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Author Topic: Paddle Steamer engine  (Read 10137 times)

ENSONIQ5

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Paddle Steamer engine
« on: April 04, 2013, 08:25:21 am »

With a lull in other projects I thought I'd re-visit a favourite subject of mine (steam engines) and a favourite 3D software (Anim8or).  The engine I'm building is a twin cylinder single expansion unit of the type often used in the paddle steamers that still navigate the Murray River in Australia.  These boats were once the main thoroughfare for produce and passengers from the coast of South Australia into the fertile interior of the Murray-Darling basin.  Although many are still running, these days they mainly serve the tourist trade.

This engine is not modelled precisely on any particular engine, rather it uses ideas and systems drawn from a number of engines of the type.  There's still much work to do on the modelling, once complete the intent is to animate it in motion, preferably in Anim8or.  Maybe one day I'll model a boat for it to go in, but that's getting a bit too far ahead of myself!
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johnar

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Re: Paddle Steamer engine
« Reply #1 on: April 04, 2013, 01:21:03 pm »

 Thats awesome.

You said it's not modelled precisely on any particular engine, but uses ideas and systems drawn from other engines of that type.  So, if its a runner, then you've actually made an 'ENSONIQ5 steam engine, and should be applying for patents as we speak.  ;)
   Beautifull piece of machinary ENSONIQ5. Awesome job so far.  I'm sure it'll look like a million dollars when its done. (hope you put an 'ENSONIQ5 badge on it somewhere  ;) )
 It'll be a gr8 thing to see it running.!

 (something RudySchneider would be proud of too.   ;)  )
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RudySchneider

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Re: Paddle Steamer engine
« Reply #2 on: April 05, 2013, 02:41:30 am »

...(something RudySchneider would be proud of too.   ;)  )

Darn right!  Looks great ENSONIQ5!  Makes me itchy to see it animated!
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ENSONIQ5

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Re: Paddle Steamer engine
« Reply #3 on: April 05, 2013, 01:07:28 pm »

Thanks guys.  Remodelled the cylinders/valves case and couldn't resist johnar's suggestion re the badge!  Couple of test renders to check the materials, the ART attributes look good but I'll probably have to wind them back for the animation for speed reasons.  Still to go are the boiler, firebox, flywheel, oilers and about a hundred feet of pipeline!

(PS: never mind the background, just a placeholder)
« Last Edit: April 05, 2013, 01:10:07 pm by ENSONIQ5 »
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Raxx

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Re: Paddle Steamer engine
« Reply #4 on: April 06, 2013, 07:15:35 am »

Excellent attention to detail as usual, ENSONIQ5, it surely reflects your passion for steam engines! Unfortunately (or perhaps fortunately), my area of expertise lies well outside of such engineering, so I'll be enjoying your progress for other reasons ;)

--also, the badge is a nice touch

Good luck with the final detailing and rendering!
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johnar

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Re: Paddle Steamer engine
« Reply #5 on: April 07, 2013, 08:32:03 am »

 Lookn good ENSONIQ5. Will be keeping an eye out for updates, and yeah, i'm "itching too see it animated" as well.
 Lookn wicked so far. ;)
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headwax

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Re: Paddle Steamer engine
« Reply #6 on: April 07, 2013, 11:35:06 pm »

hehe Great badge as well as Raxx says
nice work ensoniq5
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Blick Fang

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Re: Paddle Steamer engine
« Reply #7 on: April 08, 2013, 06:05:47 pm »

looks fantastic!!       :D
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ENSONIQ5

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Re: Paddle Steamer engine
« Reply #8 on: April 15, 2013, 12:41:43 pm »

Update: Engine mounted on boiler/firebox.
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Blick Fang

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Re: Paddle Steamer engine
« Reply #9 on: April 15, 2013, 06:10:13 pm »

One word:  Holy crap!!  Wait thats 2.  Nice Job Ensoniq5!!
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johnar

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Re: Paddle Steamer engine
« Reply #10 on: April 20, 2013, 11:59:42 am »

great to see it coming together. (awesome badge.  ;) )
  Are you really going to be able to start it up and get it running. (i'm sure you can). That will be so awesome. Would be, maybe, even awesomer if you can get a decent fire going inside the firebox as well.  :)
 hoping you still hav time to work on this machine....inspiring....
 A little off topic but... inspires me to look into robotics, hydraulics, pistons etc..
 Nice stuff ENSONIQ5   :)
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ENSONIQ5

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Re: Paddle Steamer engine
« Reply #11 on: May 04, 2013, 05:24:28 am »

The modelling isn't really finished but couldn't help jumping ahead and animating this SOB.  Totally....doing....my....head....IN!  Just setting up a short running cycle, 4 or 5 revolutions of the crankshaft, and it's really taking forever.  Some elements just have to be keyframed at every frame otherwise they want to rotate the wrong way (I know why it does this, but it's still a pain!).  And it would be great if you could hide elements in wireframe mode as well as the other modes (or is there a way and I've just forgotten....!), it's really difficult lining everything up with all the objects showing.

