Abstract Chat about 3D Modeling Techniques With Strong Feelings and Emotions

[CI]

My First Steam Engine 3D Model:

This was probably the first engine I created a 3D model for, and it was a barstock engine my dad built.
This was a good beginner's training exercise.
I recall at the time that this was a difficult model, but now I could make it in minutes.

I can post the screencaps for the 3D model creation for this engine if anyone wants to see them, but keep in mind that this was the first engine I modeled, and I really had very little idea of how to do this, so looking back at these screencaps, I think "what the heck was I thinking, there is a much easier way to do that".

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[CI]

Here are the 2D drawings for the above engine, if anyone wants to try to create a 3D model from them.

When I get the 3D assembly done, I like to create assembled views fo the top and sides, plus an isometric, which makes it easy to visualize how the parts fit together.



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[CI]

Motion Studies:

Solidworks will run motiion studies.
You can import an assembly into motion study, apply a motion to the shaft (either rotating, linear, etc), and if you have a correct design, the engine will run in animation.
This is really handy when designing steam engines, since you can make the steam chest transparent, and verify if you have the correct valve travel over the port openings.
For internal combustion engine designs, you can verify piston travel, valve travel, cam movement, etc.

I ran this motion study during the green twin build, and discovered that it is a really bad idea to create the entire assembly before running the study.
Solidworks is extremely picky about running assemblies in motion study, and if there is the slightest problem the simulation does not run.
I learned to join two pieces together into an assembly, test that in the motion study, then add one additional part at a time, testing in the motion study after each addition.
If the motion study stops working after the addition of a part, that part does not fit correctly, and needs to be redesigned.

I had conversations with several magazine editors about publishing this engine, and they all said "We need to see a running engine before we can talk about publishing".
I told them "I can guarantee that the engine will run, because it runs in motion study".
Not one of them believed me, so I thought perhaps they knew something I did not know.

I built the engine, it did run just like the motion study, and I was right about if it ran in Solidworks motion study, it would run in real life.

Motion study is another of the surprisingly powerful features of 3D modeling.


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[CI]

The green twin oscillator 3D model started out as a casual conversation with our member "woodguy", who showed me three photos of an engine in England.
He had started a 3D model for the engine, but had decided to not continue with it.

I literally started the green twin 3D model just as an exercise to become more proficient at 3D modeling.
I really had no hopes of ever finishing this design, because I was not very good at 3D modeling at the time, and had never built a complete model engine.

I 3D modeled one part, then another, and things started snowballing, and we started dreaming, and so we just kept on going, then we started 3D printing patterns, then made castings, and well; the rest is history.
It all started on a whim as a 3D modeling learning exercise just like this one.

It just goes to show that one should never underestimate what one's potential may be, regardless of whether you have ever done 3D modeling, or model engine building.
This was my first (and only, so far) engine build, and one of my early 3D designs.
Every 3D model for this engine was derived from three photos of the original engine.

The last photo is the original engine from England.

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[CI]

This is my 2nd attempt at building a model engine.
It will be a 1/2 scale 4hp Baker Ball Hopper Monitor.

This engine was developed from photos sent to me by someone who owns one, and also developed from some material that was in an original Baker catalog from the early 1900's.

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[Jasonb]

Don't get so excited about motion study. I know of others who also use solidworks and put out drawings. They have been known to fudge details so the model "works" in a motion study but in real life having pivot pins running in oversize holes is not good practice and will make your engine knock.

A motion study will not tell you if you have the ports and passages are the right size so the engine can breath and reach the speeds hoped for or whether it will be restricted. Or if the spring holding the cylinder to the port face is the right stength to stop the cylinder lifting due to the applied steam/air pressure.

The motion study only confirms the geometry is correct and it all turns over without any clashes. Not that something will actually run.

[CI]

Motion study is just another tool in the toolbox.
Just like 3D modeling, or importing sketches are tools.

What tools to use, and how to use them is up to the individual, because it varies with what your background is, what you want to do, and how you want to do it.
There is no "one size fits all" 3D modeling method.

