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faster hand drilling


Original Post
Jonathan Croom · · Unknown Hometown · Joined May 2015 · Points: 391

Hey everyone,

Legends from the days of yore report some freakishly fast drilling times for 1/4" bolts, and some say it was in part due to superior drilling set ups compared to SDS carbide tipped bits. What's the situation now? Does basically everyone use a Petzl drill and SDS bits because they are so widely available? Is it worth putting together a different rig, if you wanted the fastest drill for drilling 1/4" pull-and-replace from stances?

Also, from what I've seen, the bit of choice was an A taper HSS, which are now unavailable. Is there anything that makes modern HSS bits unusable for hand drilling? Either in type of shaft, or shape of the flutes/tip? I'd be willing to fab a custom drill holder, and reshape bits, but the fact that I've never heard of anyone using modern HSS bits makes me question if they're suitable. 

All input is welcome. Curious to hear from anyone who has hand drilled with both an old school setup as well as modern, and could give a comparison. 

Jonathan

Greg Barnes · · Unknown Hometown · Joined Apr 2006 · Points: 1,823

Yes, sharp HSS bits with chisel tips can drill much faster than SDS carbide bits, depending on rock type and bolt size (softer rock can be drilled quickly with SDS so HSS is not needed). HSS bits in 1/4" (actually 17/64") in granite can be WAY faster, I found 3/8" (25/64") to only be slightly faster than SDS (in Yosemite granite). There are a bunch of reasons they're not used frequently: 

- the bits are fragile and don't last long. If you are sloppy with your drilling technique you can snap them off in the hole. Also if you are planning to yard on the drill bit to rest once the bit is in the rock a little, that's fine with an SDS but marginal with HSS.

- you need a Hurricane drill or another drill with swappable collets (or A-taper bits for an A-taper drill), and you need to get the correct collet for the bits you're using. Some Hurricane copies were made a few years back, there's a big thread on Supertopo: http://www.supertopo.com/climbing/thread.php?topic_id=1384069&tn=0&mr=0 

- you need to grind down a bunch of bits to chisel-tips (takes a while with a bench grinder, have to cool the bits with water). The angle of the chisel tip can be hard to optimize.

- if you have 3/8" (25/64") HSS bits and you want to drill out an old 1/4" hole, you have to use an SDS bit until you're all the way through the old hole, the HSS will break.

You just use black oxide jobber bits, they are widely available. There are a bunch of tips and tricks - first off is that you need larger drill bits than you think. SDS bits are actually a bit bigger diameter than advertised, so when you get bits for HSS you get 17/64" for 1/4" bolts and 25/64" for 3/8" bolts (25/64" is the collet size that comes with the Hurricane - it is also the correct size for using SDS bits in a Hurricane).

Anyway, HSS setups are awesome for doing routes where you'll be doing a lot of lead drilling of 1/4" on granite. Generally you're drilling a single bolt, then swapping bits immediately (assuming you hang/rest on your newly placed bolt). Then you sharpen the bits later (just need a file to do it in camp, or it's super quick with a bench grinder).

I always had a Petzl drill with 1/4" SDS bit on my harness in case the HSS bit broke - also I could quickly and easily swap out the 1/4" SDS for a 3/8" SDS bit in case I got to a good stance (or belay stance) so I could place a 3/8" immediately.

Anyway, the simplicity, convenience and reliability of a Petzl Rocpec plus SDS bits is super nice. That's why HSS are not commonly seen - also not many folks are putting up long granite slab routes on lead with 1/4" bolts!

Jonathan Croom · · Unknown Hometown · Joined May 2015 · Points: 391

Thanks for the lowdown Greg. I have heard of the preference for a chisel tip; does that basically mean that you grind the tip of the bit so in profile it is "flat", i.e. not pointed like a wood or metal drilling bit generally is?

Trad Princess · · Not That Into Climbing · Joined Jan 2012 · Points: 1,175
Greg Barnes wrote:

Also if you are planning to yard on the drill bit to rest once the bit is in the rock a little

DAB

kevin deweese · · Oakland, Ca · Joined Jan 2007 · Points: 420
Jonathan Croom wrote:

Thanks for the lowdown Greg. I have heard of the preference for a chisel tip; does that basically mean that you grind the tip of the bit so in profile it is "flat", i.e. not pointed like a wood or metal drilling bit generally is?

Yes. 

Part of the reason for the speed (and thus the preference) is that the SDS handles and bit allow for "play" in the bit allowing it to move back and forth in the handle (just like in a rotary hammer drill) So the bit bounces a bit in the hole. This makes SDS faster when in a hammer drill but slower in a hand drill. The chisel tip systems (Hurricane and Rawl) doesn't allow the bit to move and so more of the force travels through the bit into the rock. Though you ca use an SDS bit in a Hurricane, it doesn't work so well because the carbide tips shatter if there's no play. 

If you're looking for a Hurricane handle Runout Customs miiiiight have some still but I'm not sure. My advice is to stay away from the Rawl handles because those tapered bits for the Rawl handle are getting harder and harder to come by. 

Jonathan Croom · · Unknown Hometown · Joined May 2015 · Points: 391

Thanks for the info everyone, much appreciated. I think I will try building a simple holder for 17/64" bits. 

So what bevel angle should I aim for when reshaping/sharpening bits? Start somewhere close to a carbide bit, and go from there? Does the best angle depend much on rock type?

Randy Sandoval · · Elk Grove · Joined Dec 2016 · Points: 5
Jonathan Croom wrote:

Thanks for the lowdown Greg. I have heard of the preference for a chisel tip; does that basically mean that you grind the tip of the bit so in profile it is "flat", i.e. not pointed like a wood or metal drilling bit generally is?

Yes

Guideline #1: Don't be a jerk.

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