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AfterBurners

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I just realized that I need to add some nose weight to my Madcow Patriot. I had set the rocket aside for awhile and never painted the nose cone. Now I know why.

Anyway I need to cut the shoulder and get a bulkhead, but my question is if I add the epoxy and nose weight will the heat of the epoxy damage the primer even if I have it submerged in water?

I don't think it would, but wanted to put it out there and see what you guys think?
 

o1d_dude

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I always submerge the tip of the nosecone in cold water while the epoxy cures and have never melted anything. Can't say for sure that the water actually prevented melting as I've never tried without it.

Bear in mind that the Madcow nosecones seem resistant to paint and epoxy so you may want to drill a few holes through the tip and drive some bamboo skewers through the holes before your do any ballasting. That's what I did with my Squat. Used BBs for weight.

Be sure to also scuff the inside of the nosecone with a very coarse rat tail file to reach all the way down into the nosecone.

The bulkplate may need to sized such that it fits past the shoulder so that there is a physical barrier to prevent if from being pulled out. The bulkplate will be a bit larger than the opening and you will have flex the opening of the nosecone to allow the plate to slide in sideways and then rotate it into position. Be sure install your u-bolt or eyebolt first...makes it easier to remove the plate for fit adjustments. You'll figure it out.
 

AfterBurners

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I always submerge the tip of the nosecone in cold water while the epoxy cures and have never melted anything. Can't say for sure that the water actually prevented melting as I've never tried without it.

Bear in mind that the Madcow nosecones seem resistant to paint and epoxy so you may want to drill a few holes through the tip and drive some bamboo skewers through the holes before your do any ballasting. That's what I did with my Squat. Used BBs for weight.

Be sure to also scuff the inside of the nosecone with a very coarse rat tail file to reach all the way down into the nosecone.

The bulkplate may need to sized such that it fits past the shoulder so that there is a physical barrier to prevent if from being pulled out. The bulkplate will be a bit larger than the opening and you will have flex the opening of the nosecone to allow the plate to slide in sideways and then rotate it into position. Be sure install your u-bolt or eyebolt first...makes it easier to remove the plate for fit adjustments. You'll figure it out.
Yep that makes sense.
 

Micromeister

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In all the years I've been mixing Shot Nose weight in epoxy I've only had to put BT-80 Nosecones in tap water during curing. and only then because someone else recommended it with PNC-80k thin wall styrene nose cones.
All that said: most of the thick wall MPR & HPR plastic nose cones shouldn't actually need the water bath unless your using a HUGE amount of epoxy (More the 4 oz.)
 

AfterBurners

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In all the years I've been mixing Shot Nose weight in epoxy I've only had to put BT-80 Nosecones in tap water during curing. and only then because someone else recommended it with PNC-80k thin wall styrene nose cones.
All that said: most of the thick wall MPR & HPR plastic nose cones shouldn't actually need the water bath unless your using a HUGE amount of epoxy (More the 4 oz.)
Do certain epoxies get hotter than others say WS verses 30 hobby epoxy?
 

dhbarr

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Faster setting epoxies in a warm environment would be more susceptible, I'd imagine
 

Micromeister

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Do certain epoxies get hotter than others say WS verses 30 hobby epoxy?
Well in most cases and manufacturers not much. 2 part 5minute Epoxies do get a little warmer then 30 minute or longer setting epoxies.
I'm not sure exactly at what temperature the hottest 5 min. epoxy cures but Polystyrene melting temp is 240deg C or 464deg F, it molds at 180deg. I doubt any epoxy cures at or about that temperature. Get hot sure, Deforming hot I don't see it.

Ps: I've had large amounts (3/4oz & Up) Water thin CA cure at higher temps then epoxy went using an accelerator. That is; high enough to deform Standard Estes type Styrene Nosecones.
 

