Like the title says, this is a primer for bolting sport climbs. It assumes you know the basics of route "design" and can pick a good line and get all the placements in the right spots, without making the climbs a pain for shorter people or sending leaders for groundfalls when they blow the second clip. I'm just trying to let people intent on rap bolting know how to do it without screwing up. I've included a limited amount of information for people with loftier goals, such as replacing anchors and bolting on lead. My experience has mostly been with first ascents of shorter (Grade I and II) crag climbs, so take anything that makes me sound like a hard man as the boldfaced lie that it really is.
I have also tried to include some information on how to assess in situ bolts. This may or may not scare the crap out you. Realize, however, that identifying solid vs. questionable bolts in the middle of a climb is somewhat analogous to gathering wild mushrooms while being chased by tigers -- it takes a little practice and preparation before you can do it comfortably.
I also have included some information and discussion on removing and otherwise erasing bolts, but I have left quite a lot out here. Other "missing" information includes photos of in situ bolts, photos and descriptions of rare plants and raptor nests, and discussion of the ethics of taking over other people's projects. I also gloss over the stainless vs. non-stainless question somewhat, taking the stance that in most areas removability for maintenance (life of the hole) is more important than resistance to corrosion (life of the bolt). When I do this, I am making some assumptions -- a bolt that is removable when new may not prove to be removable when it is old and corroded.
Finally, I welcome comments. Send them to email@example.com. Thanks to the people who have helped improve this page.
So you think you've found a route? There are plenty of issues you should consider before you start trundling and drilling, so I've divided this into subsections:
What's worth climbing?
Before bolts became commonplace, if you wanted to do a first ascent you had to find a route and climb it, quite possibly gripped out of your mind. Since your ascent did not change the route forever, it didn't really matter if the route turned out to be worthless -- the plants and loose rock you pulled out of the cracks on your way up would eventually return, and nobody would be particularly annoyed.
(OK, if those were rare desert plants, they might not have come back. And all sorts of styles have been practiced over the years, so be aware that the good old days may never have existed.)
These days, however, it seems that most rock first ascents are being done top down, with bolts. With a little care on the part of the FA party, this technique can yield safe, high quality routes. It can also yield safe shitty routes and dangerous shitty routes. (To create a dangerous high quality route, you have to place any and all bolts on lead. Sorry, no points for rap bolted death routes.) The problem is that any wanking bozo with a Bosch or a manual kit can put up a new route just about anywhere, and become immortalized in the appendix of some guidebook. If you are a wanking bozo (be honest and soul-searching, now. . .) please take up ice climbing or curling instead.
OK, what makes a route worth bolting? Well, if it's easy to rig as a toprope, it probably makes a lot of sense to leave it as one, especially if it is not significantly different in character from nearby routes. This is especially true in established climbing areas, where dozens of others have no doubt already eyed and ignored your "leftover" route.
As an example, there's a knobby little 5.x slab that I once toproped with a friend after leading another knobby little 5.x slab. It wasn't quite as nice as the original climb, but I had a big backlog of route names and I wanted to put up a new route. Luckily, none of my partners were enthused about it, and now I am immensly relieved that I left the damn thing alone.
Before you drill, do a lot of climbing in the area, and think hard about whether your line will enhance or detract. Hike around on rainy days to scope out other possibilities. Look for routes you can put up which don't require any drilling. Don't bolt something now that you might be embarassed about later. And don't think belay stations are exempt -- multipitch routes with no fixed gear are truly the path to enlightenment.
If you have been climbing outside for less than five years, or if you have climbed in fewer than twenty different areas, you should think about getting some broader experience, or at least good mentorship, before drilling sport routes.
Access and Crowding
Don't bolt on private land without permission. Don't bolt on public land except in accordance with current rules. Don't trundle rocks onto highways. Don't bolt next to hiking trails. Pay attention to your area in the spring raptor nesting seasons to make sure you don't develop a route next to a big hoot-owl nest.
Don't bolt unless you want crowds to someday arrive. Remember, bolts bring guidebooks which bring crowds who will stomp the place to death and turn it into such a hellhole that you will never want to go back. Really. Most of my climbing in the last year has been in places where there was nobody else around but myself and my partner. I've become spoiled. At some point, these places may be overrun too. Especially if I put in so many bolts that everybody and her Mom will want to come.
