Double pendulums

[Calloway]

The outside stiff shaft pendulum weights are heavier than the inside string pendulum weights.
The outside stiff shaft pendulums have a hook mounted on each one. At 12 o'clock in a cw rotation,
the hook grabs the inner pendulum string and holds it until it reaches the 6 o'clock position in which it is then released. The hooks are mounted facing outward so that this will happen.

The objective here is to transfer some of the inner pendulum weight to the outer pendulum weight and then release it at 6 o'clock.

Maybe this design will interest some of you guys. If not, maybe it could be used in other builds.

Please excuse the poor drawing, but maybe it's enough to understand my thought.

[daxwc]

Interesting drawing callaway, although it doesn’t look like it if the outside weights are a lot heavier than the inside weights then the light ones are actually being raised in the top right-side quarter. Either way as the masses get closer to the same weight the more they will just average their masses on the board. I don’t believe the swinging will add anything as I doubt there will be much movement. It does bring up an interesting question about lifting on the fall. It should be easy for you to SIM if you want to see the real dynamics.

[Calloway]

Hello daxwc, Well I thought about just rigging up a couple of them at 180 degrees apart and see what happens. It may drag the outside pendulum weight in too far and balance out the whole wheel. When I get some time I think it's worth trying imo.

Cheers

[Tarsier79]

Good call. That is what I do when I have a design that needs testing.

[Calloway]

Well I tried and it doesn't work for me. The stiff outside pendulum tries to lift the string pendulum as it turns. Not enough weight transfer to overcome this. On to something else I suppose.

[Fletcher]

Calloway can I ask where you got the clear acetate sheet from ? What was its trade name ? And was it easy to cut and drill, and generally work with ? Sheet sizes and thicknesses ? Can you see pencil lines on it etc, or what do you use for marking out ? Any problems with it over and above wood ?

I make my stuff out of mdf these days but for table top models and even mock-ups the clear sides would be a bonus to easily see the workings for a closed in two-sided version. If it is easy to find and easy to work with that is !

ETA : I was reading over at JC's blog his problems with fine detail with age getting in the way. I know myself my eye sight for close up small scale work is not what it used to be in my 40's (B. was 32 when he produced his first working wheel). I need the reading glasses and blazing LED lights and even use a forehead reading lamp as well to work in millimeters. Of course if I didn't build table top models working fine detail wouldn't be so critical or necessary.

[Calloway]

Hello Fletcher, I just call it plexiglass is the way it's sold here. They cut mine out into a 36" wheel with a center hole also. Mine is 1/2" thick. It is very easy to drill, saw and work with. However a hand drill will tend to "walk" some for precise drilling. So a drlll press is needed at times to prevent that. I use sharpie magic markers for making segment lines as lead pencils will not leave good markings. Like you mentioned, I like being able to see thru the wheel. Mine has been used many times for different design tries. I wouldn't hesitate to use it again over wood. Plexiglass is strong and holds its shape very well. It's worth the investment of 100.00 dollars in my opinion.

Cheers

[Fletcher]

Thanks for that Calloway. I couldn't for the life of me remember the name plexiglass, tho that's what we called it when I was a kid. I'll look into it at the local hardware chains. Getting it pre-cut into a circular shape with center ID would be a bonus, so I'd have to find somewhere to machine it if I don't do it myself.

I do have a drill press I purchased 2 decades ago and it's been to Fiji and back with me. Wouldn't do without it, for accuracy as you note. The only problem is when I want to drill a near to center hole on a radius larger than the clearance the drill has (can't get near the center). Then I revert to a hand scribe (sharp - like a braddle, or I sharpen a nail on my grinder using the battery drill) to make a small indent. Then carefully press down with a center punch before drilling in successive sizes to the ID I want. This stops as much wandering as possible fwiw.

If I'm making 8 parts for example I generally make 10. With all the care in the world 1 or 2 will still wander just because the wood density changed while I was drilling etc, or I got careless in my hurry.

Nothing is that super critical tho. Wheels have to turn from sustained imbalance imo, so complete accuracy tho a nice aesthetic, shouldn't ultimately be a show stopper to a design working (within reasonable tolerances).

[Robinhood46]

I use my router for cutting my wheels, take the plastic/nylon plate off the base and screw a length of plywood to it with a bearing at the desired distance for the radius of your wheel. The precision is more than enough, unless you want a wheel of 6 metres in diameter.
It is easier to make a perfect circle around a drilled hole than drill a hole perfectly in the middle of a 4 foot circle.

[Fletcher]

Good advice RH .. I'll have to get a Router lol.

[Tarsier79]

I have done the same with both a power saw mounted upside down and a jig saw.

[veproject1]

Calloway, I could make a "working" model just to show how it should work in your mind.

[agor95]

It woud be interesting to see Calloway's first device "working" as he imagined. https://www.besslerwheel.com/forum/down ... p?id=20221

[Calloway]

Veproject1, Sir I'm game. Show me how.

[Calloway]

Agor95, You and me both Agor. But the back drag is a killer as I see it. I spent several dollars trying to get it to work. But maybe I missed something and someone else can work with the idea.

Cheers