COPYCAT

HEY GUYS I NEED HELP .I HAVE AN OLD FUSE (15 YRS OLD ) WHICH IS NOT MADE ANYMORE CAN I MAKE
A COPY OF THE FUSE WITHOUT DESTROYING IT,AND IF SO WHAT CAN I USE ON THE INSIDE SO THAT
WHEN I LAY IT UP IT DOES NOT CAVE,KEEP IN MIND I DO NOT WANT TO DAMAGE THE FUSE.
I WELCOME ANY ADVICE.

seanreit

My Feedback: (60)

Try the search function. Of all the questions that get asked in this forum, your question is the one that comes up most often. Read everything you can so that you can ask more intelligent questions.

To answer yours, yes, it's possible to make a copy. Usually the "plug" or "old fuse" is destroyed in the process as sacrificial to the process. To do this right you are going to spend somewhere near $2,000 for the right materials, development of the new empty fuse etc. This is not a two hundred dollar process, especially if it's your first time.

I always tell first timers, that this needs to be one of your passions in the hobby to really get into composites. It's the only way you'll come up with something you can truly be proud of.

Here's a picture of my copy of a BVMJets.com Bobcat XL, my first try at cloning a fuse. I've gotten better over time, but that was not a cheap process, and still not near what I can churn out today two years later.

Ed Smith

Many, Many years ago I had an airplane that I truly enjoyed built from a kit. It met the usual end. The fuselage was a glass fuselage. To fix it to make it flyable would have added too much weight. So I decided to fix it to make a plug. This was very early in my glass work experience. Two pounds of glass and filler later I had a plug. From it I made molds, somewhat crude compared to the molds I make today.

The first picture shows parts from the mold. The second the airplane ready to prime, the third picture the finished wheelpants.

As Seanriet says there is a long learning curve. Ask lots of questions and listen only to those that are actualy doing it.

Ed S

jnp

I have made several moulds over the past years (30 years - started making moulds when I was still at school) . I currently busy with a F3a patternship and must admit tend to agree that you may have to sacrific the orginal . The most important thing to me is too make sure the plug is absolulety perfect before making a mould - so ... preparing the plug is vital . You will not catch me making a mould from a plug that has defects or imperfections . I use P/U expandable foam ( not the type you buy in the hardware !!) store to fill the fuselage ( to make it rigid ) . from there I will take out imperfections using light weight auto filler etc to get the desired surfaces. Dont be put off by making moulds .... it is a lot of hard work but most satisfying to see a perfect mould and making your own parts ....most of the time even better than the original !!

COPYCAT

THANK YOU FOR ALL YOUR INFORMATION I THINK I WILL HAVR TO FILL THE FUSE WITH FOAM TO GET IT
RIGID .JNP SAID NOT TO USE THE FOAM FROM THE HARDWARE STORE.COULD YOU GIVE ME THE NAME
OF ONE I COULD USE THAT COULD BE PURCHASED IN USA.

jnp

Hi Copycat , my supplier says the product is called FOAM-IT manufactured by SMOOTH-ON INC in the USA . Being imported into South Africa it is expensive but worth every rand ...or should I rather say Dollar!

Best is to mix small volumes at a time . I use a styrene cup to mix it in filling appox 1/3 of the cup ( volume of the 2 parts together ) at a time . When pouring it onto the part try to cover the surface only with an as light as possible layer buy "rolling" the part whist the foam is in liquid form. I then build it thicker untill I am happy with the stiffness of the part . You dont have to fill it completely . I did so because I had to buy 5 litres (smallest qty available)-and its was going to waste eventually as it has a shelf life .

Do not be tempted to use the air drying hardware variety . Believe me I have tried it , paid the price and have the T-shirt !! . Once I pumped into a Carl Goldberg Finesse fuselage and it kept on expanding for days on end - had to hack it out to avoid it turning the fuselage into that of a GEE BEE !!

