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And one more on the to do list from you. I am really impressed by the speed and really want to see it going in front of me.

Once again many thanks for sharing the instructions!

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Impressive! And another MOC on my to-do list. Keep on working on further interesting creations.

Greetings

Alex

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On 11/5/2016 at 6:40 AM, nico71 said:

And new creation !

This reminds me a lot of my own braiding machine that I created last year (link), but it looks like yours works more reliably at faster speeds. Nice work  :thumbup:

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Hello, a new creation ! First attempt to create a working shooting mechanism, I will improve it for the next version (magazine and power)

IMG_5113

 

:)

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Nice mechanism.  It has much in common with the bolt action carbine from the "Lego Heavy Weapons" book.

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On 2016-12-10 at 3:56 AM, nico71 said:

Hello, a new creation ! First attempt to create a working shooting mechanism, I will improve it for the next version (magazine and power)

 

What haven't you built Nico?! Very clever design. Looking forward to the next crossbow 2.0.

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New creations for christmas !

A lego interpretation of a 3 pendulums harmonograph drawing machine.

IMG_5138

Drawing machine always fascinated me, especially when they are fully mechanical. For instance a Spirograph is a mechanical drawing harmonograph, it simply not uses the same basic functioning to draw. The purpose of the harmonograph here is to draw Lissajous curves thanks to 3 pendulum connected to arm and felt pen. The basic functioning is :

  • The main pendulum is a free ball joint articulated on the frame and hold up the drawing sheet
  • The two other pendulums are simple way articulated which are connected together to the red arm
  • This arms is built in 90° angle shape in order that it can move in one direction thanks to the first pendulum, and in other (90° of the previous one) thanks to the second pendulum
  • A felt pen is attached to the red arm and draw on the drawing sheet

IMG_5152

To draw something, it needs only to launch one or two or three pendulum, therefore the system moves and draw something, especially geometric and continuous figures. Of course the result is always different depends of if you starts to move the main pendulum (give the main circular motion) and/or the two other (give the direction of circular motion and its evolution in time). And there are plenty of different harmonograph with more or less pendulum or connected pendulum or arms and so on. Here is the basic version of best known harmonograph.

IMG_5146

Note that the main red arm is equipped with counter weight at these ends in order to have the less friction of the felt pen of the drawing machine. That is why I use also a felt pen because of its low needed force to draw. Thanks to that, The felt pen is maintained in upper position and when the arm is push down, the felt pen maintains its low position with low friction. Nevertheless, the friction is still here and the weight of pendulum not as heavy as the real harmonograph (made in steel), so well that the main pendulum slowly tends to apply circular motion to the other pendulum which reduce the autonomy and drawing time  (around 1 or 2 minutes).

IMG_5148

You can also see that I keep the idea of knife edge suspension for the pendulum from my Galileo clock. It enables to have very low friction and better Q factor on the pendulum (pendulum oscillate a long time). The main pendulum is built with two of this system in order to create a real ball joint articulation. You can note that the weight of main pendulum tend to taken apart one of the knife edge solution, need to improve it with technic brick instead of liftarm (which is of course better for rigidity but bad for compactness).

IMG_5141

To conclude, I am pretty happy to have made this piece of mechanical engineering, there are several important point to succeed to get that, regarding the weight of pendulum, rigidity of frame, main arm and pendulum (all parasite vibration will reduce the efficiency) and of course lot of test to understand which movements in the pendulum make final drawing. It is still always different and sometime unexpected ! See the gallery to watch it.

IMG_5182

:)

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Ooh, thats so nice! I wonder if one can work out the math beyond these curves? Looks very complex though... two planar and one spherical oscillators, very interesting. 

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Very nice.. I remember playing with one of these (non lego!) in a Kids Science Museum, a few years ago.. was lots of fun to play with!

 

on a side note, I recently built your ball pump GBC, and will be using it on our layout at Brickvention, in Melbourne in a few weeks..

I was unable to get the spiral down to work 100% reliably.. so have had to change the output a little

 

 

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Reminds me of the one on display at the UN building in New York. If I recall, the change of orbit is due to the earth's rotation i.e., Coriolis force. Hence the question: How much time it takes to go through a full cycle?

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2 hours ago, DrJB said:

Reminds me of the one on display at the UN building in New York. If I recall, the change of orbit is due to the earth's rotation i.e., Coriolis force. Hence the question: How much time it takes to go through a full cycle?

As far as I'm concern, coriolis effect introduced by Earth rotation has no influence on such contraption :) Or very, very, very negligible if you will. The phenomena here are the independent oscillations of the three moving bodies. Ideally, if there was no friction in the joints, it would draw the same curve (although a complex one with many twists perhaps) over and over, repeating the same cycle. Due to the energy losses as all three oscillatory motions are damped, the trajectory converges to the equilibrium point.

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I really like this one, I just love those futuristic styled cars from the atomic/jet era. Also, the whole cockpit sliding open is an awesome feature.

The only thing I could say is that maybe the front has somewhat much of a DS-vibe, but that's only my thought. For all I know that was maybe your intension. :p

Great car and I'll probably reverse engineer it to have on my shelf. 
EDIT: I read your article and saw that you already have BI, much appreciated. 

Edited by tibivi

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On 12/27/2016 at 9:48 AM, krisandkris12 said:

As far as I'm concern, coriolis effect introduced by Earth rotation has no influence on such contraption :) Or very, very, very negligible if you will. The phenomena here are the independent oscillations of the three moving bodies. Ideally, if there was no friction in the joints, it would draw the same curve (although a complex one with many twists perhaps) over and over, repeating the same cycle. Due to the energy losses as all three oscillatory motions are damped, the trajectory converges to the equilibrium point.

I never said the 'orbits' (or phase plane trajectories as some would call them) were due to Coriolis Effects. But, I did say they REMINDED me of the pendulum at the UN. The contraption in this thread (most likely) has too much friction for the Coriolis forces to manifest themselves. :)

Edited by DrJB

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The car design and functionality are amazing , the door-steps and sliding cockpit are something very cool, but my only complaint would be the music ( it's a retro car after all...)

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Nice car, it reminds me retro-futuristic world of Fallout games(with exeption the fact, that that world was ruined).

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On 25. 4. 2017 at 10:01 PM, DrJB said:

I never said the 'orbits' (or phase plane trajectories as some would call them) were due to Coriolis Effects. But, I did say they REMINDED me of the pendulum at the UN. The contraption in this thread (most likely) has too much friction for the Coriolis forces to manifest themselves. :)

My bad interpretation then :) All clear now. Btw what you talked about is Foucault pendulum and oddly enough, I have one few feet away from my office in main entrance hall of my university :D This one is 21 m long and in theory should display the phenomena really well, although there are some discrepancies cause by vibrations of the building and people walking around so I'm not sure how well it actually performs :D

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