Epoxy


One Sky Dog
 

Dan,

For structural patches use EZ-poxy or Aeropoxy. 

For fairing the 105 is easier to sand and cures faster.

Regards,

Charlie


On Dec 5, 2018, at 6:34 AM, Earnest Martin MartinErni@... [Q-LIST] <Q-LIST@...> wrote:

Safe-t-poxy is now called EZ-poxy 

On Dec 4, 2018, at 10:46 PM, nitsudls1@... [Q-LIST] <Q-LIST@...> wrote:

 

I'm needing to buy some epoxy to do some patches on the fuselage, wing, and cowling. I understand the safe-t-poxy stuff is a thing of the past, so would the west coast 105 stuff be ok? I'm not sure how much heat the cowling gets.


As an update, I've got the tail cone mostly sanded down to bare fiberglass as well as the engine cowlings down to the UV barrier or primer. I work at Dynamic Aviation in Bridgewater, VA, and I was talking to one of the guys on the paint team about spraying paint over old primer. He was really skeptical about the idea, so I might go ahead and take the cowlings down to bare glass as well. I found it interesting that the cowling appears to be only one layer of glass thick! Wow. 


Dash panel is out as the old one was wood and kind of junky. I really like the layout though, so it'll just be a copy, past and cut activity for the most part.


Still haven't put he engine back together. Got four new exhaust valves from Revmaster and talked to Joe a couple of times. He wanted to see the compression lower as the stock configuration is 9.34:1. He said it was just a bit high for those engines and recommended adding some shims between the cylinder and head to get it down a little. 

Dustin Graber




ΕΔΔΥ . <overlordmustafa@...>
 

I've done many repairs on fibergass, I used to build RC models.
One great method to get a smooth final coat of glass is to get the absolute lightest fiberglass you can get your hands on.

After laying up whichever weight of glass (which most people use is rather a heavy weight, compared to what i'm used to using) you can place a layer of  0.5oz/sq ft  fiberglass as a top coat.  This adds virtually no weight, you don't have to add any epoxy. This 'trick' works significantly.  It's like getting strength at no extra weight.

If you're worried about sanding through the fiberglass you could add a layer of this light cloth.  Apply it differently than thicker cloth.  Brush on the thinnest layer of epoxy onto the fin then place the glass over the wet surface.  Slow cure is better over fast cure for this (I prefer slow cure over anything else).

So, if you're worried about digging though fibergass, this is an easy fix.  When you're done it's amazingly smooth.  You'll still need to sand it to get it perfect, but it's close to perfect.

You might want to even bump up the weights(of glass) a bit.  The lightest glass is so thin you can't move it around very easy when placing it (so be delicate when setting the glass down).  An advantage to using the extremely thin stuff is it goes around corners and bends like nobody's business.

Eddy


One Sky Dog
 

Hi Eddy,

This is a great technique for reducing print through of structural fabric weaves in molded epoxy parts. It works by trapping extra epoxy between the fine weave and the structural plies the stiffness of the glass compared to resin minimizes the surface shrinkage reducing print through.

Our goal on a repair is to scarf in and replace structural layers one for one , same weight same direction, slightly below the surface. Any fairing required should be done with a similar resin chemistry filled with glass micro balloons to reduce the epoxy weight and facilitate easier sanding prior to paint.

Grams count our power to weight ratio is way less than your RC models and our repairs can be bigger. I appreciate your thoughts and methods for model repair. Most of our guidance on repairs goes back to Burt Rutan and his pioneering work on mold less composite structures.

Regards,

Charlie Johnson


On Dec 5, 2018, at 9:42 AM, ΕΔΔΥ . overlordmustafa@... [Q-LIST] <Q-LIST@...> wrote:

I've done many repairs on fibergass, I used to build RC models.
One great method to get a smooth final coat of glass is to get the absolute lightest fiberglass you can get your hands on.

