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View Full Version : Nutcracker: Can this be built?



smeighan
08-22-2012, 07:58 PM
Well, this is a first. I am posting in something other than software.

I am pretty handy, see the two 9' nutcrackers my sons and i built last christmas: http://meighan.net/build_your_own_nutcrackers

i have helped my brother build houses, have put in plumbing and electrical .etc. But, i am not sure mechanically how i might buiild this

I want teh ability to have a megatree and a matrix during my show. I plan on having my flexible strings be attached to u channel steel. I am not sure if that is the right name. They sell it at Home depot about 1/2" on 3 sides used for shelving.

I want to build a track and have my 32 strands roll together on the top into as tight a cluster as i can to get the megatree effect and then other times separate and give me a vertical matrix.

horizontally the matrix should be about 4" spacing. the bottom of the tracks would need to rise as i make the megatree since all 32 strands are the same length (approx 13').

Has anyone though of making such a mechanical device?

thanks
sean

macebobo
08-22-2012, 08:07 PM
What about something using a curtain rod? First thing that popped into my mind.

Skunberg
08-22-2012, 08:15 PM
After all you've done for us, of course we're going to help. I've got a concept without part details. Your metal rails with lights are vertical. You need two horizontal rails. The bottom one you bolt the light rails in place but leave them a little loose so they can pivot. The top rail needs to be mounted to vertical rails so it can slide up as the light rails move out and down as they move together. The light rails need bearings on the back to slide inside the upper rail (or pieces of nylon rod). You use a small cable between the light rails to pull them out to proper spacing and the ends go around to the backside, a motor with a drum to wind up the cable pulls the light rails out for matrix. Springs between each light rail pulls the megatree together as the motor unwinds and loosens the cable. Questions?


Brian

smeighan
08-22-2012, 08:44 PM
What about something using a curtain rod? First thing that popped into my mind.

i wonder how much the vertical angle iron might way for 13'? Maybe 1-2 lbs. i will have 16-32 of them depending how much my bonus check is.

kychristmas
08-22-2012, 09:44 PM
If I'm understanding you correctly, you want something that will allow you to switch your 32 verticals from being parallel to forming a Flat Megatree (your term I believe was Ray)...
If that is correct, then I believe you could do this using a Scissor devuce setup. Stretch out the scissor device for Matix, collapse it for Tree. This could be driven by an actuator or a screw. Working on drawing.

The other ideas I thought of was more along the lines of a Track as you mention. Something like Vertical Blinds would use. In fact you may be able to use two old Vertical Blind Tracks. I think this would be easy to drive with a couple of motor to open and close the tracks.

Edit:
Obviously there's a bit more engineering, but I think this basic concept will work. The issue I see is the extra length needed when switching to a tree. Each lenth would have to be different.


Is this something you want to change in the middle of the show or just between seasons (Halloween to Christmas)?

n_gifford
08-22-2012, 10:03 PM
I think Skunberg's on the right track, but it's a difficult challenge to say the least. When you say mega tree to vertical matrix, I envision something 3 dimensional that is circular top and bottom converting to something 2 dimensional in a flat plane. This would mean that the top and bottom of the vertical 'rails' would have to move front to back as well as side to side.

I'm thinking some type of 'flex-steel' (Like you'd find in windshield wiper blades), that has a circular memory so that it always wants to go back to the round shape of the mega tree. It could then be straightened out in a manner like Skunberg described with a cable system, and would automatically retract when tension is released.

I like challenges, and I like the idea of a flexible display item. I see some hours spent on this in my near future..... :)

smeighan
08-22-2012, 11:41 PM
If I'm understanding you correctly, you want something that will allow you to switch your 32 verticals from being parallel to forming a Flat Megatree (your term I believe was Ray)...
If that is correct, then I believe you could do this using a Scissor devuce setup. Stretch out the scissor device for Matix, collapse it for Tree. This could be driven by an actuator or a screw. Working on drawing.

The other ideas I thought of was more along the lines of a Track as you mention. Something like Vertical Blinds would use. In fact you may be able to use two old Vertical Blind Tracks. I think this would be easy to drive with a couple of motor to open and close the tracks.

Edit:
Obviously there's a bit more engineering, but I think this basic concept will work. The issue I see is the extra length needed when switching to a tree. Each lenth would have to be different.