Steve Shannon

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Epoxy tends to cook off when in a deep container, which a nose cone surely is. I've had Aeropoxy cook off when mixed in a paper cup and not used right away. This is epoxy that has a 24 hour cure time and nearly an hour working time when mixed in a shallow container, yet it was hot within 10 minutes and cured well before a couple hours.
Add your epoxy to your nosecone in lifts, a small amount at a time and submerge the nosecone in cold water. The different lifts will cross-link and bond chemically with each other if done within a few hours of each other. (West Systems recommends within 24 hours).
And, yes, epoxy that cooks off gets hot enough to melt right through plastic. That's why I use paper hot drink cups.

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AfterBurners

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Epoxy tends to cook off when in a deep container, which a nose cone surely is. I've had Aeropoxy cook off when mixed in a paper cup and not used right away. This is epoxy that has a 24 hour cure time and nearly an hour working time when mixed in a shallow container, yet it was hot within 10 minutes and cured well before a couple hours.
Add your epoxy to your nosecone in lifts, a small amount at a time and submerge the nosecone in cold water. The different lifts will cross-link and bond chemically with each other if done within a few hours of each other. (West Systems recommends within 24 hours).
And, yes, epoxy that cooks off gets hot enough to melt right through plastic. That's why I use paper hot drink cups.

[emoji1010] Steve Shannon [emoji1010]
Steve thanks for the tip. Much appreciated and I never thought to use the paper cups. That makes sense because some of us mix on old scrap pieces of card board.
 
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Rex R

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'Dixie' bathroom cups work...just don't leave them standing filled with water(they will start to leak after a while).
Rex
 

Banzai88

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I added a metric butt ton(9 1/4 ounces) of #7 shot and RocketPoxy to the nose of my Cowabunga to make it stable on any 3G 38mm motor. I drilled in two drywall screws 90 degrees opposed, about 1 inch up from the tip, and cut the ends off with a dremel flush with the plastic. A little spot putty and sanding and it's like it's not even there.

Nose cone barely got warm to the touch.

I wouldn't put that much in again, but it taught me not to be afraid of heat with RocketPoxy in the PVC HP nose cones like I would be with the polystyrene ones on LP/MP stuff.
 
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Steve Shannon

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Steve thanks for the tip. Much appreciated and I never thought to use the paper cups. That makes sense because some of us mix on old scrap pieces of card board.
For small amounts I use a post-it notepad. Mix on top and throw away the top sheet when done.


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Steve Shannon

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'Dixie' bathroom cups work...just don't leave them standing filled with water(they will start to leak after a while).
Rex
I wouldn't want the wax to mix with my epoxy and I think it would as soon as you stir. If the epoxy does get hot the wax melts and can get mixed in.
Paper condiment cups work well for small amounts also, but I would steer clear of any coated cups.


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o1d_dude

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I mix on cardboard squares cut from cereal boxes if the batches are small.

Larger batches I mix in special mixing cuts that release the cured epoxy...most of the time.
 

Rex R

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if the epoxy gets hot enough to melt wax(over 120F) I am doing something wrong :). we may be thinking of different products, I was referring to the 3 oz. size.
Rex
 

AfterBurners

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What about glass jars? I also know plastic coffee can lids work well. It's getting the BBs and epoxy all together.
 

o1d_dude

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What about glass jars? I also know plastic coffee can lids work well. It's getting the BBs and epoxy all together.
I'd stay away from glass jars.

This is where mixing cups come in handy. West Systems makes them, paint stores and Walmart sell them. They're usually made of some sort of white "plastic" and have graduated mixing scales on the side. Expect to pay less than $2 for 1-2 of them.

Mix your epoxy in one of these cups and then add the BBs, air gun pellets, or whatever you will be using for ballast. Lead air rifle pellets work well, especially the .22 caliber as they weigh about a gram a piece IIRC. They are expensive, though...$14 for big tin of the Crossman brand.

Did mention weighing out the ballast? You will need to do that, too. I usually pour the mix out on the scale until the weight is what I need and then pour into the nosecone.
 
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Rex R

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at a guess you will need something that can hold roughly 4 - 5 fluid oz.s for your 23 oz. of BB's. a jelly jar would probably suffice.
Rex
 

AfterBurners

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23 oz seems like a lot not sure if I should mix a little at a time day 3-4 batches and do it that way? I know Wildman sells epoxy cups but never bought them and was wondering if they are those small ones you can get at Hobbylinc?
 

o1d_dude

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23 ounces???

