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Tip: Cutting Fiberglass Parts

DHeal

Well Known Member
I just finished making the initial cuts on my various RV-12 fiberglass parts (tail fairing, cowl, etc.). I used my cheapy Craig's List Skil bandsaw with excellent results. Here's how I did it: I carefully ran dark masking tape along the mold cut lines - on the outside surface of the fiberglass. I made a saw blade kerf guide out of a scrap piece of clear plastic. I backlit the kerf guide from underneath the saw table using a small worklight. Now I could easily see the saw blade and its relationship to the masking tape through the translucent fiberglass. I was able to accurately guide the fiberglass piece so that the blade cut within 1/16" of the masking tape. Worked great for me -- be very careful, no cutting of fingers permitted!

ps -- You may want to have a trusted associate help you hold the large lower cowl piece as you maneuver it through the saw.
 
Also Try Diamond Dremel Wheel

For sharp radius, angles and non flat pieces etc. try the dremel diamond wheel. Cuts like butter.

Gary Eldridge
 
The dremel with a small abrasive disk is the SUPERIOR tool for the fiberglass pieces!!! Also borrow or get a 4 inch bench mount belt sander - the kind where the belt is horizontal with the rounded end exposed. You can very easily make straight and curved lines right up to the scribe line with great control and much faster than hand sanding. I think you have better control with the big pieces using it than a saw. Use coarse paper.
 
Fibreglass is very abrasive and hard on band saw blades. Extended use will quickly take the edge off steel blades and drill bits.

Clive Whittfield
 
Make sure you wear a dust mask or respirator when working with fiberglass. The fiberglass dust is now classified as a potential carcinogenic. Do the work outside if you can and avoid bringing dusty clothes into your house. If you use an airhose to blow the dust out of the shop wear a mask. It is better to use a vacuum with a good fine particle filter, but wear a mask also.
 
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I forgot to mention in my initial post that one of the benefits of using my band saw for these cuts was that I could easily hook up my shop vacuum to the band saw and vacuum away most of the fiberglass dust while cutting. Always use a mask -- that fiberglass dust is nasty stuff. I agree that the Dremel tool with cutting wheel works -- especially for the curvy cuts.
 
Perma-Grit Tools are made of Tungsten Carbide Grit. These cut through fiberglass like it isn't even there. And they last unlike the dremel disks.


http://www.aircraftspruce.com/catalog/cmpages/rotarycutting.php
PN:12-00069


12-00067.jpg
 
Anyone tried to use the dremel vacuum powered cutter that vacuums up dust and is powered by a shop vacuum to trim the engine cowling?

Jeff
 
Perma-Grit Tools are made of Tungsten Carbide Grit. These cut through fiberglass like it isn't even there. And they last unlike the dremel disks.

Good to know! I destroyed about 6 Dremel disks this past weekend working on the wing tips.
 
Here is an update. Although the new vacuum powered Dremel drill does vacuum up the dust, it does not have enough power to easily cut the engine cowling fiberglass. Instead, I used duct tape to attach a shop vac hose to an electric Dremel with a good result. The Dremel 543 1-1/4 cutting/shaping wheel cuts like butter and seems very durable.

vacuumDremmel2.jpg
 
Hi to all Dremel friends but...


I would recommend Fine tools there is only a little dust down on the floor

Daniel

#12383

Flying over 300 hours
 
Shop dust is a constant battle. Keep in mind that a lot of fiberglass parts rough trim very well with a big pair of tin snips.
 
when i started on my cowl i finally bit the bullet and drilled a hole thru my shop wall into the pole barn and made my fresh air respirator a permanent fixture in my shop. and whenever i cut with any power tools i have a vac. hose in one hand. the vac must get 80-90% of the dust.
 
Shop dust is a constant battle. Keep in mind that a lot of fiberglass parts rough trim very well with a big pair of tin snips.

I like using tin snips for rough cuts as well. I've noticed that fiberglass can tend to delaminate when sheared like this, so I always make sure I'm sanding or fine grinding away enough that you have sound material in the final piece.

Don
 
rotary scissors

On my Lancair kit, I had to trim probably 100 linear feet of fiberglass. The tool of choice for doing that job was an electric tool the size of a sabre saw called "rotary shears" or "rotary scissors". The tool had two 1/8" thick hardened steel wheels which played against each other like the halves of a pair of scissors. One wheel was driven by the slow-speed motor and the other was freewheeling. The discs weren't sharp like knives rather, the edges were flat. I think this tool was designed for cutting fabric. They worked great on cured fiberglass, but I don't think they're available any more. I sold my pair long ago.
 
Dremel makes a diamond cutting wheel that creates significantly less dust than its grit wheel. https://www.amazon.com/gp/product/B000Y4ZTFS/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

Hardly any dust with the vacuum.

And it is hard to explain: the FACE of the cutter/shaper is a shaper. Push up against the cut line and it is like using a rotary sander. So you can cut leaving a small band or residual here and there and by slightly pushing UP into the cut line you can sand off any residual material flush to the cut line.
 
Get yourself an oscillating cutter. They are the bomb for cutting fiberglass. Fein tools sells the Cadillac version but I saw a Dewalt on amazon for $130. Carpenters use them for fine cutting jobs. The vibration action makes dust that simply falls to the floor. They are similar to what hospitals use to cut casts off. Very,very safe and a kerf line ,cut line, about .032 or less.

https://www.amazon.ca/DEWALT-DCS355...10635&sr=8-1&keywords=dewalt+oscillating+tool
 
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