Alternatives to Rocketpoxy?

What are your recommendations for an alternative epoxy in lieu of Rocketpoxy? I've just been using all-purpose epoxies from Home Depot like those made by Loctite or J-B weld.

Nope, Rocketpoxy is It...

Not kidding...

Proline 4500 is good. I use it along with RocketPoxy.

Oh no, a glue thread......

FOlks like West Systems, folks like US Composites, folks like Aeropxy (structural and laminating),....the lsit goes on!

I’ve used a lot of commodity 5 minute and 15 minute epoxy for building rockets. If you’re not doing an exotic flight, you don’t need exotic epoxy. Other people here swear by T-88. If Im putting more time into finishing, I use a general purpose laminating epoxy (my go to is System 3 Silvertip but others work too) filled with wood flour or another structural filler for fillets. Cover with a thin layer of epoxy filled with micro balloons and you have beautiful fillets.

Agree with all of you as far as all of it will work. Just do a cost per weight/volume on it and..

Point being, the "cheap" stuff costs more..

Us Composites is the best cost per..

Or Y'all can prove that theory wrong. And I suspect you will.

Rocketpoxy works for me personally because "I" find it easy to work with, so I use it. You can use what you enjoy working and or struggling with... Or, argue the point...

I would not recommend Proline 4500. It makes great looking fillets and lays down easily, but is brittle. A hard landing will likely lead to cracked fillets.


Rocketpoy in my opinion is still a little on the brittle side for my liking, but definitely better than Proline 4500.

For a strong, tough/ nonbrittle epoxy I have reverted to using Aeropoxy ES6209. It is not the easiest to work with but I have managed to lay down decent fillets with it, and use it for most adhesive aspects of a rocket build.

There is also Loctite Hysol ## epoxy, which is strong non-brittle higher temp adhesive epoxy that has become popular on minimum diameter builds lately. A forum search would turn up the specific number hysol epoxy. I can't recall what it is at the moment.

Dunno about that. I’ve got a min diameter that’s landed on road a few times and fillets rock solid. Can’t say that about rocket poxy. They’ve cracked a few times landing hard on sod.

And I have several "instances" that show the opposite. Without real data, all mean nothing..Here it comes...

Hysol 9462

The gun and mixing tips are very convenient.

Just a FYI in case it hasn't been said enough, the ratio for 4500 has been changed from 5.5-1 to 100-16 (6.25-1).

Wallace said:

And I have several "instances" that show the opposite. Without real data, all mean nothing..Here it comes...

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Here it is lol, before any of you say anything, yes it was poorly bonded.

Poorly bonded how?

By all means if you've identified the error let us learn from it lol

Nytrunner said:

Poorly bonded how?

By all means if you've identified the error let us learn from it lol

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If you look closely the fillet are ripped clean from the surface of the carbon tube. If this was properly bonded the glue would have ripped some fibers along with it or probably the fins would have not ripped off upon landing.

The fins were offset from the end of the tube so it’s clear that the hard impact caused them to break apart. It fell under drogue.

Clarification:

What was your original surface prep

Ok, that's potentially good info. What with and how?

Nytrunner said:

Clarification:

What was your original surface prep

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This was not mine, this is from high school students. They attached the fins over a shot of clear gloss coating. I told them to sand it away first, but they didn’t bother. I guess they wanted to see what would happen.

I was amazed that it held up to Mach 1.2, of course shortly after only the drogue deployed and the hard landing knocked all three fins off.

That is really good info. Thank you.. But what epoxy?

Wallace said:

That is really good info. Thank you.. But what epoxy?

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Sorry I forgot to answer you on that, this was rocketpoxy.

Well, there you have it......any glue will fail at the separation strength of the underlying material. In the case in the picture, the paint to the tube. That's just like folks doing a museum quality paint job on a rocket, then realizing that they forgot the launch lugs, gluing them to the paint, and wondering why the joint failed.

To the OP's question: I use RP for structural joints and 4500 for fillets. I find both easy to work with for what I use them for. Like anything else, there's a learning curve. Dropped a few pretty hard due to mishaps.....never broke a RP joint or cracked a 4500 fillet, the underlying material like cardboard or plywood or fiberglass all gave way before the glue joint.

Surface prep, surface prep, surface prep.

BSI epoxies work, plenty of folks and plenty of rockets do just fine. Know what you're buying and how to use it and it's limitations and you'll be fine.

https://www.aircraftspruce.com/menus/cm/epoxy.html The site is mostly used by home-built aircraft people. Their lives depend on how they build things.

I've used BSI, West, Systerm3, 3M, J-B Weld and Loctite. I've used, but would never recommend, some polyester based resins. Epoxies with and without milled fiber, milled cotton, microspheres, wood meal, wood flour and fumed silica.

Lots of options, lots of different intended purposes and different price-points. Find one that works well for you and go for it. For nearly all applications, material and surface prep is vastly more important than the bonding resin.

I use RocketPoxy. I know how to mix it, how it performs, how much to use, how well it mixes with chopped CF, etc. I find a lot of merit in being consistent. and so far, I have not found a need to switch to anything else.

.

Arsenal78 said:

I hate RocketPoxy and how you have to wait 15 minutes before even using it on fillets. Oddly enough I use JB Weld. I built a Binder Design Jackhammer completely out of the stuff with the exception of sliding in the motor mount which was done with Gorilla Wood Glue. External fillets were also done with JB Weld. The nylon shock cord broke last month and it fell from a height of about 1300ft with no damage other than some cracked Bondo and scratched up paint.

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You can get RocketPoxy for roughly $35 a quart. That's about $0.16 a fluid ounce. JB Weld is about $2.00 a fluid ounce. If you are building large, that's a huge cost difference. Not practical.

Building L2 rockets up to 4" only to this point, I've used BSI exclusively and had ZERO issues with that product. I use the 30-minute variety (to me it cures stronger than 5-min or 10-min) on centering rings, fin to motor mount and centering rings, internal fillets, aluminum tubes for my AV sleds, bonding coupler inserts to couplers, and more. The only thing I don't use BSI epoxy for is external fillets - haven't moved from using Fix-It epoxy there due to its ease of shaping after cured. I have had a a couple of external fillets crack (hairline cracks) when something went wrong like a motor failure on a 4" Patriot last year, but otherwise this works in my building and I'm very happy with the results.