Kato P42 Ditchlight Question

[eja]

I asked this on the weekend update and got no response, so I try again in a separate thread.

The data sheet that came with the Digitrax decoder I installed in my P42 has instruction regarding converting the ditchlights to some that that can be controlled but the decoder.  This include cutting the Kato light tube and polishing it where the cuts are made.

Can someone tell me how to polish the light tube ?  I have no idea.

eja

[jpwisc]

I wet sand the cut end with some 400 grit sanding sticks. That works pretty well.

[ryan_wilkerson]

I'd like to see any in-progress photos and the results if you have the time.

[peteski]

I wet sand the cut end with some 400 grit sanding sticks. That works pretty well.

Just like with any other item (plastic or metal), it is all about progressively smoothing out the surface. Cut, file, then wet sand with progressively finer sandpaper: 220, 320, 400, 600, 1500. Then start polishing. Novus polishing system provide what you need.  After that the surface will be glass smooth.  Alternatively, to skip the polishing, after 1500 grit sanding simply paint some clear lacquer or enamel on the sanded surface. The clear will smooth out the surface without polishing.

EDIT: for even simpler method, use one of those 4-way fingernail polishing boards you can pick up at a beauty supply store. It has 4 grits - after going through all 4 you have almost perfect polished surface. An addition of a coat of clear will make it pretty much as good as the method I described earlier.

[craigolio1]

Does heating the end work like it does for fiber optics?

[peteski]

Does heating the end work like it does for fiber optics?

Heating (melting really) any thermoplastic material should have similar results. But it is easier to do that with a small diameter fiber optic than with a much larger (and often odd-shaped) plastic light conduit.

Heat-polishing (running a propane torch flame along the edge of cut Plexiglas) is a method often used by plastic fabricators for smoothing out the cut edges.

[Wutter]

Not very helpful to answering the original question but everyone else basically covered the same technique I used. Also make sure to paint some surfaces black or used some type of shrink tubing to shield the light from leaking to other tubes.

[peteski]

Also make sure to paint some surfaces black or used some type of shrink tubing to shield the light from leaking to other tubes.

Good advice. For even better light reflection, first paint the light conduit white (not silver). Then the light blocking layer can be applied (silver, black or whatever color works for you. Heat shrink tubing does work well too. But start with white.

[eja]

I'd like to see any in-progress photos and the results if you have the time.

Ryan

This is not yet a work in progress ... only something I might try later on.

All ... thanks for the suggestions

Wutter ..... looks like some kapton tape in  your photos  ..... mind telling me why it is there ?

[Wutter]

..... looks like some kapton tape in  your photos  ..... mind telling me why it is there ?

I used surface mount 1206's in my installation and the way that I made sure my ditchlights had the most directional light was I cut the light pipes shorter than usual and made the plane of the LED face directly towards the front of the light pipe. In this mounting configuration, the pads on the back of the LED were sitting pretty low and close to the frame so to be safe I put a piece of kapton tape down to make sure I wouldn't burn out the LEDs.

[eja]

I used surface mount 1206's in my installation and the way that I made sure my ditchlights had the most directional light was I cut the light pipes shorter than usual and made the plane of the LED face directly towards the front of the light pipe. In this mounting configuration, the pads on the back of the LED were sitting pretty low and close to the frame so to be safe I put a piece of kapton tape down to make sure I wouldn't burn out the LEDs.

Thanks for the explanation !

ed

[Ngineer]

This product (Micro-Mesh Craft Kit - Model: 3KCRAFT, Made in the USA)

http://micro-surface.com/index.php?main_page=product_info&cPath=188_189&products_id=76

http://www.amazon.com/Micro-Mesh-Model-Polishing-Kit/dp/B000X4J4G4/ref=sr_1_3?ie=UTF8&qid=1415115488&sr=8-3&keywords=micro-mesh+craft+kit

is absolutely AMAZING if you want to polish a surface. I highly recommend it.

Javier

[mcjaco]

Not very helpful to answering the original question but everyone else basically covered the same technique I used. Also make sure to paint some surfaces black or used some type of shrink tubing to shield the light from leaking to other tubes.

At that point, wouldn't have just been easier to run the LEDs to the holes???

[Wutter]

At that point, wouldn't have just been easier to run the LEDs to the holes???

Maybe....but I wanted to keep the "lenses" of the light tubes original on the outside without making new lenses from Kristal Klear. Also mounting the LEDs right at the holes would have resulted in even more light seepage through the lightblock and into areas of the nose.