Diamond coring

rampantbunny

I need to core a series of 45mm holes to a depth of approx 150mm into dense concrete block. The holes will be on the vertical face of a block on flat wall.
I spoke to a man who was onsite drilling larger holes for services into house and he advised me to hire out the equipment myself as the job seemed very straightforward.

I didn't get a chance to quiz him on the equipment required, nor have I rang around any hire shops yet, but what sort of hardware are we talking here?
The rig he had was large and had to be bolted into place but for a 45mm hole would a hand-held core drill be sufficient?

tedimc

Yeah, you should be fine with a hand held drill - I drilled 4 inch holes by hand. The drill was crap and it was a pain, but 45mm should be fine.

Just tell them you want a large drill for 45mm holes. Probably a better name/description for it, but that's what I asked for. They usually charge for the bit as well, and perhaps a transformer.

Just a couple of considerations -
Do you need exactly 45mm? Or can you go a little bigger?
A bigger drill will eat through the holes, but can be a brute to hold up for a long time when your not used to it. Have you many to do?
150mm into a block is a long way - are they for supports fixings or something?
Have you drilled out a core before? The bit will often fill with the 'cutout' of the concrete and it can sometimes be a mofo to get out. Not sure if a deeper or shallower bit is better, but if you find yourself not making progress half way in, it could be because the bit is full.

rampantbunny

tedimc wrote: »

Yeah, you should be fine with a hand held drill - I drilled 4 inch holes by hand. The drill was crap and it was a pain, but 45mm should be fine.

Just tell them you want a large drill for 45mm holes. Probably a better name/description for it, but that's what I asked for. They usually charge for the bit as well, and perhaps a transformer.

Just a couple of considerations -
Do you need exactly 45mm? Or can you go a little bigger?
A bigger drill will eat through the holes, but can be a brute to hold up for a long time when your not used to it. Have you many to do?
150mm into a block is a long way - are they for supports fixings or something?
Have you drilled out a core before? The bit will often fill with the 'cutout' of the concrete and it can sometimes be a mofo to get out. Not sure if a deeper or shallower bit is better, but if you find yourself not making progress half way in, it could be because the bit is full.

The drill unit required is not a standard drill, but a diamond core drill. I've drilled a few cores with smaller drills for waste pipe runs but I think I'd burn what I have out in no time. Diamond core drills probably have better torque, possibly lower speed.
I've upwards of 28 holes to drill in which steel bars will be fixed with chemical anchor. Holes might even be less than 45mm dia depending on engineers final spec. Not sure if the hole saws only come in standard sizes TBH.

One niggling thing is that I need to keep the hole plumb and level (with a bit of tolerance). Without fixing to the wall this is difficult but I have some ideas on how to do this so it's not a deal breaker.

tedimc

If you have a little bit of tolerance, I would think it would be easy enough to keep the drill level. Also - if you are using chemical anchor, who have a bit of wiggle room.

For 28 holes, I would think you would nearly spend as much time fixing the drill to the wall than you would actually drilling. Could you fix a timber plank along the top and bottom and then try to affix the unit to the timber? Would be quicker that drilling the wall for each hole. They might also help with you alignment.

I am curious - what is this for? Elevated decking or balcony?

rampantbunny

I'll PM you what it's for. I've seen too many threads veer off into conversations along the line of 'what are you doing that for, why are you doing it that way, what does your engineer say, how dare you do this when you're not a professional' so this thread is about coring and equipment.

To keep the bit plumb/square to the wall, I'm having a thick timber template cut with holes pre-drilled. The bit can slot through this hole and should act to keep the bit in a reasonably straight line.