Is this something you want to change in the middle of the show or just between seasons (Halloween to Christmas)?

let me clarify

i think a ray type megatree, a mega tree in 2d going to a matrix would work for me

so i think a track along the top and small tracks along the bottom that the strands can move up and down might work

here is my megatree/ray
http://meighan.net/nutcracker/images/mtree.png

and it then moves into a matrix
http://meighan.net/nutcracker/images/matrix.png

the blue lines on the bottom are tracks to guide the bottom of the strands
green line on the top is a track

RED lines are the strands while in the megatree position, purple lines are strands in the matrix position.
Note red lines form an arc when gathered up into their mtree(ray) position.

if i changed from a Ray (2D) to a true Mtree (3d) the movement would get more complicated.



thanks

n_gifford
08-23-2012, 09:25 AM
That makes things much easier!.... :)

jess_her
08-23-2012, 11:47 AM
Hello Sean and DIYC,
What if you use a carbon fiber pole like a tent pole for the lower plain. Have a track system like a barn door track and a rod that slides 90 degrees to the track to retain the rods shape in the plain. Draw the ends of the carbon rod together to form the arc using cables. The upper plain would be like a curtain rod again on a sliding door type setup. Have a power shaft driven by a windshield wiper motor with wooden pulleys to draw in and let out the cables. Use relay logic for motor direction control and limit. Also have bungee cords on the strings to take up or pay out slack so they stay straight. Let me know if the might work and I’ll put my thoughts down on paper.
Jess

Bob Moody
12-19-2012, 11:09 PM
The issue that strikes me right off the bat is that the upper plane will need to be able to travel vertically, and the lower plane travel horizontally in proportion...
When the strings are in the "Matrix" config you have parallel lines all the same length... but when you "pull the blinds closed at the top" the lengths will change...

Without both planes in motion, the outer strings will need to get longer and the center strings will have to shorten.

If the strings were mounted on "U" channel. The device could be engineered to collapse the top while expanding the bottom proportionally so the vertical lengths never change.

Would take a little cipherin ... IMHO...

Bob

Skunberg
12-19-2012, 11:55 PM
Bob, If the tops travel together on one track. The bottoms need to do one of two things, if staying 2D them the outsides need to rise as the tops move in. However if you use 3D the bottoms can move into a circle as the tops move together into a regular megatree or halftree.

Brian

Bob Moody
12-20-2012, 11:24 AM
Brian,

Okay.. the top is a fixed plane (collapsable, but in the same plane)..
I agree the bottom has to rise but it also has to move in the horizontal plane as well
Stick a pencil perpendicular to the base of your keyboard.. this fixes the point at the top. now rotate the bottom to the left and the top to the right keeping the pencil against the keyboard ... we have to account for an arc.. which means as you mentioned that we have to a vertical but also a horizontal component to the bottom plane .. and they cant be all tied together

The outer legs of the vertical matrix will have to move further than the one adjacent...

of course all this based on the premise that I actually understand what Sean wanted to accomplish.. which sometimes for me is a hurdle upon itself ..

Great discussion .. lets keep going ..

Bob

Bob Moody
12-20-2012, 12:39 PM
Brian,

On second thought, maybe we are over thinking the problem... what if the top were on a fixed plane that could close like a curtain... the bottom would be set to the max length of the strings (variable) in a 2D tree config with the bottom being shielded by a panel. Then only the bottom would have to move vertically as the top "curtain" was opened and closed.

The wild length and bottom movement would be shielded from view by a decorative panel. (?)

yes, no, maybe ?? clear as mud... right ? LOL

Bob

battle79
07-14-2013, 10:20 AM
If you are still thinking of something like this for your tree/matrix sean, I'm planning something similar and this is how I'm overcoming it.

Set your bottom horizontal bar about a foot up from the bottom of the strips. I used 12 bolts welded to the bar sticking out ready for nuts. Then you cut slots in the vertical braces, in my case PVC pipe. Each slot is cut to allow the pipe to move from its "lowest point" when in matrix mode, to its "highest point" when in ray tree mode. The top I just have a bar with 12 holes drilled for matrix placement, and 12 for ray tree placement. Just hook each pipe into its hole and tighten nut at bottom and your ready for whatever config you need.

Hope that makes sense,
Rowan