Don't squeeze them in if they don't want to be squeezed in. There is a 250' route I bolted last fall. The second pitch is a kick -- simply beautiful climbing with great views. If somebody puts in another route 10' or 20' to either side of it, it will reduce the aesthetics of the line without adding anything new of its own. In general, I'd say that if two similar routes can be climbed on the same "toprope" (Let's assume 1000 foot ropes here, and ignore the pendulum at the top. . .) they're really just variations of the same thing. So pack 'em snugger in the little 1/2 pitch sport amphitheatres, but leave some room on the longer routes. Leave TR's here and there to avoid grid bolting. You get the idea.
If you don't need to scrub the route much, and the route is not near your free climbing limit, you and your partner might be able to get a pitch bolted in a day or two. Some people certainly seem able to bang out more than one pitch per day. But don't count on those pitches to be masterpieces. If the route is worth bolting in the first place, it will have multiple difficult spots, each of which must be protectable by gear or by bolts which can be reached by shorter leaders. It should contain challenging moves which are protected by bolts which are somewhere (well) below waist level. All of its bolts should be in solid rock. The route should follow natural features and not be contrived or forced. Usually, these requirements conflict in some way with one another. When such conflicts arise, it takes time and discussion to sort them out and design a good protection arrangement.
If you are hand drilling, you will probably take this time, as you won't want to drill anything you don't have to. If you have an electric drill whose batteries you need to draw down so they'll be ready for the next recharge, you will be tempted to just drill a few extra holes and be done with it. But while rushing will increase your odds of bagging the redpoint before you go home for the week, it will almost surely result in an inferior final product, something to be ashamed of rather than proud of.
As another example, there's an excellent 1/2 pitch stemming route in a vaguely secret granite area which I recently decided to drill. We had TR'ed it several times, but one day we were in the area and ran into another climber. He was gung ho about the place, and seemed eager to come back in a week with his gas powered Ryobi. We decided it was time to stop sitting on our projects and bolt the thing, and did so the next day. After I led the final result, I was disappointed and upset. In our haste, we had overbolted the route and, I fear, ruined a classic. I plan to go back and try to eliminate and erase some of the bolts, hopefully giving the route the treatment it deserves.
"Prepping" a route
I hate that word -- it trivializes an incredibly ugly high impact activity. You're not walking softly in the wilderness when you trundle 300 pound blocks off the top of your latest conquest. And you're no steward of the environment as you scrape ancient lichen and moss ecosystems off of its holds. Of the routes I've put up up, I would say that 70% of the environmental impact has taken place during this stage. Another 5% comes from the drilling of the bolts, and the remaining 25% will be from the crowds that eventually find the lines. I'll refrain from going into the hideous details of how to remove lichen and loose rock, other than to point out that perched death blocks are usually frowned upon on modern sport routes, and to mention that vegetation should be left in place when feasible, especially in the desert. Research the local ecology a bit before going overboard.
Keep in mind that climbing gear is designed for climbing, not for window washing or rap-bolting and rap-scrubbing. The first ever fatality at Squamish was caused (I believe) by a rhythmic brushing motion abrading a rope. And nylon left overnight can be chewed by varmints, which live everywhere. If you are rap bolting, I recommend "rescue grade" rigging. And wear a helmet -- rocks fly right and left on virgin routes. I was pegged hard on my Joe Brown last fall while pulling the rap lines from the top of a new six pitch route.
One rap-cleaning tip which works well on 1/2 pitch routes: Tie into one end of the rope, feed it through a TR anchor, and put yourself on belay with an ATC or equivalent (Gri-Gris don't work very well for this, as the your 1/2 weight may not be enough to lock them up). Then slowly lower yourself, brushing and clearing loose debris as you go. This will increase overall wear on your (old, beater) rope a bit, but the wear will not be concentrated at a single point. And (duh!) pull your rope up out of the way before you send anything big down. Other methods that work well are rapping with a Petzl Shunt (prusiks work fine too) backup with the extra rope flaked into a daypack, or just getting slowly lowered by a belayer with a Gri-Gri and a good book.
