Idea for Treaded Robot
September 29, 2013
I've been meaning to show Dickel my experiments with Vex treads. His MDi #2 continues to look amazing but Dickel has expressed some concern about the frame of his treads. Rather than using increased thickness of polystyrene, I wonder if some sort of box shape could be used to increase the stiffness of the structure.
Here are some photos of prototype tread mechanism.
The mechanism closest to the camera is made from 3mm expanded PVC. The other one is made from foam board.
Here's another view.
The ePVC structure is on the left side of the photo.
My attempt to heat a t-nut in order for it to seat well into the ePVC caused some damage to the ePVC (burned it).
In the above photo you can see some "T" shaped cutouts to allow nuts and bolts to be used in holding the structure together. Some of the nuts are held in place with a bit of Polymorph.
I like Dickel's method of mounting the wheels to the motor. I used a different method.
I drilled the centers of the sprockets to match the motor's 4mm shaft. I then drilled a hole for a setscrew from the side.
It's important to add the nut so the screw has something solid to push against. With the nut and screw in place, I filled the side of the sprocket with Polymorph.
You can kind of make out the setscrew in this next photo with the sprocket mounted to a motor with the Vex track attached.
This robot is currently on hold while I finish putting my CNC router together. If gotten really tired of cutting out parts by hand (and Dremel). I'm hoping the CNC router will make it easier to build the next version of this robot.
After seeing how nice Dickel can make robot parts look, I think I'll put some more effort into making my robot look nicer than it's current boxy appearance.
The motors in the above photos were purchased on Pololu's Black Friday Sale last Thanksgiving. Here's a link.
I'm planning on using these motor controllers.
One of the things that concerns me with this present design is the lack of a way to adjust tread tension. I'm not sure if I can get away with some sort of adjustment where one of the sprockets can slide a bit and be locked into position in order to adjust the tension or if some sort of spring loaded mechanism will be needed.
I wish I had know about the treaded robot OddBot is working on before I started building this. I have a feeling OddBot's robot will do what I want for less money than I'll spend on this robot (though it wouldn't be as much fun just to buy a robot).
Edit (9/29/13): I fixed the link to OddBot's robot. The original link was to the wrong robot.