06-11-2017, 02:02 PM
I took this part apart today, it was the only bit I hadn’t touched yet and I assumed that it would just need new bearings. Its the drive for the knee. It was covered in grease and I didn’t expect corrosion.
![[Image: Mill%20018.jpg]](http://i375.photobucket.com/albums/oo198/jpwbrookes/Harrison/Mill%20018.jpg)
After all of the grease was washed off there was a lot of end float and once apart and cleaned up it seems that at some time in the past it has been subject to moisture.
The inboard end is corroded and is loose in its bushing. Because the drive pinion is on a spline that is the same diameter as the shaft, I cant machine the corrosion off and make a smaller ID bush.
By chance I found a piece of EN24T in my box that is the same diameter as the largest part of the shaft (one inch) and it is about 3/4" longer than the shaft. Perhaps fate is telling me to make a new one?
![[Image: Mill%20046.jpg]](http://i375.photobucket.com/albums/oo198/jpwbrookes/Harrison/Mill%20046.jpg)
Close up of corrosion
![[Image: Mill%20047.jpg]](http://i375.photobucket.com/albums/oo198/jpwbrookes/Harrison/Mill%20047.jpg)
Its fairly simple lathe work except for the splines on both ends. I am new to machining splines so I am looking for advice. I am thinking that I could make a form tool once I have figured out the right shape and then figure out how to index my lathe chuck and cut the splines one at a time with the form tool in the tool post. Any better ideas? Also, what is the best source for establishing the geometry of the splines so I can grind a tool?
John
After all of the grease was washed off there was a lot of end float and once apart and cleaned up it seems that at some time in the past it has been subject to moisture.
The inboard end is corroded and is loose in its bushing. Because the drive pinion is on a spline that is the same diameter as the shaft, I cant machine the corrosion off and make a smaller ID bush.
By chance I found a piece of EN24T in my box that is the same diameter as the largest part of the shaft (one inch) and it is about 3/4" longer than the shaft. Perhaps fate is telling me to make a new one?
Close up of corrosion
Its fairly simple lathe work except for the splines on both ends. I am new to machining splines so I am looking for advice. I am thinking that I could make a form tool once I have figured out the right shape and then figure out how to index my lathe chuck and cut the splines one at a time with the form tool in the tool post. Any better ideas? Also, what is the best source for establishing the geometry of the splines so I can grind a tool?
John