Simon, in case I find the instrument is actually working in the right direction I might be interested in the gearbox of yours if you would sell it.
Cheers,Michael
Cheers,Michael
Misc: Everything Else Smith rev counter
- Thread starter MichaelOrgzey
- Start date
Some people incorrectly interpret this as if they have x-ray vision and can see the cable rotation through the case. To repeat what David wrote in different words, hold the speedometer/tachometer with the bottom facing you. If the cable needs to turn CW to operate the unit, it's a CW unit, and vice versa.
To add some mystery to the issue, you can't necessarily believe everything you read about these units. For example, several tables on the web, including on this site, incorrectly say the SC1302/02 tachometer on one of my Gold Stars is 4:1 so needs a 2:1 gearbox. It actually is 2:1 and uses a BG1508/04 1:1 gearbox. Either that, or I've never exceeded 3000 rpm when riding the bike...
Hello Magnetoman, all very interesting stuff, I do have a cable so at least I should be able to check rotation. Obviously the ratio is not quite so easy to check. I will work my way through it....thanks for your message
If you have a reversible, battery-powered drill, you can look up the manufacturer's specs. My Makita is two-speed, with maximum speeds in the two ranges of 550 and 2100 rpm. The precise values don't matter because they are different enough that it's possible to determine if your tachometer is 1:1, 2:1 or 4:1. Assume the latter to start with and use the low speed. If the tachometer registers anywhere near 2000 rpm, it's 4:1, ~1000 rpm is 2:1, and ~500 rpm is 1:1. After you've determined the ratio, switch the speeds on your drill to confirm your findings.
On one of my boxes of Smiths instruments I keep a piece of Al rod into one end of which I've filed a square. I first flick it manually to determine whether the unit I'm about to test is CW or CCW, then install it in my drill and set the direction of rotation accordingly.
I have a Makita 2 speed drill as well, so will definitely try your method. I'm very glad about all the advice I'm getting here, the accumulated experience and knowledge here cannot be appreciated enough. Thanks everybody !