Some people seem to get hung up on things that are irrelevant to the actual model being created, and the focus gets shifted away from what is being created, and shifted to how others feel you should be creating it.
Do you own thing for your own reasons; you are not a sheep; you don't have to do exactly what everyone else is doing.

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[CI]

One should think of 3D modeling as a machine tool, like a lathe or mill.
Nobody uses a single tool for the lathe or mill, to the exclusion of all other tools.
Instead most have an array of interchangeable tools and bits one can select and use.
Some folks have attachments that can be used on both the lathe and mill.
Nobody ever gives a second thought to the diversity of how machine tools and tool bits are use.
Nobody would ever suggest using a single tool only on the lathe or mill.

On the other hand, with 3D modeling, there is ONLY one way....................and you must NEVER question "THE WAY".
Its like a parody out of a Monty Python movie.
Monty Python and "THE HOLY 3D MODELING METHOD".
If you suggest another method, you get the "NONE SHALL PASS" treatment.
We have some self-appointed gatekeepers of 3D modeling philosophy, but the reality is that there is a great big 3D modeling world outside the bubble here.

With 3D modeling you have a wide range of options and methods.
Your tools; your choice as to which ones you use, and how you use them.
Use the tools that work best for you, and achieve your goals and objectives.
Don't get roped into monochromatic thought, because you are just limiting your tool set, and limiting the possibilities of what you may be able to achieve.

In the beginning, there was a resistance by some to 3D modeling for model engine building.
Comments were posted on this forum such as "Its just a pretty picture, but not of much use for anything".
Some non-believers have become believers.

Times have changed; methods are still changing.
More people are learning and using 3D modeling these days, and it will only become more prevalent in this hobby, and in the greater world.
There are a multitude of uses for 3D modeling and 3D printing, and a multitude of different ways to use both.
I would recommend keeping an open mind, and ignoring the naysayers.
Be open to suggestions, but don't let anyone micromanage your 3D modeling for you.

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[Jasonb]

But you do need to know what the too actually does and what it is telling you.

As I said a motion study will only confirm that all rotates as you intended without clashing.

If you have mis calculated the timing or worked out the wrong compression ratio, drawn too small a flywheel to carry the engine over TDC, etc the motion study will still work but the engine may not.

You should NOT take a working motion study are proof that an engine will run.

[petertha]

Motion Studies:

Solidworks will run motiion studies. You can import an assembly into motion study, apply a motion to the shaft (either rotating, linear, etc), and if you have a correct design, the engine will run in animation.

I had conversations with several magazine editors about publishing this engine, and they all said "We need to see a running engine before we can talk about publishing".
I told them "I can guarantee that the engine will run, because it runs in motion study".
Not one of them believed me, so I thought perhaps they knew something I did not know.

I built the engine, it did run just like the motion study, and I was right about if it ran in Solidworks motion study, it would run in real life. Motion study is another of the surprisingly powerful features of 3D modeling.

You are using specific SW terms somewhat interchangeably. Animation is essentially physics-blind. It treats your components as hollow mathematical shells rather than solid physical objects. If you rotate your crankshaft 360-deg & a steel plate in the way, the part will simply ghost right through that plate during the animation. It does not care about physical reality, it only cares about satisfying the mates instructions you provided. SW-Basic motion includes specific (but still limited) tools like collision detection which can be selectively turned on within parts assemblies and/or specific parts within assemblies ignoring others. Maybe that is what you were fiddling with? Anyway it doesn't necessarily stop an animation as a diagnostic tool. But maybe that implementation has varied over the years & specific to your install?

Motion Analysis solver is not included in the SW-Standard or SW-Professional bundles, its treated as a Premium add-in ($$$) like simulation. At least its been that way for many years. And just to clarify, this is SW specific, other 3D CAD apps vary dramatcally in their capabilities despite being 3D.

[CI]

I was surprised to get motion study in the basic Soldworks package.
It is a very basic motion package, but very useful.