Brgds
Juan

TeamSeacats

http://www.shopmaninc.com/foam.html

http://www.fiberglasssupply.com/Prod...pour_foam.html

http://www.fibreglast.com/showproduc...-Foam-156.html

http://www.aircraftspruce.com/menus/cm/foam.html

crow

hi,

as here is already this thread i join and look for some help dublicating old fuse. my firend has this nice little sailplane and i`d like to have one as well. Its already glass fuse and needs some minor sanding.
Is it absolutely necessary to ruin original fuse to make a mold of it? Isn`t it like makeing a mold of any plug, just more wax and should come off easely? Of course all the existing holes need to be closed, stab, rudder removed etc.

brgd
Crow

jnp

Hi Crow , you can try it if the fuselage is stiff enough ( does not dent easily ) . I have just this week finished the mould of the belly pan that you see on the photos that I posted . As the one corner was tricky to get out I destroyed the plug ( original ) . In the 30 odd years (started doing moulds as a kid) that I have been doing it I have never used the originals . I prefer to use original , take out imperfections , block it properly .If it is a choice between a good mould and using the original again , I go for a good mould .

To give you an idea , the kit of the plane that I am doing now is worth approx $1000.00 - I will not use the original fuselage again .

You will also find that original fuselage that you have may have quite a few imperfection - this you dont want in the mould . If it is not a very expensive kit , it is most likely made from inexpensive materials ( possibly polyester resin ) - not worth the worry

Good luck , if you need help let me know - I still have 6 sections to make ( can take photos and post it ), including the fuselage - have made moulds for wheel spats and belly pan thus far . I tend to work slow as I believe the plug must be perfect

Brgrds
Juan

crow

Thanks JPN

The fuse is regular glass and a good coat of paint on it, i don`t think it dents easily. But as i read between the lines, your suggestion is not to use original because i most likely ruin it, yes? Next question is if i ruin it, will the mold still be usable?

Please let the photos come of your building process. Any information needed, And as stated earlier, one pic is worth of thousand words.

brgd
Crow

Ed Smith

I have used old fuselages to make a plug several times. The old fuselage/plug should be finished to exactly the required configuration and surface finish that will be required on the molded part. There is no stress applied to the plug during the mold making procedure, at least there should not be. However the plug, if a little fragile, can be destroyed when removing it from the mold. The mold will still be usable as it will be an exact representation of the plug it surrounded. This is why it is absolutely essential to get the plug right.

Ed S

jnp

Hi Crow , I agree with Ed , there is no big pressure on the plug whilst being moulded . I will take some photos and post it so soon as I am ready to mould again ( unfortunately I work very slow ...only weekends and have been busy with it for three months now ).

In the meantime you should start finishing the plug ..most important and time consuming .

1) make sure original fuselage rigid enough ...if not, reinforce in the inside ( this on its own will add weight etc which will make the original fuselage not useabe...dont worry about
this)

2) close all the holes , eg where canopy fits onto fuselage .

Brgds
Juan

Note : you can also take photos , as you progess and I can tell what I think ....and others who may know a trick or two that I dont

crow

i will take the pics when i start with the fuse. Got green light from the owner of the plane, no problem if original will be destroyed. Within few days i`m gonna finish the cowl i started and next thing will be fuse.

crow

jnp

If i understand you right you are busy doing a cowl for another plane ? Good to start with small part . Post some photos and lets see what it looks like . what type of resin are you using for the mould ? Epoxy or polyester ?

crow

HI

Yes building cowl for my extra, and as you noticed this is a good start to practice. I`ve done wheelpants for my extra. these turned out well, so i´m moving to bigger parts step by step.
I`ll take some pics of cowl plug tomorrow. It is almost finished, needs some polishing.
The wheepants mold was done with polyester. But guy who is producing sailplanes here said not to mess around with it and go for epoxy. So epoxy has ordered and should get it within few days. As from bad side, epoxy costs to me but polyester, so as wax was free, i got it from yacht building company.

crow

crow

hi,

here are the pics of cowl plug for extra300s. Almost finished. Start to wax it today.

crow

jnp

Hi Crow , that looks pretty good neat and no imperfections etc - to me that is 90% of the art - making a mould any fool can do . Epoxy moulds are the way to go .

