Author Topic: Fibreglassing nose (Read 2661 times)

Paul Allen · « **on:** March 09, 2010, 04:03:01 PM »

guy's
Ready to glass the nose of the Vector with .5 cloth, my question is
how to stop the strands from pulling when appling the cloth? Cut out the
piece nice and square over newspaper, no matter how careful it never
keeps the nice straight edge across the fus in front of the wing.
I saw a reference to hairspray somewhere re fibreglass?
Thanks
Paul

Wynn Robins · « **Reply #1 on:** March 09, 2010, 04:31:21 PM »

yep - the hairspray trick works makes it easier to cut

Paul Wood · « **Reply #2 on:** March 09, 2010, 06:35:55 PM »

You can also use spray adhesive, but I find it a bit messy compared to the hair spray.

Paul

Balsa Butcher · « **Reply #3 on:** March 09, 2010, 07:01:42 PM »

Use real sharp scissors. I have a pair I reserve just for fiberglass. Another word of advice; "overlap". Apply a neat, light coat of epoxy. End in a straight edge if that is what you want. Let the fiberglass overlap the edge. When it cures, a couple of swipes of 400 sandpaper will cut through the excess fiberglass and leave a nice edge. Use Z-poxy brand if you can get it. Apply a second coat of epoxy as desired.

Larry Fulwider · « **Reply #4 on:** March 10, 2010, 06:05:38 AM »

Quote from: paul allen on March 09, 2010, 04:03:01 PM

guy's
Ready to glass the nose of the Vector with .5 cloth, my question is
how to stop the strands from pulling when appling the cloth? Cut out the
piece nice and square over newspaper, no matter how careful it never
keeps the nice straight edge across the fus in front of the wing.
I saw a reference to hairspray somewhere re fibreglass?
Thanks
Paul

http://stunthanger.com/smf/index.php?topic=15123.0

After I posted this, I tried the hairspray not on fiberglass, but cloth hinges. The hairspray worked fine on the hinge material, no fraying at all, kept the fiber orientation correct.

I would probably still use the "school glue" technique for fiberglass. Totally eliminates fraying.

Larry Fulwider

Ward Van Duzer · « **Reply #5 on:** April 14, 2010, 07:45:28 AM »

Pete's "Real sharp scissors"...

Get them in a sewing, or material store. Don't be cheap! These are for cutting silk or F/G weave ONLY! Never cut paper or cardboard. (Don't use hers, you'll get a raft .. .......)!

W.

john e. holliday · « **Reply #6 on:** April 15, 2010, 05:15:14 PM »

When you go to your sewing/fabric store to get those extra sharp scissors, don't forget to get the sharpener for scissors. I use mine quite a bit when cutting glass, silk, nylon, monokote and the polyester fabrics.

Bill Little · « **Reply #7 on:** April 26, 2010, 12:17:43 PM »

Not fiberglass, but for cloth hinges, a light coat of dope to the fabric keeps everything straight until you *glue* them down, either with cement,thinner, or dope.

Mongo

Brett Buck · « **Reply #8 on:** April 26, 2010, 05:43:17 PM »

Quote from: Ward Van Duzer on April 14, 2010, 07:45:28 AM

Pete's "Real sharp scissors"...

Don't use scissors, use rotary cutters:

http://www.threadsmagazine.com/item/4981/rotary-cutters-and-mats

Brett

Bill Little · « **Reply #9 on:** May 05, 2010, 10:57:10 AM »

A *little* late, but I re-read th epost and remembered/thought of something (oh no!!!).........

I leave the piece oversize when it comes to hanging down below the fuse sides. It is super easy to trim it away on the bottom corners of the cowl opening, etc,. if that is a problem.....

Big Bear

Allan Perret · « **Reply #10 on:** May 05, 2010, 02:27:52 PM »

Quote from: Pete Cunha on March 09, 2010, 07:01:42 PM

Use real sharp scissors. I have a pair I reserve just for fiberglass. Another word of advice; "overlap". Apply a neat, light coat of epoxy. End in a straight edge if that is what you want. Let the fiberglass overlap the edge. When it cures, a couple of swipes of 400 sandpaper will cut through the excess fiberglass and leave a nice edge. Use Z-poxy brand if you can get it. Apply a second coat of epoxy as desired.

Just how light do you do the first coat. For applying balsa skins on foam cores I read where they scrape off as much as they can with credit card or wipe off with paper towels. Is that what you do for your 1st coat in prep for fiberglassing ? What about the 2nd coat after putting on the glass, how do you apply it. Do you fill the weave of the glass with the epoxy, or switch to dope/filler because of weight ?

Steve Helmick · « **Reply #11 on:** May 05, 2010, 07:30:28 PM »

Tape can also work nicely when cutting the FG cloth. Apply the tape where you want, and cut down the centerline of the tape, leaving both edges pretty clean and tidy.

A very useful trick is to start by first lay a single layer of masking tape or electrical tape where you want the FG to stop (high point of the wing, or just outboard of the wing/fuse fillets, for example). Once the epoxy is hard, sand the FG down adjacent to the tape, until you get a nice trimmed edge at the tape edge. Better than having a few loose strands of glass glued to that soft balsa, where you'll get sanding divots.

