[Vulcan50]

Tools Needed:
Dremel or die grinder
Diamond grinder bit
Tape
Water
Medium sized container
A spacer (bottle cap, nut, really anything ⅜" or so thick)

Step 1:

We want to project the lens from lipping and grinding the len. Once marked it's not feasible to repair it. Start at the base of the curved side and slowly work the tape around the lens. Once all the way around press it down to the lens. Depending on the size of the tape/lens there will be an open spot that you just go across with a few pieces of tape. It's safest to do 2 layers.

https://photos.app.goo.gl/aJdje6MkBHg9nf7w8

Step 2:

There are 2 ways to do the back, though they are very similar. Lay 2 layers of tape perpendicular to each other across the back. Leave excess overhang, just tearing the tape works fine. Once you have the 2 layers, lay the lens down on a cut safe surface and go around it with a razor.

You can also do this on the stock lens then transfer the tape to the new one. This allows you to see how much material there to remove. This is only worth the extra work if you have a lot of material to remove.

Mark both sides of the lens 2 times (180* apart) on each side

https://photos.app.goo.gl/prfB1xXoVMqGBca1A

Step 3:

Fill a disposable container with water about a ¼" deeper than the thickness of the lens. Place lens curved side down in the water.

Step 4:

Begin grinding, start at a medium speed, and work up as you feel comfortable. Work your way back and forth between your marks, then rotate the lens and repeat the same number of passes on the other side.

As you remove material check that the edges are remaining perpendicular to the flat side. If not, correct it by placing the lens flat side down on top of the spacer (prevents you from grinding the container) then and work around the same way as the other side.

https://photos.app.goo.gl/NLWTnSAUqQp3MnjK7

https://photos.app.goo.gl/VCMcaHNRQwY9rSzZ9

https://photos.app.goo.gl/tziV4nsCvZw4icfA7

Step 5:

Check fitment of the lens in the holder. Repeat steps 4 and 5 as necessary until you have achieved the desired result. Don't remove the tape until fitment is confirmed, or wait until install to prevent scratches.

Tips:

When installing the lens to check fitment, it is easier to see if the lens is all the way inplace if it is installed upside down.

Change water frequently as the glass dust clouds it fairly quickly. Depending on the volume of the container the number of changes may vary. The easier you can see, the better.

It's better to go slow, you can always remove more.

If you accidentally create a "divot" it's not a big deal, the depth of the divot doesn't affect the positioning but the width does.

The larger the diameter of the diamond grinder bit, the safer in terms of smoothness (and divots).