Tip: Cutting fiberglass cloth

Learned something today that is probably known to experienced glassers but thought I would share as I was cutting down an intersection fairing on my new cowl.

As I opened up a piece of cloth from Aircraftspruce, this time it had a piece of masking tape on the edge and was cut in half. Hmmmm, never got it that way but made me think... If they shipped it that way, why not give it a try.

Taped the line I wanted to cut and put the scissors to it. No frays, straight line, a piece of cloth that you could handle and it would stay intact without stray strands.

Used the cut piece and didn't get ONE piece of stray frayed edge in the epoxy.

Wish I had known this a long time ago.........

cutting fiberglass

You should try a rotary cutter. Once you do, you won't go back to scissors!

And for the best of both worlds - use a piece of tape AND a rotary cutter!

Webb,

So did you leave the tape on as the piece was placed and cured and then pull the tape afterward? Or did you take the tape off when the piece was in place and before the epoxy cured? And I agree that a rotary cutter is much nicer than scissors. Easy to get a decent one at any good sewing store.

greg

Greg Arehart said:

Webb,

So did you leave the tape on as the piece was placed and cured and then pull the tape afterward? Or did you take the tape off when the piece was in place and before the epoxy cured? And I agree that a rotary cutter is much nicer than scissors. Easy to get a decent one at any good sewing store.

greg

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If you are glassing the side down and not going to cut, that would be a different story. I'm referring to an edge that will be cut later and the extra material discarded. For that, I just left the the tape on. You're going to cut off the edges anyway. Best part is there is absolutely no glass strands getting into your work. I also found the cloth easier to handle. It also keeps the cloth you aren't using from fraying since half the tape was on the cut line.

I've used a rotary cutter. Very nice. Will tell you that once you tape the cut line, scissors work very well and cloth is much easier to handle. To tell the truth, I thought the taped line was easier to cut than a rotary cutter.

Mental picture. You need to glass a 10 inch circle. Cut out a 12 inch square that has the borders taped. Put the resin on an inch past the circle. Let cure and cut to size.

Here's another trick. Cut the glass anyway you want. Lay it up on aluminum foil and wet the cloth. Then cut the glass and the foil to the right size and flip it over and lay it on your part. Nice straight cloth lines and a clean edge. Better yet, use a marker to lay out the outline of your part on the aluminum foil before you put the wet glass on and you will have an outline of your part to cut out.

I always use 24 hour epoxy and cut before cure

I guess every one knows this but for what it's worth I always use 24 hour curing epoxy resin and cut the excess off with a sharp X-acto knife when it is in a semi-cured state several hours before it gets hard.

Bob Axsom

Cutting Fiberglass

Get the Black & Decker electric shears. Cuts in one continuous stroke and leaves a straight edge. The composite guys use'em. They're only twenty bucks or so.

BD4Guy said:

Get the Black & Decker electric shears. Cuts in one continuous stroke and leaves a straight edge. The composite guys use'em. They're only twenty bucks or so.

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Well, yes and no. I was really excited when the B&D electric shears came out. They're very similar to the Dritz and "EC Cutter" electric shears that I've used several of in my composites shop, and mechanically they seem more robust than the Dritz. But they have one important and disappointing difference: No carbide inserts.

The Dritz shears have carbide inserts on the cutting blades, and last for literally thousands of feet of cutting in 9oz and 18oz fiberglass cloth. I still have the first set I bought back in 2004, and it still soldiers on, having cut enough cloth for about two whole sailplanes.

However, the B&D shears don't have carbide inserts. When I tried a set of the B&D shears, they went like 20 feet before the plain steel blades became so dull as to be useless.

What would be great is if somebody would make blades for the B&D shears that have the carbide inserts like the Dritz shears. That would be a killer combo of good mechanicals and stay-sharp blades.

Thanks, Bob K.

Fiberglass tips

Pictures tell a much easier story.

My empenage fairing was such a POS that it would never have fit. All I could do was cut it up and make a base for constructing a new fairing, ala Dan Horton.

Here are some of the techniques that made it easier for me.

Make a template



Thin strips(the thinner the better) of painters tape easy to see on a slightly oversize piece which is cut on the bias (important)
Olfa rotary cutter, expensive but the best, 45mm disc
Mark the template on 4 mill plastic and make a sandwich
Final cut is on the plastic just the right size.
Here is a mockup sample



Thank you Professor Horton.



Dave A.
6A build forever
P.S if you you lay the template on the fiberglass and then mark the borders with the thin strips of tape, you can cut the fiberglass through the tape with the rotary cutter. The tape keeps the fiberglass part from stretching and distorting. It also keeps the original roll exactly as it was, with no fraying or mess.