Getting a smooth surface with fibreglass  
View related threads: (in this forum | in all forums)

Tower Hobbies
Enter up to 4 keywords or Tower stock numbers
Logged in as Guest



Users viewing this topic: none
  Printable Version
       

All Forums >> RC Airplanes >> Composites Fabrication And Repair >> Getting a smooth surface with fibreglass
Page: [1] 2   next >   >>  

Login
Message << Older Topic   Newer Topic >>
Getting a smooth surface with fibreglass - 1/4/2004 3:19:51 PM   
English Electric


 

Posts: 17
Joined: 12/18/2003
From: London, UNITED KINGDOM
Status: offline 		I have just covered the aircraft I am constructing with fibreglass and the associated polyester resin and hardener. I now need to create a smooth surface, due to the set fibreglass is course. The back of the package which the fibreglass and the complement products came in, suggests filler (plastic padding), which can be glasspapered smooth. I cannot help thinking that this will consume a great deal of time and money. Is it possible to just sand down the fibreglass as it is, without having to add any further material?
       Post #: 1

RE: Getting a smooth surface with fibreglass - 1/4/2004 6:59:31 PM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		Yes, you can sand the lumps down. Basically, you'll be reducing the strength by cutting up all the glass fibers into short pieces, but it's quite likely the structure is already strong enough. You can also use one of the lightweight fillers, often sold at home DIY centers as "lightweight spackle" for fixing holes in walls. You can spread this on with a broad spatula and then sand it smooth after it has dried. Then prime and paint as desired.

-David

(in reply to English Electric)
       Post #: 2

RE: Getting a smooth surface with fibreglass - 1/4/2004 7:23:58 PM   
3dd



Posts: 883
Joined: 12/16/2002
From: pyote, TX, USA
Status: offline 		you don't say how many coats of resin you put on but i like to put my cloth on with one thinned layer of resin then put on one coat of unthinned resin and sand this with 300 wet and dry paper to get a smooth surface that is not to heavy.then fill any little dings with a patch of resin only with micro ballons in it and sand that to a glass like finish

(in reply to davidfee)
       Post #: 3

RE: Getting a smooth surface with fibreglass - 1/4/2004 8:07:06 PM   
English Electric


 

Posts: 17
Joined: 12/18/2003
From: London, UNITED KINGDOM
Status: offline 		Thank you for your replies. They are most useful. I will probably apply a standard paste, regardless of the time it will take.

(in reply to 3dd)
       Post #: 4

RE: Getting a smooth surface with fibreglass - 1/5/2004 4:44:59 PM   
RCHYFLYER



Posts: 279
Joined: 4/29/2003
From: Sykesville, MD, USA
Status: offline 		I'm getting ready to glass my cessna with West System resin and .75oz cloth. I am looking at doing one coat to hold the cloth down and then finish with evercoate top coat filler. Do you think this will work or will it be too hvy?

_____________________________

RADIAL ENGINES DON'T LEAK OIL, THEY ARE JUST MARKING THEIR TERRITORY!

(in reply to English Electric)
       Post #: 5

RE: Getting a smooth surface with fibreglass - 1/6/2004 12:30:51 AM   
Jetman007



Posts: 294
Joined: 1/7/2002
From: Spring Lake, MI, USA
Status: offline 		Here's one tried and true way

http://artshobby.com/fiberglassing.htm

_____________________________

Art Gajewski

(in reply to RCHYFLYER)
       Post #: 6

RE: Getting a smooth surface with fibreglass - 1/6/2004 1:10:27 AM   
CAPtain232



Posts: 2467
Joined: 12/15/2001
From: Waynetown, IN, USA
Status: offline 		Hey guys,

i have used the technique as described in ART's article with good results. After a good paint job, the surfaces are a slick as glass

_____________________________

CUSTOM GIANT SCALE BUILDER
PROTOTYPE MODEL BUILDING for full scale aircraft
current project can be seen at http://www.geversaircraft.com

(in reply to Jetman007)
       Post #: 7

RE: Getting a smooth surface with fibreglass - 1/6/2004 1:53:47 PM   
English Electric


 

Posts: 17
Joined: 12/18/2003
From: London, UNITED KINGDOM
Status: offline 		It is fine for those who are using the mysterious 'Z-Poxy Finishing Resin', but for those of us who are not, it does not help. Furthermore, there is absolutely no way the instructions are substantial enough to undertake the task in hand. If I even attempted to follow them, I would have one project ready for a scrapping order.

I will just have to use car filler paste over the rough fibreglass surface and sand it to a smooth finish, regardless of how much time it will really take.