Forget the BBs and just buy a bag of small nuts, bolts, screws in bulk from your local big box store. Way cheaper and gravity will never know the difference.
 

AfterBurners

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23 ounces???

Forget the BBs and just buy a bag of small nuts, bolts, screws in bulk from your local big box store. Way cheaper and gravity will never know the difference.
I never thought of that, but wouldn't BBs conform better? Since they are all the same size and not odd shapes?
 

o1d_dude

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I never thought of that, but wouldn't BBs conform better? Since they are all the same size and not odd shapes?
Possibly but with the hardware store items being irregularly shaped, you might get a better "clump" bond that's resistant to landing shock.

Dunno for sure so I'm just speculating.
 

rharshberger

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Usually I mix my epoxy then dump the BBs/shot into the cup and stir thoroughly to coat the shot completely and then dump the coated shot into the nose cone that has already been prepped with two brass cross pins. Never had a problem with overheating the nosecone material. I believe the shot acts as a heat sink.
 

AfterBurners

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Usually I mix my epoxy then dump the BBs/shot into the cup and stir thoroughly to coat the shot completely and then dump the coated shot into the nose cone that has already been prepped with two brass cross pins. Never had a problem with overheating the nosecone material. I believe the shot acts as a heat sink.
what kind of epoxy are you using?
 

Steve Shannon

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if the epoxy gets hot enough to melt wax(over 120F) I am doing something wrong :). we may be thinking of different products, I was referring to the 3 oz. size.
Rex
I would say you're doing something right!
Epoxy usually doesn't cook off. The things that lead to it cooking off are:
Mixing it in too large/too deep of a batch.
Mixing it when the unmixed parts are already hot (hot summer days).
Letting it sit too long in the mixing container.

When it does cook off it's a chain reaction. The mixture begins getting warm which increases the reaction rate which makes it warmer until it's extremely hot. You don't ever want this to happen by accident. I've had it happen twice. Once when mixing nearly 6 fl. oz. of an Aeropoxy laminating mixture in the deep paper cup I mentioned earlier and once in a one oz. plastic Great Plane's mix cup (it was all I had at the time) after putting BSI 5 min. epoxy and hardener on the defroster first to warm them up and reduce the viscosity. That time the cook-off just started and I poured the epoxy out.
Neither time resulted in a burn, but the first time, with the large amount, taught me to respect reaction. The second time surprised me because I thought the small amount couldn't possibly cook-off.
Funny thing about those small epoxy cups. The graduations become totally invisible to me once the mixture is in the cup. The refractive index of the plastic must be the same as the epoxy mix.
 
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AfterBurners

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Steve - I usually use these little guys that I get at Hobbylinc

http://www.hobbylinc.com/great-planes-epoxy-mixing-cups-50-r8056

As far as epoxy as mentioned I have some West Systems but one pump from the resin would surely overfill one of these little cups, which is why I'm considering just using regular hobby epoxy like 30 minute BSI and mix in smaller batches and add to it.

Does it make a difference in how long you should wait between each batches?

Do you have to wait until batch completely cures and hardens before mixing and adding additional batches?

As said before Wildman sells mixing cups, but not sure if they are like the ones in the link? I thought maybe they would be made out of the same type of plastic, but maybe twice or 3x the size.

Has anyone purchased the mixing cups from Wildman?
 

AfterBurners

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20160706_163817_HDR.jpg20160706_163827.jpg20160706_163708.jpg

This is the epoxy I have on hand.

And I also have some of this flex epoxy from Red Baron. It's suppose to be good on fillets and provides flex without cracking. I should probably pick up some hobby epoxy when I start this process. It's not like I have to do it tomorrow, I should at least start painting it.
 
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o1d_dude

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I think these are the mixing cups I use.

www.ezmix.com

The pink, white, and blue ones are widely available. Even Walmart stocks them in the paint department.
 
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