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jeric_synergy
10-03-2015, 07:20 PM
I've made Spirograph®-like rigs to whirl a point around and then use that point as an extrusion path, but the rigs are only Spirograph®-like. The are missing some essential element that the rig is not capturing, possibly some sort of cam-like constraining, or something to do with the gear ratios.

Anyone got any suggestions? I attach a scene to get the juices flowing.
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jeric_synergy
10-03-2015, 09:04 PM
This may help conceptualize a LW rig: http://nathanfriend.io/inspirograph/

lertola2
10-03-2015, 10:26 PM
A spirograph is basically a sine wave bent into a circle. You can plot a sine wave with the plot2d command. And then you can get various designs by using the bend tool to bend it at different locations. I imagine you can go way beyond what a real spirograph can do by plotting more complicated shapes and bending those.

http://forums.newtek.com/attachment.php?attachmentid=130158&d=1443932528

jeric_synergy
10-03-2015, 10:37 PM
Managed to crash Modeler first thing out of the gate with Plot2d..... Zmax&min=0 does not play...

Any idea why the default equation is whatever the hell it is???

EDIT: g*****mn, that's one stupidly designed interface. WTF?

EDIT2: no RESET button. Niiiiiiiiiiiiiiiiiiiiiiiiiice. And the default for PLOT1D? Well, see for yourself.

jeric_synergy
10-04-2015, 12:03 AM
So, Lertola: how many degrees did you need to bend the white sample above, around? It looks like many many times.

lertola2
10-04-2015, 07:46 AM
I made a sine wave with plot2d about 90 meters wide (sin x). I used the curve option and then deleted all the curves except the one at the top of the plotted shape. The plot2d edit fields should be labeled Xmin, Xmax, Xmesh, Ymin, Ymax, Ymesh from top to bottom. The X, Y, and Z labels are very confusing and wrong. Also the dialogue does not remember the Xmesh or Ymesh values. I probably bent the curve like 7200 degrees or more to get the curve to wrap around multiple times.

http://forums.newtek.com/attachment.php?attachmentid=130159&d=1443965965

jeric_synergy
10-04-2015, 09:20 AM
It may have slipped off the menus, but look for Plot1D, perfect for this job. Same stupid stupid UI (what, couldn't move a g.d. LABEL properly???) but saves a step.

Coulda used some interesting sample equations in the dox, or better, as presets, but noooooooooooooooooooo. :devil:

JoePoe
10-04-2015, 09:36 AM
Cool. :heart:

I did one in 3D.
Gonna push it some more when I get a chance....

One continuous loop :).
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jeric_synergy
10-04-2015, 10:01 AM
JoePoe,

I did one in 3D.
Workflow?

+++++++

A spirograph is basically a sine wave bent into a circle.
Lertola, not all the pieces in a Spirograph® kit are circular. Of interest is the "Rack" and the "Bar", but mostly the Rack.
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JoePoe
10-04-2015, 10:19 AM
Super simple. I figured a sine wave looked basically like a spiral as seen from the side. So I just bent a spiral around in a multiple of 360° (in this case 3).
(The ends coming together were one segment short so I added that by hand. It's a tiny bit funky at that junction.... will have to investigate closer.)

Edit: and yes, the Spirograph shapes can get much MUCH funkier!! That's what I meant by pushing it above :hey:.

jeric_synergy
10-04-2015, 10:33 AM
Super simple. I figured a sine wave looked basically like a spiral as seen from the side. So I just bent a spiral around an odd multiple of 360° (in this case 3).
OH! that's all one piece? I thought it was duplicates w/an offset.


Edit: and yes, the Spirograph shapes can get much MUCH funkier!! That's what I meant by pushing it above :hey:.

It seems like perhaps the MOTORS in Bullet would maybe help in this endeavor...

JoePoe
10-04-2015, 12:55 PM
Interesting. On a more complicated shape (when using some spacing needed to keep overlapping from occurring in 3D) the object starts looking more like a jumble.
Some of the 2D beauty is lost.
At least that's my first impression.

Gonna continue on.

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Jeric, not sure what you mean by using Bullet for this. How?

Slartibartfast
10-04-2015, 01:07 PM
Interesting. When using some spacing needed to keep overlapping from occurring in 3D, the object starts looking more like a jumble.
Some of the 2D beauty is lost.
At least that's my first impression.

Gonna continue on.

130165

Jeric, not sure what you mean by using Bullet for this. How?

I guess he means to model the gears and stuff and simulate the real thing with bullet. Actually, it sounds tempting to make a try :-)

JoePoe
10-04-2015, 01:19 PM
I guess he means to model the gears and stuff and simulate the real thing with bullet. Actually, it sounds tempting to make a try :-)

Ohhhh! :foreheads. That would be interesting.
Guess I've been barking up the wrong tree the whole time. To be honest, I think I just got all excited at the word Spirograph, and jumped right in :).

On re-reading (actually think it's my first time) the OP, the end desire was to get a path for extrusion purposes, so I wasn't too far off.

Still gonna have an overlap problem.... unless, maybe, you oscillate the whole gear rig in space as it's doing it's "spiro" thing.. hmmm :stumped:.

jeric_synergy
10-04-2015, 01:20 PM
I guess he means to model the gears and stuff and simulate the real thing with bullet. Actually, it sounds tempting to make a try :-)
Bingo.

Of course, {teenager mode} I guessssss you could get {tm=off}the same effect of gear ratios using Expressions, but what fun is that?

For more elaborate 'tracks' than the rings, Bullet might actually be EASIER than Expressions. Imagine the 'rack', but with a wave in it-- that's some James Clark Maxwell level math. (JCM as a teenager wrote on 'rolling functions', where one shape rolled over another. --Stone. Genius.)

For THIS posting, a 2d pattern was all that was required. But I made another post where the 3d helix for a spring was the goal. LWM is kinda weak on those.