Chipping and Glueing
Chipping of holds to modify the difficulty of a route is a serious no-no, according to almost any climber you speak to. But what is chipping, really? Old pin scars, opened up by past climbers with no plans of freeing a route, are generally excluded from the definition, since subsequent free climbers climb the route as they find it, rather than deliberately altering it to change the difficulty. Incut jugs drilled with rotary hammers are generally included in the definition. But here's an example that falls in between the two.
While preparing a relatively loose and dirty route on rappel recently, I encountered a large detached flake at what I was pretty sure would be the crux. It looked ready to break off, so I gave it a quick tug with a crowbar and it was talus. So much for that key hold. The underlying rock was flaky and rotten, and I scraped and chopped at it until only firm granite remained. That firm granite turned out to be in the shape of a usable hold, and that hold was one of the keys to the route. Is it a chipped route? Maybe, depending on your definition. But if it is, so are a huge fraction of the routes being established on rappel these days.
An alternative some people have come up with is glueing. The idea is that I could have discretely glued the original key hold in place, and thus left the route in a more pristine condition.
The flaw is that when you aggressively clean all the loose rock off a route, except for a few key holds that you just can't live without, you have manufactured a line and might as well have been course setting in a gym. Once you make the decision to aggressively remove loose rock from a route, it's time to go all the way. If you end up with a line you can't climb, tough patooties. If that line is a line that is too good to pass up, consider putting a bolt at that stopping point and make it 5.x A0. This strategy is commonplace at Squamish, BC, and seems to work well.
Finally, if you find all this business about prepping and trundling and chipping repugnant, do all your first ascents ground up.
How to drill the hole
Two sections here, Tools and Technique.
A power drill yields a somewhat better, cleaner, safer hole than you can drill by hand, but the difference is largely academic for 3/8" bolts. For mostly good reasons, it is illegal to use one in a wilderness area. If you use a power drill, you will be tempted to overbolt, but you will also have no excuse for placing undersized bolts. Bosch Bulldogs work well; Hilti makes a somewhat beefier unit, and AEG also apparently has a decent device. I use a Bosch on rappel and on lead and generally like it, although a spare battery or a gel pack is recommended. After a break in period, you get 9 or more holes per charge in granite. (At least one of my batteries has matured to this stage now; better results may be possible.) Ryobi has a fearsome gas powered model which is supposedly very loud and obnoxious, and there may be a few other units on the market as well.
An AC inverter may also be useful for road trips where no AC power is available -- my new $40 unit seems OK with my Bosch charger so far. Use it when you won't need to run the starter motor for the next 2-3 hours, as the voltage drop from starting the car may screw up the charging cycle. And run your car for a good while between uses.
If you do drill by hand, go with the new SDS systems (Pika or the nice looking Wilderness Drill from Hurricane Mtn. Works / A5). I use a homemade version of the Pika -- if you have access to a machine shop and want to save some $$, this is a workable option. A plastic Sears power drill side handle can be modified to hold your drill -- buy it first, then size your hex stock. Epoxied in set screws, suitably filed, give you your keyway slot.
SDS bits come in all US and probably all metric sizes. They are the same bits you use in Bosch and other power drills. The FISH drills also work, and apparently have improved recently with the introduction of carbide tipped bits, but my only experience with FISH was with the older, brittler designs, which were not as nice as current systems. (Click here to see what big-wall Russ of FISH has to say and sell about all this. Note as you thumb through his catalog that what he calls "drills" I call "bits," what he calls "holders" I call "drills," and what he calls "rubber grips" I call "holders." Got that?)
You should sharpen your carbide tipped bits on a bench grinder, quenching regularly, Bosch or no Bosch. It makes a huge difference in efficiency.
Put on some glasses or safety goggles. Practice this and other techniques (such as bolt removal and hole patching) on your pet rock at home before you get too far along.
Bosch or no Bosch, start by whacking the rock with a hammer and inspecting it carefully for fracture lines to find solid placements. Occasionally very solid looking rock will sound hollow -- drill elsewhere. Occasionally this may make the clip a little more difficult, but knowing every placement is solid is more important than that. If the rock is so bad that you have to put a "don't skip clips" indicator in the future guidebook to get people to back up their easy clips with more solid ones, consider doing another route.
