It’s in the Details

I dont know what people usually think about how much work should be done for items that are not usually seen by most people but I just had to do what I could to make my “Tin Platted Booby” as spiffy as possible. They say the suit makes the man but the shoes tell you were you have been and were your going!
With that thought, I got a nice set of aluminum wheels from Norm Sockwell (a previous vendor). They already had the lightening holes in them but they did not have any bearings in the wheels, nor were they even drilled for them. These were designed to use a Delrin rod and a 1/4 machine screw to hold the wheel on. For those who do not know, a Delrin rod is a nylon rod that serves as a self lubricating PTFE material (feels like a slippery plastic) axle for which the wheels would rotate. This works great if you are just manually pulling or pushing your robot short distances but is not good if you plan on motorizing your’e treadsection. So I chose a wheel bearing that had an inner diameter as close as I could get to the 1/4″ machine screw. Then I drilled out the wheels on both sides to insert the bearings. I press fitted them in. I also had an inner sleeve (made from Delrin) that was press fitted into the tread section so I could keep the spacing correct inside the wheel wells.
Wow, what a difference in the resistance. It made the treadsection glide along like it was on a cloud. I did notice there was a little slippage on the inner bearing when it would go faster than 2 miles per hour because the machine screw wasn’t the exact diameter needed to get a good grip on the inner sleeve of the bearing; so I made my own axles. Bytheway, the degree of polish/reflection of this wheel is demonstrated by viewing the ceiling’s reflection and my picture photographing the wheel. The polishing was done by Hands off Polishing in Garland,TX. They did a great job!. They also just happened to get the NASA contract job for the Mars Lunar Rover. They did an outsatanding job!!!
The picture to the left is of a custom washer made out of delrin. This works perfectly with the sealed bearings in the wheels above. You have to drill out the opening in the tread section and press them in. This keeps the wheels in the correct position and ensures smooth rotation of the wheels. The delrin bushings press into the existing 5/16 holes in the tread sections. The axles are .249 precision ground stainless shafts. The bearings where 5/8 diameter and the holes where .624 diameter for a press fit.
Stay tuned for pictures and comments on my motor mount design that fits inside the tread section, the modification to the soil sampler as well as a bubble lifter that is servo controlled and more….

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