Fox Valley GP60M's

[C855B]

I haven't taken mine apart yet, but judging from your picture and Wutter's comments, that light pipe is quite the contraption. It's no wonder you find the result unacceptable. If I get the bug to fix this issue, I'd get rid of all the bendy stuff, cut the light pipes about halfway under the walkway and be looking at retrofitting pico LEDs at the ends of the remaining pipe material.

[wmcbride]

OK, once again in the name of tinkering, I did some exploratory surgery to see how the ditchlight pipes were run on the FVM GP60M. The front walkway piece is a separate part from the rest of the walkway but was held in place with some glue, making it a bit difficult to pop off. Once I had it off, one side of the light pipe came out of the bottom of the ditchlight housing OK with some gently prying but the other side fractured at the base when I tried to pry it free. It appears the light pipes and the lenses in the ditchlights are separate pieces as well. I tried painting the light pipes white in hopes that this would help increase light intensity but, unfortunately, doing so robbed the light entirely. This is the second time I ever tried painting light pipes and I had poor results both times.

Russ,

You get the tinkerer's medal for attacking those ditchlights.

My initial thought on seeing that massive "pipe" was that it was too much pipe for the LED to illuminate. Quite a difference from what Kato does in their SD70ACe's.

While I like my GP60Ms, this is a hosed up design for the ditchlights. 

[peteski]

I tried painting the light pipes white in hopes that this would help increase light intensity but, unfortunately, doing so robbed the light entirely. This is the second time I ever tried painting light pipes and I had poor results both times.

I hope that I didn't mislead you in my earlier post. In my experience white paint is much better than silver for bouncing the light, but in general painting the plastic light pipes is not a good idea.  It wasn't my my intention to tell people to paint the light pipes white. 

[GaryHinshaw]

From the looks of this pipe, I would guess that a lot of light is going to spray out of the T joint, especially the big flat end section between where the two pipes split off.  This geometry violates a basic principle of fiber optic design, which is based on the concept of total internal reflection, nicely illustrated here:



In order for the light to stay trapped in the pipe, it needs to strike the walls at a shallow angle, otherwise some fraction of it transmits outside on each bounce.  (This is why the Kato pipes stay narrow and bend as gradually as possible.)  In the GP60 pipe, the light has no choice but to hit that T section at a very steep angle - almost perpendicular to the surface - causing a lot of it to either transmit out (down to the tracks) or to reflect back up to the LED.   

Sadly, no amount of tweaking the light source will remedy this.  If you don't mind sacrificing a sample, you could try cutting a V-shaped gap in the last big straight section to eliminate that big flat area at the bottom.  But the cuts have to be really well polished, otherwise you'll lose a lot of light at all the small defects on the rough surface.  A better solution would be to snake some new optic fibers through - or wait until FVM redesigns this and offers replacements...   

-Gary

P.S. As an experiment, it would be interesting to darken the room and shine a light into the pipe (while cupping your hand over it to otherwise block the light) and see where the light comes out the other end.  I'm pretty sure I know the answer though.

Added - I just reread Russ' description and will add that having the pipes be more than one physical piece of plastic is a huge no-no.  You need a really tight joint for that not to be lossy.  Further, I suspect that painting the pipe, particularly that flat section at the T, just causes more light to reflect back up to the source, since it can't transmit out through the paint.

[jereising]

OK, once again in the name of tinkering, I did some exploratory surgery to see how the
{snip}

Too late, Russ.

I painted the tubes white with the same results - no light.  So 129 is no longer leading.  We'll try removing the paint today.

I suspect if you want bright ditchlights you'll need to add some LEDs.  But given the light board I'm not sure just how.  With a PNP board there are pads for additional lighting - but this is not a PNP board.

In other news, according to FVM's FaceBook page, the H2 BNSF's are shipping to dealers now - the November release is H3 - two A's and a B - hello Mr. Wallet.

[wmcbride]

Maybe remove the pipe and run fiber optic off the existing LED to the ditch lights?

I was going to order the Swoosh units but as of right now, I am not. I will stand pat with my four GP60M/B's

It was a bit of a chore to add white LEDs to my eight FVM GEVOs but the result was worth it. Sharp engines and good runners and EASY decoder installation.

I am a bit concerned about the FVM SD70ACe's I have on pre-order. If the ditch lights on those are similarly designed, that will not be good. 

Bill McBride

[JSL]

The new runs of GEVO's are much better and brighter ditch lights. I would be confident that they will be the same as the Gevo's. At least they have ditch lights.

[wmcbride]

True.

The problem with the early GEVOs was the off-color LED. Once that was replaced with a white LED, angled downa  bit, the ditch lights looked a whole lot better.

Bill McBride

[JSL]

I guess it's hard to get everthing right on a new model. I do enjoy having another manufactuer that is making nice equipement. Now what will be the next new mode for FVM?? after the SD 70ACE - SD70-2???

[Scottl]

SD70M-2  (Wishful thinking, anyway)

[JSL]

If you looked at the pics from Milwaukee, there is a 70M-2 in the pics. I swear I wasn't dreaming!

[Scottl]

I know, and I thought there were pics from Amherst in January too.  But nothing on the FVM website or Facebook page...

[Ian MacMillan]

I guess it's hard to get everthing right on a new model. I do enjoy having another manufactuer that is making nice equipement. Now what will be the next new mode for FVM?? after the SD 70ACE - SD70-2???

SD40-2 

[wmcbride]

The SD70M-2s were in those photos.

I think FVM could make a killing with SD40-2's...

Bill McBride

[Scottl]

SD40-2 

Who would buy those?  We all know what the real -2 project is.