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Cutting lenses by hand (a guide)


Premium Member
Lifetime Member
A few days ago @iamFLIP asked me if I had any tips when it comes to cutting lenses by hand. I was just about to cut a Radar lens shield for a Trenchcoat for @hondazcrxsi so it was the perfect opportunity to take some pics of the process and share how I go about it.

DISCLAIMER! This is how I do it, if you **** up your lenses its on you. Use common sense and don't rush.

First things first. The tools you need.

Pen - I use a fine tip Black Sharpie. It really needs to be fine tip so you know where to cut to.

Dremel - I use a Dremel 3000, any speeds I talk about pertain to that model. I have no clue if other models behave the same on the same speeds.

Sanding drums - I use 240 grit for the main work and 80 grit sometimes if i need to.

Cut off wheel - I use 409 wheels but 420 wheels work too, and they're 420 lol

Sandpaper - I use 80 grit and 2000 grit wet paper.

Tape - I use Scotch Blue painter's tape with edge lock. I've used plain masking tape too and it worked good enough. I've been told Frog Tape should be just as good but I've never personally used it.

Lenses - Old lenses to use as a pattern and new donor lenses to cut.

Time - I've done relatively a lot now so it takes me about 30 minutes to do an easy set like NSJ or XX Twenty and it takes a little longer to do X Metals because of the bevel. The bevel needed on X Metals is a pain in the ass. Either way, plan on a few hours the first few times you do it. You don't want to rush it. Remember you can always take more off but you can't put more back on.

For this cut I used a Radar shield lens.

Step one is to tape the lens. Try to stretch the tape a little and follow the curve of the lens and it will have less bubbles.

Next we need to take off the excess tape. Use the 80 grit sandpaper and hit the edge at a slight angle with a moderate amount of pressure and the tape will score and fall away from the edge.


When you're done you should have a well taped lens with exposed edges.


Next we need to cut the shield in half. Obviously this only applies to a shield lens. At this point I should have marked the lenses left and right. Being oval shaped they need to be marked so they don't get turned around or mixed up.


Now we line up the old lens and make sure its within the edges of the new lens. Most of the time you'll have plenty of room but this one was super tight. TWSS


Now use the fine point Sharpie to trace the old lens. Hold them tight so they don't slip while you're tracing. Get a good dark line and try to keep is consistent. I angle the pen tip a bit to get it closer to the edge of the lens.


Now you can see the line to cut. Notice the top is right on the edge. In some cases this will leave a flat spot in the lens but here I had to cut passed the line so there was no flat spot.


Both lenses traced. Now we need to remove the larger parts of material. Use the cut off wheel here to take out the big chunks. I use speed 7 or 8 on the Dremel. Don't get too close.


This is what we are left with after removing most of the meat. At this point we really need the lenses marked L and R.


Both lenses marked. Now we know top from bottom and left from right. The majority of meat has been removed from both.


Now we use the 240 grit drum to grind down close to the line. I use speed 6 on the Dremel here. You'll notice that the plutonite grinds away while the tape curls up. Get fairly close to the line and when the tape curls to the point that you can no longer see the line, STOP. Use the 80 grit sand paper and take off the excess passed the line like we did in the beginning.


Uncurl the tape before you sand the excess away.


Now we are much closer to the line. Keep going until you are right on the line. I use speed 6 here as well and when I get really close I use speed 4. Don't grind into it yet. You may or may not have to.


Once you get to the line you will see the edge is flat and ugly and it won't fit into the lens groove of the frame.


We need to bevel it a bit, not a lot, just a little. I use the 240 drum here still and sometimes the 80 if I feel its needed. It's hard to see but there is a slight bevel here. I use speed 4 from here on out. Use 3 if 4 is taking off too much.


This will not be your final bevel. We still have to fit the lens and probably shave it down a bit more.
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Now we test fit the lens. It should fit in most of the frame so look at it and see where it doesn't. Take off a little material and fit again.


Now we see it fits better but still not all the way. See where you need to take off some material and do it.


Notice where its hitting the frame still. Shave off just a little **** hair and it should fit.


Close, just a little bit more now. Remember to bevel the edge after you shave off anything.


Perfect fit.



Check your inside, make sure you don't have any parts not in flush. If you have gaps here it's too late. DO NOT REMOVE THE TAPE YET.



Now is the time for wet sanding the edges to get that nice smooth bevel. You can see here its still pretty rough. I've just started it and only one spot is smooth. I use 2000 grit wet sandpaper and I let my thumb be the guide for the lens. I use a moderate amount of pressure and let the lens cradle in the sandpaper and my thumb to get the entire edge and the line where the edge meets the back and front side of the lens. Imagine a sponge flexing to allow more surface area contact with a plate as you wash it. Same thing. Leaving the tape on prevents scuffing the Iridium coating.


Go all the way around the lens and get the whole bevel nice and smooth.


Now pull the tape and clean the lenses. Pop them in the frame and you're done.

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