Drills for Bolting

A Review of the Bosch GBH 18 V-EC

Bosch versus Hilti

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General advice when choosing a cordless hammer drill for bolting is to select a minimum operating voltage of 24v or preferably 36v due to run time being the sum of voltage * battery capacity (Ah). The higher the voltage and battery capacity in Ah then the more number of holes that can be drilled per battery. On that basis, an 18v drill would seem to lack sufficient voltage to achieve a reasonable number of holes drilled per day without requiring an impractical number of battery packs being taken to the crag. The new 18v hammer drill from Bosch however is a serious contender to the 24v or 36v drills already available.

For this comparison I will compare the Bosch against my Hilti TE-6A which is a common drill used by climbers.

Weight

The Bosch is light; feather light compared to a Hilti TE-6A. Without a battery attached, the Bosch weighs in at 1.9kg versus the Hilti at 2.3kg so for those who travel overseas with their drill, this is a significant advantage on minimising excess baggage. The Bosch is a very practical drill for placing bolts on lead and has a handy attachment point on the grip for threading a length of accessory cord through and securing for a lanyard.

Winner: Bosch

Impact Energy

The energy the drill generates for hammering is measured in Joules and in practical terms; equates to how fast a hole can be drilled. The Hilti bangs out an impressive 2.0J, which is higher than the Bosch at 1.7J. For harder rock types such as granite or volcanic tuff the Hilti offers a clear advantage.

Winner: Hilti

Run time

The total energy available to drill is calculated by multiplying Volts times Amp hours. This unit otherwise called Watt-hours is both important for real world performance on the crag but for compliance with restrictions on lithium batteries when flying. Hilti manufacture a maximum of 3.9Ah capacity in their battery packs however Bosch manufactures 6.0Ah packs for their drills. When considering battery packs alone, Bosch is the clear winner with nearly double the capacity for a mere 0.6kg versus 1.3kg for the Hilti 3.9Ah pack. Bosch packs are considerably smaller and easily carried onboard aircraft as hand luggage. Bosch packs fit a number of their cordless tools so that is another advantage if you are considering a cordless angle grinder. On run time only however, Hilti packs generate a higher 140.4Wh versus 108Wh, which is a clear winner.

Winner: Hilti

Performance

Newton’s third law accounts for why controlling drill bit skate is easier with the heavier Hilti – an important consideration for those who use resin or glue-in bolts and thus need to create notches for countersinking the bolt. The lightness of the Bosch can be countered however by using a cross tip bit that makes controlling bit skate easier and improves the ability to create notches not just with the Bosch but for both drills.

Vibration dampening is not a strong point of the Bosch when compared to the flexible chassis of the Hilti that is noticeably better at absorbing vibration. Wearing gloves however helps to an extent.

Whilst the Hilti is a solid performer, it is the brushless motor of the Bosch that ultimately results in a drill that overall, outperforms the Hilti when holes drilled per a comparable weight is considered. This is however conditional upon acquiring the high capacity batteries.

Bosch GBH18VEC Hilti TE-6A Comments
Voltage 18 36
Drill weight 1.9 2.3
Battery weight 0.6 1.7
Charger weight 0.8 1.1
Battery 6.0Ah 3.9Ah
Battery performance 18 @ 12mm 20 @ 12mm S.E Asian Limestone
Battery performance 6-8 @ 14mm 8-9 @ 14mm Volcanic Tuff
Impact energy 1.7 Joules 2.0 Joules
Total weight inc charger 3.3kg 5.1kg 1 Battery only per drill

Note: New Hilti drill bits used for all performance tests.

Winner: Bosch

Conclusions

The Hilti is a solid performer; certainly when drilling hard rock, but the Bosch has many advantages and is the winner overall. For those who travel and/or want a high performance drill in a small, lightweight package, the Bosch is a great choice.

Sourcing lithium ion batteries can be difficult at time due to restrictions on carriage via commercial mail. BC Fasteners in Canada (Google BC Fasteners online for their website) were able to send batteries in under 2 weeks from Canada to any global address.

 

 

 

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