MetroGTi's blog archive for December, 2012 - RC Groups
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Archive for December, 2012
Posted by MetroGTi | Dec 23, 2012 @ 12:08 PM | 5,782 Views
I've got a Maximat V10 lathe/mill combo in my shop. A few weeks ago the gears in the milling head gave out. As the machine was built in the 1960's, replacement parts are non-existent.

The two gears that gave out were the same size, and were made from a plastic/fiber composite similar to phenolic. After quite a bit of searching I found a suitable stainless steel gear blank (Stock Drive Products/Sterling Instruments: S12N15M024S1016) that had the correct pitch angle and tooth count, and could be modified to replace the damaged plastic gears.

The new gear was 2mm too thick, and needed a larger hub diameter with a step. I made an aluminum "collet" to hold the gear blank in my 3 jaw chuck. I faced the gears down to the correct thickness then bored out the hubs. I needed to tailor each gear hub to fit the knurled portion of the original gear shafts for an interference fit

When the gears were done, I put the new blanks shafts in the freezer and the shafts new blanks in the oven. After an hour or so I put the gear and shaft on the arbor press an "Presto!" the shaft goes into the gear.

After putting the repaired parts into the head and adjusting the shift forks I now have a working 4 speed milling head again.