After laying up whichever weight of glass (which most people use is rather a heavy weight, compared to what i'm used to using) you can place a layer of  0.5oz/sq ft  fiberglass as a top coat.  This adds virtually no weight, you don't have to add any epoxy. This 'trick' works significantly.  It's like getting strength at no extra weight.

If you're worried about sanding through the fiberglass you could add a layer of this light cloth.  Apply it differently than thicker cloth.  Brush on the thinnest layer of epoxy onto the fin then place the glass over the wet surface.  Slow cure is better over fast cure for this (I prefer slow cure over anything else).

So, if you're worried about digging though fibergass, this is an easy fix.  When you're done it's amazingly smooth.  You'll still need to sand it to get it perfect, but it's close to perfect.

You might want to even bump up the weights(of glass) a bit.  The lightest glass is so thin you can't move it around very easy when placing it (so be delicate when setting the glass down).  An advantage to using the extremely thin stuff is it goes around corners and bends like nobody's business.

Eddy


ΕΔΔΥ . <overlordmustafa@...>
 

This technique I'm suggesting is not for molding, it's for placing over an are which has had a repair or even as a repair.

If you're worried microballons offer no strength, glass does.  The power ratio of the planes I've used this one is zero, it's for sailplanes and this method has a MUCH higher weight to strength ratio than using most weaves of glass.  I worry about weight WAY more than any homebuilder.  The trick to making fiberglass light and strong (lighter, it's fairly heavy) is to minimize the epoxy.  If you had an entire wing with a wet layup and added 1 layer of 0.5oz/yd^2 you'd end up with a much smoother wing without adding any epoxy.  It's free strength with virtually no added weight.  Although, this is a tangent. 

I'm just suggesting if someone is worried about sanding through a spot of fiberglass, this is a way of repairing without.  Realistically, if one uses fine sand paper, they will not compromise the structural integrity of the fin.  Sand carefully and there will not be any need for any repairs (and I'd certainly take off the primer).





On Wed, Dec 5, 2018 at 12:49 PM Charlie oneskydog@... [Q-LIST] <Q-LIST@...> wrote:
 

Hi Eddy,


This is a great technique for reducing print through of structural fabric weaves in molded epoxy parts. It works by trapping extra epoxy between the fine weave and the structural plies the stiffness of the glass compared to resin minimizes the surface shrinkage reducing print through.

Our goal on a repair is to scarf in and replace structural layers one for one , same weight same direction, slightly below the surface. Any fairing required should be done with a similar resin chemistry filled with glass micro balloons to reduce the epoxy weight and facilitate easier sanding prior to paint.

Grams count our power to weight ratio is way less than your RC models and our repairs can be bigger. I appreciate your thoughts and methods for model repair. Most of our guidance on repairs goes back to Burt Rutan and his pioneering work on mold less composite structures.

Regards,

Charlie Johnson


On Dec 5, 2018, at 9:42 AM, ΕΔΔΥ . overlordmustafa@... [Q-LIST] <Q-LIST@...> wrote:

I've done many repairs on fibergass, I used to build RC models.
One great method to get a smooth final coat of glass is to get the absolute lightest fiberglass you can get your hands on.

After laying up whichever weight of glass (which most people use is rather a heavy weight, compared to what i'm used to using) you can place a layer of  0.5oz/sq ft  fiberglass as a top coat.  This adds virtually no weight, you don't have to add any epoxy. This 'trick' works significantly.  It's like getting strength at no extra weight.

If you're worried about sanding through the fiberglass you could add a layer of this light cloth.  Apply it differently than thicker cloth.  Brush on the thinnest layer of epoxy onto the fin then place the glass over the wet surface.  Slow cure is better over fast cure for this (I prefer slow cure over anything else).

So, if you're worried about digging though fibergass, this is an easy fix.  When you're done it's amazingly smooth.  You'll still need to sand it to get it perfect, but it's close to perfect.

You might want to even bump up the weights(of glass) a bit.  The lightest glass is so thin you can't move it around very easy when placing it (so be delicate when setting the glass down).  An advantage to using the extremely thin stuff is it goes around corners and bends like nobody's business.

