Stainless Eyebolts

[T-Rex]

This is probably in the wrong place, and I know the disapproval of bent eyebolts but saw this and figured some may be interested
Came across a reputable dealer who has 1/4" stainless eyebolts in their clearance section @ 50cents each. Not sure what shipping will be...

https://www.boatdesigns.com/Turned-Eye-1_4-x-2-5_8-Stainless-Steel/productinfo/11-230/

Enjoy!

 

[Nathan]

They may be disapproved of by people building 100 lb rockets but I'm pretty certain that my 5 lb rockets can't generate enough force to unbend a 1/4" steel eyebolt during parachute deployment.

 

[GDJ]

Just tack weld it together as one piece. Thus problem adverted.

 

[TopRamen]

Stainless in general is not very Rigid. I make Knives, but I make them out of Steels with a high Carbon Content, so that they can be annealed for Shaping, then after they are ground, they can be properly Hardened and Tempered, for rigidity anf pliability. Stainless Steel is soft, and has a low Carbon Content. It is most often used in Food Processing since it has Anti-Bacterial Properties and is easy to Clean.
It does not however have a lot of Strength when it comes to Torsion.
I doubt a Rocket would ruin it, but in general, it might not be what you are looking for.
If anything, you will simply pay more for it. Regular Carbon Steel Eye Bolts with a Nitride or Galvanized Coating, will likely serve you just fine.
Heck, you can "Paint" any Metal with a Bake on Finish, and for Rocketry Purposes, the Finish will outlast you and the Rocket. KG Guncote comes to mind.
I can see where worrying about Corrosion on Eye Bolts could be an Issue with Deployment Charges composed of actual Blackpowder, but if you build Rockets big enough to need Deployment Charges, you likely clean your Equipment when you're done Playing with it.
I don't see where a Stainless Eye Bolt would have any Advantage over a regular "Hardware Store Grade" Eye Bolt.

 

[troj]

They may be disapproved of by people building 100 lb rockets but I'm pretty certain that my 5 lb rockets can't generate enough force to unbend a 1/4" steel eyebolt during parachute deployment.

Do enough searching, and you'll find a picture here on the forum where someone's 5 pound rocket did just that.

 

[chadrog]

Stainless in general is not very Rigid. I make Knives, but I make them out of Steels with a high Carbon Content, so that they can be annealed for Shaping, then after they are ground, they can be properly Hardened and Tempered, for rigidity anf pliability. Stainless Steel is soft, and has a low Carbon Content. It is most often used in Food Processing since it has Anti-Bacterial Properties and is easy to Clean.
It does not however have a lot of Strength when it comes to Torsion.
I doubt a Rocket would ruin it, but in general, it might not be what you are looking for.
If anything, you will simply pay more for it. Regular Carbon Steel Eye Bolts with a Nitride or Galvanized Coating, will likely serve you just fine.
Heck, you can "Paint" any Metal with a Bake on Finish, and for Rocketry Purposes, the Finish will outlast you and the Rocket. KG Guncote comes to mind.
I can see where worrying about Corrosion on Eye Bolts could be an Issue with Deployment Charges composed of actual Blackpowder, but if you build Rockets big enough to need Deployment Charges, you likely clean your Equipment when you're done Playing with it.
I don't see where a Stainless Eye Bolt would have any Advantage over a regular "Hardware Store Grade" Eye Bolt.

I agree with this. Some grades of stainless are stronger than others, but the ad does not say what grade these are. I'd guess it's 316 due to the application they're selling it for. The one benefit it offers over carbon steel is corrosion resistance, strength not so much.

 

[michigander]

Checkout my 4lb. empty darkstar jr , eye bolts bent from high speed deployment mach speed , who ever welded them great job I'm positive saved my a** all of rocket was found , the way these bent 99.99999999% sure would have opened

glue only the 5 minute stuff used on threads cracked , rest of rocket was built with rocketpoxy and fine
motor was the 38/1320 J510 separation at burn out so still going like bat out of hell

https://www.rocketryforum.com/showthread.php?58892-I-am-sold-on-Fiberglass&highlight=sold+fiberglass


I do have the used eyebolts and chute shroud lines for sale

 

[GDJ]

Just tack weld it together as one piece. Thus problem adverted.

