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Well I've been reading this discussion - and it seems a lot of you are using pendulums. Are you just using a simple pendulum with no escapement then? Like you just count the number of swings yourself?

I've been wondering-with the constraints given, do you think a pendulum without an escapement mechanism will last 5 minutes? Im inclined towards a no on that...I was also wondering about metronome-like devices, with a counter weight, but I doubt that will also hold up for a max of 5 minutes. This is my first year, and I had very short notice(2 weeks), anyone have some ideas? I developed a spring-based idea, but it seems that with the time left before competition a water clock is the best bet. I've figured a pretty easy way t compensate for the pressure inconsistency in water clocks, but I don't think they'll work out very well to .1 of a second. :-/

Yes, a pendulum without an escapement can easily last five minutes.

SkInventor wrote:I've been wondering-with the constraints given, do you think a pendulum without an escapement mechanism will last 5 minutes? Im inclined towards a no on that...I was also wondering about metronome-like devices, with a counter weight, but I doubt that will also hold up for a max of 5 minutes. This is my first year, and I had very short notice(2 weeks), anyone have some ideas? I developed a spring-based idea, but it seems that with the time left before competition a water clock is the best bet. I've figured a pretty easy way t compensate for the pressure inconsistency in water clocks, but I don't think they'll work out very well to .1 of a second. :-/

Careful with a water clock; they can be harder than you think. My partner and I spent many many many hours trying to get consistent data; often it'd be great and then start being really erratic. We think we figured it out... but think it through before you go down that road.

If you make a long enough pendulum with low friction it will last for over 5 minutes. It is also important to have a heavy bob on the end.

Yes but with a longer pendulum I thought the period would be too long. Therefore can you get an accurate measure of time to be close to the .1 sec requirement? How would you read the final place of the pendulum and correspond it to the time if it's not at the end of its swing?

The short answer would be yes. If you were ever in band you learned how to subdivide a beat. This same priciple can be applied.

Is anyone interested in trading tests with me? the best way to find out what you need to learn more about is by doing practice tests

I have a question about the parameters of this competition. In the rules it clearly states that the entire timing mechanism must fit inside of an 80x80x80cm cube. I am using a pendulum with a falling weight to keep the swinging arm in motion. In order to reach a full 5 minutes my weight must fall 140cm. Will we be allowed to set our timers on top of a table/lab station during the competition? I can always lengthen my pendulum's arm in order to get 5minutes in 80cm of drop but that will make it much less accurate. If we are permitted to set the 'complete timer' ontop of a table than I can probably get away without lengthening the period.

The rules state that it must fit within the 80cm^3 box at impound, however it is able to go beyond that during the competition. You should be able to set it up on a table at the test.