make a small 'Gripper' with your motor, the simplest way would be with 2 cogs and a worm gear that would open and close two 'fingers' you would need feedback though in the form of 2 switches so as not to open or close to far!!!!
Check out what this guy came up with. He is pretty inventive when it comes to robotic stuff.
Here is cardboard crane and gripper: http://www.kickstarter.com/projects/392540503/cardboard-robot-robotic-arm-and-smart-phone-camera (http://www.kickstarter.com/projects/392540503/cardboard-robot-robotic-arm-and-smart-phone-camera)
It is 5' plus, which is kind of crazy for cardboard. I bet a smaller one could lift a bit more.
For a simple gripper, you can pretty much go to a toy store or a walgreens (or similar pharmacy) and find one.
At the toy store, they are usually sold as "robot arms" or something stupid; basically a stick with a grip and trigger, and on the other end a "claw"; squeeze the trigger, and the claw closes. They are pretty cheap - for instance:
Now - if you go to a walgreens/cvs/pharmacy - you can pick up a medical device that is basically the same as the above toy, but engineered a bit better for use by those to reach top shelves and such - like:
Words to search ebay with:
"Robot" "Toy" "Grabber" "Reacher" "Medical"
They come in a variety of styles/types. I've even seen them "used" at Goodwill and/or other thrift stores - grandma no longer needs one when she passes away, and so the kids donate it; much cheaper than buying new.
You can use a servo or a strong solenoid (or a gear motor) to actuate it.
My wife unfortunately needs to use one of these grippers. I recently bought a backup gripper from American Science and Surplus that folds up in 1/2 when not in use: http://www.sciplus.com/singleItem.cfm/terms/15684 (http://www.sciplus.com/singleItem.cfm/terms/15684). Sciplus has an fascinating selection of various odds and ends, and their descriptions are fun to read as well, including electrical stuff, robot parts, etc. Note, they have a minimum order of $10.
I've had this servo gripper unit on my ebay watch list from Jameco for awhile if you want something smaller and made for servos: http://www.ebay.com/itm/110776214322?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649 (http://www.ebay.com/itm/110776214322?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649).
The best info for robotic arm gripper design is to search using google and on youtube. I got one of the below (way too big for use with servos without mods) at the DollarTree store for $1. As to general robotic arm tinkering with servos, large craft sticks and hot glue are an easy practical starting place.