:eyeroll: :wink:

 

[Winston]

This topic reminded me of something I've previously wanted to investigate, but forgot about - the relative strengths of the various recovery components.

Even just 9/16" tubular nylon can handle 9 kilonewtons (2023 lbs) of force. Here's the stuff I usually use. Wash it and run it through a tumble drier to eliminate initial stiffness:

https://www.rei.com/product/610111/bluewater-916-climb-spec-tubular-webbing

Now, check out the specs for drop forged carbon steel eyebolts with shoulders, eyebolts specifically designed for heavy machine lifting:

https://products.kenforginginc.com/...elf-colored-fully-threaded-unc-2a-astm-a489-?

Consider that data along with a bold warning I found elsewhere about this same sort of primo eyebolt: RATED CAPACITY IS DRASTICALLY REDUCED WHEN LOADING AT ANY ANGLE. LOADING MUST NEVER BE MADE AT AN ANGLE GREATER THAN 45° FROM BOLT CENTERLINE. AT AN ANGLE OF 45°, RATED CAPACITY IS REDUCED TO 1/4 OF THE TABULATED VALUE.

From that data, you can see that you need to get up to a nearly 2" eye section OD bolt with a 7/16 - 14 shank before they begin to approach (@1800 lbs vs 2023 lbs) the capacity of just 9/16 tubular nylon. I can't find data on the bent-formed-eye eyebolts, but their capacity must be much, much lower for a given size.

So, it looks like the big time limiting factor is the eyebolt.

 

[Winston]

While the limiting factor in the system is the bent-formed-eye or "turned" eyebolt, considering the rarity of reporting of the bending or failure of such eyebolts, they seem to be fully adequate for the vast majority of cases and the rated capacities of nylon webbing typically used must be massive overkill. One thing I haven't taking into consideration because I don't know the figures is how much force various 'chutes can take before shredding or experiencing shroud line failure.

As a WAG, consider a 5 lb rocket with a too-long delay coming down at 300 MPH. The payload section or nose cone pops off and lets say the rocket decelerates to (another WAG) 120 MPH (approx. human free-fall) in 0.5 seconds due to drag. According to:

https://measurespeed.com/deceleration-calculator.php

That's a 16.5g deceleration with no major stress yet on the shock cord or eyebolt. In the next 0.5s, the parachute fully opens and the rocket decelerates to 20fps (~14 mph). That's 9.64g that must be withstood by the shock cord and eyebolt, only around 50lbs for a 5 lb rocket.

 

[Winston]

One more consideration for recovery system relative strengths is the pull-through failure strength of the material used to anchor the eyebolt, something for which I have no data.

 

[dave carver]

Now, check out the specs for drop forged carbon steel eyebolts with shoulders, eyebolts specifically designed for heavy machine lifting:

https://products.kenforginginc.com/...elf-colored-fully-threaded-unc-2a-astm-a489-?

I have these eyebolts avalible to me right across the street from me at Boise Rigging Supply, sitting in a box. Plan on getting several things from there for my 3rd level project. Straps, eyebolts, things like that. Fastenal about a mile away. Think I got my hardware covered.

 

[bobkrech]

This topic reminded me of something I've previously wanted to investigate, but forgot about - the relative strengths of the various recovery components.

Even just 9/16" tubular nylon can handle 9 kilonewtons (2023 lbs) of force. Here's the stuff I usually use. Wash it and run it through a tumble drier to eliminate initial stiffness:

https://www.rei.com/product/610111/bluewater-916-climb-spec-tubular-webbing

Now, check out the specs for drop forged carbon steel eyebolts with shoulders, eyebolts specifically designed for heavy machine lifting:

https://products.kenforginginc.com/...elf-colored-fully-threaded-unc-2a-astm-a489-?

Consider that data along with a bold warning I found elsewhere about this same sort of primo eyebolt: RATED CAPACITY IS DRASTICALLY REDUCED WHEN LOADING AT ANY ANGLE. LOADING MUST NEVER BE MADE AT AN ANGLE GREATER THAN 45° FROM BOLT CENTERLINE. AT AN ANGLE OF 45°, RATED CAPACITY IS REDUCED TO 1/4 OF THE TABULATED VALUE.

