dont do it!! i have one of those, it will put the rad into the next room.lol
not only that it will kill your arms due to the weight within a couple of rads.
go for the evolution drill for £50 found on fleabay for that job.
It doesn't have variable trigger but has speed adjustment 1-6 on the wheel on the side. Will be ok just whacking it on 1 or 2 and not putting much weight behind it?