Rod end bolts

[AeroAggie]

Have any of you used a rod end bolt like this in place of an eye bolt?

It takes up a bit less volume than a similar sized eye bolt. Seems like a good application for nose cone anchor or small rockets where payload volume is limited. My concern is that because it's designed for a bolt to go through the eye, you have somewhat sharp corners that could cut the harness. I have a couple of these already for non-rocket usage, and the corners are slightly chamfered. One could take a dremel to it and round it out a bit.

Any experience here?

 

[rharshberger]

no experience with the product pictured, but instead of a bolt through the eye, the pin of a small clevis could be used.

 

[TonyL]

This is sometimes called a 'solid rod end', I have also seen hardware like this called a 'swing bolt' [like for swings]. I have used both in rockets. Swing bolts are nice and small for small rockets. Look for load rating data, though in modest sizes and rockets it probably does matter if it looks reasonable. Mcmaster sells solid rod ends [call them if you don't find them, they have more stuff than what is listed]. Amazon sells swing bolts.

If it has sharp edges, debur it? I would hit it with a single flute countersink [good for many things].

br/

Tony

 

[AeroAggie]

no experience with the product pictured, but instead of a bolt through the eye, the pin of a small clevis could be used.

That's true, but adding more hardware kinda defeats the purpose of using smaller hardware in the first place - tight spaces.

This is sometimes called a 'solid rod end', I have also seen hardware like this called a 'swing bolt' [like for swings]. I have used both in rockets. Swing bolts are nice and small for small rockets. Look for load rating data, though in modest sizes and rockets it probably does matter if it looks reasonable. Mcmaster sells solid rod ends [call them if you don't find them, they have more stuff than what is listed]. Amazon sells swing bolts.

If it has sharp edges, debur it? I would hit it with a single flute countersink [good for many things].

br/

Tony

Yep, I got that picture from McMaster. I'm not worried about material strength at all; they're steel with a very thick, compact cross section.

I assume you didn't have any issues with your harness breaking at the edge of the hole? I'm only considering these for 29mm and 38mm min diameter rockets, under 2 lb, with kevlar harnesses.

 

[JohnCoker]

Sure, that'll work. You can put a nut on both sides for use with a bulkhead. I generally prefer eye nuts if I'm connecting to a threaded rod:
McMaster-Carr eye nuts

 

[TonyL]

In my experience, eye nuts are large and heavy unless you hunt down the stainless marine version that Commonwealth used to sell [like Sea Dog]. The swing bolt is smaller and lighter than even the marine eye bolt or eye nut.

That said, I'm glad I revisited McMaster, as their #10 Flat-Shoulder Rod End Bolt looks very nice for a 38mm rocket. They didn't used to show this style. They actually called me up a few years ago when I bought a regular one to see what I was using it for.

The hole may already have a chamfer, if not put one on it. I have never had a corner cut a shock cord, but then I don't leave a sharp corner on hardware either. A little quality time with a countersink usually does it.

br/

Tony

 

[G_T]

If a bolt is any good, a countersink shouldn't work on it. You'll destroy the countersink while perhaps chamfering the edge. A small grinding wheel in a dremel is a better bet, just keep the work cool and don't breathe the dust.

(If your countersink is carbide then the above does not apply)

The bolt should be properly hardened and heat treated, or it isn't manufactured for structural purposes. There are plenty of just decorative bolts out there that you should not trust. For rocketry purposes the bolts need to be able to withstand shock loads, and loads that are applied in oddball directions.

Gerald

 

[ChuckH]

I've used solid rod end bolts for years for recovery harness attachment when space it at a premium. The only downside is that they can get a little spendy.

 

[davdue]

Sure, that'll work. You can put a nut on both sides for use with a bulkhead. I generally prefer eye nuts if I'm connecting to a threaded rod:
McMaster-Carr eye nuts

I got a eye nut from Teddy at One Bad Hawk. Worked great in a 2.6" Wildman Darkstar for my daughter's L1. I try to support our rocket vendors whenever I can rather than the big corporations.

 

[TonyL]

I just received my 1/4 rod end bolt and #10 shouldered rod end bolt. The 1/4" is plenty of overkill for small rockets and nicely compact. The #10 seems even better for 38mm and smaller diameter rockets, very compact and not too much shank. the 1/4 shouldered version has more shank than I would like. Neither is sharp enough to really be concerned, and either could be deburred easily anyway. minimal weight and should be strong enough.

 

[TonyL]

I think what Gerald is saying is that if you use a countersink intended for wood on a hardened bolt, you can expect it to damage the Csink. If you use a proper HSS or Cobalt Csink, it should be fine if used carefully. Carbide is very nice and very pricey, plus it does not tolerate chatter very well [tends to chip the edges].

That said, Grade 2 [and also most stainless] hardware can be just fine if used appropriately, but a proper HSS or better is still the way to go for a Csink.

br/

Tony

 

[JohnCoker]

Those look really good; I'll have to check them out.

 

[dhbarr]

I see there's m4 stainless eyenuts, would that be about the smallest possible anchor of this type?

 

[conman13]

I see there's m4 stainless eyenuts, would that be about the smallest possible anchor of this type?

I've seen M3 stainless eye nuts on amazon however nothing smaller then that.