How to repair GEL coat?
Thanks
Bill
A few pictures of the affected area inside and out would help in deciding what may or may not be needed.
Thanks Bill
Local Hobby Store brands work just as good at about 1/2 to 3/4 the price.
http://www3.towerhobbies.com/cgi-bin...?&I=LXCX58&P=0
I run a Glider repair business in Australia R/T AIRCRAFT SERVICES we specialize in composite repairs.<o></o>
It looks like the basic matrix structure is damaged around the undercarriage mounts.<o></o>
I can give you the information to repair your model or if there is a glider repair place close to where you live drop in and see them. We repair model aircraft and it usually works out cheaper for us to do it than <o></o>
The owner to repair it themselves, mainly because we have all the materials in stock but we are also happy to sell the small quantities to them with the free advice and we also give them a Photostat copy of the relevant parts of the Manual of Repairs. You can also get the materials from Home build aircraft suppliers in small quantities.<o></o>
As far as the exterior surface damage you need to sand the damaged paint work back being very careful not to damage the underlying glass epoxy structure. I would suggest you repaint the area with a polyurethane system we use DULUX highfill as the undercoat; I don’t know what is available in the USA. Go to a local motor vehicle repair place and they can supply you with all the paints and mix the colors to match. Hope this helps and if you need advice on structure repair I am quite happy to write them out for you. As far as gel coat repairs it’s a bugger to do on such small areas and the models we’ve repaired we’ve always used polyurethane Paint. With Gel coat you need to paint thin layers to stop pin holes and then spend hours sanding it back smooth with gradually finer wet and dry paper then polish it hoping you don’t go too far and have to start again. <o></o>
All the best <o></o>
Rachael <o></o>
Thanks
Bill
the jell coat is not very strong itself but when it is stuck to the matrix material it adds quite a bit. It is really hard to get chopped fibers commonly used for filler to be strong enough to prevent future cracks. Also be sure to end any joining cracks with a drilled hole. If you don't it will crack down the road. Most of the time "down the road" doesn't happen in models as their life time is too short. haha
We don't even class chopped strand mat as structural.
Ifyour giveing out advice Know what your talking about first.
Sorry mate but I've seen so much stupid information posted under this Forum it just got my goat so you've copped it.
REALY PEOPLE Before advising somebody don't if your not an expert on the matter.
ALLTHEBEST
Rachael
R/TAIRCRAFTSERVICES
Sailplane Repairs
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Composite, Wood, Metal Sheet & Tube
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For cosmetic repairs on the outside epoxy and micro-balloons make a nice filler and sands fairly easily, then just paint it up and your good to go.
To fix it right this is a bit of a project, it's going to requiring a lot of sanding and time on your part to fix it right.
.....Allow each layer you use to cure completely before you add the next layer.
Perhaps someone who works on a regular basis with composites could correct me if I am wrong.
I'd think as you do that a molecular bond would be stronger myself, but like I said I read that it is an issue with the "cure".
The calculation for joining dry joints is the strength of the cloth divided by the strength of the Epoxy.
E type Glass cloth is 55000 Lbs per square inch and epoxy 10,000 Lbs per square inch. Hence if you repair a crack you allow 3/8" per layerin a tapered scarf joint
if 2 layers taper the edges 3/4" 1st layer goes out the whole3/4" next layer is cut 3/8" smaller wet on wet.In an ideal layup the epoxy should weight the same as the cloth used."Ideal world"
temprature plays a part also, after solidification the layup should be held at a temp. of about 50c for 12 hours.
Gets involved but a model hasn't got a person in it so a bit of fudging will not hurt to much.
ALLTHEBEST
Rachael
PS If I get the time I may post a set of instructions on how to repair differant types of damage in area's Skins Gear Mounts Bulkhead attachment etc.
It is my understanding that it will adversely affect the curing of the next layer, I could be wrong I recall seeing something that said that it was an issue.
Perhaps someone who works on a regular basis with composites could correct me if I am wrong.
I'd think as you do that a molecular bond would be stronger myself, but like I said I read that it is an issue with the "cure".
It is my understanding that it will adversely affect the curing of the next layer, I could be wrong I recall seeing something that said that it was an issue.
Perhaps someone who works on a regular basis with composites could correct me if I am wrong.
I'd think as you do that a molecular bond would be stronger myself, but like I said I read that it is an issue with the "cure".
Mrs R, wouldn't a glass layup that has a 50:50 ratio by weight be very resin rich? That translates to a 30 (fiber):70 (resin) ratio by volume which is pretty poor. We typically get 65:35 ratio by weight (44:56 by volume) with e-glass.
I have only done fairly thick layups so far and have not done a model using that much composite material yet. Most of my use of composite materials have been for repairs not for actual construction and it has held up well. I have used carbon fiber veil and it has worked out well for what I was using it for. I am looking at doing a model in the near future that will be mainly composite construction and am glad to have input on the process.
Bob
This is in an Ideal World but on repairs of model aircraft even we can not achieve and that is a layer of peelply with an absorbent under vaccum.
KNDREGARDS
Rachael
My post stated that the weight "NOTVOLUME" of resin should equal to the weight of the cloth in these thin lightweight layups.
This is in an Ideal World but on repairs of model aircraft even we can not achieve and that is a layer of peelply with an absorbent under vaccum.
KNDREGARDS
Rachael