Seeking Hardware for Alternative Featherweight Raven 3 Recovery Retention

I am seeking a single course for some small widgets I'm seeking--a 4-40 coupling nut and 4-40 eye bolt _or_ a 4-40 eye nut.

In another thread, jsargevt suggested an interesting alternative to the "clamp the Kevlar on the mounting posts:" attach a coupling nut to one of the 4-40 threaded rods and insert a 4-40 eye bolt into the other end of the coupling nut. Would probably want to epoxy, solder or otherwise bond the eye bolt to the coupling nut, but that would make a much cleaner, more convenient way of attaching a shock cord for LPR/MPR applications at least.

Another possibility is to find a 4-40 eye nut.

I've found the 4-40 coupling nuts at a few places. They are typically steel and 7/16" long.

I've found the 4-40 eye bolts at a few modelling supply places.

I haven't found the 4-40 eye nuts at all.

So...

* Does anyone know if there is such a thing as a 4-40 eye nut? I suppose I could cut the head off a 4-40 eye bolt and tap it for 4-40, but I don't have the equipment for that.

* Does anyone know of a single source for 4-40 coupling nuts and 4-40 eye bolts? As I said, I've found the nuts and the bolts at a few places but never at the same supplier.

Dog House Rocketry has a great solution--a 4/40 anchor post. There's a picture at Dog House Rocketry

The only issue now is to find a 4-40 lock washer or gasket/bushing

You can try a rod end instead of an eye nut.
https://www.amazon.com/dp/B0006O8TJY/?tag=skimlinks_replacement-20

For a coupling nut, you can use a threaded standoff.
https://www.amazon.com/dp/B000GOKVVS/?tag=skimlinks_replacement-20

4-40 eye bolt...
https://www.amazon.com/dp/B0006O8OAI/?tag=skimlinks_replacement-20

Honestly, if it were me, I'd just spread the Kevlar over the threaded rod.

Polyalcoholic said:

[...]Honestly, if it were me, I'd just spread the Kevlar over the threaded rod.

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Thanks for the links. I searched Amazon for every combination of 4-40 standoff, eye bolt, and coupling nut (which is a threaded standoff for all intents and purposes) several times, so I guess I haven't achieved my goal of having to know nothing except how to run a search engine.

You're probably right. The anchoring mechanism suggested by Featherweight is probably as secure as it will get, because getting those rod-ends, eye-nuts, standoffs, and eye-bolts to stay still under a spinning canopy will be a challenge. If I have to safety-wire the damn thing to the av bay it defeats the purpose.

I don't have a Raven 3, but I have three Raven 2's and they don't use 4-40 hardware. Hole mounts are for #2 hardware, and even then smaller screw heads are best.

dixontj93060 said:

I don't have a Raven 3, but I have three Raven 2's and they don't use 4-40 hardware. Hole mounts are for #2 hardware, and even then smaller screw heads are best.

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I have a hunch the thread is actually about the Raven av-bays, which I think use 4-40 rod.

CarVac said:

I have a hunch the thread is actually about the Raven av-bays, which I think use 4-40 rod.

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Oh, OK.

CarVac said:

I have a hunch the thread is actually about the Raven av-bays, which I think use 4-40 rod.

Click to expand...

Yes, Raven 3 and the 38mm av bay specifically.

I've decided to go with Dog House Rocketry's anchor posts (https://doghouse.blastzone.org/DogHouseRocketry/Alt_Bay_Elect.html), but I'm going to do some tests with coupling nuts/standoffs and eye bolts first because I can get them locally (small independent hardware stores still exist, and apparently beat the pants off the big boxes at least some of the time).

The major issue which the Dog House folks raised to me right away is keeping such hardware attached to the rocket under recovery stresses. They recommended safety wiring, which I'd rather avoid but on reflection is probably the safest option.

I am going to try a small lock washer first, but when all is said and done I may end up doing what Featherweight and others in this thread have recommended: clamping the Kevlar to two of the terminal posts. It turns out some people know what they are doing after all (which is a novelty to me, because I never do).

atrobinson said:

Dog House Rocketry has a great solution--a 4/40 anchor post. There's a picture at Dog House Rocketry

The only issue now is to find a 4-40 lock washer or gasket/bushing

Click to expand...

try using some locktite there are several versions. one of them says permanent and it's strength( it's not really permanent just tough to remove), there are other versions that you might prefer. works great on engine parts should be able to hold a 4-40

accpool said:

try using some locktite there are several versions. one of them says permanent and it's strength( it's not really permanent just tough to remove), there are other versions that you might prefer. works great on engine parts should be able to hold a 4-40

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It's usually color-coded (at least the grades you buy in a hardware store). Red is usually meant to be 'permanent' and blue is 'removable.' YMMV, naturally, but my experience thus far has been that you only want to use red if you don't intend to pull it apart again... or if you're willing to use BIG tools to loosen the screws again.

Be warned: it's surprisingly expensive. A 0.2-oz tube is $5 or so, but it'll last pretty much forever, especially if you only use it on 4-40s and similar.