Reply
 
Thread Tools Search this Thread
 
Old 16 February 2009, 14:29   #1
Member
 
Leapy's Avatar
 
Country: UK - England
Town: Sheepy Parva
Boat name: Sadly Sold
Length: no boat
Join Date: Sep 2008
Posts: 1,728
Drilling Concrete

OK, here's one for the builders amongst us...I'm installing a 12v front-of-the-Land Rover-type recovery winch in the garage to winch the RIB in. I need to drill four holes into the garage concrete floor for rawlbolts that will hold the winch down.

So, using a Bosch 240v 800W drill (set on hammer) and a new Bosch 16mm masonry drill running at or abouts the Bosch recommended 1000rpm I've got exactly...nowhere significant. At best, I've got several holes about 5-10mm deep: I need to get to 60mm for the rawlbolts. The garage floor must be made of recycled industrial diamonds or perhaps harder

What's the professional advice?
__________________

__________________
Leapy is offline   Reply With Quote
Old 16 February 2009, 14:50   #2
Member
 
Country: Other
Town: San Carlos, Mexico
Boat name: INDE
Make: LOMAC 730
Length: 7m +
Engine: 200 Merc.
MMSI: Please press 1
Join Date: May 2006
Posts: 1,688
Send a message via Skype™ to Limey Linda
1000 rpm sounds awefully fast!!!!. My guess is the drill bit is just skidding.
__________________

__________________
Running around like a head with it's chicken cut off.
Limey Linda is offline   Reply With Quote
Old 16 February 2009, 14:55   #3
Member
 
Country: UK - England
Town: Essex/Vendee
Boat name: shockwave,Voluntry 2
Make: Pac 22/ searider5.4
Length: 6m +
Engine: 180hp turbo,yam 90
Join Date: Nov 2004
Posts: 1,015
Hi,I would imagine you have a high amount of flint/stone in the concrete and your drill is very diy or old and you need a neumatic action and more modern drill.You could try starting with a smaller diameter bit 6mm to act as a pilot hole
__________________
PeterR is offline   Reply With Quote
Old 16 February 2009, 15:01   #4
Member
 
chewy's Avatar
 
Country: UK - England
Town: Up Norf
Make: Avon SR4,Tremlett 23
Length: 4m +
Engine: Yam 55, Volvo 200
Join Date: Apr 2007
Posts: 5,217
Like Pete said make a pilot hole first but most importantly use decent quality bits.
__________________
chewy is offline   Reply With Quote
Old 16 February 2009, 15:01   #5
Member
 
Leapy's Avatar
 
Country: UK - England
Town: Sheepy Parva
Boat name: Sadly Sold
Length: no boat
Join Date: Sep 2008
Posts: 1,728
Quote:
Originally Posted by Limey Linda View Post
1000 rpm sounds awefully fast!!!!. My guess is the drill bit is just skidding.
Took the speed recommendation straight off the packet the drill came in
__________________
Leapy is offline   Reply With Quote
Old 16 February 2009, 15:06   #6
Member
 
Leapy's Avatar
 
Country: UK - England
Town: Sheepy Parva
Boat name: Sadly Sold
Length: no boat
Join Date: Sep 2008
Posts: 1,728
Quote:
Originally Posted by PeterR View Post
Hi, I would imagine you have a high amount of flint/stone in the concrete and your drill is very diy or old and you need a neumatic action and more modern drill.You could try starting with a smaller diameter bit 6mm to act as a pilot hole
The drill bit is (was) brand new and Bosch branded. I figured the job would be hard - no pun intended - so went for a good quality drill bit.

Thought about pilot holes to build up to the 16mm but a friend recommended against it. I must admit, it seems a sensible way to go.
__________________
Leapy is offline   Reply With Quote
Old 16 February 2009, 15:18   #7
Member
 
Nasher's Avatar
 
Country: Other
Town: Principalite d'Chaos
Boat name: The Nashers Revenge!
Make: Ocean & Bombard
Length: 6m +
Engine: Suzi DT200EFI, DT9.9
MMSI: "Mmmmm SI" she said!
Join Date: Jan 2004
Posts: 4,147
As has already been said the 1000rpm sounds a bit too fast to me at that diameter, despite what the packet recommends. I'd be tempted to go with @650rpm.

The Pilot drill should also be the way to go, but to get to 16mm I'd start with a 6mm, then open it up to 10 or 12mm, then finish off with the 16mm.

I had exactly this issue when we moved @10yrs ago, and I needed to bolt my Lathe and Pillar drill down to the floor in my new workshop. Despite having been put down as a normal garage floor by the builders several years before, the concrete slab was really hard. I only needed to go out to 12mm for the holes, but did it in 3 stages.

My Bosch Hammer drill(I think it was 850W) coped well, but I had to change the brushes very soon afterwards. We had however just moved in and Mrs Nasher had me drilling holes all over the place to install stuff.

Nasher.
__________________
RIBBED For extra pleasure.
Member of the ebay Blue RIB cover club.
Member of the Bombard 380 Aerotec club
Nasher is offline   Reply With Quote
Old 16 February 2009, 15:28   #8
RIBnet supporter
 
Erin's Avatar
 
Country: UK - Channel Islands
Town: A large rock
Boat name: La Frette
Make: Osprey Vipermax
Length: 6m +
Engine: 200 Suzzy
Join Date: May 2004
Posts: 2,830
I bought a pro grade Bosch SDS hammer drill (2-26DRE) http://www.bosch-pt.co.uk/boptocs2-u...object_id=8733 a short while ago and have never looked back. Compared to my dad's bosch 850w diy drill it makes hard concrete seem like cheese and it's actually only 800w. You really cannot imagine the difference it makes until you've try both. My suggestion would be to hire an SDS hammer drill. I think mine is referred to as 3 joule 2kilo type.
__________________
Erin is offline   Reply With Quote
Old 16 February 2009, 15:40   #9
Member
 
Bigmuz7's Avatar
 
Country: UK - Scotland
Town: Glasgow
Boat name: stramash
Make: Tornado
Length: 5m +
Engine: Etec 90
Join Date: Feb 2006
Posts: 5,068
16mm is big for a hand drill .. you dont state the type, so hard to know the specs, 1000 rpm is too fast too If you dont have enough weight to force the bit down, your progress will be minimal.

All these points have been mentioned, as has this,.. drill a pilot hole first but as Nasher says..in two stages, I'd prefer 8, then 12 , then your final, by that time witha 16mm, you'll really feel the torque on your wrists believe me plus you'll probably waste all three drills in the process, cos if its hard stuff they will get hot and not cope, so use water to help with that.. but its the only way for an 800 watt job if is a strong concrete mix ..

If you hit reinforcing inside it, you'll be humped with a masonary bit unless you want to buzz through several best plug the hole and try another spot, or if that fails, time to get a jack hammer out
__________________
Bigmuz7 is offline   Reply With Quote
Old 16 February 2009, 16:15   #10
RIBnet admin team
 
Poly's Avatar
 
Country: UK - Scotland
Boat name: imposter
Make: FunYak
Length: 3m +
Engine: 2 stroke YAM 20 HP
MMSI: 235089819
Join Date: Sep 2005
Posts: 10,114
Quote:
Originally Posted by Leapy View Post
Thought about pilot holes to build up to the 16mm but a friend recommended against it. I must admit, it seems a sensible way to go.
simple solution tell your friend to drill the holes (with his tools and bits!)
__________________
Poly is offline   Reply With Quote
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off





Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -5. The time now is 08:20.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.