Carbon Fiber Helmet/X-Shut Mounting

[pkrfce 0]

This is what I have:

Bonehead Optik 210
An X-Shut camera mount

I need to:
Make a 45 mm circle to insert and mount the X-Shut flush into the helmet.

Question:
What is the best method other than using a 45mm hole saw?

Specifics I need:
Type of tool (i.e dremel etc.), Type of drill bit material (i.e carbide etc), Special care techniques (i.e sealing with clear resin/clear coat nail polish), and any other information you would feel is necessary

I don't have:
A spare piece of carbon fiber to test this with... :P

[PharmerPhil 0]

If I were you, and I didn't know how to do this, I would find someone else with experience to do it for me. Seriously, if you've never done something like this before, it isn't wise to try it for the first time on your prized helmet without even a trial run on a scrap piece of something.

However if it were I, I would remove the helmet liner, tape the area to be cut with blue painter's tape, draw a very accurate circle in exactly the right place (double checking both sides of the helmet for clearance, and the circle for accuracy), and use a hand-held air-grinder with a tapered carbide tip to cut the circle (I guess one could use a Dremel tool, but I like the speed and horsepower of an air grinder). On the first pass, cut at least an 1/8-inch smaller than your circle, and then do a second pass to bring it right to the line. You could alternatively use a high-quality saber-saw (I like Bosch) with a very fine blade, but I would still stay a little shy of the line and clean it up with a die-grinder or half-moon files.

Either way, consider how you will hold your helmet still during this operation. I have done a lot of things like this, and I prefer to sit and hold the helmet between my knees, brace my elbows on my knees, and hold the grinder securely with both hands. Eye, and ear protection and a high-quality dust mask are recommended (a real cartridge mask, not a cheap, medical, ear loop face mask).

Yes, most people recommend covering the exposed CF with nail polish on the theory that these tiny particles could get in to your electronics and wreak havoc. In practice though, I have never seen this actually happen. But better safe than sorry...

Good luck!

[pkrfce 0]

--------------------^ Is exactly what I'm looking for. If someone else has more information...feel free to give it up.

[antonija 0]

I'd use one of these. With masking tape and eye and ear protection and all that.

I understand the need for conformity. Without a concise set of rules to follow we would probably all have to resort to common sense. -David Thorne

[davelepka 4]

I'll second the vote for a hole saw. You don't need to use a 45mm saw, just use the closest, smaller standard measurement hole saw, then use a rotary type tool with a sanding drum to slowly work the hole up to 45mm.

Keep in mind that a hole saw isn't always going to produce a 'percision' hole, not as percise as the machined surface of the mount, so that's whay you want to use a smaller one, and work your way up. You can hold the X-shut behind the hole, and just slowly work the hole up to size and achieve and very good fit.

Carbon fiber is very easy to work with, cuts and drills easily with a minimum of splitering or other trouble. Do use making tape to cover everything for protection and to write on.

I have had success using a clamp to hold a helmet to a workbench. If you use a block of wood on the inside for the clamp to rest against, and a rag or towel between the bench and helemt, you can get away without damaging anything. If you want to work on the left side of the helmet, remove all padding, and lay the right side down on the workbench, then use a big C clamp with one side on the bottom of the workbench, and the other side pressing on the inside of the righ side of the helmet. This should the helmet down, and leave the left side facing up and free of obstructions.

Use a mask or other breathing protection. I don't know what CF does to you lungs, but it gets in there. You'll be blowing black snot out of your nose for a day or two without a mask. Ditto for the general area, expect fine black dust to get everywhere. If you have a helper, have them hold a vacuum cleaner hose 2 or 3 inches from the hole saw/grinder to suck up the majority of the dust, and this takes care of most of the problem. Wiping down the shell with a damp paper towel after any cutting or grinding, and before you handle it will also help control the dust.

I also have never sealed any edges with clear nail polish and never had any trouble. As mentioned, it can't hurt if you want to do that.

[antonija 0]

Nail polish, superglue or even better - epoxy resin will seal the cut just fine.

Problem with CF dust is that it is very very very light. CF fibers themselves are so light that a very thin CF fabric (not the one you buy to build helmets and stuff, but a veil-like very thin piece of CF fabric) will almost float in mid air (there was a show on discovery channel with that asian physics professor demonstrating this), and so will dust. When it gets into your lungs it's just as bad as any other small-and-sharp particles, like asbestos. It irritates mucosa inside your lungs and increases chances for lung cancer, which is not cool . It also makes your snot kind of black, which is cool .

I understand the need for conformity. Without a concise set of rules to follow we would probably all have to resort to common sense. -David Thorne