Core drill for rock

[paul_h]

My 65mm core drill is no more. I was installing a split today and most of the carbide tips broke.
Unknown to me, under the rendered walls was concrete and rock. Chisels didn't last long either.

Anyone drilled through stuff like this before?
I probably need a diamond core drill, (and a new masonary drill ), has anyone used an ebay cheapy designed for cutting holes in tiles to drill through a wall?

I don't mind getting a subbie to finish the hole for me and pass on the full costs to the customer, but where to find such a sub contractor. I've never seen a "hole specialist" for such small jobs advertised
The hole is in a prick of a position ender a brick and tile window awning too, so nothing big will fit there...

[Electrocoolman]

Hi Paul,

Are you trying to drill thru the lintel above the window?
These often have steel reinforcing in.
Buy a decent diamond core drill...you only get what you pay for!

[paul_h]

It's adjacent to the window, ~200mm+ across, ~200mm above, so shouldn't be near any reo, as it's a fair bit above and across. It's just a really old house in an old expensive area.
Nothing much different about it, standard 3bd, single storey, just the rendering was done with concrete and small stones.
edit:
I understand you only get what you pay for, but as diamond tips aren't usually inpact/sds or do deep holes, I've got to get a new decent expensive carbide masonary bit anyway. The diamond drills I've seen on ebay are $20, if they last long enough to drill through 2" of rock, I don't care if that's the end of them, the $20 will be added to the customers bill, I can't pass on the costs of expensive gear.
They don't need to last long, future jobs will be more carefully examined before I start work and I'll avoid similar work, so no point in getting an expensive specialist tool for it.

[monkey spanners]

Could you hire a diamond core drill and the drill to power it locally? This is what we do for the bigger holes we drill. You need a high speed drill to run a diamond bit, to slow and they don't cut too well, same for the cheaper core drills, they don't cut well in the harder materials.

Jon

[richelli]

We use a dry dimond core bit for most holes but sometimes we end up hiring a wet core drill for the day. Cuts through most conrete etc like a knife through butter. Only problem is the water does go everywhere so no good if the the room your drilling into isnt gonna be decorated. Best to drill from outside as well. The dry dimond cores are good but we have a type of red brick which just eats the tips in minutes and any walls where there are loose stones or slate just chops the tips clean off. Also if you use dry dimond and the wall is damp at any point feel free to pull your hair out and cry like a baby when the core bit sticks and you then spend all day trying to get it out! Oh the joys of hole drilling !!!!

[Grizzly]

My 65mm core drill is no more. I was installing a split today and most of the carbide tips broke.
Unknown to me, under the rendered walls was concrete and rock. Chisels didn't last long either.

Anyone drilled through stuff like this before?
I probably need a diamond core drill, (and a new masonry drill ), has anyone used an ebay cheapy designed for cutting holes in tiles to drill through a wall?

I don't mind getting a subbie to finish the hole for me and pass on the full costs to the customer, but where to find such a sub contractor. I've never seen a "hole specialist" for such small jobs advertised
The hole is in a prick of a position ender a brick and tile window awning too, so nothing big will fit there...

Hi Paul.
From personal experience I prefer to still use the carbide tipped drills and if feed gently will happily cut through steel reinforcing ECT.

The trick is to have good quality bits and a good "pneumatic" hammer drill. definitely not rotary percussion.
I am lucky enough to own a couple of Hilti drills which are the muts nuts.
When the bits wear down or loose their edge I take the to a local saw grinding and sharpening company.

Who re-tip and grind them for a fraction of the renewal cost

Incidentally I purchased my 4" and 6" core bits from the local Tool Hire Shop second hand as when they wear down they quite often discard them.

I know a lot of guys swear by diamond tip bits and they have their uses.
But if I ever get the situation where one is needed.
I can always hire one!

Besides have you ever tried drilling a vertical hole (from above) with one they clog up for a pastime.

Yes you could pass the cost on. but you could charge for the cost in-case you need to hire and if you don't it more profit!