(in reply to CAPtain232)
       Post #: 8

RE: Getting a smooth surface with fibreglass - 1/7/2004 8:25:00 AM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		Z-Poxy is nothing more than a reasonably good low viscosity epoxy, similar to most laminating epoxy resins. It just happens to be sold to modellers in a convenient small package, unlike most good epoxies (which are sold by the gallon).

As for the sanding and filling, what weight of fiberglass did you use? It should be a light glass with a fine weave, so there should not be much filling or sanding to do really. A lot of guys seem to like applying a wet coat of resin to fill the weave, but resin is fairly heavy and it's not particularly strong... so in my mind it's wasted weight. But whatever. If the glass is fine then my suggestion would be to sand it smooth and if there are any dry spots or deep wood grain, fill those with spot putty or lightweight wall spackle as needed. There should be no "Bondo" car body filler on your airplane (very heavy)! After the largest bumps have been sanded down, then spray on a high bulk "sandable" primer... and when dry, sand back down to the glass so the primer just fills the low spots remaining in the weave. Repeat until satisfied with surface, then paint as desired.

One of the best tips anyone can give is to try any new technique or material on a piece of scrap... not on your pride and joy. Patience here will really pay off.

-David

(in reply to English Electric)
       Post #: 9

RE: Getting a smooth surface with fibreglass - 1/7/2004 2:16:00 PM   
English Electric


 

Posts: 17
Joined: 12/18/2003
From: London, UNITED KINGDOM
Status: offline 		Purely out of interest, may I ask which fibreglass is generally stronger - fine weave or course weave? Personally I would have thought the latter was the stronger (myself having used it on several vehicle tasks).

(in reply to davidfee)
       Post #: 10

RE: Getting a smooth surface with fibreglass - 1/7/2004 5:55:18 PM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		If the fiberglass cloths you're comparing are essentially the same weight (oz/yard^2 or grams/m^2) then there should be only a small difference, if any, in the relative strengths of the two. The coarser weave will have larger yarns, so it might have greater bending stiffness in a flat piece, but the finer weave will result in a torsionally stiffer finished panel because the fibers are more straight... curving less around the other yarns. If you're comparing different weights of glass, then the heavier one will obviously be stronger.

-David

< Message edited by davidfee -- 1/7/2004 7:34:19 PM >

(in reply to English Electric)
       Post #: 11

RE: Getting a smooth surface with fibreglass - 1/8/2004 3:11:32 AM   
newbiepilot


 

Posts: 89
Joined: 12/29/2003
From: , BC,
Status: offline 		Hi guys,
Just reading the posts here, and I was wondering, what is spackle?
Thanks for the info.

(in reply to davidfee)
       Post #: 12

RE: Getting a smooth surface with fibreglass - 1/8/2004 3:13:24 AM   
newbiepilot


 

Posts: 89
Joined: 12/29/2003
From: , BC,
Status: offline 		Oh yeah,
And does anybody know where you can get "Z-Poxy" ?
Thanks.

(in reply to newbiepilot)
       Post #: 13

RE: Getting a smooth surface with fibreglass - 1/8/2004 3:44:12 AM   
davidfee



Posts: 691
Joined: 6/21/2003
From: San Diego, CA, USA
Status: offline 		Spackle is the putty you fill pinholes in your walls with (in your house) before painting. Lightweight spackle usually has microbaloons (tiny glass bubbles) in it and it is very light. Bondo, by contrast, is filled with solid glass bits... and is relatively heavy. They use it on cars to fix dents.

Z-poxy should be available at most hobby shops, or from Tower Hobbies, etc.

-David

< Message edited by davidfee -- 1/8/2004 3:42:27 AM >

(in reply to newbiepilot)
       Post #: 14

RE: Getting a smooth surface with fibreglass - 1/8/2004 2:55:03 PM   
hnesitd1



Posts: 206
Joined: 12/16/2002
From: Halifax, NS, CANADA
Status: offline 		davidfee - great info. What ratio of microballoons/epoxy would you recommend for filling 3/4 oz cloth (if necessary). What ratio for forming fillets. Thanks.

_____________________________

What has four legs and an arm? A happy pit bull -Doc Hemp (2006)

(in reply to davidfee)
       Post #: 15

RE: Getting a smooth surface with fibreglass - 1/8/2004 3:12:09 PM   
hnesitd1



Posts: 206
Joined: 12/16/2002
From: Halifax, NS, CANADA
Status: offline 		Davidfee - I've always assumed that Poly Resin has a very strong smell, ie, not good for covering glass fiber in a basement enviroment, eh? Isn't Z-Poxy, poly resin? Has the smell been removed; can this stuff be used indoors or should a person invest in epoxy resins? Your reply would be appreciated.........thanks.

_____________________________

What has four legs and an arm? A happy pit bull -Doc Hemp (2006)

(in reply to hnesitd1)