![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgYfq5p4DK80wXV_UnHGa1_xlccQhss7lehL-ndtQolwM0LyRKhBPlrpVGaYGZuYbHJ-B1Vf6vD6Jl49TT1qUthl3Fdp2gLq7AbMkFNmU5rMGa3uh0fz-74WWUFUNzSmYBn-BJPnFyB8AE/s320/1.jpg)
I was working on this massive autonomous robot project and needed to adapt the axles from a pickup truck rear differential to take a set of bearings and sprockets. Sure, I could have sent them to the shop and paid $150 to have them machined on a lathe, but I did not want to fork out the dough any more than I wanted to wait a month to have this done, so I decided to pull a "MacGyver" and machine down the axles without needing a lathe. Impossible do to the precision needed? Heck no! I even added a keyway to each axle using an angle grinder and the end result was a perfect fit.
Let me show you how I adapted the axle shafts shown here to fit onto the 1 inch diameter bearings and sprockets.
A lathe in its simplest terms is a machine that spins a part so that a cutting bit can remove metal a little bit at a time. So, I knew if I could get the axle to spin, then I could just use my grinder to carefully remove the metal around the end of the shaft until it was exactly 1 inch in diameter. At this point, the axles were about 1.25 inches in diameter and tapered. To spin the axle, I welded a bolt to the center of the hub flange and then placed it in the chuck of my hand drill. The axle was then placed into a simple wooden jig and greased so that it would spin freely.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh0W8DsmDXwMK4_x4T6xdk4_4PxXakE4c8nwpHK6tsCwCg5splj8dZGALWd3NOn6-ivCLjxyU8ZM4L_FIBijJFQ9uUKPNFnkpO76KBYtA60zv5fDuL5-QjeS-sYFYYkHafTJtA12x-hS-Q/s320/3.jpg)
Going from 120 volts AC to 24 volts DC slowed the drill down to the perfect speed, yet gave it enough torque to spin the axles as I held the grinder disc to them. To power the drill from 24 volts DC, I just took two of the four robot batteries (marine batteries) and wired them in series with the drill power cord completing the circuit. I didn't even use wires for the plug; it was just sandwiched between the two battery terminals and held there by friction.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi6bHyut0amJgEkTo1P6cLXEVX2PM2szgHABChKOHyWV9ozpkxlcQHoUlwJb0egE7SvGi7Evup4odI-x0LtLLI0r5e3PUtQvKy4YXtIxKqLJ2FiD5g3XZ12tvExN_3bT0Yo_Xc3Ti6zu_E/s320/2.jpg)
To machine down the axles, I ran my grinding disc back and forth along the 2 inch section while the drill spun the axles at about 120 RPM. I did not push hard on the grinder, and tried to keep a constant pace as I moved it back and forth along the area to be reduced. After about 50 strokes, I would stop the drill and check the axle thickness using the bearing I intended to install.
Once the axle was just slightly larger than necessary, I switched from the grinder disc to a sanding disc so the final machining could be done more accurately.
![](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhqj_8qagWDWEYApBWgsjXA0WniMSgVQnuX6O3-O6niIsmz7qZz6IHTEtcWhVEqAyzoFcqHBpSZ50uzkXtskOlLTpz6IpG4FRy1Y-OTL30RlbRk4jpYEnF3zTIPMoEcp7ONLa18Ged4d5Y/s320/4.jpg)
![]() | |
http://www.AtomicZombie.com |