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[on:]

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.

[Reply #1 on:]

I'm intrigued about what you mean that you stuck the servos together in an arm fashion!

Can you post a photo please?

Jim

[Reply #2 on:]

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.

[Reply #3 on:]

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!)

[Reply #4 on:]

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!!!!

[Reply #5 on:]

Check out what this guy came up with. He is pretty inventive when it comes to robotic stuff.

http://forums.parallax.com/showthread.php?137471-Arm-Wrist-Gripper-Uses-9-gram-servos

[Reply #6 on:]

Here is cardboard crane and gripper: 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.

[Reply #7 on:]

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:

http://www.ebay.com/itm/2-ROBOT-PICKUP-CLAW-GRABBER-novelty-hand-toy-reacher-/330560700872

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:

http://www.ebay.com/itm/PickIt-Reacher-MEDICAL-BLUE-/110929634306

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.

[Reply #8 on:]

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.  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.

[Reply #9 on:]

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.

http://www.harborfreight.com/36-inch-pickup-and-reach-tool-94870.html