Eddy


One Sky Dog
 

Hi Eddy,

I am suggesting your developed method of repair is not appropriate for our aircraft.

A proper repair is to: Remove all paint and fairing to expose the damage. Remove damaged plies and core. Replace core with same type and density leave a few thousands of an inch low. Scarf glass plies 20:1 ratio. Replace repair layers one for one same direction with just enough resin, not floating. For 9 oz. cloth this will leave the visible weave of the top repair layer. Lightly scuff with fine scotch Brite to remove the shine and fill the weave and repair area with epoxy and micro balloon mix to fair in with the surrounding surface. Prime and paint.

Sailplanes are powered by “gravitational acceleration is approximately 9.8 m/s squared” weight is good unless you want to be a leaf. Drag is bad for sailplanes competition sailplanes carry a lot of water to increase their wing loading.

You are right high strength composites are made by precisely controlling the fiber volume and minimizing voids. Your laminate turns out with greater specific strength but gives up stiffness because it is thinner.

I am only worried because your repair methods are not the ones that the designers of our airplanes have approved. I can patch a hole in my Cessna with a beer can and it would probably be strong enough if I bonded it on instead of riveting, but it would not be the right way to do it according to the designer.

That is my point not designer approved, and I do know there are a thousand ways to make and repair composite stuff.

Regards,

Charlie Johnson


On Dec 5, 2018, at 12:10 PM, ΕΔΔΥ . overlordmustafa@... [Q-LIST] <Q-LIST@...> wrote:

This technique I'm suggesting is not for molding, it's for placing over an are which has had a repair or even as a repair.

If you're worried microballons offer no strength, glass does.  The power ratio of the planes I've used this one is zero, it's for sailplanes and this method has a MUCH higher weight to strength ratio than using most weaves of glass.  I worry about weight WAY more than any homebuilder.  The trick to making fiberglass light and strong (lighter, it's fairly heavy) is to minimize the epoxy.  If you had an entire wing with a wet layup and added 1 layer of 0.5oz/yd^2 you'd end up with a much smoother wing without adding any epoxy.  It's free strength with virtually no added weight.  Although, this is a tangent. 

I'm just suggesting if someone is worried about sanding through a spot of fiberglass, this is a way of repairing without.  Realistically, if one uses fine sand paper, they will not compromise the structural integrity of the fin.  Sand carefully and there will not be any need for any repairs (and I'd certainly take off the primer).





On Wed, Dec 5, 2018 at 12:49 PM Charlie oneskydog@... [Q-LIST] <Q-LIST@...> wrote:
 

Hi Eddy,


This is a great technique for reducing print through of structural fabric weaves in molded epoxy parts. It works by trapping extra epoxy between the fine weave and the structural plies the stiffness of the glass compared to resin minimizes the surface shrinkage reducing print through.

Our goal on a repair is to scarf in and replace structural layers one for one , same weight same direction, slightly below the surface. Any fairing required should be done with a similar resin chemistry filled with glass micro balloons to reduce the epoxy weight and facilitate easier sanding prior to paint.

Grams count our power to weight ratio is way less than your RC models and our repairs can be bigger. I appreciate your thoughts and methods for model repair. Most of our guidance on repairs goes back to Burt Rutan and his pioneering work on mold less composite structures.

Regards,

Charlie Johnson


On Dec 5, 2018, at 9:42 AM, ΕΔΔΥ . overlordmustafa@... [Q-LIST] <Q-LIST@...> wrote:

I've done many repairs on fibergass, I used to build RC models.
One great method to get a smooth final coat of glass is to get the absolute lightest fiberglass you can get your hands on.

After laying up whichever weight of glass (which most people use is rather a heavy weight, compared to what i'm used to using) you can place a layer of  0.5oz/sq ft  fiberglass as a top coat.  This adds virtually no weight, you don't have to add any epoxy. This 'trick' works significantly.  It's like getting strength at no extra weight.

