seeking input on large scale-up of toy

[dberndt]

Hi,

The following is just sort of an semi-serious exercise in design brainstorming.

I've been thinking about making on ofthese but scaled up to be on some grander scale, like 6 feet by 4.5 feet.
Now I havent really mapped it out yet or anything but I was thinking about having 10 pins per square inch or so. That'd probably be something like a .25" diameter rod, 9 per square inch or some such thing. That'd be like ~35000 rods/pins.

So the drilling part doesnt seem to hard, make the back board in smallish pieces and then attach it all together or get a large router table to do it. One of the questions would be what to use for a backing material, how thick etc.
Secondly the pins, well thats alot of pins, and each one needs to have one end crushed/mushroomed out so that it is retained. Some sort of an automated gadget for this would be good, or prebought because if each rod was 1" long that'd be ~2916 feet of .25"dia rod. Which isnt a small amount.

So, how would you go about doing this, what changes would you make, what insights do you have

[HuFlungDung]

Doesn't the back have to be left open to allow somewhere to place the object to form the relief?

One problem you'd have is the substantial weight of the whole thing: 800 pounds or so. 1" pin length may not give you all that much travel to form a significant relief, since the pins must be nested for some length. Depending on what you wanted to do, maybe a 2" long pin would be more practical.

Perhaps headless pins would be better, a spiral roll pin would be a tiny bit less heavy. Just let them nest against one another. Perhaps if you magnetized the whole lot of them (roll pins are hardened and probably will acquire and hold some residual magnetism), they would kind of stick together well enough to stay put (or maybe not). Perhaps placing a real magetic "booster rod" every so often would accomplish the same thing.

You might want to fashion some kind of a vise type frame for it, so you could tighten the whole thing up to lock in a shape in the relief.

[Bloy2004]

I've seen several versions of this "toy". The older one was heavy despite its small size because of metal rods/pins. The newer one used composite or plastic pins which made it considerably lighter and also "glowed" neon when under certain lighting conditions.
The big model could use these same plastic rods(larger diameter) to decrease its weight.
Using this material would allow using heat and jigs to create the needed "mushroom" ends on the pins.

[ViperTX]

Well....I'm not sure what the purpose is...but if it does not have to remain vertical you might use some of that memory foam / gel to get the same result.

[Kmed]

Well if I was going to do that I would probably use 1/4" polycarbonates for the flat areas and add a few standoffs to replace a few of the pins to keep everything flat. Then you could actually use off the shelf hollow plastic rod, and mushroom the end by heating it up and pressing it into a mold. You could also use a heated mold and just press each pin in. Another option for 35,000 pins would be to injection mold them. I would also have a custom bit made to dril and ream the hole at the same time that way you have good sliding action and only have to drill the holes once. Cut down on the cycle time.

[dberndt]

Hmmm, plastic pins. That seems like an excellent idea. Except I was playing around at one point with the idea of magnetizing them or using a magnet to move the pins around, neither would obviously be possible with the plastic pins. It's a tradeoff.

As far as pin length goes, yes, maybe something like 1.5" or 2" length makes sense because I had hoped to have most of the 1" available to play with.

The unit will be permanently installed in a vertical position, thanks for bringing up the weight issue. That will potentially be a problem. Mainly in terms of what backing material do I use to hold the pins. Some sort of uhmw or something like that in a sheet form might be a good choice? One of those self lubricating plastics should be easy to drill and provide smooth pin action. I was hoping to make the large panel out of many smaller panels joined together somehow in a nearly seamless way. Welll it doesnt matter if there is a seam the important thing is that it be strong and that it not interrupt pin flow so that its not obvious there.

[ViperTX]

You haven't mentioned a purpose for this.

Another thought which I would consider more exciting is creating a hologram...any thoughts....

[dberndt]

The purpose is ofcourse top secret. Errr, ummm, actually its more or less an attempt at an art piece. It will render shapes by using a stepper motor setup in the rear. Sort of a piece of continuous moving art. I had thoughts about letting it render fractals, that should keep it busy, give it a few patterns to switch between and it'd always be making nice new designs.

[lerman]

Have you considered using nails. 60d nails should be around the right diameter -- and they already have heads.

Ken

[dberndt]

Lerman gets a gold star.


Yes, some sort of nail with the right finish and shape would be excellent and I'm sure thats where the project will end up heading. I am inclined however to think that this is the easy part of the project and getting the 10000's of holes in the backboard might be the harder part.

[nervis1]

I can't think of anything to add to the above...but when you are finished I want to be the first one to get a running start and jump into it.

[HuFlungDung]

I thought about the headed pin, but thought maybe it would add the unnecessary complexity of making the "tube sheet", which is a formidable job.

What if you were to simply use plastic soda straws? These have a good length, low mass and would pack together nicely (with good compressibility). All you might have to do is devise a method to close off the ends, with a suitable material which might have more aesthetic properties than hacked off steel pins.

Are you going to program the stepper system to push the pins a certain distance outwards?