Bought a pack of 3 400mm long "masonry" drill bits to use as pilot for drilling a 20mm hole for outside tap. Each drill completly wore the red tip down to nothing in about half inch drilling of a crap scottish brick. Guess I will have to spend more than a pound on a set...
Geo
Don't feel too bad. I just bought a set of 3 1000mm SDS drills for £19... they might last a couple of holes each.
Cue for Scottish jokes....
Seriously though, some of the cheap masonry drills seem fine and some are rubbish. Name and Shame!
Steve
OK - from the Pound Shop in Falkirk, Blackspur Tools 3Pc 400mm Masonry Drill Set
- tips reduced to rounded lumps in 30 seconds... Geo
Blackspur!! (clenches fist and spits) I bought a pack of 6 flat bits from a cheap shop in Liverpool. I had to power the drill in reverse to make a hole. :)
Arthur
Sounds like a special brand for cowboys...
Made in China,will we ever learn,buy cheap gets cheap
No problem here with a 10x1000mm from Screwfix. After a whole afternoon of probing into Scottish bedrock (trying to find somewhere to sink an earth rod), it happily drilled through three layers of engineering brick. The tip still isn't showing much wear.
SDS tends to be far kinder on the bits than hammer. It's the heat that kills them.
Masonry Drill Set
Ah, Blackspur... its ancient Saxon and means 'beware, you wont even get one job done with this POS.'
I bought Blackspur screwdriver whatnots. Managed one screw. The screw head was fine, but the driver had acquired a new shape altogether.
NT
Suppose it's horses for courses. Only Blackspur thing I ever bought were some clamps - they work like a sealant gun - don't know the proper name. They work an absolute treat, better than some more expensive ones I have.
Dave
Masonry Drill Set
Got an angle grinder? Cut slots in them and dip in water to harden, drill another half inch, cut em again and dip in water, etc etc etc.
Crude, but sometimes it can be quicker than going to the shops.
I was going to say it might just be theyre being overheated and need more rest, but probably not: my experience of blackspur work bits is no hardening at all, and quite useless. In which case grinding and dipping might make them last better.
NT
Would heating them red hot on the stove then quenching them in water be of benefit?
That is how you would normally soften hardened metal... it this case it sounds like it is not going to get much softer ;-)
Or maybe not. Bought a set of 3*1000mm (8,15,122mm) and the 22mm bit has done about
30*8" holes in concrete and 10*8" in granite (to punch a hole through a concrete slab to run cabling)No perceptible wear.
John Rumm wrote :-
Nope, to soften you normally allow to cool very slowly
Regards Jeff
Dave Plowman (News) wrote :-
Years ago I had a B&D drill that had a switch for the 2 speeds, 3300 and
2800 iirc both far too fast for masonry drill bits, it used to burn 'em out rapidly. I had a very frustrating time fitting a 4" fan in quite hard bricks. Slow, 900 rpm is the answer or better still SDSRegards Jeff
Not with ferrous metals IIRC.
(slow cooling will anneal copper for example, but quenching works better on steel)
John Rumm wrote :-
I beg to differ my good man :-
To harden most steel it is heated to a medium red or slightly above the point where it becomes non-magnetic. It is then quenched in water, oil or air depending on the type of steel. The steel is now at its maximum hardness but is very brittle. To reduce the brittleness the metal is tempered by heating it to some where between 350°F and 1350°F. This reduced the hardness a little and the brittelness a lot. Most steels need to be tempered at about
450°F for maximum usable hardness but every steel is slightly different. To soften steel so that it can be cold worked and machined is called annealing. To anneal steel is is heated to slightly above the hardening temperature and then cooled as slow as possible. Cooling is done in an insulating medium such as dry powdered lime or in vermiculite. High carbon and many alloy steels can only be cooled slow enough in a temperatue controlled furnace since the cooling rate must be only 20 degrees F per hour for several hours.source =
Regards Jeff
Hi John
But surely on a masonry drill bit we are talking about tungsten carbide and not ordinary steel?
Dave
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