From that data, you can see that you need to get up to a nearly 2" eye section OD bolt with a 7/16 - 14 shank before they begin to approach (@1800 lbs vs 2023 lbs) the capacity of just 9/16 tubular nylon. I can't find data on the bent-formed-eye eyebolts, but their capacity must be much, much lower for a given size.

So, it looks like the big time limiting factor is the eyebolt.

Not so fast. You need to understand how the specs and ratings are determined.

Here are the testing specs for your tubular nylon. https://www.bluewaterropes.com/home/Uploaded/Downloads/3220127510.pdf The REI claim for the rope is that the peak force imparted to the falling climber is 9 kN. (The maximum standard limit is 10 kN.) This is not the breaking strength. Breaking strength tests for a 9/16" tubular nylon webbing supplied for testing was ~1366 pounds but the webbing source or specs were not available. https://rocketmaterials.org/datastore/cord/index.html

Rated eyebolts are drop forged. A safety factor of 5 is included in the vertical rated load for lifting eyebolts. An eyebolt rated for 1,800 pounds will break at ~9,000 pounds which is significantly higher than 9/16" tubular nylon.

Bent wire eyebolts are not rated for lifting. (You can easily bend wire even though you can't break it.) Welding the wire eyebolt shut will strengthen it somewhat but it is not readily quantifiable because you can't easily predict how the yield and tensile strength of the metal has been changed by the welding.

Bob

 

[hball55]

Not so fast. You need to understand how the specs and ratings are determined.

Here are the testing specs for your tubular nylon. https://www.bluewaterropes.com/home/Uploaded/Downloads/3220127510.pdf The REI claim for the rope is that the peak force imparted to the falling climber is 9 kN. (The maximum standard limit is 10 kN.) This is not the breaking strength. Breaking strength tests for a 9/16" tubular nylon webbing supplied for testing was ~1366 pounds but the webbing source or specs were not available. https://rocketmaterials.org/datastore/cord/index.html

Rated eyebolts are drop forged. A safety factor of 5 is included in the vertical rated load for lifting eyebolts. An eyebolt rated for 1,800 pounds will break at ~9,000 pounds which is significantly higher than 9/16" tubular nylon.

Bent wire eyebolts are not rated for lifting. (You can easily bend wire even though you can't break it.) Welding the wire eyebolt shut will strengthen it somewhat but it is not readily quantifiable because you can't easily predict how the yield and tensile strength of the metal has been changed by the welding.

Bob

So you're telling me that I am using forged eyebolts for the right reason (superior strength), but that it's way overkill for the application I am utilizing because tubular nylon is the weak point, but even it is way overkill for the application I am utilizing. I like that . . . :grin:

 

[GDJ]

Not so fast. You need to understand how the specs and ratings are determined.

Here are the testing specs for your tubular nylon. https://www.bluewaterropes.com/home/Uploaded/Downloads/3220127510.pdf The REI claim for the rope is that the peak force imparted to the falling climber is 9 kN. (The maximum standard limit is 10 kN.) This is not the breaking strength. Breaking strength tests for a 9/16" tubular nylon webbing supplied for testing was ~1366 pounds but the webbing source or specs were not available. https://rocketmaterials.org/datastore/cord/index.html

Rated eyebolts are drop forged. A safety factor of 5 is included in the vertical rated load for lifting eyebolts. An eyebolt rated for 1,800 pounds will break at ~9,000 pounds which is significantly higher than 9/16" tubular nylon.

Bent wire eyebolts are not rated for lifting. (You can easily bend wire even though you can't break it.) Welding the wire eyebolt shut will strengthen it somewhat but it is not readily quantifiable because you can't easily predict how the yield and tensile strength of the metal has been changed by the welding.

Bob

So you're telling me that I am using forged eyebolts for the right reason (superior strength), but that it's way overkill for the application I am utilizing because tubular nylon is the weak point, but even it is way overkill for the application I am utilizing. I like that . . . :grin:

IN SHORT...

You got nothing to worry about, as long as you use the right glue.

 

[patelldp]

So you're telling me that I am using forged eyebolts for the right reason (superior strength), but that it's way overkill for the application I am utilizing because tubular nylon is the weak point, but even it is way overkill for the application I am utilizing. I like that . . . :grin:

But in this application, the forged eyebolt comes at little to no financial, weight, or size penalty over a bent wire eyebolt. Why wouldn't you use a forged eyebolt, all things considered?

