internal vs external thread ss sleeve bolts

Everyone knows power bolts are the best there is... they're strong, removable, and in stainless they should last quite a while. But, they're expensive at $3.80 each. There are other stainless sleeve bolts available, like the redhead dynabolt, that are available in 3/8 X 1 7/8 SS for about $.80 each. The dynabolt doesn't seem like a bad option to me, as

• they seem strong (over 3000 lbs shear according to the tech specs)
• they can be started w/ one hand (unlike the power bolts)
• at least in my experiments are easily removable.

I know that the ASCA advises against using dynabolts, but why?
anyway, like I said, the bolts are easily removable, as my experiments proved to me. The trick is to drill the hole about 1" deeper than the bolt. (note the bolt shown is carbon steel, not stainless)

drilled 3/8 hole w/ rotohammer

I installed the bolt and hanger and torqued (dead reckoning) to spec

I removed nut, washer, and hanger. Then, using a hammer and a punch, drove the stud back down the hole to reveal the slightly proud sleeve.

I grabbed the sleeve with needle nose vise grips and yanked out to reveal the stud

At this point the stud was sitting loosely in the hole. It was so loose, in fact, that by inverting the rock the stud fell out into my hand. Since this approach is not practical in the real world, I made a little hook out of a key chain and used it to hook the first thread on the stud and slide it out.

I don't know how this process would go with a bolt that had been in the hole for 20, 50, or 100 years, and if the hole was not overdrilled it would be impossible, but at home it was easy.

So, back to my original question, why not use these cheap, removable bolts?
-jesse

The 3/8" ones suck. They are much weaker than 5-pieces or stud bolts. Incorrect installation torque is much more important on these bolts since they are relatively weak. The ultimate load capacity in shear for 3/8" is actually 2600lbs not 3000. While it sounds high, 2600lbs is not that good - 5-piece bolts are rated in the 7000-8600 lb range in shear (as a comparison, 1/4" buttonheads are rated to 2090lbs). People regularly break them during installation - they are much easier to overtorque. I've pulled these bolts before, and also broken them to remove them when they didn't pull - it's very easy to snap them by just tightening them.

Remember that the ultimate load capacities are assuming that there's nothing wrong with the placement. In the construction industry, they divide the ultimate load by 4 to get the safe working load - producing a SWL of only 650 lbs!

However, the 1/2" versions are frequently used in desert sandstone since you can't bind the cones like you do with 5-pieces, and the 1/2" are strong enough for climbing, especially for desert tower-top rappels (where those bolts are typically used since the rock is super soft).

If the stainless bolts are too expensive, better to use a non-stainless 5-piece bolt that can be replaced in the future than a stainless bolt that may break on people.

Actually this is the relevant article (mentioned in passing in the other article):

safeclimbing.org/education/…

hmmm... I know that the correct answer here is "as strong as possible!" but how strong does a bolt really need to be? The ASCA website devotes a little discussion to this point, but the calculation they use involves factor 2 falls, which are impossible to generate on single pitch climbs. I just went to the petzl website and used their fall simulator, and if you weigh 220 lbs and fall from 100m with a single cheapo sleeve bolt at 50m, the bolt will hold. Powers for anchors on multipitch... but everything else?

How many times would you like that bolt to hold?

Here's an interesting question: Should bridges, elevators, automobile brakes (to name a few obvious examples) be designed to be just barely stronger than the load we consider to be the worst case scenario?

What if we fail to imagine the worst case scenario?

What if someone clips his daisy chain into that bolt, then falls from 3 feet above it? How does the worst case scenario change?

Well, after people's responses here and a bunch of reading elsewhere on the internet, i decided not to place these bolts. I think they would be safe enough, the fixe triplex uses a very similar design, but ultimately I'm not just taking my life into my hands but the life of anyone else who would ever clip one of my bolts. Since I am still cheap, though, I'm going to use 3/8" stainless wedge bolts.

Jesse, Kudos to you for posting your question in spite of whatever ensuing beratement that could have come. You lucked out here bc this isn't the other site but I would like to add to please use correct torque on that ss hardware. Over torquing ss bolts is a very common mistake that pushes the harder (and, incidentally, more brittle) stainless bolts closer to failure.

Jesse Davidson wrote: Since this approach is not practical in the real world, I made a little hook out of a key chain and used it to hook the first thread on the stud and slide it out.

Magnet??

lucaskrajnik wrote: Magnet??

Magnet won't work on most stainless bolts.