I was tempted to script all the motion as I've done before but there are two things that bother me with this.  It is very difficult to script the motion of a conrod accurately, it isn't just a sine-wave reciprocal with a lateral motion in a single axis, the wave is slightly skewed ('egg shaped' is the best analogy).  This basically means that the big ends don't track the crankshaft correctly (though this could possibly be countered in the script...something to think about...)

The main reason I am avoiding scripts is that there is no way to pass variables from one frame to the next, making it EXTREMELY difficult to animate acceleration and deceleration.  If I can figure out a way to do this I may create a second scene with scripted motion instead (see, THAT's why I love Anim8or!).  Hopefully will have something to show soon...
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Blick Fang

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Re: Paddle Steamer engine
« Reply #12 on: May 04, 2013, 07:00:32 am »

where's the like button?  ;)
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Raxx

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Re: Paddle Steamer engine
« Reply #13 on: May 04, 2013, 07:16:28 am »

Hey ENSONIQ5, not sure why you're having issues hiding elements in wireframe mode, if you select an element in the scene and press 'h' or go to Edit->Hide, it works as expected.

As for your second dilemma, I can't really tell what's supposed to be going on at the other end of the conrod, so not sure. But there's always the trick of parenting the rod to one end that's moving or rotating, and then set it to face the other end piece, and so long as the two ends' motions are accurate then it'll look like it's working correctly.

For acceleration/deceleration, you'd have to use if statements based on what frame it is supposed to start accelerating/decelerating, to set the acceleration/deceleration multiplier based on either the frame or time squared or to-whatever-power, minus the number of frames or time that has already elapsed at the start of the acceleration/deceleration.
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ENSONIQ5

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Re: Paddle Steamer engine
« Reply #14 on: May 04, 2013, 09:22:56 am »

The reason I was having trouble hiding the elements was that it been so long since I've animated in Anim8or that I forgot you could.  I was using visibility.  *slaps forehead*  Thanks Raxx!

I am using a lot of parent/child relationships but they can only go so far.  Taking the near-side valve gear as an example, the upper valve drive rod is a child of the crankshaft, so it pivots smoothly around the eccentric on the shaft.  I could then have the gear 'slider' as a child of the upper valve rod, and the lower valve rod as a child of the gear 'slider', but then the lower valve rod has to pivot smoothly around the other eccentric on the crank shaft.  It's a "closed system" rather than a hierarchy, so at some stage manual tweaking to line things up is inevitable.  I realise the above probably doesn't make any sense...

The gear mechanism's motion is so darned complex, the mechanical design causes some elements to move in very unusual patterns.

Regarding scripting acceleration, the problem occurs when using Frame or Time as an 'input' into a motion script, the output being the angular position of the element.  Even using IF statements to govern the speed of rotation, as the motion is not cumulative there is no way for the system to calculate the angular position the element would be at if it had changed speeds over previous frames.  For example, lets say an element decelerates from 100 RPM to 20 RPM from frame 500 to frame 600 by using IF statements in the script.  At frame 600, the script will set the 'speed' to 20 RPM, and hence calculate the angular position of the element accordingly, but as it is not cumulative the actual position of the element will be set as if it had rotated at 20 RPM for all previous 599 frames.  In a nutshell, the script defines the angular position of the shaft, not the speed, and there's the problem.

Previously I have used invisible objects as a kind of variable, in one instance I had all the scripts get the scale of an invisible sphere as a multiplication factor, which was great at keeping all the elements in time and I could change the speed by enlarging or shrinking the sphere, but the same acceleration/deceleration issue occurred if I tried to animate the sphere's scale.  When decelerating, the rotating elements actually ran backwards, which makes sense when considering the above paragraph but was dang irritating.  I even attempted to use invisible objects as running variables, having the script change an attribute of the object at the end of the calculation (ie. 'speed'), then picking it up at the start of the script for the next frame, but Anim8or wasn't having any of that and delivered a 'circular script' warning.

As I type this I'm thinking there might be a kind of 'best of both worlds' solution here.  If a single element's motion was keyframed to include accel/decel events, for example the crankshaft, then every other moving element could use a script to pick up the crankshaft's angular position and use it to define its own angle or position.  There'll be a lot of trial and error to get the factors right but it would be preferable to keyframing the whole thing by a long shot.  My scripting is rusty as hell but I'm sure a bit of WD40 will get the gears moving again!
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