EPOXY SUCKS! A development thread.

[chris97rockets]

However, why include them in an L1 kit since that seems like overkill and also likely drives up the cost a lot (possibly a third of the cost or more)? Couldn't you have 3D printed CRs instead?

It changes it up.

I know $150 isn't the cheapest but If you bought a aeropack (~$30) and a Loc IV ( ~$110) you are already at $140. A pack of JB is around $8. So it ends up being net even for something unique and clean to assemble. The kit also includes all the recovery hardware, assembly hardware, and even a hex key. Just add motor.

Earlier versions were entirely printed. But they warped, melted, and I personally wouldn't want to buy it. And the aluminum CRs in the kit are just an ounce. It was lighter than some of the chunky plastic rings! I did get a version of the printed ring working with brass insert in it. But it was very time consuming. Ultimately there are a lot of people that do plastic printing as a hobby. That doesn't interest me personally and the lightweight aluminum is just a different take on an already solved problem. I'd love to really get into printing, but my wife said I am not allowed another hobby. At the end of the day all of this if for fun!

 

[KenECoyote]

It changes it up.

I know $150 isn't the cheapest but If you bought a aeropack (~$30) and a Loc IV ( ~$110) you are already at $140. A pack of JB is around $8. So it ends up being net even for something unique and clean to assemble. The kit also includes all the recovery hardware, assembly hardware, and even a hex key. Just add motor.

Earlier versions were entirely printed. But they warped, melted, and I personally wouldn't want to buy it. And the aluminum CRs in the kit are just an ounce. It was lighter than some of the chunky plastic rings! I did get a version of the printed ring working with brass insert in it. But it was very time consuming. Ultimately there are a lot of people that do plastic printing as a hobby. That doesn't interest me personally and the lightweight aluminum is just a different take on an already solved problem. I'd love to really get into printing, but my wife said I am not allowed another hobby. At the end of the day all of this if for fun!

Ah, great reasons! I would think that having the CRs metal helps to keep fins straight and thinking things over, that's probably the safest part (least likely to cause any problems) being metal in the event of something going wrong.

Heck, companies make metal AV bay lids and thrust plates.

 

[kc9qzf]

After recovering from the threaded insert incident and getting the itch again, I started on the latest iteration in March.

The biggest improvement was the brackets. Instead of using threaded inserts, it just uses a locknut. I designed geometry into the bracket so you don't need another tool to tighten. I also made all the hardware #8 so the assembly goes together with one hex key. Now when I order from my manufacturing partner, I don't need to spend hours with specialized tools to get it ready for the user.

View attachment 653460

The rest of the assembly is the same, except that it’s now color coordinated.

View attachment 653465View attachment 653464View attachment 653461View attachment 653463View attachment 653462

This is the current and final version of the level 1 sized kit.

• Assembles using no epoxy.
• No special tooling is needed.
• Reasonably priced

After showing this to peopleI have gotten a lot of feedback on the assembly. Most people want the assembly for other rockets. I made the assembly alone available for sale. If you want one you can get it here.

What is next?

I am going to scale this system up for larger rockets. I have some clever ways to delete the bracket and replace it with something that can accept any fin. While I enjoyed designing the kit, I think this system is more beneficial if it works for a variety of designs. Instead of dumping years of stuff at once, I'll just update this thread. The first thing I need to do is determine a size.

I think the 4" airframe with 54mm motor mount would be popular choice. What is your favorite rocket diameter/motor diameter combo?

Chris,
I think the 4inch with 54mm motor mount (which could accept a bolt on aeropac retainer) sounds good. That gives the option of going up to an L motor fairly easily.

 

[astronwolf]

Ah, great reasons! I would think that having the CRs metal helps to keep fins straight and thinking things over, that's probably the safest part (least likely to cause any problems) being metal in the event of something going wrong.

Heck, companies make metal AV bay lids and thrust plates.

Caution. You did a thought experiment and concluded, ah, it seems safe. Heck, everybody does it. This is normalization of deviance in action.

 

[KenECoyote]

Caution. You did a thought experiment and concluded, ah, it seems safe. Heck, everybody does it. This is normalization of deviance in action.

I think I am a very cautious person when it comes to safety, but I also consider what is out there in common use as well.

Heck, HP motor cases are metal and we have catos all the time (some very scary stories too).

When you look at the more dangerous scenario of a rocket coming in ballistic or landsharking, I think metal nose cone tips, body tubes, fin cans, fins, all-thread, fin brackets, eyebolts, etc (some ubiquitous in hp rocket construction and kits), are all likely more dangerous than metal AV bay lids, thrust rings*, and CRs since the latter would likely hit flat with pressure distribution over a wider area vs. pointy part in first or slicing.

*Edit add: thrust rings, plus the CRs are in the rear with a lot of other stuff ahead of them.

Just my 2c.