Double pendulums

[Calloway]

Fletcher, Some of the glass dealers handle plexiglass and can cut a wheel for you. I meant to comment on your eyes as I have the same problem here. I'm up to 2.75 in reader glasses myself and still need a magnifying glass at times for delicate measuring. My "check engine light " has come on and I need some prostate surgery done. A rotor rooter job of sorts. I would luv to be able to learn how to sim like you, wubbley and others do. But my ram and harddrive has weakened considerably. It would save alot of time and money compared to building a design. So I do what I have to do.

Cheers

[ME]

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

https://youtu.be/B3CsOx5U9Gs?t=60

[Fletcher]

Thanks Calloway for the advice about glass dealers. And all the best on your health. I learned a sim program because of the increasing frustrations of slow turnover of ideas, with too little time for my hobby. So something had to change if I were to ever cover enough ground and actually learn something from the process and not forget it because of too much time elapsed. I was very pleased I took the plunge but I understand it's not for everyone.

ME .. a little overkill for what I had in mind :7) Tho there are times I could do with a precision mill for sure. Fortunately Engineering Shops and Sign Writers (most people don't think of them - my brother was a sign writer) often have the kit to computer design and water jet cut, mill etc etc.

Maybe I'll start with just an electric hand router and have a play !

[Robinhood46]

I was very pleased I took the plunge but I understand it's not for everyone.

Fletcher,
Six months ago i didn't think there was a lot to be gained using sims. My thoughts were that the benefits of real builds outweighed the time saved.
I now agree totally that sims are a godsend for the PM seeking community. When we imagine how a mechanism should/would/could/might function, this is all well and good. More often than not the mechanism itself actually functions how we thought (maybe not exactly, but not far off). The problem isn't that we were expecting a miracle at this level, the problem is the accumulation of all the forces of every aspect of each mechanism that doesn't quit happen where we were expecting it.

A good sim or a crappy animation allows us to visualise where and when everything is, or at least probably would be, occurring. This is more often than not plenty enough to see clearly that what we thought would be happening as a whole and what is really going to happen are two different ballgames.
A few hours on a computer or a few days/weeks/months on a real build give us the exact same information; the mechanism itself does pretty much what we thought it would, but it will not be a runner, because we hadn't anticipated this or that aspect of the whole thing collectively.

I use the word "we" because i see this to be the case in many members attempts and i know for sure that it is often my problem with my own builds. Anyone who wishes to think this is never their problem, please feel free to do so.

I took to animation because of the lockdown, i was unable to get the material needed to continue my project, and i was unable to express my thoughts without images.
I too am very pleased i took the plunge, even if it was in the shallow end, with a toytown simulator.

[ME]

The problem isn't that we were expecting a miracle at this level, the problem is the accumulation of all the forces of every aspect of each mechanism that doesn't quit happen where we were expecting it.

The miracle is often implied when a force should operate twice... but somehow only does it once.
For example, thinking that many mechanisms combine are able to lift a single other overlooks the fact that this one mechanism is now responsible for lifting all the others.

[johannesbender]

I was very pleased I took the plunge but I understand it's not for everyone.

Fletcher,
Six months ago i didn't think there was a lot to be gained using sims. My thoughts were that the benefits of real builds outweighed the time saved.
I now agree totally that sims are a godsend for the PM seeking community. When we imagine how a mechanism should/would/could/might function, this is all well and good. More often than not the mechanism itself actually functions how we thought (maybe not exactly, but not far off). The problem isn't that we were expecting a miracle at this level, the problem is the accumulation of all the forces of every aspect of each mechanism that doesn't quit happen where we were expecting it.

A good sim or a crappy animation allows us to visualise where and when everything is, or at least probably would be, occurring. This is more often than not plenty enough to see clearly that what we thought would be happening as a whole and what is really going to happen are two different ballgames.
A few hours on a computer or a few days/weeks/months on a real build give us the exact same information; the mechanism itself does pretty much what we thought it would, but it will not be a runner, because we hadn't anticipated this or that aspect of the whole thing collectively.

I use the word "we" because i see this to be the case in many members attempts and i know for sure that it is often my problem with my own builds. Anyone who wishes to think this is never their problem, please feel free to do so.

