Building a self looping "SMOT"

[MeggerMan]

Hi Elecar,

Excellent thread!

This reminds of a few years back when Greg Watson built the first SMOT and was offering it in kit form but never managed to send any kits out if I remember right. 
I am not sure if he did get it to loop, but I think he claimed he did.

What you have here is very interesting.
This evening I have been playing with some 10 x 13 x 10 x 1.5mm x 1m aluminium chanel and a 24mm steel ball bearing and a very large 6 x 4 x 1" ceramic 8 slab magnet.
I can see the effect where the ball is pulled up the incline and then falls back down again under gravity, the cycle then repeats, with the ball zipping up and down the track for around 30 seconds before it stops.
I tried it with the track sitting on top of the slab magnets long edge on so the N-S faces of magnet face out to the sides.
Not sure it this config would be good for your setup as the magnet is below the track.
I have been using Lego bricks to build the support for the tracks.

You are right about the null spot in the middle of the magnet array, this would make the logical exit point away from the magnet using the downward momentum to carry it away from the null point and back around to the start.
I think a key thing is to have one uniform magnet as any ripples in the field tend to spoil the effect.

I am still trying to figure out the best way of get the ball to use the exit track on its downward journey.
My thoughts are with 3 rails that come to a point, as the ball reaches its max position it falls onto the outer 2 rails then returns down the 1/3 section before swinging out and away from the magnetic field.

For material, brass would be a good choice for tracks too as it can also be soldered and is easy to get hold of from B&Q and places like that.

I would like to see your working prototype if that is possible.

Meggerman

[elecar]

Hi Meggaman, thank you.

The reason your ball is going up and down is the large magnet. I believe having the steps works best. The first part of my ramp has 2 small magnets, then 4 then 6 then 8 and so on. The "bottom" of the ramp is much weaker.
Yes the middle is a "null" area, thats the area you must take advantage of, you can 100% get the ball to leave the field there. I have shown that to one member of the forum.
All the info to build one is right here in this thread, I will not be showing my unit until I am done with the toy manufacture, as soon as I am. like I promised I will post it here and may even stick a web cam on it.

[maw2432]

Hi Bill, I did not use a bumper as such during my trials, what I did was attach a very slim wedge shaped piece of acrylic to the magnet side rail of the track to try and guide the ball, it did NOT work the resistance was enough to stop the ball and it was held where it was by the magnets.
Please look at the drawing, the rail circled is the critical rail. It must allow the ball to travel smoothly up the ramp and when the ball descends it must be positioned to guide it onto the exit. It does take a lot of playing with you can not have the rail sit too high where it impedes the ball traveling up but high enough that it will bias the ball rolling in reverse to the exit. although that is how I did it, I really do believe there are easier ways. Something else that is important is that you can not divert the ball just as it starts to reverse, you have to allow it at least a third of the straight section to gain enough momentum to exit. That is why I said you should do the tests because they will help you get the magnet positions correct. You will get an idea of how the ball reverses and how much space/length you need before the junction. Do not build your ramp with too steep an angle otherwise the magnets will have to be placed to close to the track and your ball will not escape the field.

Elecar,   Thank you for your reply. I think I understand about the reverse momentum.   
I am curious about how you keep your base level.  If sold as a Toy it may be difficult to get everything level for kids.   Also, you mentioned you used aluminum rods.  Did you space the rods like a train track or another method?
Bill

[telecom]

Anyhow I believe the "high road low road effect is probably the way to get some work from the ramp.

http://www.youtube.com/watch?v=H2QPMO6bo4E

http://www.youtube.com/watch?v=JzZ9AKwZw28

http://www.youtube.com/watch?v=IoOtDBCJ7T0
[/quote]
I've never learned this in school, but it appears that the ball which gains more speed in the beginning has more energy, even though the potential energy is the same.
Not sure how it can be explained though...

[elecar]

Elecar,   Thank you for your reply. I think I understand about the reverse momentum.   
I am curious about how you keep your base level.  If sold as a Toy it may be difficult to get everything level for kids.   Also, you mentioned you used aluminum rods.  Did you space the rods like a train track or another method?
Bill

Hi Bill, the base is just MDF, I would think more along the lines of executive desktop  toy/novelty the track is set up just like a marble race.