In the UK the norm is to hire and avoid specialist firms unless you have to because they are very expensive.
Good Luck Grizzly

[nike123]

My hummer drill is Makita HR4011 and core is Hawera (Bosh) for concrete and stone:
http://tinyurl.com/4kxw5j
I drill with him till I sense that is hitting armoring. Then, I use this bit to cut thru armoring (drilling few holes till I drill thru armoring): http://tinyurl.com/3krnat
and when I pass thru armoring, i keep drilling with first one.
These two bit cost me about 500 US$, and I usually use them 2-3 years each (but I newer, ever give anyone else, except me, to drill with them, and I don't even sweat at all).
In my country, reinforced concrete of 25 cm and good quality is 70% of drilling for instalation of split type air conditioner, and wet and dry diamond drilling is not option (dry is to destructive to bits, and wet is not option, because it is already equipped and inhabited flat).

[Electrocoolman]

Hi Paul, recently had experience of a 'boot lintel'.
It was cast in situ when the house was built On the outside it looked about 4" (100mm) but inside it was a good 12" (300mm) and covered with plaster. Rebar inside.
A s*d to drill

[paul_h]

All seems too hard, some said drill slow, someone else says drill fast. I've got no guarantees anything I buy or try will work, you're all scaring me with the chances of steel bars/plating and the wall thickness

Thanks for all replies, I found someone that will drill the hole for $150.
Their minimum callout/job is $190+10%GST, but they will do it for $150 for me. Nice rates they charge I'm in the wrong trade because I was only charging $400 for the whole install!
(I did charge him $140 before to remove the old unit, and the wiring is all there, that's why my price was low.)

[kiwireeferman]

First rule! If it looks easy, it will most likely to to Cr*p on you.
Thats why you shouldn't cut the guts out of the price. Been there-done that many times.

[paul_h]

Took the drill specialist 3 hrs to drill the hole today. 1 hour of that was him going to get a new electric drill when his burnt out .
8 inches of concrete and quartz, 2 steel lintels!

[Grizzly]

Took the drill specialist 3 hrs to drill the hole today. 1 hour of that was him going to get a new electric drill when his burnt out .
8 inches of concrete and quartz, 2 steel lintels!

Wow.
You obviously got it right by calling the guy in then Paul!!
Have you had to carry his costs or could you build it in.
Grizzly

[paul_h]

I quoted the install at $400. When I came to this problem and got the $150 drilling quote, I told him that due to unforseen circumstances, the job would now cost $600
The driller ended up charging $200 which was fair, so the price ended up going up to $650 in the middle of the job, I got the customers Ok each time.
I was open and honest about it, I wasn't trying to mark back up the cash discounts the driller was giving me to their retail costs and earn some extra. I just explained that it's not me ripping him off, it's the costs you have to pay due to the wall construction and no one else could do it cheaper.
He was suprised with the cost at first when I quoted him the extra on the phone, but said he trusted me and paid up the $650.
edit: He wasn't surprised at the cost when he saw how bad it was to drill, I think he might have realised he got a bargain
these driller charge $190+ 10% tax for callout and one hour, he got the driller there for over two hours for only $200

[nike123]

these driller charge $190+ 10% tax for callout and one hour, he got the driller there for over two hours for only $200

Did he drilled with diamond core or with regular?

[paul_h]

Diamond, it was a ~800mm long cylinder core drill with four blades on the end

[Jadeair]

I use a dry diamond core cutter for my splits 80mm dia 160mm long cuts through brick and concrete, even been through rio ( don't think it was designed for that?? ).
There's an extension bar that doubles the length, coupled with a battery drill makes life easy. Cost about $200 aus.

[nike123]

I use a dry diamond core cutter for my splits 80mm dia 160mm long cuts through brick and concrete, even been through rio ( don't think it was designed for that?? ).
There's an extension bar that doubles the length, coupled with a battery drill makes life easy. Cost about $200 aus.

That battery drill must be of some special kind!

[Jadeair]

That battery drill must be of some special kind!

It's a milwaukee 28v rotary hammer drill, although you use the drill not the hammer selection for the core holes.
Saves runnig out leads..

[paul_h]

I'm up for a new drill anyway since I stuffed up my masonary carbide bit. Where did you get the diamond bit? Can you get them in 65mm size?

[Jadeair]

They come in a 62mm or 67mm.
Call sothern cross fasteners 07 5524 3919 and speak to Gary about the dry core bit and they'll be able to sort it out.
Happy drilling..

[Inverter man]

There's acompany called D-Drill in the UK, try googling them for address or tel No. They may be able to give advice, if not now, then the future.