Just finishing up the body mold (buck) for the C-cab, the framing is 2x1 pine and is covered with 1/8 ply, I noticed on the sides I could flex the ply slightly by pushing it with my finger, this got me thinking, when I fibreglass over, will it distort as it sets up? (I want flat sides not wavy) should I put more bracing behind the ply? would sealing the back of the ply with paint be of benefit? My plan was to 1. paint the ply with resin 2. put on a layer of woven mesh/mat and resin 3. a layer of cloth and resin 4. a layer of woven mesh/mat with resin. This will possibly be a 2 to 3 day process i.e. a layer a day. I would appreciate your thoughts on this. Sorry no photos, but in Projects and Builds - under C-cab build there's a shot of the frame taking shape.
Fibreglass help
- Thread starter phantom
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old round fart
Well-Known Member
A trick we use when 'glassing wings for RC airplanes is after applying the resin we put dress lining material over the glass and it works like peal-ply only cheaper. It peals right off and leaves a real slick finish. May save you a lot of work!
If I understand: you don't actually have a "mold", but rather a substructure that you'll build up fibergalss onto, to form a body? a quality fiberglass won't distort the wood to any significant degree as it dries, and it will need LOTS of sanding when the resin is cured anyway. what weight cloth do you plan to use? by "woven mesh/mat" do you mean roving? or mat? or simple cloth? I hope you have plenty of resin on hand cause this is gona take a LOT of resin to compleat a project of this size. I'd also concider not spreading the layup over that long a time period. if the resin is allowed to cure you're next layer won't bond well unless you sand it, and I sure wouldn't recomend doing it that way. I'd inlist some help and try to get it all layed up in one marathon day. that's gona be one heck of a big project for a first timer any way you look at it. make darn sure you have all your ducks in a row before you dump the mek in the first batch. where are you getting the resin from?
love those C cabs,
Russ
ellis8500
Member
Fiberglass/epoxy and fiberglass/polyester do not shrink nor expand as the resin cures. From your pictures I'm guessing that you plan to leave the plywood and some of the frame in-place after it all cures. If that is true, then your finished body will only be as flat as the buck is now. Painting the back side of the ply will not be of any benefit. Any flexure during application will not be a problem as long as it returns to its flat state while the resin is still wet. The hard part will be maintaining a flat surface with mat material. If fiberglassed a boat that I built from plywood and it worked well; but, I only used cloth.
I'm sure I'll get a fair amound of dissagreement on this, but I've owned several wood drift boats over the years, and always found that the glass bonded better to plywood if first coated with Polyurathane (or similar). you'd think the resin would grab ahold of the bare wood better, but my experience was much different. I could actually pop the cured glass off the bare wood (with some effort), but when coated first it would rip large chunks of wood out, along with the fiberglass.
your milage may vary,
Russ
your milage may vary,
Russ
ellis8500
Member
On the side of the wood that is glassed, it does need to coated first with the resin so that it soaks into the wood. I used epoxy [more expensive than polyester but much safer for the homebuilder] and after 12 year still looked as good as the day it was new. Also one can use different epoxies that are thinner/thicker and have different cure times. There are very good instructions available on the net for fiberglassing wood structures. The homebuild boat forums are good places to look for advice. Check out www.uscomposites.com
US Composits is where I get my glass and resin also. great company and products!
I've tried coating bare wood with just the resin first, but still had better results by initially coating the wood with polyurethane.
I live 2 miles from the Rogue River and my dad owned Marial lodge, down in the wild and scenic part, for 25 years (my cousin owns it now). I spent a lot of years running the lower Rogue in both drift boats and kayaks. I also made my own fiberglass whitewater kayaks (ya, that was before the tuppaware boats of today). anyway.... when you take a wood drigft boat down the lower Rogue you may hit a rock on the way :shrug: . When wood boats were being used commercially it was needed maintanence and std practice to reglass the bottom each season. what happens is when you hit a rock hard, it often delaminates the glass from the wood in that area. you may not even notice it except for the lighter color in that area (air pocket). if this happens near the edge of the glass, it continues to delaminate and let water in between the wood and the glass (and you can see where this is going). what I'm saying is that I've experimented a LOT with this and have real world experience with glass over wood, in very severe conditions. now you may not want to float your C cab down the lower Rogue River, but I'm just telling you what experience I had in the glass over wood thing, and what worked best for me.
Russ
Russ and Bill have obviously had moe experience and are very knowlegable on this subject. I have done my share of 'glass work and have a couple ideas for you.
Get your mat'ls from a boat manufacturer. I have saved around 40% bying this way. I would also suggest using matt over cloth. Cloth, for me at least, always seems to show thru somewhere.
I don't know how familair you are with 'glassing but I would take a piece of the plywood, add a couple ribs to it and cover it as a test pannel. You can develope a method of applying the resin in a vertical postion, work on getting airpockets out, etc. I have found adding a second layer the next day works if you sand the previous layer and brush on resin, add the matt and saturate it with more resin. On large flat pannels there is a roller that has pins or spikes on it that help level the glass out.
Ron
Get your mat'ls from a boat manufacturer. I have saved around 40% bying this way. I would also suggest using matt over cloth. Cloth, for me at least, always seems to show thru somewhere.
