I am building a new payload bay for a Level 3. I have used 1/4-20 forged eyebolts in the past, but I have never been satisfied with my results. (Too heavy and the coupling nut always interferes) This time I am going to use all-thread, in 1/4-20 all the way through and then screw on a 316 Stainless 1/4-20 threaded eye nut, and put those on both ends so I can secure shock cords to them. I have found them mail order for about $3.00 each plus S&H. Would anybody like me to get some for them also and you can share in the S&H? I am going to make the order this week, so let me know. You can PM me if you care to. They also have larger sizes like 5/16, 3/8, 1/2", etc. but they are more expensive too. Let me know what you want and I will check out the prices. I figure if I wanted to I could take two of them back to back make a pretty heavty swivel also with just the addition of a couple of washers and a shoulder bolt.
CD Fasteners has 1/4"-20 eye nuts in stock. I've bought all of mine from them. They aren't stainless but should be more than sufficient enough for rocketry use.
Edward
Thanks for the update. I will try them in the morning. They are normally my first choice. the guys at Clays Ace and the Downtown Ace just looked at me with funny looks wondering what I was talking about.
The 3 Dogs Rocketry Eye Nut Anchors are also a superb choice. I use those for my L3.
http://www.rocketryplanet.com/content/view/3708/29/#axzz1oAUQIVfU
Edward
I use both forged eyebolts and stainless steel eyenuts (from a sail boat supply place) - what I use depends on the application. My more recent projects have all used eyenuts to be honest. I now prefer to use a threaded rod and an eye nut for motor retention and on my e-bays I use a threaded rod down the center and eyenuts on each end. Do be aware they will unwind unless you drill through them and the threaded rod and use a cotter pin or similar or use locktight on one of them.
Every application is different but if you are only using 1 threaded rod then eye nuts my be your best bet. If you are using multiple threaded rods then I would us an eye bolt or a u-bolt. I prefer using u-bolts to eliminate the chance of twisting loose or over tightening. It really depends on the room, the eye nuts that John W has work great for the real small or tight quarters. If you can reduce failure points you have a greater chance of success.
L3 = U-bolts, though both work well in their level. I have always tended to over-build. After failing far too many times at L1, I always over-build. A joke, but lessons learned.