I took to animation because of the lockdown, i was unable to get the material needed to continue my project, and i was unable to express my thoughts without images.
I too am very pleased i took the plunge, even if it was in the shallow end, with a toytown simulator.

there is always that unforseen "gotcha" moment , when you think you solve one aspect in mental capacity , another "gotcha" pops up in reality and you end up adjusting your thoughts for a new idea by compensating the new information , merely the facts about how things are related to eachother in the physics world , some sort of trade off is always going to happen.

coming to the realisation of that unforseen event , just happens faster with the help of technology , whereas with builds it takes quite some time effort and money before it happens.

builds have theire upsides too though , you can lay an idea to rest or proof it with letting nature take its course , without caring about the underlying math you would need on more complicated sims and whether you simmed it correct or not, reality will however show you straight up yai or nay.

[Georg Künstler]

Hi Calloway,
the problem with this type of construction is that the carrier and the pendulum weights are representing one system.

To get OU you need at least 2 systems which can interact.
If you have 2 systems, one can accelerate the other, or they can slow down.
The typical way which is shown are two pendulums, one acting against the other.
Sometimes with a spring in between.
All this examples are leading to a dampened oscillation.

What we need is an undamped oscillation.
I will prepare some pictures so that you can see what I mean.
It requires a system under stress from gravity.
Or with other words, gravity preloads the system.
One weight is arranging the other.

A little push on the pendulum weight and the oscillation will begun.

[Calloway]

Georg, I suspect you are correct. It worked flawlessly in my mind. But the real deal failed miserably. On to something else.

Cheers

[Fletcher]

This was my experience fwiw .. in the early days I used to just do real world builds. I would draw things out on graph paper and work out turning moments etc. The static analysis. I very quickly built myself a white board and bought some erasable colour markers. Soon there were arrows going this way and that, and lots of numbers. Now I could draw up more than one iteration of a concept side by side at a much larger scale than A4 or A3 paper. And rub things out and change things then and there, as you do.

I already had a pretty good knowledge of Classical Physics, access to the internet and some text books on the Physics of Mechanics etc. But just because I knew some formulas and how they were derived I did not always appreciate the nuances when things were in motion. The dynamic analysis. I had to compartmentalize the Conservation Laws and my education to let my imagination wander off the trodden path.

So I'd draw things up, looking for a workaround or cheat of mechanics. Usually within a day or two, or maybe even just in hours, I'd find the fallacy of the argument. The highs and lows we all experience.

I got better and better at anticipating what a device would do in the real world, from just my imagination and the white board. I'd build an experiment to confirm that my imagination wasn't playing tricks on me too often. Most of the time I could work out about 95 to 100% of how something should work dynamically. In a few cases I just couldn't in my mind get past 95% (my hydrostatic wheel and aerodynamic wheels as examples). So I'd decide to build it in real world and learn the other 5%. More highs and lows, as we know so well.

That's when I concluded I needed to cover more ground, more quickly. It was taking a long time to learn 5%. Law of Diminishing Returns. So I got introduced to dynamic sim programs, and started learning them. I quickly got to grips with one in particular and could see the immediate benefits in being able to explore an experiment or full concept within hours instead of weeks and months.

Interestingly, my anticipation success improved to 97-98% (imo) using the sim, and as my sim skills improved. Before I'd even built the next sim ! Ironically I started building less and less experiments and sim builds. There were fewer and fewer rocks worth turning over it seemed. But every now and then some thought or concept (usually while power napping or upon waking in the morning) would pique my interest and I'd knock it out to compare to how I thought it'd behave. I'd learn something, so nothing was ever a failure.

All the while I read everybody else's topics and threads. And contributed or commented on their discussions and concepts where I could add something, and perhaps give myself an opportunity to be surprised and learn something today. I know others do too.

I think many people miss out on that opportunity to grow their knowledge base and experience, either by using sims, or discussing others ideas in threads not their own. So I highly recommend both.

Anyhoo, once the sim genie was out of the bottle, and I was using my free time to pursue this hobby way more effectively, I found the experience more satisfying, and the fun factor came back into the quest for me, in spades.

[johannesbender]

Ironically I started building less and less experiments and sim builds. There were fewer and fewer rocks worth turning over it seemed. But every now and then some thought or concept (usually while power napping or upon waking in the morning) would pique my interest and I'd knock it out to compare to how I thought it'd behave. I'd learn something so nothing was ever a failure

The pathway becomes more incapacious , as we go along learning, i find this to be very true in my experience , it seems more and more plausable to me that , there are perhaps one single way only to reach the goal , but when and if possibly reached , you could perhaps branch out on the concept from there onwards.

[Fletcher]

I think you are right jb.

[veproject1]

I game too. It's easy, just check out my posts. 100% "working" garanty

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