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While I was working on something else, my bugeye's tachometer died. Dang! I pulled apart the tach drive (the cool little gearbox hung on the generator) and found that the output shaft had broken. Since a replacement gear is $76, I decided to do some metalwork.
Fortunately I have a little Sherline lathe. I used this to clean up the pieces, drill a longitudinal hole in the output shaft for a 2-56 screw, and put it all together with a lot of permanent loctite. Very proud of myself, I reinstalled it and drove off.
It lasted about 15 minutes.
OK, the 2-56 screw was too small. I put in a 4-40, then pinned it together. That sucka ain't gonna break! No way!
It did. Took a couple hours this time, though.
Now, what's going on? Why it is breaking? I disconnected the cable at the drive and, this time, tried to twist the generator end of the tach cable. It would not turn. No way. Totally frozen! I pulled the tach out and found that the input shaft, which protrudes through a fitting in the tach body, was simply frozen. It must have been jamming on and off for some time. I'm amazed that it lasted as long as it did.
So, I pulled the tach apart, reamed it out, and now all is in order. I repeated the fix for the drive gear, which is getting a little chopped up at this point. But it all turns smoothly, no binding, and I'm optimistic that THIS TIME it will last.
The moral of the story: when something like this breaks, there is a reason for it. Don't just fix the break; find the reason. I know, this should be obvious, but sometimes, it's easy to forget.
Fortunately I have a little Sherline lathe. I used this to clean up the pieces, drill a longitudinal hole in the output shaft for a 2-56 screw, and put it all together with a lot of permanent loctite. Very proud of myself, I reinstalled it and drove off.
It lasted about 15 minutes.
OK, the 2-56 screw was too small. I put in a 4-40, then pinned it together. That sucka ain't gonna break! No way!
It did. Took a couple hours this time, though.
Now, what's going on? Why it is breaking? I disconnected the cable at the drive and, this time, tried to twist the generator end of the tach cable. It would not turn. No way. Totally frozen! I pulled the tach out and found that the input shaft, which protrudes through a fitting in the tach body, was simply frozen. It must have been jamming on and off for some time. I'm amazed that it lasted as long as it did.
So, I pulled the tach apart, reamed it out, and now all is in order. I repeated the fix for the drive gear, which is getting a little chopped up at this point. But it all turns smoothly, no binding, and I'm optimistic that THIS TIME it will last.
The moral of the story: when something like this breaks, there is a reason for it. Don't just fix the break; find the reason. I know, this should be obvious, but sometimes, it's easy to forget.
