Fiber Optic question

[BobaTi]

Hi all. Long time lurker here.

I need some advice on reinforcing fiber optic cable not exceeding 4mm diameter.

I will be using lengths not exceeding 6” and placing a model on top not exceeding 2oz/60g.

I am looking to reinforce the fiber so it can remain rigid and hold the weight of the model. I haven’t found the right kind of tubing yet. Was looking at clear straws but can’t find the right size.

I was also considering heat shrink but I’m not sure if it will be rigid enough, let alone how it will affect the light.

I was also thinking about clear epoxy resin.

If you guys have any ideas it would be much appreciated.

Of course I will show the final product.

 

[zapwizard]

Heatshrink is too flexible to actually reinforce anything, and the heat used to shrink the fiber will probably melt the fiber, especially if it is a flexible fiber.

If your adding material to the outside of the fiber anyways, can you not just use a thicker fiber that can hold the weight, such as an acrylic rod? The rod itself can act as a fiber optic light transfer. If you don't want light visibly leaking from the plastic, you can paint the rod. As long as the fiber has a glossy exterior, you can coat the outside without disrupting the total internal reflection aspect of the fiber. A matte paint like plasti-dip would work well, and is removable from glossy surfaces.

If you need to keep the fiber optic flexible, say because it is traveling up and into a specific part of the model, you could look at running the fiber up through a secondary tube. If it needs to be clear you can get acrylic, glass or polycarbonate tubes.

If it doesn't need to be clear, look at using a carbon fiber tube. The smaller tubes are not too expensive, and can easily hold the weight needed. At just 6 inches, steel tubing will also work and hold a lot of weight.

 

[BobaTi]

Thanks for getting back to me. I am trying to keep the fiber around 4mm for the scale I am going for. It is side glow fiber as well. I might see how an acrylic rod looks. It would be a better option if it does.

If not, some sort of rigid tube would do the trick. I just haven’t been able to find the right kind.

If you have any links could you share?

 

[zapwizard]

The issue your going to run into is that there is a physical limit to the strength of a given material. The smaller the diameter, the weaker it is. There aren't too many materials that are strong at 4mm diameter. Basically hardened steel and carbon fiber are your options if your needing to hold that much weight out on the end of a horizontal rod.

A 4mm hard acrylic rod can probably hold that weight if the weight is centered directly above the rod. But it would also be very fragile. A 4mm rod can be snapped with your fingers, so if the 60g mass were jostled it would also snap the acrylic rod.

Since it sounds like you want the outside if the support to be illuminated, you could look at using a clear tube, with something in the middle to reinforce it. You can sand the outside of the tube to get the side-glow effect. The middle would probably need to be a carbon fiber rod to hold that much weight. Carbon fiber is also extremely resilient when flexed, and takes a lot of force to snap.

Finding a thin-walled clear plastic tube might be very tough. A plastic straw might work, but it wouldn't carry much light. A glass tube might be used that can have thicker walls, and be clear enough to carry the light. With the a carbon fiber rod at the core, the glass tube might actually be somewhat resistant to breaking.

I don't really have any links to share. I just typically hit-up McMaster.com to see what materials are commercially available, and then either order from them or hit up eBay for a cheaper source.

Finally, can you light up the rod using an external source? For example, painting a strong rod with a UV paint, and using a blacklight to cause the glow effect.

 

[tdb68]

doing some searching on google for about 1/2 hr i came up with this. the smallest they have is 1/4OD but looks like you can get small quantities for not alot of money.

Clear Acrylic Tubes, Clear Plastic Tubes : TAP Plastics

Check out this great deal on our Clear Acrylic Tubes! Stay within budget with our great selection of products.

www.tapplastics.com

from this link fill in the blanks. hope this helps. its a challenge for sure. i have lathed swizzle stirers and the like before to make things like this.

 

[BobaTi]

Thank you both for your advice. I will definitely explore those options. After some searching I found that Plastruct makes acrylic rods both clear and fluorescent. I am going to see if they are strong enough and then go from there.

I love the backlight idea though.