When you've decided where to drill, start by spinning the bit a few times to get the hole going. No hammer or power hammer action at this point -- just grind out a little divot. Then start whacking. Keep it straight and true, spinning your hand drill 1/6 turn or so between each blows. A big hammer speeds things up, but may cause the carbide on 5/16" and smaller bits to chip off. Try 20oz for 3/8" holes, 16oz for smaller.
Drill the hole deep enough, blow it clean with a tube (or squeeze bulb and bottle brush if you are gluing), and check it with a depth gauge. I use a spare hanger on some threaded rod with a locknut and a washer on one end to test my hole before I put the real bolt in. This allows me to chip away any protrusions at the surface that will prevent the hanger from lying flat, and gives a good honest test of whether I got the hole deep enough.
In this section, I will review several styles of bolts and bolt hangers, good, bad, and obsolete. As appropriate, I will discuss installation and removal methods and ways to recognize and assess the bolt in situ. (If you clip fixed gear, you owe it to yourself to learn to recognize what's out there even if you never bolt anything yourself.) The brands I describe are generally available in the United States and/or Canada -- others may have to fend for themselves.
There are dozens of concrete fasteners on the market, some good, some terrible. When possible, do future generations a favor by sticking with a style that is already in widespread use in your part of the world, and which can eventually be removed for maintenance. If you use something I haven't described here, make sure it's either designed for climbing or already well tested in your neck of the woods.
The hardware issues covered, by no means a complete list, are as follows.
A note on "stainless" steel
If you're a little rusty on your metallurgy, here's a primer.
There's no such thing as stainless steel, really. All steels corrode over the years, some faster than others. In seawater, where a mild steel will corrode at a rate of about a millimeter every six years, an austentitic stainless steel (303, 304, and 316 are common classes, and there are many different specific grades within each class) will corrode about a millimeter every 200 years. This corrosion can be greatly accelerated by galvanic coupling when two different grades remain in contact, as is being seen on the seeping limestone sea cliffs in Thailand, where six year old stainless bolts have already begun to corrode and fail, causing several serious injuries.
In other words, corrosion engineering is a complex subject, and you shouldn't think you've mastered it when you pick up that box of stainless bolts and hangers at your local Wall Mart.
Hangers and chains
The best deals on hangers these days are the Petzl 10mm and the Mammut, at CDN$2 from MEC in Vancouver, BC, 1-800-ONE-COOP. These are nice versatile stainless steel hangers. MEC has decided to sell hangers at wholesale prices, so you won't beat this price anywhere. The only reason I might consider other hangers such as Fixe or the powder coated Metolius camo hangers would be if I were bolting in a highly corrosive environment and galvanic corrosion between different grades of stainless steel were a concern. ("Stainless" refers to many many different steel recipes, and any mismatch between anchor components may accelerate corrosion of one or more of the components which are in contact. If I found out that Fixe used the exact same stuff for their bolts and hangers, I might consider an all-Fixe system in places. The powder coating on the Metolius hangers will also help slow the corrosion process.)
Chain anchors and their equivalent are a bit of trouble to set up, but are highly recommended wherever brightly colored slings would otherwise be visible to the general public.
The simplest system is to clip a pair of appropriately sized 3/8" proof grade or 5/16" high grade chains to hangers via a pair of quick links. The 5/16" high grade is much stronger and more reliable than the fatter 3/8" proof, but is more trouble to pass the rope through. The quick links and chain you select should have a working load limit equivalent to about a ton, or 1/3 to 1/2 the breaking strength of a carabiner, and should be placed in pairs.
If the rock allows side by side bombproof bolts, a really nice system is a pair of the new Fixe ring anchors, available from REI for about $5.50 apiece. These are stainless hangers with bomber welded on rings, and are a nice improvement, I think, on the Metolius rap hangers, which are simply oversized bolt hangers that you can thread the rope through. I don't like the Metolius design as much because it generates more torque on the bolt by failing to load it flush with the rock.
Homemade hangers and anchors
A decent chain or ring station costs about $10 to $15. Some people have cut corners by just using a pair of chain links, plus washers, attached directly to the bolt. Others have played with home welded or unwelded cold shuts. These are less reliable than standard hardware, but the fact that the predicted rash of cold shut induced fatalities hasn't yet arrived suggests that they may still have legitimate applications. If you use cold shuts, place them only as top anchors, never as belay anchors on multipitch routes. And use the half inch ones, unless you are a very good welder. Avoid them on overhanging terrain and in other situations where they may pry on the bolts. I personally prefer not to use them at all.
