Discussion in 'Techniques' started by RocketRoll, Jul 24, 2019.
This may be of of interest:
I read John Coker's epoxy test years ago and started using Aeropoxy ES6209. Simple 1:1 mixing, long working time, doesn't smell and easy to work with. Only downside is a long cure time, but the stuff is gruesomely strong--never seen anything stronger. I've used it on everything from mid-power LOC type kits to a 6" diameter/98mm MMT fiberglass rocket, and everything in between. I use a cheap scale from Amazon and mini Solo cups to mix in--never had a problem getting the mix right. I've tried other epoxies throughout the years but keep coming back to ES6209.
One thing not mentioned is economy in mixing. West Systems is great stuff, but I have seen too much waste with the pump system. Similar with Rocketpoxy, as it is harder to get just the right amount mixed without waste. Aeropoxy ES6209 is so easy to mix only the amount you need with very little waste. Over time I have learned just exactly how much epoxy I need for different tasks and my Aeropoxy lasts a lot longer than anything else.
I'm confused. Rocketpoxy sounds EXACTLY like your ES6209. 1:1 mix, long work time, and doesn't smell (mostly; I'll admit if you don't use it fast enough, the hardener gets a bad funk/ammonia smell. But it goes away if you let it breathe for a few minutes before using). In fact, when new, I find the Rocketpoxy has a rather pleasant smell. And if you eyeball measure, you're gonna have waste no matter the brand. Now, I don't know how the two compare on price, but I get Rocketpoxy from Wildman, so I never have to pay for shipping... I've tried weighing the Rocketpoxy also. Haven't noticed any difference in performance and/or cure. To each his own...
Edit: Just looked using your Link. RP is $62.00ish. ES6209 is $60.00ish. So, pretty close.
Rocketpoxy is more of a thick paste and is similar to Aeropoxy ES6279.
This is the real takeaway! Whether it’s Aeropoxy (my choice for exactly the same reasons) or RocketPoxy, learn how to use it and it’ll serve you well. I also keep bottles of BSI 30 for quick repairs and squeeze tubes of JB Weld for retainers. I’m familiar with both of them and their limitations.
My personal favorite is Aeropoxy laminating epoxy. With the right fillers I can make it serve adequately in almost any role from retainers to potting to external fillets. The only thing I cannot do is make it reliably cure in 30 minutes.
Do what I have done (accidentally) all too often. Mix up ten times what you need via miscalculation. Can't unmix it, so wait for it to begin to kick, apply, throw away the rest.
Best -- Terry
For fillets I have been using rocket poxy. I never wait the 15 minutes. I put down blue painters tape alongside where the fillet goes, lay in the RP with a popsicle stick right after I mix it. I also put up blue tape dams at each end of the fillet so it doesn’t run. Wait 15 to 20 minutes then pull the tape off. Gives me very clean edges on the fillet. Give it an hour or so and then rotate the airframe and do the next set.
If you buy JB Weld in the little bitty tubes from the big box stores, you're right, it can be cost-prohibitive esp. when used in large rockets. But in the industrial size (5 oz steel resin, 5 oz hardener, or 10 oz total) from zoro.com at $10.35, it's much more reasonable at $1.04 an ounce. Still not cheap, but approaching half what you might pay at the local hardware or auto parts store for the industrial size. And WAY less ounce-for-ounce than what the small tubes cost. In my opinion, the performance of JB Weld (slow curing variety ONLY) justifies the premium price.
Sure about your math? I assume you're calling a quart of Rocketpoxy the 1-pint hardener, 1-pint resin package. ($34.99 from Mad Cow, or $43.75 from Apogee as of this post)
$35 for 32 ounces = $1.09 an ounce. Slightly more expensive than industrial size JB Weld from Zoro, unless I'm missing something.
That's what I'm doing now. Allows the epoxy to settle into the gap. I wait a little longer to pull tape.
You're right, man. I don't know where my brain was. How did I come up with $0.16? Only The Shadow knows. But are you sure the "ounces" referenced on the JB Weld are fluid ounces? I think that's a weight, not a volume. The HW store 2-tube JB Weld comes to about a 1/4 cup when squirted out, I think. So that's 4 fluid ounces, raising your unit cost to $2.59 per fluid ounce. I may be wrong about the exact volume, though.
Hmm . . . "Common Core" Math ?
It felt like $0.16, so that must be right!
it works if you initially start with the cost in CAD dollars. Then it comes out to $.16 USD
(We're at, what.. $1.00 USD = $0.755 CAD right now..)
I made the mistake of waiting too long to pull the tape.... Yes my fillets a supposted to have blue pinstripes on both sides...
I use Systems 3 Epoxy Putty and its pretty darn strong.
Here's my 2%...
I use RocketPoxy for fillets, I weigh it out, mix it and apply right away.
I usually do 1 or 2 fins and then let it sit overnight.
I use the back end of a #2 (large) exacto handle to smooth the fillets,
that works up to 4" diameter BT size. (the largest I own..SO FAR..LOL)
I will if needed, dip it in alcohol to help smooth the fillet at first.
Then I will dip my finger in alcohol and smooth it out a bit more, and to blend the leading/trailing edge transition of the fin.
As far as "structural" glue-up, I always used to use the 5 minute Loctite......with the self mixing attachment.
It set up a little to fast for some applications....
But I finally bought some BSI 30 minute and took an empty 5 min Loctite syringe and cleaned it out by letting it soak in 90% rubbing alcohol and making sure it had no remaining residue from the Loctite.
"I've been "recycling" the mixing attachments with the alcohol for some time"
Anyway, I use the 30 minute BSI in the Loctite syringe for getting into tight spaces and internal fillets and such...
But yes, RocketPoxy is great for me for fillets....
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