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Senior Space Cadet

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I know most of you don't use epoxy, for low power rockets, or even mid power.
But if you've never built a stitch and glue boat, you may be surprised at the variety of epoxies and additives available. Or tools for using them.
I've always used System Three. It's good to stick with one brand, since the mixing ratio can be different between brands. Confuse the mixing ration and you're in trouble.
There are a number of things you can add to epoxy to thicken it, including saw dust. When I need to make a really strong fillet, I use chopped fiberglass to thicken it. If it needs to be really, really strong, I put glass tape over the fillet.
Repeated or prolonged contact with uncured epoxy can be unhealthy. It's good to wear protective glove and a barrier cream.
 

NateB

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It is a little off topic, but do you have any tips for building a stitch and glue boat, or just jump right in and try? I have thought that a kayak would be a fun project, but a $1000 kit is a little intimidating to try sight unseen.
 

rklapp

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I use Bob’s for fillets. Erockets.biz has them in larger bottles. I don’t find much difference between 15 minute and 30 minute epoxy.
 

Funkworks

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I use whatever I find locally, or recommend at rocket stores:

  • Dollar-type store epoxy
  • Bob Smith
  • JB weld
  • RocketPoxy (first use planned on 38 mm Terrier motor mount)
  • FixIt (first use planned on Terrier fin fillets)

For low-powered wood and cardboard, I stick with CA and wood glue, depending on how quickly I want it to set.

Never heard of System Three. Seems quite specialized. Great if you already have some and are familiar with it, but hard to justify over the other proven options if you don't.
 

jrap330

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I use whatever I find locally, or recommend at rocket stores:

  • Dollar-type store epoxy
  • Bob Smith
  • JB weld
  • RocketPoxy (first use planned on 38 mm Terrier motor mount)
  • FixIt (first use planned on Terrier fin fillets)

For low-powered wood and cardboard, I stick with CA and wood glue, depending on how quickly I want it to set.

Never heard of System Three. Seems quite specialized. Great if you already have some and are familiar with it, but hard to justify over the other proven options if you don't.
System 3, Bob Smith and West were the 3 most recommended epoxy when I became a bar in 1998-2000.... I have only used (once) Harbor freight since I still at Estes stage builds.
 

caveduck

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I think I'm bucking the consensus, but I build almost all my LPR with 5-minute epoxy and CA. Current favorite is the West stuff. Used to use Z-Poxy with good results too.
 

jrap330

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I think I'm bucking the consensus, but I build almost all my LPR with 5-minute epoxy and CA. Current favorite is the West stuff. Used to use Z-Poxy with good results too.
Well on the positive you now have epoxy skills......but it is harder to work with vs glue...white and wood are so easy....no worry about smell...sticking to your skin because white. yellow peels off those fingers.

Negative- Heavy..adding weigh to your model...maybe affecting marginal stability rockets like Bull Pup
 

caveduck

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Contrary opinion - I think epoxy is *much* easier to work with (zero grabbing) and drastically faster to build with. As for mass, for competition I always used CA with very thin epoxy fillets and had no particular weight disadvantage. I think there's a tendency for people to use a lot more epoxy than needed.
 

John Kemker

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I agree with @caveduck. I find epoxy much easier to work with, now that I've got some experience with it. I use gloves when using any adhesive, anyway.
 

jrap330

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great......then which epoxy is easier...5 min.....30 min and whatever else there is. I see the putty epoxy could be easier like fix-it sold by Apogee........they did a good video for it.
 

rklapp

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great......then which epoxy is easier...5 min.....30 min and whatever else there is. I see the putty epoxy could be easier like fix-it sold by Apogee........they did a good video for it.
They all (5/15/30) seem to get tacky around the same time, just takes longer to cure. At least with my experience using Bob’s...
 

jqavins

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There are many epoxies and many additives. Epoxy is mich stronger than Wood glue. Some of the additives, like chopped fiberglass and chopped carbon fiber, make it stronger while others, like wood meal and talc, mostly make it thicker which is good for fillets.

The thing is, Mr. Cadet (may I call you Senior?) that's all old hat around here. Please don't think I'm trying to be dismissive or disrespectful; it just seems like you're trying to deliver good news, but it's not new. The glues you're talking about are very common in high power, and really overkill in low power (except maybe for the grabbing issue).

Check out high power.
 

Chad

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in high power builds i really like rocketpoxy for fillets and fin bonding.

i've used Aeropoxy laminating resin + milled fiberglass for fillets before. It works just fine but takes a while to get the mixing right, plus working with milled fiberglass makes me nervous hah. It would be a disaster if you spill it because it's so fine.

John Coker has a page where he tests a few different kinds of epoxy
 

Nytrunner

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great......then which epoxy is easier...5 min.....30 min and whatever else there is. I see the putty epoxy could be easier like fix-it sold by Apogee........they did a good video for it.
5 min has noticeably short working time. I like it for quickly affixing components that arent structural (like switches or charge wells. Havent noticed much difference between 15 and 30, but they do day the longer the cure, the stronger the resulting bond.

Fix it epoxy clay.....eesh. will never use it again. No surface penetration, pops off, heavy, etc...
 

jrap330

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There are many epoxies and many additives. Epoxy is mich stronger than Wood glue. Some of the additives, like chopped fiberglass and chopped carbon fiber, make it stronger while others, like wood meal and talc, mostly make it thicker which is good for fillets.

The thing is, Mr. Cadet (may I call you Senior?) that's all old hat around here. Please don't think I'm trying to be dismissive or disrespectful; it just seems like you're trying to deliver good news, but it's not new. The glues you're talking about are very common in high power, and really overkill in low power (except maybe for the grabbing issue).

Check out high power.
When I made the comment about West Systems not being "new" to the hobby....I believe I recollect the high power guys were using it for fiber glassing their air frames.......which is why Mr Senior has knowledge and experience since he fiber glassed his boats.
 

afadeev

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great......then which epoxy is easier...5 min.....30 min and whatever else there is.
"Easier" is a highly subjective term.
All epoxies have different properties, and varying time to cure ranges, and all have their "optimal" applications.
There are times when a 5 minute epoxy is most appropriate (for tacking fins), but you need to measure, mix, and apply it really quickly. Then there are times when 30-minute epoxy is too fast (inject fin fillets in the summer).

It all depends on what you are trying to achieve, and how fast you work.
If you want maximum strength of the glued joint, longer-cure Epoxy (30-min BSI, West Systems 105+205, etc), will give epoxy the maximum amount of time to soak into the surfaces, and spread out evenly.
If you want maximum resistance to heat (e.g.: for gluing motor mounts, etc), then be prepared to wait 4-6 hours for JB Weld to cure.

I see the putty epoxy could be easier like fix-it sold by Apogee........they did a good video for it.
Yeah, and it is a total garbage product for Rocketry use-cases: https://www.rocketryforum.com/threads/fixit-epoxy-sculpt.160913/#post-2028929
 
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