Cutting into painted fiberglass, need a few suggestions

I bought some new headlight lenses for my 41 willys and they require me to cut out some of the fiberglass fender in order to fit the new buckets that I am installing in the back. I am a little nervous about cutting into painted fiberglass, but it does not have to be perfect due to the lense covering the area I am cutting. What kind of cutting wheel should I be buying at the local paint shop? This is the first time I am doing something of this sort, but I figure that if I am careful I should be able to tackle it.

Very hard to say without pictures showing what you're needing to cut for the new lenses. Your post says "...some new lenses...", but then says "...new buckets that I am installing in the back." I'm probably dense, but I don't understand what you're asking here? Fiberglass is about as easy to cut as anything - abrasives, toothed blades, die grinder bits... Maybe some pictures would help?

As long as you have plenty of area being covered by that new light bucket, probably a cut off wheel would work the best. A jig saw or Sawzall blade will vibrate that fender, possibly causing a big chip in the gel coat if the blade was to catch going one direction while the fender is vibrating another direction. Mask it off really well with multiple layers of tape so if that wheel decides to take off, you are 'covered'. Dress it with a die grinder and carbide burr afterwards. Here's a page from McMaster Carr with several different kinds of cut off wheels. I would just get a couple of the high performance or long life versions and have at it - McMaster-Carr

If you need to drill fiberglass, they also have special 'plastic' drill bits that work great in 'glass - I have a few, not cheap though

When I cut the hole in the front clip for my blower scoop on my corvette, I used a die grinder with a cut off disc. I then used a carbide bit in a die grinder to make the rounded curves. I'm guessing a dremel tool with a fine toothed bit will work just fine. I like you, was very nervous about wrecking the whole deal. :)

Measure twice, cut once.

Normally I use a die grinder and cut off blade.

Another option is to go to the hardware store and buy a handle that holds a hacksaw blade that sticks out of the end. You can use this... but only cut on the "in stroke"... lifting away from the edge you are cutting...so you don't lift up on the painted edge when you pull it out on the backstroke. Slower... but accurate and careful.

I agree with Dave (IC2). Just make sure you take it slowly and you should be fine.

Hey I found that a Fein MultiMaster tool works great for cutting fiberglass(It vibrates back and forth)You can buy a cheaper version of one(black and decker,sears,porta cable) use the metal blade and keep a cup of water handy to dip the blade in when it gets hot,also this tool keeps the fiberglass dust down!! Pete

Not sure how thick the glass is, but I would guess with the very first attempt to remove material you will know if the process you have chosen is going to work. Chipping will be the devil that needs to be controlled. I would make my strokes or work from the front side painted and into the opening. When done sand the upper and inner edges of the opening so they are rounded and feel smooth.

An aggressive file might work the best, saws, power air tools can get away from you real quick want to remember that if used, light pressure to start. Air offers the most control because you can roll back the pressure and slow the tool down, think die grinder.

I'm sure you will mask off the area and draw two lines the outer edge of the trim ring and the actual opening for the bucket. Just stay with close tolerances to the opening and you will have things come out nicely for you.

BTW when I say aggressive file I am talking about something like this, it is a half round file.

Example:

Nicholson Wood Rasp File, American Pattern, Wood Rasp Cut, Half-Round, 10" Length: Amazon.com: Industrial & Scientific

Have fun modes are always cool as hell when done, wow factor for the modifier is 10.

Good luck,
Greg

Regardless which tool you use, but especially if you use any rotating power tool like a cutoff wheel or die grinder be sure you're wearing a quality mask or respirator. Inhaling fiberglass dust can cause a wide range of health issues, and the power abrasives throw out a cloud!

Go to Harbor Freight, get a cheap vibrating tool and two blades.
Makes simple work of fiberglass and no chipping.

All I use is a cut off wheel,,about 1.5 mm thick..I use them daily..and it's still the best way of cutting fiberglass.. Much cleaner cut,no chipping..

Thanks for all the replies guys! Work has been crazy so I haven't gotten to it yet, but ya have to make the money to play with these kind of toys. I have a dremel tool sitting that I never used actually, looks like I'll see how the cut off wheel route works with that. I have a good amount of glass to remove, probably a few inches in some areas.

I've used the dremel tool on mine. I found a burr for the dremel works well also. You can plunge it in and make circular cuts.

Well I bought the bits today at Lowes for the dremel tool, I bought a diamond cutting wheel and a carbide burr bit. Expensive little suckers, it all totaled 30 bucks...but its still much cheaper than paying to have it done. I'm excited to get cutting! The lights came with a nice template to lay down so I can trace it out as well, so ill use plenty of tape and have at it. Maybe i'll post some pictures, though once I get working I have a hard time stopping to take a picture.