By Aaron Cromer
From Tucson, AZ
Oct 7, 2009
| What kind of bolts should i use to place in sandstone??? I will be placing bolts just for a rappel. So glue in's are not really an option since i am going to use it right away. thanks | 
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By mtnkid85
From Billings MT
Oct 7, 2009
| Glue ins. Depending on quality of rock anything from 3/8x3" to 1/2x4.5"+.
Do some searching on here and over at rc.com, theres been a fair bit of disscusion on Sandstone bolting. |
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By Skyler Penrod
Oct 7, 2009
| Around Moab I have seen and heard people using 3 1/2x1/2 inchers. |
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By Mike Anderson
Oct 7, 2009
| It's pretty much the same story as any other rock type. The best thing you can place is a stainless glue in, the worst is probably a carbon steel stud bolt. Use the best you can afford.
Glue in's are pretty useless unless you are bolting on rappel because you can't use them immediately. If you're using a bolt gun, then you should use 1/2 inchers at least. They'll cost a bit more, but won't take any more time or battery juice to drill. If you're hand drilling on lead, you'll probably want 3/8" bolts, but if you're just placing belay bolts, it actually doesn't take much longer to drill a 1/2 inch hole, even by hand, and you'll be way more psyched on the results.
Powers five-piece bolts seem to work pretty well in sandstone, but they should be at least 3" long...the wider the better. To reduce spinners, tap the bolt in the hole partway, then snug up the bolt finger tight, then tap some more, re-snug, etc. If you just pound the bolt in there all at once with out snugging it, you may never get the sleeve to tighten on the cone because the holes get too big in sandstone. You could also try using an undersized bit... ala a metric, but I've never tried it. Also, resist the urge to overtorque the bolt. In fact, you should probably undertighten it. You probably won't be able to tighten the bolt as high as the specs dictate (25-30 footpounds, I think). |
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By Brian in SLC
From Salt Lake City, UT
Oct 7, 2009
| Mike Anderson wrote: Powers five-piece bolts seem to work pretty well in sandstone, but they should be at least 3" long...the wider the better. To reduce spinners, tap the bolt in the hole partway, then snug up the bolt finger tight, then tap some more, re-snug, etc. If you just pound the bolt in there all at once with out snugging it, you may never get the sleeve to tighten on the cone because the holes get too big in sandstone. You could also try using an undersized bit... ala a metric, but I've never tried it.
12mm is slightly smaller than 1/2", 10mm is slightly bigger than 3/8", for reference.
For powerbolts, I think if you're in fairly hard sandstone, especially with a patina on it, where the outside is harder than the inside, I've had better luck with shorter bolts. Since the cone needs to both bite and not bind, driving longer distance into soft rock sort of is a diminishing return. Also, I think its super important to really brush the hole out well, and blow out the dust with a bulb, as well as drill the hole deeper so the crud pushed by the cone has a place to go in the hole.
I think the tap, snug, tap method works pretty well. And, tap the bolt, don't beat the heck out of it. Take a good look at how the bolt actually tightens and think along those lines.
Long 3/8" stainless are really hard to get to snug in sandstone, especially the softer stuff in So. Utah. The cones seem so much softer and prone to damage than non-stainless, so, you have to be pretty crafty and careful setting them. Also, be prepared to yank them if they don't seat.
Hanger location surface prep is important, too. Try to get that hanger flat, with no crystals or loose debris under it. Since you won't probably be torquing them down super tight, they'll get looser faster if the hanger isn't perfectly situated. I almost wonder if you can't get a flat placement, to use some of that concrete putty (or JB weld) to balance out the low/high spots so the hanger sits flush. I've done that and it seems to work pretty well in keeping constant tension on the hanger.
My bet Sam L. knows some tricks too. Seems like he's been doing a bunch of anchor work in the Moab area.
Good luck!
-Brian in SLC |
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