Removable bolts

Discuss vertical caving, equipment, & techniques. Also visit the NSS Vertical Section.

Moderator: Tim White

Removable bolts

Postby ron_miller » Aug 4, 2012 9:46 pm

Has anyone used Cobra SuperSleeve bolts for protection or aid on cave climbs? These bolts are advertised as capable of being removed and reinstalled, are available in 3/8" diameter at 2", 3" and 4" lengths, and all 3/8" models appear to be plenty strong - 2,800 lbf (12.5 kN) pullout strength and 3,000 lbf (13.3 kN) shear strength in 3,000 psi concrete.

Any other small-diameter (3/8" or less) removable bolts out there than anyone recommends? The Fixe Triplex anchors are a bit larger diameter (12mm, just under 1/2") than what I'm looking for, and of course the ClimbTech RB Anchors are no longer available in small diameters (they now start at 3/4").
ron_miller
NSS Hall Of Fame Poster
 
Posts: 235
Joined: Jan 5, 2007 6:24 pm
  

Re: Removable bolts

Postby Scott McCrea » Aug 5, 2012 12:25 pm

I have used these quite a bit: Rawl 5 piece sleeve bolts
Image

They do come out and you can use them again, but you need something to pry them out with. A small pry bar or a claw hammer.

We drilled some holes at the local practice quarry, where lots of groups practice rappelling—scouts, camps, etc. We just take them out when we leave. Just have to keep the holes clean.
Scott McCrea
SWAYGO
User avatar
Scott McCrea
Global Moderator
 
Posts: 3198
Joined: Sep 5, 2005 3:07 pm
Location: Asheville, NC USA
NSS #: 40839RL
Primary Grotto Affiliation: Flittermouse Grotto
  

Re: Removable bolts

Postby Martin Sluka » Aug 5, 2012 2:54 pm

Heco Schrauben, stainless-steel Multi-Monti screws?

http://www.heco-schrauben.de/ceasy/modules/cms/main.php5?cPageId=123 - MMS-S Hexagon head
User avatar
Martin Sluka
NSS Hall Of Fame Poster
 
Posts: 380
Joined: Mar 17, 2006 11:28 am
Location: Prague, Czech Republic
Name: Martin Sluka
NSS #: 29010
  

Re: Removable bolts

Postby Extremeophile » Aug 14, 2012 3:24 pm

I've tried the ClimbTech 1/4" and 3/8" removable bolts, that are no longer available, but I didn't feel real confident on them. As you probably already know they're a type of spring loaded slider nut designed to be cylindrical so that they fit in a hole, but since they go inside the hole it's hard to inspect them to see how well they're seated. The only way to determine the quality of the placement is to bounce test them. Then you need a custom tool to remove them. James Hunter and Larry Shaffer must have most of the world's supply, and they claim they're good for catching leader falls, but I'm not so sure. You can get by with a slightly shallower hole than you would drill for a wedge bolt, but then all the bounce testing and extra time to clean them means they aren't all that much more efficient (at least in my limited experience). These have been used a lot in recent years in Lech where hand drilling is necessary.

If you want a removable bolt and you can power drill, then the Fixe Triplex 12mm x 55mm is a good choice. I used these in Hellhole a little while back. The hole is a larger diameter than the more standard 3/8", but the shorter length of these bolts means about the same amount of rock removal and battery depletion per placement. For temporary removable placements I use the larger diameter bolt hanger (12mm) and place the hanger under the lip of the sleeve. This makes them easier to clean because you can yank and pry the hanger to get the bolt out. I put a 3/8" o-ring around the base of the hanger to keep from losing the bolt during cleaning. For long-term placements I use the smaller 10mm hangers and put them on top of the sleeve collar. If I'm placing them during an aid climb and then immediately cleaning them, I don't even bother to clean the holes.

If you can power drill, and the main reason for wanting removable bolts is to mitigate the cost of leaving a bolt every 3 feet, then consider using non-removable steel wedge bolts. You can buy these in bulk for around $0.30 each so a 100' dome climb means you only have to sacrifice $10 in hardware. The hangers of course can be recycled. The small stud that is left behind isn't very noticeable and isn't going to cause any significant environmental impact.

Other options include rivets (threaded hex head bolts hammered into a hole), or concrete screws. I haven't really used these on aid climbs, but I've experimented a little. The Tapcon 1/4" x 1 1/4" hex head concrete screws might make a good quick body-weight placement. These appear to be similar to the link Martin posted above. I believe they are rated to hold 400 lbs so you don't want to bounce test too vigorously. I have a bunch of butterfly rivet hangers that can be used with these. The hole is only 3/16" diameter and just over 1" deep, so for hand-drilling there's significantly less effort, and they go into rock amazingly easily.
http://www.concretescrews.com/
http://classic.mountaingear.com/pages/product/product.asp/imanf/Yates+Gear/idesc/Butterfly+Rivet+Hanger/Store/MG/item/215440/N/1045%204294967263
User avatar
Extremeophile
NSS Hall Of Fame Poster
 
Posts: 761
Joined: Dec 7, 2009 7:37 pm
Location: Littleton, CO
Name: Derek Bristol
NSS #: 34941
Primary Grotto Affiliation: Colorado Grotto
  

Re: Removable bolts

Postby Extremeophile » Aug 14, 2012 5:27 pm

Correction - the 1/4" x 1 1/4" Tapcon concrete screws have a pull-out strength of 750 lbs or greater and shear strength of 900 lbs or greater in concrete (similar to limestone). Still bodyweight only, but a little better safety factor.

http://www.confast.com/products/technical-info/tapcon-concretescrew.aspx
User avatar
Extremeophile
NSS Hall Of Fame Poster
 
Posts: 761
Joined: Dec 7, 2009 7:37 pm
Location: Littleton, CO
Name: Derek Bristol
NSS #: 34941
Primary Grotto Affiliation: Colorado Grotto
  

Re: Removable bolts

Postby ron_miller » Aug 15, 2012 12:50 am

Thanks for the comprehensive reply, Derek.