I lay the FG on the surface dry, pull it snug, then flow on the epoxy. I think I've used the Z-poxy, but have also used various 30 minute types thinned with alcohol (shellac thinner). Blot up the excess with a roll of TP, disposing of the TP as it gets soaked. Don't f'get to clean off the surface wax with a cleaning solvent (Naptha, etc.). If you sand FG cloth too aggressively, you'll cut the strands, making for a hard surface...but without the strength you want.

Steve

Allan Perret · « **Reply #12 on:** May 05, 2010, 07:46:13 PM »

Quote from: Steve Helmick on May 05, 2010, 07:30:28 PM

Tape can also work nicely when cutting the FG cloth. Apply the tape where you want, and cut down the centerline of the tape, leaving both edges pretty clean and tidy.

A very useful trick is to start by first lay a single layer of masking tape or electrical tape where you want the FG to stop (high point of the wing, or just outboard of the wing/fuse fillets, for example). Once the epoxy is hard, sand the FG down adjacent to the tape, until you get a nice trimmed edge at the tape edge. Better than having a few loose strands of glass glued to that soft balsa, where you'll get sanding divots.

I lay the FG on the surface dry, pull it snug, then flow on the epoxy. I think I've used the Z-poxy, but have also used various 30 minute types thinned with alcohol (shellac thinner). Blot up the excess with a roll of TP, disposing of the TP as it gets soaked. Don't f'get to clean off the surface wax with a cleaning solvent (Naptha, etc.). If you sand FG cloth too aggressively, you'll cut the strands, making for a hard surface...but without the strength you want. Steve

On the tape method for cutting, what happens when you remove the tape? Doesnt that cause a bunch of loose / frayed ends..

"Don't f'get to clean off the surface wax with a cleaning solvent" What wax, where does that come from ?

john e. holliday · « **Reply #13 on:** May 06, 2010, 08:29:07 AM »

It is something that happens as the epoxy cures.

Brett Buck · « **Reply #14 on:** May 07, 2010, 10:30:14 AM »

Quote from: Allan Perret on May 05, 2010, 07:46:13 PM

"Don't f'get to clean off the surface wax with a cleaning solvent" What wax, where does that come from ?

It's the filler material that makes the mix 1:1 (or 2:1). Unfilled epoxies don't have that.

Brett

Neville Legg · « **Reply #15 on:** May 08, 2010, 11:29:26 AM »

Don't forget to pour the epoxy down the middle of the work, then with an old credit card, spread the epoxy to the edges. This way you shouldn't get wrinkles in the cloth!

Cheers Neville

Steve Helmick · « **Reply #16 on:** May 08, 2010, 04:41:54 PM »

"On the tape method for cutting, what happens when you remove the tape? Doesnt that cause a bunch of loose / frayed ends.."

The tape leftovers would be in the surplus you trim off after the epoxy has setup. What's left on the big sheet of cloth...leave it alone until time to FG the next model, and work from there. Leave plenty of surplus. FG cloth is cheap...this isn't a good place to try to save ten cents.

Steve

Pinecone · « **Reply #17 on:** May 10, 2010, 12:30:21 PM »

Epoxies don't have wax. Polyester fiberglass resins have wax in them for finish coats. Humidity in the air prevents polyester from fully curing, leaving a tacky surface. Good for laminating, but not good for the top layer.

Epoxies can cure leaving an amine blush on the surface that needds to be removed. The amine blush can be sanded off or removed witha Scotchbrite pad with water.

Do NOT try to sand polyester finishing resin without removing the wax first, or you will drive wax into the sanding roughness.

Allan Perret · « **Reply #18 on:** May 12, 2010, 12:03:23 PM »

When adding fiberglass to gain structual strength , either on the nose or across the center section of a foam core wing, do you think you can achieve the same strength using nitrate dope versus the finishing resin ? If not the same strength as the epoxy resin, would it still be sufficient strength ?

Steve Helmick · « **Reply #19 on:** May 12, 2010, 09:35:38 PM »

Quote from: Allan Perret on May 12, 2010, 12:03:23 PM

When adding fiberglass to gain structual strength , either on the nose or across the center section of a foam core wing, do you think you can achieve the same strength using nitrate dope versus the finishing resin ? If not the same strength as the epoxy resin, would it still be sufficient strength ?

Absolutely....NOT! It's essential to bond to the structure and to isolate each fiber from it's neighbors. That's what the various resins are designed to do. Epoxy is much more user friendly than Polyester, FWIW, and has a much better shelf life. Cheaper? No, but yes, in the long term sense, for most of us. Much less fire hazard, but not without some risks. Handle with care (vinyl gloves).

Steve

Paul Allen · « **Reply #20 on:** May 16, 2010, 08:13:27 PM »

Guy's
Have been slow in updating what I did,used Pete Cunha suggestion and masked
up a straight line at wing leading edge, glass went on no problem with neat blend line.
Should be a photo.
Paul Allen