Fixe Powers 3/8" sleeve (5 piece) bolt

Thoughts on these ? The torque is said to be 12 foot pounds for the 3/8". Experimenting on my pet rock (granite) , that seemed loose as fuck. Took a crowbar to it and was able to move it out and around (cant do that with a normal wedge bolt.) Tightened it more and the stud broke off. I was looking for a bolt for softer rock, is this just chintsy?? 

Are you using the stainless steel or the plated steel?

Stainless 5-piece are the best 3/8" mechanical bolt widely available in the U.S.

Install them correctly with only 12 ft-lbs of torque, tap head lightly (light tap with hammer), re-torque, tap head, re-torque, tap head, re-torque (same trick for 1/2" stainless 5-piece).

Stainless 3/8" wedge bolts have much higher installation torque. But here's the problem. Installation torque, prying with crowbars, etc do not simulate a climbing fall. Here are the ultimate strength numbers for a quality stainless wedge bolt (Power-Stud) vs a stainless 5-piece, 2" embedment on both, 6,000 psi concrete (they don't test on rock):

Stainless wedge:  3,760 shear (16.9 kN)

Stainless 5-piece: 7,440 shear (33.5 kN)

Stainless Hilti wedge bolts are closer to 5-piece, but still not as strong. Tension doesn't really matter 99% of the time, but a 5-piece is also much stronger (5,915 vs 4.075).

A more seasoned expert will chime in, but my understanding is that with the “new” Power Bolt +, the 3/8” bolt had a decreased bolt diameter and increased sleeve thickness, weakening the strength of the bolt. This was done intentionally due to over torque problems and bolt rupture that would occur during installation of 3/8” power bolts. Either way, it is no longer an appropriate choice for climbing hardware.

I’ve also been admonished to not use 3/8” power bolts, only 1/2” (Power Bolt+, that is). Your story of heads shearing off is not the first time I’ve heard of this either.

In my understanding we are only talking about stainless bolts - the stainless Power Bolt has an installation torque of 12 ft-lbs, not the carbon steel PB+, which has an installation torque of 20 ft-lbs.

Charlie S wrote:

Charlie S wrote:

A more seasoned expert will chime in, but my understanding is that with the “new” Power Bolt +, the 3/8” bolt had a decreased bolt diameter and increased sleeve thickness, weakening the strength of the bolt. This was done intentionally due to over torque problems and bolt rupture that would occur during installation of 3/8” power bolts. Either way, it is no longer an appropriate choice for climbing hardware.

I’ve also been admonished to not use 3/8” power bolts, only 1/2” (Power Bolt+, that is). Your story of heads shearing off is not the first time I’ve heard of this either.

This was my impression of them.  The actual structural component of the bolt seemed pretty insubstantial.  

Greg, thanks. I'll try another one with the method you described. 

Ira OMC wrote:

 Tightened it more and the stud broke off. I was looking for a bolt for softer rock, is this just chintsy?? 

I’ve had this happen to me twice installing Powers 3/8 five piece.   It freaked me out enough that it made me wonder how many are out there that are torqued just before the breaking point.   I’m sure it was just a freak accident that happened twice but it was enough to make me switch to stainless wedge bolts.   I’ve never been able to snap a wedge bolt and I’ve tried.  

I have placed a few hundred 3/8 stainless power bolts and never had an issue with snapping the bolt off. The main issue with this type of bolt is if your drill bit shoulders are getting worn down and drilling too narrow of a hole, it can cause problems with the cone when hammered in and may not torque down properly and just spin in the hole. Definitely more care needed then just pounding in a wedge bolt, but they are great bolts when used correctly. 

Ira OMC wrote:

I was looking for a bolt for softer rock, is this just chintsy??

I’ve never been a fan of 3/8 five piece bolts (stainless) in any sort of rock, especially the softer stuff. My main complaint is that they regularly loosen if the bolt sees any sort of repeated falls or is at the anchor on a well trafficked route. Greg’s tapping and torquing method definitely helps, but the thin sleeve and blue crush collar get worked pretty bad. At one point I emailed Powers’ engineering department, and while they won’t officially condone their bolts for climbing use, they did say the stainless five piece can be tightened to 15 ft-lbs with out compromising the bolt. I doubt an extra 3 ft-lbs makes a big difference though. In my opinion, 1/2” five piece bolts are a much better choice for softer rock, and the 25 ft-lbs tightening torque greatly reduces the likelihood of the bolt loosening.

Just to be clear the stainless Powers bolt is unchanged since the Rawl days. (80s)

I bet Greg Barnes has placed thousands of them. 

I have placed hundreds myself and I alternate between them and Hilti KB3 for hard rock in 3/8.

I agree that better hole prep is a good idea. Reem the opening of the hole. Dont let the bit get too worn before Replacement. Clean the hole well. 

Truely Softer rock I would go bigger as well.

I have never broke a 3/8 5-piece bolt during installation and I have placed a bunch.

                                                                                                                        Roger Brown

I've never broken one either - and between just the two of us, Roger and I have probably placed 4,000 of them. No one on the planet has hand drilled as many 3/8" bolts in granite as Roger! Of course nearly all of them (and most of mine) were expanding 1/4" holes.

The other key tip with 5-piece is during installation, you stop hitting them once they are fully tapped in (I try to stop just before flush, maybe half a millimeter), then tighten them down. If you keep whacking them when the hanger is flush, the energy of your hits vibrates the bolt and makes it more likely to break rock out around the cone, thereby increasing the chance of a spinner bolt (where the cone jams on the end of the bolt). This is much more likely in sandstone and softer rock, but even in the best granite, if you keep whacking the bolt after it's flush, you increase the chances of a spinner.

Thanks for the tips. 

To be clear, I didnt break it during a typical installation.  I was basically assessing how much abuse the thing could take. I like to figure out all the quirks of rock types and bolt types prior to actually placing them on a route. Put in tons of wedge bolts in granite and double wedge bolts in schist, as well as all sorts of concrete anchors in my career as a builder. 5 pieces are a new animal to me and thus I'm familiarizing myself with the product before doing anything important with them. 

Oh, OK, that makes sense. Never heard of anyone snapping a stainless one before. On the other hand the carbon steel 5-piece were definitely known to snap from over-torquing during installation, Randy Leavitt told me once that he snapped half a dozen in the '90s before switching to all 1/2". Think there was an accident years ago where a developer installed one, clipped in before torquing, then snapped it off while tightening and took a nasty fall. Presumably that's even more likely with the new 3/8" Power-Bolt+ since the bolt core is just 1/4". And a plea as an aside...developers, please don't ever use 3/8" PB+ for climbing!