"How to" Series

Creating a light tube for a rear headlight: Steps 12 - 17

 

Preparing the interior of the cab

 

Step 12 - Remove any obstructions from the interior roof of the cab (near the rear headlight lens) with a #17 X-acto blade. Care should be taken to remove as little additional material as necessary so that the light tube is flush with the roof of the cab and aligns concentrically with the lens of the rear headlight.

 

Drilling out light tube for LED

 

Step 13 - Using a #32 drill bit inside a pin vise, hand drill a 1/4" deep hole into one end of a 1/2" long section of 5/32" OD styrene tubing. Square the end with a small flat file (if needed) so that the face of the styrene tubing is perpendicular to its side.

Cutting light tube to length

 

Use a razor saw and miter box to trim the drilled end of the styrene tubing to ~1/4" in length. Square the cut end so that it is also perpendicular to its side.

 

HELPFUL TIP: At this point it's a good idea to test fit your 3mm LED inside your light tube.  The LED should "press fit" inside of the light tube but still be removable with little to moderate effort.  You want the LED to be snug inside the light tube so that it stays in place but also removable, if and when the time comes to replace the LED.

 

If the fit is too snug, use the pin vise and #32 drill bit to ream out the hole a little more.  If the fit is too loose, you can use a tiny amount of Elmer's glue to secure the LED inside the light tube later on once you have everything wired up.  To remove the LED, just wet the glue to soften the glue.

Securing light tube to cab roof

 

Step 14 - Center the light tube in the top of the cab so that its center is flush with and concentric to the rear headlight lens. Use a small amount of liquid adhesive to secure the light tube to the top of the cab; being careful not to get any on the lens. Let adhesive dry for ~1 hour.

Adding 6 x 6 bracing

 

Step 15 - Cut two (2) 1/4" long pieces of 6 x 6 dimensional styrene. Lay one piece on each side of the light tube and secure them to the light tube and cab roof with a small amount of liquid cement. (Again, being careful not to get any on the lens.) Let adhesive dry for ~1 hour or overnight.

Painted light tube with LED inserted

 

Step 16 - Once the bracing is dry, paint the exterior of the light tube and bracing with a styrene-compatible flat black to eliminate light leakage. Be careful not to get any paint inside the light tube. Let paint dry over night.

 

Step 17 - Modify a 3mm (T1) Golden-white or Sunny-white LED. (For specific details, see this page.)