Track drive / Belt conveyor - In need of solution

JBWolf

Howdy!
I am having trouble finding a solution to my project and was hoping someone with robotics experience may be able to help.
I need a belt drive system to feed objects through for inspection... The objects are all the same in dimensions and I am scanning the surface for surface differences.
The objects are 1" wide x 2" long and roughly .5" in height.

I have everything working for my project so far, but cannot find a suitable way to feed them in so that they are aligned.
I have a small stepper motor that is perfect in size which I prefer to use.... it has a smooth 3mm diameter shaft that is 6mm long.
I have put a lot of though into it and believe a mini-conveyor system with rubber belt would be absolutely perfect.
I need a screw/drive shaft that will couple to the 3mm motor shaft, and then be long enough to put a belt on that is just over 1" wide.
The length of the conveyor system needs to only be about 3" long... just long enough to feed an object in, be aligned and vertically and horizontally which I can do easily with the walls & floor of the project box.
The problem is, I cannot find a small belt drive mechanism pre-made that I can work with.... everything I have found so far are unsuitable toy tank tracks.

The only solution I can think of at the moment is to use a 5mm screw with a bearing at one end and a 3mm to 5mm coupler such as this at the other end:
http://www.ebay.com/itm/Shaft-Coupling-Motor-connector-DIY-Accessories-Aperture-Size-3mm-5mm-/160852424864?pt=LH_DefaultDomain_0&hash=item25738d38a0
The second shaft can be a 5mm screw with bearings at both ends.
For the belt, I guess a bicycle inner-tube cut to size and sewed to length?

What do you guys think... kind of a tricky problem.
Hoping someone knows of some website/company that makes custom belt tracks with gear/shaft solutions.
Say you wanted to make a toy tank with tread/tracks 3" long and driven by a tiny stepper motor with a 3mm shaft... what would you do?

Duane Degn

Vex treads are 1.5" wide. You'd need to figure out a way to attach your motor to the sprockets but that shouldn't be too hard. I've attached the Vex sprockets to motors with 6mm shafts.

Lego has made a variety of sets with both rubber treads and plastic treads. I don't know what sets are currently available with treads but I'd be surprised if there weren't current sets with treads.

kwinn

If hobbyist parts are not suitable take a look at the small cogged belts and pulleys available at industrial suppliers. You may need multiple belts and pulleys to get the width you want.

Phil Pilgrim (PhiPi)

You don't want to use anything -- like a bike tube -- that's too stretchy, or you will have trouble getting accurate distance-per-step registration.

One thing that comes to mind is miniature roller chain that has holes or hollow pins for the attachment of rigid conveyor segments.

-Phil

Duane Degn

I have a few links to tread ideas in post #12 of my index. There's one on using bicycle chains to make treads.

Paul K.

Trying to get it to 3" is the tough part. I would use a timing belt. Use idlers to set up the 3" length. Then attach your motor to a third pulley wheel which is also your tension control.

Think of a Y pattern. Small idlers at the top to set up the length and the main drive at the bottom with the motor and tension adjustment.

MotionIndustries.com have every possible belt and pulley you could need. WMberg.com is a cool site with lots of precision stuff that you could almost build anything that comes to mind.

Check out ebay you never know want old machine parts you might find.

-PK