If you're worried about sanding through the fiberglass you could add a layer of this light cloth.  Apply it differently than thicker cloth.  Brush on the thinnest layer of epoxy onto the fin then place the glass over the wet surface.  Slow cure is better over fast cure for this (I prefer slow cure over anything else).

So, if you're worried about digging though fibergass, this is an easy fix.  When you're done it's amazingly smooth.  You'll still need to sand it to get it perfect, but it's close to perfect.

You might want to even bump up the weights(of glass) a bit.  The lightest glass is so thin you can't move it around very easy when placing it (so be delicate when setting the glass down).  An advantage to using the extremely thin stuff is it goes around corners and bends like nobody's business.

Eddy


ΕΔΔΥ . <overlordmustafa@...>
 

Charlie,

I'm not suggesting to repair a damaged aircraft like this.  I was under the impression someone was removing paint and primer and they were worried about taking off too much glass.  One could sand down a quickie, down to the glass and not compromise the structure.  If they were, and they're worried about a little tiny portion, like the tail, the thin glass bit is a way of simply giving someone with an over active OCD or sense of fear some security.

If you were to build the entire plane with lots of thin layers, it wouldn't be any stiffer for the same amount of glass and less weight (I'm not suggesting to build a plane like this).  Regarding wings the foam acts as shear webbing and the glass is the load bearing structure. 

Eddy



On Wed, Dec 5, 2018 at 2:13 PM Charlie oneskydog@... [Q-LIST] <Q-LIST@...> wrote:
 

Hi Eddy,


I am suggesting your developed method of repair is not appropriate for our aircraft.

A proper repair is to: Remove all paint and fairing to expose the damage. Remove damaged plies and core. Replace core with same type and density leave a few thousands of an inch low. Scarf glass plies 20:1 ratio. Replace repair layers one for one same direction with just enough resin, not floating. For 9 oz. cloth this will leave the visible weave of the top repair layer. Lightly scuff with fine scotch Brite to remove the shine and fill the weave and repair area with epoxy and micro balloon mix to fair in with the surrounding surface. Prime and paint.

Sailplanes are powered by “gravitational acceleration is approximately 9.8 m/s squared” weight is good unless you want to be a leaf.. Drag is bad for sailplanes competition sailplanes carry a lot of water to increase their wing loading.

You are right high strength composites are made by precisely controlling the fiber volume and minimizing voids. Your laminate turns out with greater specific strength but gives up stiffness because it is thinner.

I am only worried because your repair methods are not the ones that the designers of our airplanes have approved. I can patch a hole in my Cessna with a beer can and it would probably be strong enough if I bonded it on instead of riveting, but it would not be the right way to do it according to the designer.

That is my point not designer approved, and I do know there are a thousand ways to make and repair composite stuff.

Regards,

Charlie Johnson


On Dec 5, 2018, at 12:10 PM, ΕΔΔΥ . overlordmustafa@gmail..com [Q-LIST] <Q-LIST@...> wrote:

This technique I'm suggesting is not for molding, it's for placing over an are which has had a repair or even as a repair.

If you're worried microballons offer no strength, glass does.  The power ratio of the planes I've used this one is zero, it's for sailplanes and this method has a MUCH higher weight to strength ratio than using most weaves of glass.  I worry about weight WAY more than any homebuilder.  The trick to making fiberglass light and strong (lighter, it's fairly heavy) is to minimize the epoxy.  If you had an entire wing with a wet layup and added 1 layer of 0.5oz/yd^2 you'd end up with a much smoother wing without adding any epoxy.  It's free strength with virtually no added weight.  Although, this is a tangent. 

I'm just suggesting if someone is worried about sanding through a spot of fiberglass, this is a way of repairing without.  Realistically, if one uses fine sand paper, they will not compromise the structural integrity of the fin.  Sand carefully and there will not be any need for any repairs (and I'd certainly take off the primer).