 

[hball55]

But in this application, the forged eyebolt comes at little to no financial, weight, or size penalty over a bent wire eyebolt. Why wouldn't you use a forged eyebolt, all things considered?

Yes, I agree totally. I especially appreciate the small footprint of forged eyebolts. The 1/4" size is my favorite, along with 1/4" qwik links.

 

[Winston]

Not so fast. You need to understand how the specs and ratings are determined.

Here are the testing specs for your tubular nylon. https://www.bluewaterropes.com/home/Uploaded/Downloads/3220127510.pdf The REI claim for the rope is that the peak force imparted to the falling climber is 9 kN. (The maximum standard limit is 10 kN.) This is not the breaking strength. Breaking strength tests for a 9/16" tubular nylon webbing supplied for testing was ~1366 pounds but the webbing source or specs were not available. https://rocketmaterials.org/datastore/cord/index.html

Rated eyebolts are drop forged. A safety factor of 5 is included in the vertical rated load for lifting eyebolts. An eyebolt rated for 1,800 pounds will break at ~9,000 pounds which is significantly higher than 9/16" tubular nylon.

Bent wire eyebolts are not rated for lifting. (You can easily bend wire even though you can't break it.) Welding the wire eyebolt shut will strengthen it somewhat but it is not readily quantifiable because you can't easily predict how the yield and tensile strength of the metal has been changed by the welding.

Bob

Many thanks for that interesting info. I never would have known any of that from just the stated specs I'd found.

That said, even taking all of this new info into consideration, the typical, cheap, bent wire or "turned" (which one supplier called them) eyebolts are still the weakest point by far as I'd concluded. However, considering the realistic G forces to be expected that I also touched upon, they're fine for the typical 4" OD paper/plywood model and it's the tubular nylon specs that are the huge overkill. However, for anything larger, I'd definitely use at least U-bolts as they're as readily available as eyebolts, about as cheap, and would have a greater anchor point material "pull-through" strength than even forged eyebolts.

EDIT: Or, actually, if you want to be really safe, just use appropriately sized U-bolts in everything including 4" models since U-bolts are nearly as cheap and definitely as readily available as bent-formed/turned eyebolts.

 

[troj]

That said, even taking all of this new info into consideration, the typical, cheap, bent wire or "turned" (which one supplier called them) eyebolts are still the weakest point by far as I'd concluded. However, considering the realistic G forces to be expected that I also touched upon, they're fine for the typical 4" OD paper/plywood model and it's the tubular nylon specs that are the huge overkill. However, for anything larger, I'd definitely use at least U-bolts as they're as readily available as eyebolts, about as cheap, and would have a greater anchor point material "pull-through" strength than even forged eyebolts.

EDIT: Or, actually, if you want to be really safe, just use appropriately sized U-bolts in everything including 4" models since U-bolts are nearly as cheap and definitely as readily available as bent-formed/turned eyebolts.

I disagree, completely. Considering that bent wire eyebolts do fail -- people have posted evidence here, and I've witnessed it several times, an upgrade to something more appropriate is cheap insurance to reduce the odds of a rocket coming in ballistic.

-Kevin

 

[T-Rex]

And once again, I opened my mouth and started a snowball rolling even though the original post included a disclaimer... Stupid me

 

[Winston]

I disagree, completely. Considering that bent wire eyebolts do fail -- people have posted evidence here, and I've witnessed it several times, an upgrade to something more appropriate is cheap insurance to reduce the odds of a rocket coming in ballistic.

-Kevin

Note my edit to my above post about using U-bolts even on 4" paper/plywood models if one wants to be extra safe even though all of the 4" kits I've built included the hardware store "turned" eyebolts and of the many, many launches I've witnessed including some major zippers, I've never seen a failed turned eyebolt on a 4" paper/plywood model as a cause of a ballistic recovery.

 

[Winston]

And once again, I opened my mouth and started a snowball rolling even though the original post included a disclaimer... Stupid me

No need to apologize, it's threads like this that can be the most informative.

 

[Winston]

Eyebolt related threads:

Failed eyebolts

https://www.rocketryforum.com/showthread.php?36169-Failed-eyebolts

Forged eyebolts

https://www.rocketryforum.com/showthread.php?31501-Forged-Eye-Bolts&highlight=failed+eyebolt