Making a rodless pendulum clock

[Mike Everman]

I don't know if you guys are interested, but I'm doing some work toward a clock that has a rodless and potentially isochronous pendulum (if only there were no friction or manufacturing tolerances!). You can see some videos of key elements in these youtube vids:

HD
http://www.youtube.com/watch?v=h0CB8ZoF7RY
http://www.youtube.com/watch?v=TzL-oScHrpI

std video walkaround
http://www.youtube.com/watch?v=Mu6NQhNsoGI

300 fps slow mo
http://www.youtube.com/watch?v=Dagmo_ANG90
600 fps slow mo
http://www.youtube.com/watch?v=m3v8ksDsmxY

If any of this is interesting, I'll continue to post progress here.

[Paul Loatman]

That's a very interesting design, and looks like it would work perfectly for a pendulum. I'm definitely interested.

[J.K.]

very interesting, how are you gonna connect the movement to the pendulum ?

btw I'm new here but I've been visiting the forum regularly, I'm interested in unusual clock's

[Steyr]

Very nice !
I'm "a bit" worry about friction but on a design point of view, I love it !

[Paul Loatman]

Very nice !
I'm "a bit" worry about friction but on a design point of view, I love it !

There should be very little friction since all of the surfaces are moving together, nothing is sliding against anything else.

[Mike Everman]

I just got an escapement designed last night. I've been toying with just a sensor and electromagnet, but I've had so much fun with the escapement design that I'll try and get it made up by the weekend.

I'll be very interested to know how much torque is needed so I can finish the drivetrain design.
If torque required is too much, then I'll probably abandon the dream of an 8 day movement.

[Mike Everman]

Yes, friction is an issue, so this thing may not ultimately be practical, but I'll see where it goes.
Another source of losses is just the cycling of the support rollers back and forth, acting like a foliot. Question is whether that movement is a harmonic subtraction of the energy I must drive it with.
Tolerances are an issue, too, as the difference between a circular path and a cycloidal path is very, very small, so isochronism may never happen, and I'll have to concentrate on minimizing escapement error.

Unfortunately, I'd wanted not to have to do that by being isochronous!

[Mike Everman]

Hello guys. Love the OTB forum!
Just letting you know that I'm still chugging away at my clock, and am still experimenting with pendulums. Honestly, for such a simple thing, it goes so very deep!

http://mikeeverman.com/high-and-low-ine ... ulum-bob-0

I'm keeping a blog for this and other projects. If you hit "return to blog", you'll see other pendulum experiments previous to this one. If you're interested in the next installment, it's a quick thing to subscribe to the blog and you will be alerted.

I had a paper on the rodless pendulum published in HSN. I've posted it on my blog here:
http://mikeeverman.com/clock-article-published-dec-09

[Curtis]

Hi Mike,

Thanks for the posts. What got you started on your pendulum research? It is very interesting, please keep the posts and info coming.

Cheers,

Curtis

[Mike Everman]

Hi Curtis, apologies, I forgot to respond.

As a precision mechanism guy, I've always had an interest in any type of precision devices. As I get older, (I'm 50 now), I become more and more fascinated by passive or non-electric devices for fun. I do like complex things, but now view electronics and software as cheating, especially since what I am creating has no practical application, beyond the art of it.

I started researching clockwork and was led to Philip's W5, and then to David Walter's (D)W5, which fueled the fire for clockwork.

BTW, I just got a job to make a micro cnc mill using some of the techniques I've always wanted to try. I'll be posting some work on that here. One of the neat aspects of it is how stupendously small i will be able to go with the machine. That's what's absorbing me now.

As to my pendulum research, I just made a disk-like flag that goes in the end of the high/low inertia rig, so I can now measure the ring-down and Q of different configurations. Got to see if my math model is right, which after a preliminary run, I think is not!

[Curtis]

Hi Mike,

Thanks for the response and please share your pendulum findings.

Cheers,

Curtis