It is more than just collision detection.
If you connect two parts, say a rod onto a shaft, and the diameters are not exact, the part will not rotate on the shaft, and generally this locks up any motion of the model.
This is a great troubleshooting tool.

I don't know about IC engines, I have yet to build one, but if you use a motion study for a steam engine, and change the cylinder and steam chest translucent, and verify piston and valve travel, chances are the engine will run as designed.
There is alway that individual who can snatch defeat from the jaws of victory, but gererally speaking, if the engine runs in animation, you have parts that fit exactly, not approximately, and the chances of the engine operating correctly are very high.

Solidworks does not have rendering, but does have motion study, in the base package.
I like rendering a lot, but if given a choice, the motion study is a more useful functional tool.
Rendering is a fantastic visual tool.

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[Jasonb]

I don't know about IC engines, I have yet to build one, but if you use a motion study for a steam engine, and change the cylinder and steam chest translucent, and verify piston and valve travel, chances are the engine will run as designed.
There is alway that individual who can snatch defeat from the jaws of victory, but gererally speaking, if the engine runs in animation, you have parts that fit exactly, not approximately, and the chances of the engine operating correctly are very high.

This is where you are getting it wrong. The engine will only run if the parts you have designed are correct eg sizes, valve timing, etc. They will still move and the ports open and close as you watch them but that does not verify if your basic design is correct.

Take that green twin if say instead of the pie slice ports you designed based on good research you  had just drawn 1/64" holes they would if positioned correctly still open and close as the engine was rotated on the screen but how well would the engine run if restricted by such small openings? But it will show you if a piston is going to hit the end of the cylinder or a conrod hits a trunk guide, etc.

Or take the current Seal thread. The cams as drawn will all rotate and move the tappets but for optimal running a larger tapet dia would be better. The motion study does not know about a point contact not being ideal.

Alibre will not stop the engine rotating if that piston hits the cylinder you have to look for it while moving the flywheel with the mouse. But it will stop if say a linkage  has the wrong lengths and the parts can't physically move. It also has an "interferances" option which will show things like your oversize rod in too small a hole. But won't lock the engine simulation up which is just as well if you are using press fits for some parts.

[petertha]

I was surprised to get motion study in the basic Soldworks package. It is a very basic motion package, but very useful.
It is more than just collision detection. If you connect two parts, say a rod onto a shaft, and the diameters are not exact, the part will not rotate on the shaft, and generally this locks up any motion of the model.
This is a great troubleshooting tool.

It should not have been all that surprising because its very well specified in SW documentation. Basic Motion is included in Basic SW. Collision detection is part of Basic Motion, one of a handful of useful sub-set tools. Motion Analysis is a much heavier add-in to Premium. Motion Analysis is the term you used & somewhat interchangeably with Animation & without mentioning Basic. I think SW-Premium is about a 4K$ addition to SW-Basic which costs about the same as a single license seat, neglecting maintenance fees. Kind of deep pockets territory for most mortals. SW-Maker is about 50$/yr which is SW-Basic under the hood, unfortunately have to navigate the 3DE minefield to get it. I think you mentioned you have some special lifetime deal personally which is awesome, but that doesn't do anyone else any good.

Your rod & shaft example (if I understand correctly) only pertains to mates constraints, which as mentioned, get passed on to both Animation & Motion.

[CI]

Alibre will not stop the engine rotating if that piston hits the cylinder you have to look for it while moving the flywheel with the mouse. But it will stop if say a linkage  has the wrong lengths and the parts can't physically move. It also has an "interferances" option which will show things like your oversize rod in too small a hole. But won't lock the engine simulation up which is just as well if you are using press fits for some parts.

I found out that SW will lock up the motion if any mating parts are not exact after I made a complete green twin assembly.
I had to go back and start over again, and connect one part at a time, verifying the motion of each part.

A motion study won't overcome a poor design, but it is a very helpful tool.
And you get to see the engine run before you even start machining.

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[Jasonb]

A motion study won't overcome a poor design, but it is a very helpful tool.
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My point exactly but not what you were saying originally.