Working clock

[nico71]

I present you my working clock prototype 1 :

This is a 3-hand clock with weight and pendulum. To pass 3 movements on the same axle, I use a turntable + differential + axle. The gears are 1/60 between secondes and minutes and 1/12 between hours and minutes.

1/12 = 16/16 8/24 16/16 14/56, (blue)

1/60 = 8/40 8/24 8/8 8/8 8/16 8/16, (green)

The autonomy is 15min, that is quite low. I have two choices :

-change the winch wheel to have more lenght of rope but the rope willbe moved faster

-change the position in the clock of the winch, here is on the second-hand axle with 20/12 gear.

The fact is the torque generate by the weight on winch powers the pendulum. If I place more gear (multiplication)in order to have more autonomy, the torque is lowest on the pendulum therefore I have to add more weight or increase the diameter of the winch.

I have chosen a maximun weight of 1kg and I will design my winch diameter and gear. I think it's the best approach that to start with the limits of lego.

You can also watch the video about the clock escapment :

Build a mechanical clock is a boy dream so I am happy and proud to succed :)

If you have questions, don't hesitate to ask, my english is quite bad but I understand.

[rgbrown]

The autonomy is 15min, that is quite low. I have two choices :

-change the winch wheel to have more lenght of rope but the rope willbe moved faster

-change the position in the clock of the winch, here is on the second-hand axle with 20/12 gear.

The fact is the torque generate by the weight on winch powers the pendulum. If I place more gear (multiplication)in order to have more autonomy, the torque is lowest on the pendulum therefore I have to add more weight or increase the diameter of the winch.

I have chosen a maximun weight of 1kg and I will design my winch diameter and gear. I think it's the best approach that to start with the limits of lego.

You can also watch the video about the clock escapment :

Build a mechanical clock is a boy dream so I am happy and proud to succed :)

Awesome! I'm glad these have come up again :) I have a whole lot of gears from Bricklink waiting for me when I get back home in September to make a clock as well. I take it you've seen all the various Lego escapements by BenVanDeWaal on YouTube?

edit: yes you have, I missed your credit to him at the end of the video the first time I watched it

Edited August 23, 2010 by rgbrown

[grohl]

Excellent. I wish I had patience to build working clock myself as well. That is why I admire this kind of work.

[dolittle]

Great :)

This is fantastic, how accurate is the clock? :}

Seriously - accuracy isn't really important - I do believe that ancient times they use some techniques to counter the skew (mistake) created by mechanical clocks using different methods - not sure which :)

Since you have the CAD files, can you make instructions for the clock available?

[nico71]

This is fantastic, how accurate is the clock? :}

Seriously - accuracy isn't really important - I do believe that ancient times they use some techniques to counter the skew (mistake) created by mechanical clocks using different methods - not sure which :)

Since you have the CAD files, can you make instructions for the clock available?

It's quite difficult to determine the accuracy, but with a slow down video of 1min, the total time was 1m2s. In fact it depends of the force we lunched the pendulum, after 5 oscillation, the tic-tac is accurate

I have a SR3D file, and of course we it was finished, you will have a pro-building instruction ;) I keep in mind that use a little amount of part.

But to be honnest, lego aren't watchmaking therefore I don't think the clock will be accurate during 12hrs. It works nice and it's a lovely decorating object :)

Excellent. I wish I had patience to build working clock myself as well. That is why I admire this kind of work.

I build the working clock in 10hours, 8hrs for the clock escapment, because it's difficult to settle precisely.

Edited August 23, 2010 by nico71

[Burf2000]

I think I might have ago at a motorized one, probably a lot easier

[rgbrown]

Great :)

Seriously - accuracy isn't really important - I do believe that ancient times they use some techniques to counter the skew (mistake) created by mechanical clocks using different methods - not sure which :)

I reckon you should be able to get it pretty accurate. Assuming friction and environmental conditions (like gravity) don't change, the only variables that could influence the running of the clock are

1) Different initial conditions (starting the pendulum higher, etc)

2) Change in torque exerted by the falling weight (e.g. more string length == more weight, etc)

It should be possible to design so that any transients introduced by different initial conditions are quickly damped out, and that 2) is so small as to be completely insignificant.

The really really hard part is to design an escapement that provides *just* enough energy to the pendulum to prevent it from stopping, and doesn't waste a whole lot of energy spinning around between ticks.

I think I might have ago at a motorized one, probably a lot easier

aww, where's the fun in that?

[Burf2000]

Well fair point, I dont think I could make this clock. Its very cool.

[Zerobricks]

Nice, you could use an osciloscope, to calibrate the clock. Just put a micro switch, or a infrared breaker sensor near pendelum, and watch period.

[Sam42]

nice... i thought it was going to be motorised......

[nico71]

Why motorised ? The aim is the full-mechanical functionning :)

@rgbrown, you totally righ, the first thing I changed was the escapment, in order to have more teeth to reduce the speed of the main winch.

[Sam42]

Why motorised ? The aim is the full-mechanical functionning :)

I meant i thought it was going to be a simpler downgeared motorised clock rather than your more impressive full mechanical function.

It's a great moc, and worth keeping intact in your build area once finished, to keep track of the hours spent building!

[nico71]

I have seen that I didn't post the second video of the working clock. Here :

Stil working on, but no time to do it a the moment, I have worked on a escapment wheel with 12 teeth :

Afeter replaced by the little 5-tooth gear from power miner set :

The prototyp with a big escapement wheel works better because of the inertia of wheel, The reduction qith the last prototyp is 15, so for a string of 1m with a pulley and 2kg of counterweight, the autnonmoy is 6h.

[Tobbe Arnesson]

This is really cool! I've been thinking that an escapement wheel would be a nice feature in a GBC-counter but nothing more than that, will have to try something one day or another.

My first MOC as an AFOL was an attempt at a clock, never got very far with it.

Quite ironic you don't have time when building a clock. ;)

Hope to see more videos at some point, best of luck!

[RohanBeckett]

What did you do to your big Red 40tooth gear??

all the outer holes look chewed, or bent and damaged!

I remember building the Clock in the old 8888 Ideas book! (or rather.. part of it, as I only had 4 40t gears at the time!

RB

[MrDummy]

I remember building the Clock in the old 8888 Ideas book! (or rather.. part of it, as I only had 4 40t gears at the time!

You are right!

http://www.peeron.com/cgi-bin/invcgis/scans/8888-1/?ct=1

and page 70 shows the clock with just one pointer:

http://www.peeron.com/scans/8888-1/70

I have also this book in home, but pretty damaged.

[apemax]

wow that just amazing. well done.

[CP5670]

The clock in the 8888 idea book doesn't really work that well, as I described here. nico71's pendulum design looks a lot more reliable.

[Delta 38]

Quite interesting. I think the movement of the clock hand might be a bit too rigid, but you can't fix that in this case. Anyway, nice work.