Spend the extra few $$.
Glue in systems
These are probably the most bombproof bolts on softer rock, although there are sandstone junkies who swear by baby angles driven into drilled holes, and the ring bolts of eastern Germany are probably pretty truck as well. These are expensive -- you want a metric SDS bit for the setups I've seen, and the bolts and glue cartridges are not cheap either. (The Lucky system from MEC may make these a little more affordable, and may be cost effective compared to chain anchors, but I don't know very much about it.) You have to get a clean, precise, and dry hole (no spitting, you need a squeeze bulb and bottle brush), and you can't load the bolts until the glue dries. These are apparently easy to screw up. MEC in Vancouver sells several systems, but you will have to learn how to use them. If you use the Lucky glue-ins, keep in mind that not all epoxies are created equal. I suspect that PC-7 and JB Weld are OK, but I am not an expert here. I've never placed a glue-in.
Other glue-in setups, using machine bolts or threaded rod with a standard hanger, tend to use carbon steel, which will corrode much more rapidly than stainless. Since glue-ins are likely to be a bugger to remove and replace, I would not recommend these carbon steel versions.
Most in situ stainless glue-in bolts have big loops of steel sticking out of the rock instead of hangers.
All-Stainless, and very nice. Hard rock only, and you probably want a power drill to get a big clean hole. Very expensive, so nobody ever uses them. Probably rendered obsolete by the new Fixe wedge anchors. Avoid the bolts at the hardware store that look like the Longlifes -- they are worse than the crappyPetzl self drilling bolts.
In situ Petzl Longlife bolts have no exposed hexagons of any kind, as the things snug up when a pin is driven down the middle. They say Petzl on them and tend to inspire confidence. They are pretty rare, at least in the US. You can look at pictures of these and other Petzl anchors on the PETZL Anchors web page.
The bolt I have been placing lately is the 3/8" Rawl "5-piece," AKA the Rawl Bolt or the Rawl 6-piece. This is a good solid bolt which, with some effort and practice, can be completely removed from its placement for future route maintenance. It consists of a bolt which slides into a sleeve and screws into a cone at the bottom of the sleeve. It had little blue (not red) plastic spacers and has no threads anywhere near the bolt hanger. I use the non-stainless variety, as it is equally strong and much cheaper, at $67 per box of 50 intead of about $200 per box of 50 for the stainless. I use 2.25" or 3" on good granite, 3" on other good rock. If I were bolting at a corrosive area such as Squamish-by-the-sea, I would shell out for a box of Rawl stainless sleeve anchors or just break down and use stainless wedge anchors such as Fixe or Coast. (Other corrosive environments may include limestone cliffs and polluted areas, but I'm not sure about either of these cases.)
An even nicer sleeve anchor than the Rawl is the stainless and brass Metolius SS. This would be the perfect bolt for Squamish granite -- designed for climbing, removable (more easily than the Rawl, in fact), stainless, solid -- but butt expensive, at $4 or $5 a pop for the bolt alone. Because of the high price, this bolt is no longer being manufactured. I believe Petzl makes a stainless double sleeve bolt that may also be removable, but I don't know much about it. Fixe has made prototype stainless sleeve bolts, but they also cost over $4 apiece to manufacture (in lots of 1000) and have not been made widely available. It is my hope that the demand for replaceable bolts will increase to the point where Fixe and/or Metolius will restart their production runs on their stainless designs and get the price down below $3 a bolt.
Sleeve anchors are recommended for hard rock only, but nobody ever pays any attention to this warning. They are definitely better than most wedge anchors for soft rock, with the likely exception of one of the Fixe double wedges. They are fairly resistant to thermal cycling, and, unlike most other designs, relatively easy to remove for future maintenence. Their inherent removability makes them my bolt of choice.
In situ Rawl bolts have no exposed threads and have three raised lines extending radially on the bolt head. They are generally trustworthy, but can pull out if they were not placed well. A picture of the Rawl bolt (Russ calls it a 6 piece) appears on the FISH bolt page.
Placing Rawl 5-piece bolts
Yep, I so deeply approve of these that I'm going to give detailed directions.
