fibreglassing question

[eric]

This question is for all the glass experts out there, especially our resident float flying guru, Robert, as he's probably done this a thousand times. I was given a set of gorgeous 29" long x 4" wide floats this morning that were made by the late Walter Lawrence. They have been planked and sanded to perfection and only need fibreglassing and painting for completion.


My questions: What weight of cloth should I use and how many layers?
                      I have 20 minute finishing epoxy. Is that OK for applying the glass?
                      What order do you use, bottom, sides, then top?


Can you tell I've never done this before? Thanks for any assistance!


Eric

[piker]

Ooooo....  nice floats!

I'd use my standard 1.34oz tight weave cloth that I've used on my Sandringham and Macchi M-33.  Yes it's heavier than the 3/4oz stuff but easier to work with and I feel the tighter weave quality of it reduces the ratio of epoxy used, which is the area that the majority of the weight comes from.

I don't think you need any extra layers on the bottom, unless you plan on flying from grass, or plan on running up on the beach a lot.  One layer overall should be fine.

I would glass the bottoms first with the excess extending past the edges, then when cured, trim flush and cover the tops with one piece of glass per float.  It'll be tricky working around those spreaders though.  I don't suppose they're removable.  Again, extend past the edges and trim flush and sand.

You MAY want to start the whole process by applying a narrow strip around the bottom edge and in the step area, to tie the edges together since based on what I just described, there would be no glass over the seam otherwise.  Don't try to go around tight, outside, corners with the cloth.  It won't stay and you'll end up with an area of cloth that can only be trimmed off, leaving an uncovered area.

After glassing, and curing, sand the whole thing smooth (being careful not to cut through the fibres around the edges), fill any ugly bits (I use auto body scratch filler, which is heavy but o.k. if used in very little amounts), then I prime with filler, sandable primer.  I then sand that back down to the weave then paint.  Often I'll apply a final, light coat of primer then wet sand to glass smooth before painting.

Make sure your resign is very thin, like milk.  You can thin with acetone if needed.  I dab on with a foam brush and wipe off the excess with paper towel.  You want just enough resign to thoroughly wet the cloth, but no more.  No shiny spots.

[eric]

Thanks so much, Piker! Wow, that was fibreglassing 101 with a vengeance and answers everything I was unsure about. Those spreaders are just a press fit at the moment and easily slide out.


Now I've got another project when I finish the Norseman. I'm thinking of mounting the floats on the ancient 49" span, 2 1/2 lb Great Planes Sportster (see attachment) that I got from Greg Cadez and overhauled. You mentioned in one of your workshop talks that floats needed to be around 80% of the fuselage length. These floats are 30", so at 38" in length, the Sportster seems a good candidate and it'll be something a little different. I replaced the old can motor with a Power 15, so its pushing 130 watts/lb. That should be sufficient for some water goonage.


Thanks again,


Eric

[piker]

No problem, Eric.  Glad to help.

That plane on those floats would be very cool.  Very sporty 

[eric]

Hi Rob;


Dumb question here. You stated that I should use 1.34 oz cloth. I'm assuming you meant 1 3/4 oz cloth. Pinnacle sells 3/4, 2, 5 & 6 oz. They were out of 2 oz at the moment.


Where do you buy your glass from?


Eric

[piker]

No.  1.34oz.,  and that is about as heavy as I'd go.  The only reason I feel O.K. with that weight on smaller stuff, like your floats, is because it's a tight weave so uses less epoxy.  I originally got my cloth at Composites Canada, and more recently at plastics world.  if you can't find the tight weave stuff, I'd go with the 3/4oz stuff.  Your goal is mainly to seal the grain so it's stable for painting.  Maybe if I was using 3/4oz. I might double up on the bottom for wear resistance. 

[eric]

Cool; thanks for clearing that up. I have an entire package of 3/4 oz that I've never opened, so I'll double up on the bottom as you suggest and go from there.


Can't wait for float season now.


Eric

[piker]

Float flying season is going to be great next year!  Hopefully we'll have even more cool planes out... and I'm working on plans to control the wind   

[bweaver]

I was just about to begin a new Forum thread to ask these questions when I thought (hard to believe), maybe I should search the Forum for this information. (Press the 'Search' button above and type in the key words.)

I did the search and there it was.  What a great website...

The information is dated November 2014.  It may be out of date but is a great start.

Does anyone have anything to add. 

For example, I going to use Eze-Kote which is a 1 - part water based resin.  I understand it works great?

[sihinch]

I nearly always use Eze-Kote for my fiberglassing. Used it on my FlyFly Phantom and when building Nooners/Morphines.  I just use lots of coats - about 5 or 6.

Cheers,
S

[bweaver]

Thank you Simon.  It is always nice to know I'm on the right track.

[Frank v B]

Eric,

Two weeks ago David and I bought fibreglass cloth at Plastic World just north of Downsview airport. I believe it was $8.00 a square meter.

Frank

http://plasticworld.ca

[bweaver]

Eric,

Two weeks ago David and I bought fibreglass cloth at Plastic World just north of Downsview airport. I believe it was $8.00 a square meter.

Frank

http://plasticworld.ca

Just a suggestion Frank; it is often good idea when starting to read a post by checking out the date of the entry.   (Although, if Eric is anything like me, maybe it has taken him this long to get around to get the material he was thinking about using 5 years ago.  As many people often say, "Better late than never".)

[Frank v B]

Bruce,

Details, details.