Part of me wishes the small diameter Climb Tech removable bolts were still available, but the stories I heard from climbers who used them did not engender a huge amount of confidence.

I have used rivets (5/16" x 1 1/4" s/s hex bolts) and swaged loops for aid when hand drilling in caves , with mixed success. I haven't yet gotten exactly the right match between drill bit and hex bolt sizing. The 1/4" star drill bits that my rock-climber aid friends use with great success with these machine bolts apparently drill a slightly larger hole than the SDS 1/4" bits I've used. It worked, but I ended up spalling off a good bit of rock when tapping the bolt in. Still need to fine tune that.

I do have the ability to power drill in the project I'm currently working on, and what I'm looking to do is be able to remove (and potentially re-use, though cost is not a driving factor) the bolts used on aid up a dome. I saw the Triplex, as you pointed out, the smallest bolt is 12 mm (almost 1/2") x 55 mm (about 2 5/32"); the smallest Cobra Super Sleeve, which is marketed as removable and reusable, is 3/8" x 1 7/8". Doing the math (as Bill Putnam likes to say, "No one ever does the math!"), that's 45% less rock removal for the smaller Cobra vs. the larger Triplex. That's a lot - using the smaller bolts allows significant increase in efficiency, speed, and there's the potential to nearly double the number of holes drilled per battery relative to the Triplex bolts!

But I can't seem to find anyone who has tried the Cobra Super Sleeve anchors in cave aid climbing. Looks like I may have to pony up for a few (they seem to run about $2 each in four-packs) and try them out; I bet if I got serious and liked them, I could find them in larger quantity at lower unit cost.
ron_miller
NSS Hall Of Fame Poster
 
Posts: 235
Joined: Jan 5, 2007 6:24 pm
  

Re: Removable bolts

Postby Martin Sluka » Aug 15, 2012 1:21 am

English link: http://www.heco-schrauben.de/ceasy/modules/cms/main.php5?cPageId=123

They do screws with diameters 6,0 (1/4")/ 7,5 (5/16")/ 10,0 (3/8")/ 12,0 (1/2")/ 14,0 (9/16")/ 16,0 (5/8")/ 20,0 (3/4") mm. We tested 7,5 and 10,0 mm. 10 mm looks enough for permanent bolt, 7,5 for climbing, but each few steps the 10 mm is recommended.
For 7,5 mm you need hole diameter 6 mm, for 10 mm screws 8 mm diameter. The overall trick is to drill hole 2 diameters longer then the length of screw. If the hole is not enough deep, one may twists off the screw. To unscrew it one needs to loosen it only about 1/4 of roundabout. After it is possible to unscrew it by hand.

MULTI-MONTI® European Technical Approval ETA-05/0011: Concrete screw made of stainless steel for use in concrete http://tinyurl.com/18r

Technical parameters: http://www.heco-schrauben.de/ceasy/modules/core/resources/main.php5?id=139
Parameters calculation: http://www.heco-schrauben.de/ceasy/modules/core/resources/main.php5?id=136
User avatar
Martin Sluka
NSS Hall Of Fame Poster
 
Posts: 380
Joined: Mar 17, 2006 11:28 am
Location: Prague, Czech Republic
Name: Martin Sluka
NSS #: 29010
  

Re: Removable bolts

Postby hunter » Aug 15, 2012 2:35 pm

Couple minor notes:

-I haven't tried the cobra although I have tinkered with several similar bolts. If the washer looking thing in the drawing is a flange attached to the sleeve allowing easier removal I think these should work fine for aid in caves. The most similar bolt I tried didn't have any sort of flange and getting the sleeve out proved to be difficult without damaging it.

-I found that using the triplex bolts in very poor rock I had to clean the hole well or I had trouble removing them.

-A while back I bought some 1/4 and 3/8 in bolts similar to the ones Martin shows (mine are made by powers http://www.powers.com/product_7204SD.php). Placing these in good rock or concrete with a hammer drill they worked very well but I would be reluctant to use them for anything other than aid since they seemed to easily unscrew. I tried placing these with a hand drill several times and was able to yank them out by hand every time, the problem appeared to be a slightly larger hole due to hand drilling. For those of you I see from time to time I'd be happy to give you some of these to play with since I have 50 or so of each and just use them around the house now.
hunter
NSS Hall Of Fame Poster
 
Posts: 395
Joined: Sep 9, 2005 9:47 am
Location: New Mexico
  


Return to On Rope!

Who is online

Users browsing this forum: No registered users