I don't know how familair you are with 'glassing but I would take a piece of the plywood, add a couple ribs to it and cover it as a test pannel. You can develope a method of applying the resin in a vertical postion, work on getting airpockets out, etc. I have found adding a second layer the next day works if you sand the previous layer and brush on resin, add the matt and saturate it with more resin. On large flat pannels there is a roller that has pins or spikes on it that help level the glass out.
Ron
Several years ago a friend at work(I'm no longer there)built a sports car kinda thing and he used florists foam with a cheese grater file to shape it to a rough size then finished it with a sander to the exact car he wanted.Then he laid his glass and resin over it to the thickness he wanted let it cure and then chipped out most of the foam then disolved the rest with acetone.Walla a light weight body to mount on your frame.There are two foams they use one is for absorbing water and the other if for arrangements DONT use the water one.Lumen Al also did an post on the same subject and he gave the name of the manufacture but i cant rember the name of them.I called them and they sold the blocks in sizes up to 4 foot square I THINK as i have crs.Hope this helps.
ruggs
Member
Just my 2 cents worth is that if I rough up the wood with a grinder (40 grit) before laying glass it bonds better. Since your doing a one off body and not working a mold it will never show. Another point is that if you are not using layup resin you need to rough up each layer and lightly wash with acetone to remove the wax to get a good bond between layers....only an opinion and alot of years.....Ron(ruggs)
old round fart
Well-Known Member
Laminating resin doesn't have the wax in it that comes to the top so you can put on a second layer without sanding, but it doesn't dry so you need finishing resin for the top coat.
ruggs
Member
ORFart, What you refer to as Laminating resin is what I am calling layup resin, same thing different terminology. Alot of people buy resin at someplace like Wal-mart and don't know the difference. Both resins will do the same thing just that one reqires a different approach........Ron(ruggs)
Thank you all for replying, I got helpful info from all. Just to answer some questions and a bit more info, yes most of the framing will remain, the matting here (Australia)is 450 grade the cloth I'm not sure, I brought 12 gallons (60lts) of resin, a roll of the matt and 1/2 roll of cloth at a good price from a guy who does pools. I've done a little fibreglassing before, but not as big as this job. Another concern is I would like to leave the framing on the chassis to glass it, as taking it off may cause it to go out of shape, the lower section of the body cuts in and then rolls under....any tips on making the matting and resin hold to a cut away and upside down surface?
Gerry
Well-Known Member
Whatever you do get a roller. They are available from suppliers. Without rollering the wet matt you will get air in there. Rollering the matt after its wetted makes a HUGE difference to quality and strength. And as a bonus you will find you need less resin than just trying to wet it down with a brush.
Gerry
Gerry
ruggs
Member
Les,
When you get to the point of finishing your fiberglass work (grinding sanding etc.) cover as much of your bare skin as possible. All of the exposed areas rub liquid fabric softner on and let dry. When your finished for the day ditch the clothes and go take a cool shower, then a warm or hot one. And while your working, If it itches don't scratch it!!!!
When I was only doing only corvette work I used to strip down and cover alot of my body with fabric softner redress and I was good to go for 8 hours.....Ron(ruggs)
When you get to the point of finishing your fiberglass work (grinding sanding etc.) cover as much of your bare skin as possible. All of the exposed areas rub liquid fabric softner on and let dry. When your finished for the day ditch the clothes and go take a cool shower, then a warm or hot one. And while your working, If it itches don't scratch it!!!!
When I was only doing only corvette work I used to strip down and cover alot of my body with fabric softner redress and I was good to go for 8 hours.....Ron(ruggs)
Mr. Fixit
Member
Here is an area that I can assist for whatever it is worth to you. You may want to reconsider the adhesion to your subrfame structure completely and think about creating a situation whereby you can remove all of the wood completely after the glass is completed. Since you are not seeking to make a mold from a plug, but rather use the plug for a one off part, you can do the following: Support the wood structure properly. If it easily flexes, brace it because as the resin (or epoxy) cures it does in fact shrink and pull. Sand out all of the rough areas of the wood, fill with polyester filler to acheive exactly what you are seeking as a final product. I always look at it and say "would this look good if I painted it now"? If you are happy with the overall shape, seal the wood with a coat of polyester resin. After a moderate cure, apply a second coat with styrene added, this is the surfacing wax that others have mentioned and it will permit a nice sanding without paper cloging. Don't go crazy here, just enough to lightly smooth out very rough areas. VERY IMPORTANT - NEVER MIX POLYESTER RESIN PRODUCTS WITH EPOXY PRODUCTS since they do not adhere to each other. After you are satisfied that the surface is sealed, spray several coats of PVA, or apply several good coats of mold release wax.
Now you can begin your layup process as planned and upon total completion and cure, you will be able to remove all of the wood since it will not be adhered to the glass work. I hope that this helps.. Just my 1 cent worth (it used to be 2 cents but due to the economic state here), well you know..
Now you can begin your layup process as planned and upon total completion and cure, you will be able to remove all of the wood since it will not be adhered to the glass work. I hope that this helps.. Just my 1 cent worth (it used to be 2 cents but due to the economic state here), well you know..
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