Hammer the bolt in and torque it down. 35 ft-lbs for 3/8" Rawl bolts. (30 for stainless). Twist until you feel the cone snuggle firmly up into the sleeve. Soon after it does this, it gets much harder to turn, and it's time to stop trying. [I hate to second guess the manufacturer on torque ratings, but 35 seems like a lot. You really can feel when the cone snuggles up and gets comfy -- I honestly think if you use a standard 8" long 1/2" box end wrench and just crank firmly you will be OK.]
Rawl 5 piece bolts normally take two hands to place, a serious issue when you are bolting on lead with a power drill. If you do lead with them (I do, with a Bosch), pre-squish the cones by tapping them a centimeter or so into your pet rock at home, then wiggling them out. This will allow you to get them started one handed when you're on lead and gripped out of your mind. (It's still tricky, comparable to placing a Snarg in ice, but it does work.) These bolts may also become "spinners" (see below), so get some experience before you try leading with them.
Sooner or later, you are likely to get a "spinner," a sleeve bolt that you can turn and turn but which won't come tight. This is usually avoidable, but it does happen. Try pulling out on the bolt as you twist on the wrench. Curse and scream.
Try removing the bolt by partially unscrewing, tapping down to separate the cone from the sleeve, unscrewing and pulling out the bolt, fishing out the sleeve, loosely rescrewing, pulling out the cone, and starting over. Easier said than done, and you will usually need a prybar of some sort, as well as something to hook the sleeve with (I recently filed an old flathead screwdriver down for this purpose). Practice removal tricks at home first, and plan on it being even more of a bother in the field. The Rawl 5-piece sleeve bolt is quite a bit harder to pull than the discontinued Metolius SS, but I have successfully pulled both in the field with fairly simple tools.
Here are some of the causes of "spinners:"
(a) Bit worn out, hole too small. The cone deforms too much as you pound it in, and won't seat in the sleeve. I've heard about this, but haven't had it happen yet. Pull out hard while you twist (not on lead!)
(b) Hole too shallow. Your own damn fault. Been there, worked the (Metolius SS) bolt out and finished drilling, then reinstalled.
(c) Sleeve deformed. This can happen if the cone is screwed in too tight when you start pounding the bolt in. Avoid by being careful as you hammer the bolt in.
(d) You overtorqued it and twisted the damn bolt off. You are a knucklehead.
These are basically a solid stud, threaded on the outside end for a nut, and machined into a wedge on the inside end to accept a small wrapped around sleeve, which snugs up against the wedge when the nut is tightened. Simple, cheap, and about the most ubiquitous design around. They are the bolts you often see that look like threaded studs with nuts on them. MEC carries these, for about US$1.20 per 3/8" bolt, stainless only (Coast brand). The Fixe, described below, is a newer stouter SS wedge anchor, designed specifically for climbing. A Climbing article a few years back warned that all wedge anchors look about the same, but that many are much less reliable than others. They said that Hilti and Rawl are good and USE is bad.
While wedges are pretty reliable compared to a lot of older bolts, they don't do as well in thermal loading and fatigue as the Rawl 5 piece. An older MEC catalog recommended the 3" (3.5"?) length for soft rock, but Climbing said granite only for these buggers. (There is some concern that the little sleeve may wind up in a soft patch of rock and get pulled over the wedge, allowing the bolt to fail.)
I don't like wedge anchors, because they cannot currently be replaced for route maintenance without redrilling the rock. But they are a bit easier to place one handed, and you are a little less likely to botch a placement with these while leading. (Although I've seen it done -- you do have to be careful how far to push these into the hole before you start tightening.) If you use wedge anchors, at least use stainless to postpone the eventuality of redrilling the route for maintenance.
In some high use situations, the nuts on wedge anchors may loosen up with time. One effective way to stop this is by using nuts with nylon inserts; the "loosens with ordinary tools" style of Loc-Tite will probably do the same trick.
Again, in situ wedge anchors have a nut screwed onto exposed threads. They are generally trustworthy in hard rock if they have not been overtightened. You can see pictures of wedge anchors if you look around on the PETZL Anchors web page.
