Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Hi,

I my experience with compound pendulums they are not as isochronous as simple pendulums the longer arcs do take relatively longer than the shorter ones.  This means that it is more important that the escapement gets a constant force to keep better time not just being the right length also I found that the amount of movement required to adjust it is a lot smaller.  Usually there is a third form of regulation either above or  below the fulcrum or point of balance of the pendulum. The pendulum is regulated to say five minutes a day using the the larger weights and then the smaller intermediate weight is used to improve on this.

Many years ago I rescued a old turret clock movement from a cellar in a property we were vacating. As the movement had a pendulum that was around ten feet long whose frequency was about 1.5 second but it would be called 3 seconds in America as both movements (back and fore) are counted, in the UK we are mean and count only one swing. This was so long it wasn't practical to run the clock, as the well as the problem with length the pendulum weighed about 100 lb!

So I made and fitted a compound pendulum with the same frequency with was only 1 metre long say 39 and a bit inches. We are not at home at the moment but I think I took some photographs of the pendulum made and if you are interested I could try and find them and post.

Take care Tony.

Update: My clock stopped!.... But it was easy to fix
  The clock had been running well, but we have gotten quite a bit of rain in the last couple days, this high humidity combined with the fact that it is also the start of our heating season in Michigan means I have just started my wood burner. The woodburner has a very Rapid drying effect on my home.
  The clock is fairly complex and it is not easy to spot a problem on the wall...my clock started first try so I did not think I had a problem tooth but as a good diagnostic tool I removed the pendulum(easy) and let the clock run unregulated(high speed) as the weight falls the clock gearbox builds impressive speed and it was going faster than I was comfortable with 3.5 lb weight so I dropped back to 2.7 lb....with this less wild speed I could easily hear a steady scuff...scuff...scuff sound, that quickly told me a gear was warped and rubbing (side to side run-out) Watching the gears spin at high speed, they all looked pretty good with the exception of the Escapement wheel and sure enough, this was my problem child.
  If the Escape wheel was a clock "face" than at 3 o'clock on Escape wheel the teeth past by the frame, there is about a 1/2 inch area that is thicker on frame and cause the gear side to side clearance to be tight in this area. The other gears have more clearance but this one is a +/- 1.5mm max.
  I could disassemble the clock but wanted to see if I could get it running again on the wall, I spun the escape wheel slowly to determine which of the 4 "spokes" of the escape wheel gear was most at fault, then with gentle warming of the gear(hair dryer) and then holding opposite gentle bending pressure while the gear cooled the clock was soon running again!

  I feel there is internal stress in the plywood parts from the plywood manufacturer process and also the escape wheel spokes are quite thin to give the clock that airy skeleton look...now that I know the Escape wheel is a potential problem I was thinking of ways to make this wheel more resistant to warp...perhaps better wood finish like lacquer or polyurethane? But a second thought is before I add the small spur gear to Escape wheel, I could clamp it to a small plate of glass and wick the thin super glue into the "sides" of the skinny spokes where the burnt laser cut is...this may have the effect of locking the gear in a more flat state and be more resistant to humidity changes. I am not disappointed, these type issues should be expected when building a clock out of Natural wood material.
  I am also interested in research better wood finish ideas for blonde plywood. I like working with shoe polish but want my second clock to be better... If any woodworkers out there know how to make Beech? Plywood look fancy? I would appreciate some tips.

I still love the clock and will continue to run and improve this one, I want to make a list of significant improvements including bronze bushings and great wood finish plus other performance and decorative improvements before I build clock #2

Photo: the problem child Escapement wheel, the little triangle of blue painters tape(on tooth near pallet) is very helpful in regulation of clock, I have a highly accurate atomic Casio watch and I can wait till the blue tooth is on pallet than watch my Casio and when I "hear" the blue tooth "tick" I can note if it was just before or after when my Digital second counter changed digits...in this way I can tell within 3 minutes of monitoring if my wood clock is running slow or fast. This is just for Course adjustments(1 min per revolution) the clock should run for a few days when attempting fine adjust.

[ Guests cannot view attachments ]

Good pictures! Here is my wood trick pump jack. It would be fairly easy to build compared to your clock. The sanding of the gear teeth and use of the paraffin as lube are the main points that often neglected. Here is a little video of it from my youtube channel.

That is a great looking model, also the little geared motor is a nice quiet way to enjoy it!
  When they design these as wind-up rubber band powered, there is usually a little simplified clock works Escapement , that is cool but it must "tick" very fast to provide motion, and that makes quite a clatter.
  I think if I do my "harden" the gear teeth on this one that the teeth would hold up to Stirling engine power, so the toothpick axles may be the weak link? I have found a gauge of hard music wire that closely replicates the toothpick size for stronger axles. I will likely order one soon and give it a go.
  Thanks for sharing the video!

That's a far better clock kit than all those ones that just give you a cheap quartz block.

I tend to agree! it's built from about 97% wood, it's a Mechanical clock, and if you put your heart into the build, it will Run.
  The pendulum and turning gears are mesmerizing to watch, and a Mechanical clock is about the most relaxing background noise I can think of.
  If you can get the little balloon flight special "feature" on the RH side working, than that is frosting on the cake! I have seen cuckoo clocks with special features that the clock works power, but I do not recall ever seeing a model hot air balloon rise and descend on the hour.
  I did not keep track, but estimate I have close to 20 hours into the build.

Oil Derrick Update: I found a 20% off coupon code plus free shipping, so I have one of those the way. These kits can be quite addictive to build!

I just finished a 600 piece wooden marble run and am thinking of motorizing it.
I hope to do a clock kit next and your information on the aero clock has convinced me to go for it. Thanks for all the tips!
Crazydoug

Update: All the parts are present now, I just need to decide if I want to stain all the laser cut burnt edges black to get a more even look or not?

Pendulum Update: I went all the way up to a 13 inch long balsa pendulum and got a 4 minute run time! Well the run time was nice but the action was not smooth, you could see each individual "tick" on the pump arm, the pump was basicly stopping and starting every time the Pendulum changed directions.

Photo: the complete pump jack, the Pendulum in the photo is my best performing one so far, you can see 2 Woodcock feathers taped to the Pendulum base, I get just under 2 minutes run time on this Setup, the feathers are light and small so this is longer than stock pendulum but the wind resistance seems to REALLY smooth out the action. I probably will not mess with the rubber power much more and see what I can come up with for a flywheel pulley to drive it now.

[ Guests cannot view attachments ]