I see you polish the plug to high gloss . I used to do this but these days I dont . I dont even paint it with a top coat gloss paint . I stop with automotive undercoat finish - sanded to 600grit - making it smooth with no imperfections. Reason for this is that once I have made part I am going to lightly sand in any event and apply more undercoat and want the surface not to be too smooth .

If you are going into the mould with gel coat and it being the final finish then polish to high gloss is the way to go

I worked on the splitter board for the "t caniliser"of my plane last night - will try to mould again on Wednesday - will take a picture and send it to you.

Brgds
juan

Ed Smith

I guess that is why I sometimes have problems. I am not a "Fool"

The gloss finish on a plug and subsequently in the mold is not purely cosmetic. A high gloss finish in the mold allows easier release of the molded part. Try and glue something to a high gloss finish on anything.

Ed S

jnp

Hi Ed , your message well noted . Must admit gloss or no gloss I dont have problems , but then again I use mould release polish ( which some people use as the release agent only ) and I still apply a liquid wax release agent over and above the polish - have never had parts sticking.

My first moulds were gloss but new moulds I prefer the more "matt "mould . What I also do is paint some automotive primer in the mould before moulding ...use it as my
"gel coat" . This I clean , sand lightly before painting the part .

crow

allright,

gel-coat on. now have to wait until it drys a bit and then start to cover with glass.

crow

Ed Smith

For the first couple of layers of cloth use a lightweight cloth, say no heavier than 2 oz. The cloth will then go around the corners better. This will prevent cavities between the gelcoat and outer cloth. The last thing tyou want is a lump of gelcoat to come ot of the mold with the part.

Ed S

diggs_74

Been there, done that It's sucks but in most cases it can be repaired but it's best to do it right the first time..

crow

...seems gelcoat needs more time to dry then i assumed. Anyway gonna cover tomorrow. I tought i just put one layer of light cloth and then mat.

Do you guys know what would be the best sequence to lay up this cowl? I planned to cover the top first with one piece and then a´2" strips lenghtways all around. Am i on the right way?


brgd
Crow

jnp

Hi crow , looks good nothing wrong with that . The Gel coat I use , takes approx 1 hour and then it is dry enough for me to lay up the mould . Will take photos of the T caniliser I am busy with tonight and post it tomorrow when I get to the office . That mould I lay up with 4 x 168g cloth and 4 x 290g cloth . Before I lay up the cloth I also use a mixture of cotton flocks and resin over the gel coat which helps to avoid bubbles in sharp corners

When I am finished laying up the mould I also use "peel ply" nylon type material that gets pulled off when dry - it gives the mould a nice smooth finish with no sharp edges to cut your hands when working with the mould later


I noticed that you were going to leave the gel coat to dry and continue later with the lay up ......maybe Ed can give his input here also but to my knowledge you do no want the gel coat to dry 100% before starting to lay the mould up . As memtioned before - 1 hr ( in south africa where is warm 19 degC to 25 deg C ) is enough - must still be slightly tacky

If you do a big job or get caught with time ( as I did with 27% extra 300 fuselage ), best to do is lay up one or two light lay- ups over the gel coat - then peel ply - leave to dry - pull off peel ply next day and now you have a surface that you can use to continue laying up the mould . If you have left the gel coat to dry 100% before starting the lay-up , I would sand it very rough ( 60 grit ) , put another light coat of gel coat and then start the lay- up process.

brgrds
Juan

TeamSeacats

If you actually used gelcoat and leave it sit for more than an hour or two before top coating with something else, you will not get a good cure and it will remain soft. If you are talking about tinted epoxy then you're OK. Ideally though, whatever you are using, it is better to attach the supporting layers of cloth and resin before the gelcoat or epoxy coat cures completely so you get a really good bond (both polyester and epoxy resins have a wax or amine blush (respectively) that comes to the surface during cure that needs to be removed through sanding or cleaning thoroughly to achieve a decent secondary bond. If you begin your subsequent layup before it hardens, this layer continues to move to the outermost layer and you get a chemical bond with the coating. Polyester gelcoats (except for those that have additives) will not cure their outer layers when in contact with the air.