Fixe SS wedge anchors
These designed-for-climbing wedge anchors are slightly larger than 3/8", I think, but still fit in 3/8" holes if the bit is new enough. These come in several lengths and designs, all designed specifically for climbing. REI carries them, but get hold of a Fixe catalog (call 714-751-5038) or other written info for specific information on their use. They are very strong and a nice design, but I still worry about what to do when they eventually need replacement.
In situ Fixe anchors have a big nut screwed onto exposed threads. I believe the nut has some black printing on it and is designed to be screwed on only one side up (nylon bushing?). They are generally pretty damn solid if placed with any degree of care in good rock.
These are split shaft studs which compress for a spring fit when pounded into drilled holes. They can have button heads, threaded ends for a nut, or in the case of some of Rawl's smaller models, wedge heads that look really funky on a bolt hanger. Supposedly they are fairly strong when new, but lose their grip after about ten years. I don't know too much about compression bolts, but I think they may be worth considering for bolting non-overhanging rock on lead. They can be placed one handed, I believe, and will probably be removable using brute force when the time comes. Since the ones with the threaded ends look exactly like the ubiquitous wedge anchors, however, future maintenance crews will need some way of telling the two apart.
These may also be of interest in smaller sizes as temporary lead anchors, which could be replaced immediately on rappel. Practice on your pet rock to find out how big a pry bar you need for this before starting out. A picture of a split shank bolt (Russ calls it a Rawl Stud) appears on the FISH bolt page.
Petzl self drilling bolts
The Petzl self drilling bolt setup is about the worst system you can still buy. You use soft, rapidly dulling, expensive bits to create enormous craters in the rock, and wind up with about the weakest bolt on the market. These come in two sizes, Worthless and Lame. The argument that you can rest on these as you drill on lead may have some merit, but I personally would feel more comfortable adapting an SDS bit for resting with some sort of rubber sleeve / fifi hook type of arrangement. (Before you try this at home, test on a toprope -- older hand drill designs were easily broken using similar methods and I am only guessing that the tougher SDS bits will hold up to this sort of load.)
An in situ Petzl self drive bolt (small size) has no exposed threads, and has the letters "Petzl 8.8" inscribed on the bolt head. It is one of the more deceptive weak bolts out there, as it looks a lot like a Rawl 5 piece at first glance. The hanger is often not perfectly flush with the rock. The bombproof looking bolts on top of Washington's Liberty Bell descent route are the small Petzls. You can look at pictures of these and other Petzl anchors on the PETZL Anchors web page. You will see on this page that the small Petzl self-drive bolt is "officially" approved for caving and not for climbing.
I am ashamed to admit that I put in two of the smaller sized Petzls in as an anchor once. Someday I will try to remove them by unscrewing, inserting a hard pin, and rescrewing. The resulting holes will be too large for use with 3/8" bolts, however. If you own a Petzl kit, sell it to a caver.
The Rawl split shank buttonheads come in 1/4". I think they still make a 5/16" split, but only with a wedge head, to discourage use by climbers. #5 machine bolts can get bashed into 5/16" holes (#5 is the hardness grade, go to your hardware store and figure out the size.) These are marginal systems which don't really have a place on sport routes. But in cases where a smaller hole is really the only practical choice, these are the only options I know of that aren't pure doo-doo.
One tip -- based on strength ratings I've seen for Coast wedge anchors (MEC catalog) and BD ice screws (informal discussion of BD tests), the length of the bolt does not appear to be nearly as important as the diameter, as long as the rock is good. All things in moderation, however -- bolts that look bomber should be bomber.
In situ smaller bolts look small. They also often look old and rusty and scary.
Extra epoxy and silicone
Some epoxies will corrode the metal. Silicone will trap moisture in the bolt holes and accelerate corrosion. They're both ugly. Don't bother.
Burning out old bolts
I throw this one out as pure speculation. I am talking out my butt. It might be possible to develop a method for burning old bolts out of rock using ceramic tipped oxyacetylene torches. I don't know if this would work. Concerns would include weakening the surrounding rock, burning the torch nozzle after stuffing it down the bolt hole, burning the climbing rope, and whether or not stainless steel and rust can be made to burn. Anyway, you heard it here first. Compact oxyacetylene systems (without any fancy ceramic tips, I suspect) run about $40 at your local hardware store.
Heat might work as part of a way to remove glue-ins as well, but again this is pure back-talk.