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Pinzgauer
50.2% (Neutral)
Newbie Topic Starter

11 years ago

What make of drill bit do those who endulge in rotary/percussive pursuits use ? Got a couple of holes to drill in whinstone/granite for an eyebolt about 3/8" dia. (ish)

Cheap and cheerful (B&Q ish) and launch them into low earth orbit after a couple of revolutions, or invest in one "decent" one ?

Opinions on "decent" appreciated.

Thanks.

Who threw the overalls in Mrs Murphy''s Chowder ??

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sinker
50.2% (Neutral)
Newbie

11 years ago

"Pinzgauer" wrote:
What make of drill bit do those who endulge in rotary/percussive pursuits use ? Got a couple of holes to drill in whinstone/granite for an eyebolt about 3/8" dia. (ish)

Cheap and cheerful (B&Q ish) and launch them into low earth orbit after a couple of revolutions, or invest in one "decent" one ?

Opinions on "decent" appreciated.

Thanks.

Buy a couple of decent bits. Hilti or Makita. Twice the cost but last about 20 times longer :thumbup:

Yma O Hyd....

Dolcoathguy
50.2% (Neutral)
Newbie

11 years ago

I bought a deWalt SDS+ stone / masonary bit for £15 ( 10mm), it has lasted after 5 or so uses going through several inches of Granite each time.
I found going from a normal std drill (with hammer action) to a big SDS+ drill made a massive difference. I think you need to get a certain amount of hammer force otherwise you just melt your bit with excessive rotation ...but I am not an expert or builder, just live in a granite house!

Is it safe to come out of the bunker yet?

lozz
50.2% (Neutral)
Newbie

11 years ago

Drilled lots of holes in granite with an SDS and masonry bit, most mainstream builders merchants will stock decent bits, ask them what the lads in the trade use, can't remember the make of mine but they have done plenty of drilling in the hard stuff.
The only thing they don't like are the old Hayle foundary blocks, those are bitches to drill!

Lozz.

Simon M
50.2% (Neutral)
Newbie

11 years ago

Go for a diamond bit and use it on rotary only.

Drillbilly.
50.2% (Neutral)
Newbie

11 years ago

Something a bit bigger than that.

lozz
50.2% (Neutral)
Newbie

11 years ago

A good quality SDS bit will drill granite lot's of times no problem, a 3/8 bit should romp through, don't overdo the pressure you apply, keep the hole clear as you advance by frequent withdrawal as the actress said to the bishop.
If the dust accumulates at the bottom of the hole and becomes damp you might find the the drill bit will overheat and the insert drop out.

Lozz.

John Lawson
50.2% (Neutral)
Newbie

11 years ago

Tend to use Bosch myself although as I understand it Hilti came up the original SDS drill and have used their drill bits and Dewalt without any noticeable difference in wear rate.
As has already been posted on this thread do not force the drill and remove the bit fairly frequently to remove the stone dust.
Over time the drills do wear unevenly, becoming distinctly tapered. At that stage they have to thrown out, unless someone out there can think of a use for them.
SDS drills seem to be effective in all hard rocks and granite will drill readily.

simonrl
51% (Neutral)
Administration

11 years ago

Good quality ones all the time. Dewalt or Hilti.

Nothing more frustrating than finding you've drilled an 11mm hole with your 12mm bit and the damned bolt won't go in :curse:

my orders are to sit here and watch the world go by

Tamarmole
50.2% (Neutral)
Newbie

11 years ago

#10

"SimonRL" wrote:

Nothing more frustrating than finding you've drilled an 11mm hole with your 12mm bit and the damned bolt won't go in :curse:

Oh yes there is - lending your drill with a brand new bit to a mate who somehow manages to drill two 16mm holes with the drill running backwards! :thumbdown:

Graigfawr
50.2% (Neutral)
Newbie

11 years ago

#11

If you have sufficient battery power, drilling a pilot hole first and then using the big expensive drill bit to ream it out can massively extend the life of the larger drill bit - to the extent that you more than offset the cost of the drill bits used for the pilot holes.

Morlock
50.2% (Neutral)
Newbie

11 years ago

#12

Does anyone resharpen the good quality bits?

Simon M
50.2% (Neutral)
Newbie

11 years ago

#13

Yes, I sharpen my tungsten tipped ones and son in law's who is a builder, easy to sharpen with the right stone.

Morlock
50.2% (Neutral)
Newbie

11 years ago

#14

"Simon M" wrote:
Yes, I sharpen my tungsten tipped ones and son in law's who is a builder, easy to sharpen with the right stone.

Just wondered as a lot of people throw perfectly good bits away (tip just blunt), usually because their grinding wheel's the wrong grade.

Pinzgauer
50.2% (Neutral)
Newbie Topic Starter

11 years ago

#15

Many thanks for the comments and opinions. Much appreciated.

Who threw the overalls in Mrs Murphy''s Chowder ??

Roger L
50.2% (Neutral)
Newbie

11 years ago

#16

Building sites used to be a good source of supply for drill bits which had been thrown away. In the 60s I carried what was at the time a green coloured grinding stone for use in a drill which I used for sharpening duriam tipped bits. in the 90s SDS bits were found regularly, just blunt.
Lidl do a cheap set which I have found good for general use round the house.

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