On Wed, Dec 5, 2018 at 12:49 PM Charlie oneskydog@... [Q-LIST] <Q-LIST@...> wrote:
 

Hi Eddy,


This is a great technique for reducing print through of structural fabric weaves in molded epoxy parts. It works by trapping extra epoxy between the fine weave and the structural plies the stiffness of the glass compared to resin minimizes the surface shrinkage reducing print through.

Our goal on a repair is to scarf in and replace structural layers one for one , same weight same direction, slightly below the surface. Any fairing required should be done with a similar resin chemistry filled with glass micro balloons to reduce the epoxy weight and facilitate easier sanding prior to paint.

Grams count our power to weight ratio is way less than your RC models and our repairs can be bigger. I appreciate your thoughts and methods for model repair. Most of our guidance on repairs goes back to Burt Rutan and his pioneering work on mold less composite structures.

Regards,

Charlie Johnson


On Dec 5, 2018, at 9:42 AM, ΕΔΔΥ . overlordmustafa@... [Q-LIST] <Q-LIST@...> wrote:

I've done many repairs on fibergass, I used to build RC models.
One great method to get a smooth final coat of glass is to get the absolute lightest fiberglass you can get your hands on.

After laying up whichever weight of glass (which most people use is rather a heavy weight, compared to what i'm used to using) you can place a layer of  0.5oz/sq ft  fiberglass as a top coat.  This adds virtually no weight, you don't have to add any epoxy. This 'trick' works significantly.  It's like getting strength at no extra weight.

If you're worried about sanding through the fiberglass you could add a layer of this light cloth.  Apply it differently than thicker cloth.  Brush on the thinnest layer of epoxy onto the fin then place the glass over the wet surface.  Slow cure is better over fast cure for this (I prefer slow cure over anything else).

So, if you're worried about digging though fibergass, this is an easy fix.  When you're done it's amazingly smooth.  You'll still need to sand it to get it perfect, but it's close to perfect.

You might want to even bump up the weights(of glass) a bit.  The lightest glass is so thin you can't move it around very easy when placing it (so be delicate when setting the glass down).  An advantage to using the extremely thin stuff is it goes around corners and bends like nobody's business.

Eddy


nitsudls1@...
 

😉 

I was actually just wandering if the West Coast 105 Epoxy is an acceptable equivalent to the safe-t-poxy stuff that is mentioned in the builders manual?😀

As for the types of repairs that Ill need to do, I'm gonna start with the cowling as it will probably be the most straightforward. Then I have a few small gouges in the fuselage that has core. I'll do that next then I'll tackle the wing. I'm not sure yet if it will be salvageable... Ill get some help making that decision. 

Dustin Graber


One Sky Dog
 

Dustin,

The West system was designed for encapsulating wood to make it impervious to rot. It has a lower softening point than EZ-Poxy which is important in structural applications.

Use EZ-Poxy for the cowl cracks. Start on the inside of the crack. Scarf it (taper sand) back from the crack. Leave half of the thickness. Tape over the outside of the crack and do a repair layup on the inside. Let it cure, scarf the outside of the crack back and do a repair layup on the outside keep it thin and lower than the surrounding area. After it cures sand off the shine and high spots. Fair (smooth) in the surface using West 105 and micro-balloon putty mix. Sand fair and do the next repair.

Treat it as an adventure and have fun.

Regards,

Charlie Johnson


On Dec 6, 2018, at 4:31 PM, nitsudls1@... [Q-LIST] <Q-LIST@...> wrote:

😉 

I was actually just wandering if the West Coast 105 Epoxy is an acceptable equivalent to the safe-t-poxy stuff that is mentioned in the builders manual?😀

As for the types of repairs that Ill need to do, I'm gonna start with the cowling as it will probably be the most straightforward. Then I have a few small gouges in the fuselage that has core. I'll do that next then I'll tackle the wing. I'm not sure yet if it will be salvageable... Ill get some help making that decision. 

Dustin Graber


Dustin Graber <nitsudls1@...>
 

Thanks, Ill get some ez-poxy on the way.

Dustin

 

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