Modifying Optics to Fit NightFighter BT-21 - Did / Should have done? Partial Success- Mtbr.com
Results 1 to 5 of 5
  1. #1
    mtbr member
    Reputation:
    Join Date
    Jan 2014
    Posts
    55

    Modifying Optics to Fit NightFighter BT-21 - Did / Should have done? Partial Success

    I ordered various optics from LEDDNA and Fasttech, then started modifying them to fit my NiteFighter. Not sure I did everything right, but ran into specific problem: the little plastic rings that fit over the LED while the optic sits in the ring doesn't fit the different optics in the same way.

    How do I solve this?

    Seems the outside cone shape profile of some optics is straight, and other optics have somewhat convex cone shape. This causes the optic to sit higher in the little plastic ring so the front of the BT-21 won't screw down flat.

    Here is a picture of one original optic and one modified optic sitting in the front part of the BT-21 with the rings sitting on them:

    Modifying Optics to Fit NightFighter BT-21 - Did / Should have done? Partial Success-img_1706-copy.jpg

    I measured the distance from the face of the BT-21 (shown sitting on the wood) to the plastic ring (clamping the face and ring into a dial caliper). Looks like I need a wider ID ring or cut .023" off a ring. (did not want to modify an original ring)

    Original optic: .517"
    15 deg optic: .515"
    30/60 deg optic: .540

  2. #2
    mtbr member
    Reputation:
    Join Date
    Jan 2014
    Posts
    55

    Did I modify the optics correctly?

    The optics I ordered for the BT-21 had tabs on them and were deeper than the original optic. I made them the same depth as the original when sitting in the BT-21 faceplate. (see previous post showing picture of optics in the faceplate - but note this post's measurements are without the plastic rings).

    The 15 deg optic only needed the .040" tabs taken off.
    The 30/60 deg optic needed the tabs and an additional .021" taken off the back before it measured the same as the original.

    The little hole in the back of the optic where the LED sits is now shallower by .021" is that a problem?

    Is the technique of sanding off some of the optic and polishing the edges somehow incorrect or incorrectly applied to make an optic fit?

    The black O ring that goes around the optic is too thick to work with the new optics, and I think that has been addressed in other threads.

    Modifying Optics to Fit NightFighter BT-21 - Did / Should have done? Partial Success-img_1709-copy.jpg
    Left to Right: original optic, tabs removed, optic w/o tabs removed.

  3. #3
    RAKC
    Reputation: tigris99's Avatar
    Join Date
    Aug 2012
    Posts
    7,146
    Actually all this is covered in the BT21 thread but ill go down the list for you:

    -Toss the white rings, they are only needed for stock optics because their center hole is larger than emitter dome. THEY ARE NOT NEEDED AT ALL except with use of stock optics Most other lights dont have these like yinding etc, and use the same style of optics you ordered.

    -LEDDNA/Fasttech Optics installation in yinding, bt21 and etc:
    1. At minimum file the 4 tabs at the base shorter by half, or as most of us do, carefully just cut them off with an Xacto Knife
    2. Except for the 15Deg narrow spot optic, REMOVE stock orings and replace with VERY thin ones IF you ride in the rain. May be difficult to source depending on where you live. If you dont ride in the rain, just leave them out. The new optics fit plenty tight without them
    3. Make sure the locations of the tabs you removed are lined up to fit the emitter correctly while placing them into the face plate(as if tabs were still there if removed) so optic is clocked correctly. Make sure they are seated in the face plate fully
    4. Reinstall face plate with optics and go ride. MAKE SURE when reinstalling face plate you tighten screws evenly so plate doesnt tilt drastically one way or the other otherwise you can damage emitter dome

    Steps 1, 3, 4 are standard procedure for most xm-l2 light head that uses single optic per emitter. Removing the tabs is because most slight heads have an issue with face plate tightening down all the way with the tabs still on the optics. And the beam output/tint is improved when optic sits flush against the base of the emitter dome with these optics. Even the best of these size optics, Glowworm spot optic, no tabs, no white ring, just sit on the emitter and in the face plate. Works great.

  4. #4
    mtbr member
    Reputation:
    Join Date
    Jan 2014
    Posts
    55
    (very quietly, "oh.")

    Thanks tigres99 - as much as I read the BT21 thread I obviously missed that part. It's a lonnnng thread.

    :-)

    So there is not a problem with the emitter dome being stuck right into that little hole and the optic sitting on the substrate or whatever the dome is glued to, eh?

  5. #5
    RAKC
    Reputation: tigris99's Avatar
    Join Date
    Aug 2012
    Posts
    7,146
    nope even lights light bt40s and bt70 sit on the emitters, anythign I have with optics, the optic sits right on the emitter base no problem, only issue is if not careful when assembling. If optics are not correctly lined up with the emitter dome it can put stress on it and cause it to come loose once the light is used. Which will cause really warm/yellow tint and loos of lumen output. If using the stock optics in the BT21 at all, its best to use the ring just so optic doesnt rattle around.

Similar Threads

  1. Old Rockshox bar 2.1 only getting partial travel
    By canker in forum Shocks and Suspension
    Replies: 0
    Last Post: 06-24-2015, 02:05 PM
  2. Partial fork lock out
    By skikarl in forum 29er Components
    Replies: 7
    Last Post: 02-11-2014, 09:14 PM
  3. Help! Identify this partial FS frame
    By dsalvey in forum Bike and Frame discussion
    Replies: 8
    Last Post: 10-26-2012, 10:56 AM
  4. **HD Dream Build** - I'm Partial! :-)
    By aappling72 in forum Ibis
    Replies: 37
    Last Post: 09-06-2012, 03:13 AM
  5. Partial ACL Tear -- Flats?
    By Mike Aswell in forum Rider Down, injuries and recovery
    Replies: 8
    Last Post: 10-14-2011, 03:25 PM

Members who have read this thread: 0

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

THE SITE

ABOUT MTBR

VISIT US AT

© Copyright 2019 VerticalScope Inc. All rights reserved.