Foreword

I fear it will be a bit complicated to get scientific reference for the answers to your questions as those things might be important but too less to be published. Therefore most of the evidence may be hidden somewhere in the corporate knowledge of the hammer drill manufacturers. Nonetheless I will try to answer you question on my experience in construction work and physics.

First of all I think we should set the reference frame for what we're talking about. As you already mentioned in your question, you will want to get a tool that is somewhere on the lower end of the heavy duty tools. This will include a SDS shank for the drill bits and a real hammering mechanism, not just that ratchet like vibrator module that you find in rather cheap hardware store machines. So you will end in the segment of machines that are typically sold to construction companies for their daily stuff like drilling some holes for anchors, demolish some smaller piece of wall or concrete or the like. That is typically also the type of tools you can rely on – you don't want your machine to fail in the middle of a wall.

Requirements

RPM & BPM

Unfortunately the requirements are bit different when bolting climbing anchors: the typical performance figures to characterize those machines will not hold in your case. When bolting climbing routes you often drill holes while hanging in your harness, therefore you will not be able to apply the force that you would when standing stable on a floor and pushing against the drill with all you have. Therefore RPMs and BPMs are not of great importance as you quite surely in most cases will not be able to use them to all their extent.

Voltage

Another thing is the power you need: As a rule of thumb the power scales with the battery voltage. But as you drill rather small holes (10mm to 12mm I would guess) you don't need maximum power. The machines in the range you should look for will anyways be in the 24V to 36V range. Instead, you will want some battery lifetime as you won't be near a wall plug, where you can just recharge your batteries, when bolting a route. So instead of investing in higher battery voltage you better might invest in a high-capacity battery or a second battery pack.

Weight

Then there's the factor weight: on the one hand you will want a light tool as you will have to carry it to remote places and up a wall. The heavier the tool on the other side, the less force you need to push it against the wall while drilling as inertia will be on your side here.

Drill Bits

Finally, don't forget about the drill bits. Here it is the same as for the machine itself: don't get the next best cheap ones from the hardware store down the road. Good drill bits don't just work longer but can also ease your life while drilling. From the Hilti company I know that they have constructed their drill bits in a way that they work somehow "in sync" with the hammering mechanism of their machines, therefore you need less force to push the machine against the wall – you more or less only have to hold the machine to prevent it from falling out of the hole. Sounds magic, but really makes a difference and you learn to love it when you drill the n-th hole that day.

Noise & Vibration

Concerning your additional points: For the noise level, in doubt just get a set of ear plugs, but I don't think, there will be much difference between the different tools. Acceleration/vibrations shouldn't be that much of a problem, as you will not drill hole after hole all the day but you will do a lot of other things in between.

TL;DR

Don't care too much about the usual specs but get a tool that is rather lightweight with long battery lifetime.

posted over 10 years ago

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Benedikt Bauer‭

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