what is the best type of drill bit?

[Charlie]

I was wondering what people think of these 3 diffrent types

Fischer 3 flute

found in http://www.fischer.co.uk/befestigung/index.html as SDS plus driller

Hilti standard [TE-C] drill bit

http://www.hilti.co.uk/holuk/modules/prcat/prca_navigation.jsp?OID=-27774
this is the x type with 2 main cutting edges and then 2 smaller ones following about 30o behind

or Hilti TE-C3X bits

http://www.hilti.co.uk/holuk/modules/prcat/prca_navigation.jsp?OID=-29082
with 4 cutting edges at 90o

And any comments on the best way to do a comparitive test.

Charlie

 

[nickwilliams]

I think the four tip Hilti one is probably the best although I've never done any objective tests to prove it.

However, I guess you are talking about the use of an 8mm bit to drill holes for caps, and IMHO, at this size I don't think the tip type makes a lot of odds - the quality of the machine which drives it outweighs all other factors by a wide enough margin that so long as the drill is sharp, the effect of different tip profiles is negligible. On that basis, the cheapest drill single-tip drill which you can get is probably preferable, on the basis that when it goes blunt you can chuck it away and use a new one. Single tip drill are also sharpenable - I've never tried to sharpen a multi point drill but it can't be as straightforward as for a single tip.

For bigger holes (12mm diameter, and 300mm or longer depths) then the drill tip profile (and the flute profile) starts to be more significant, IMHO.

Nick.

 

[Hughie]

Without wishing to sound facetious, I only use cheap bits.

Looked at the prices on one of your links and found the cheap bits I use (screw fix) come at a fraction of the price.

 

[NigR]

If battery power is a problem - i.e. you are intending to drill somewhere a long way into a cave and don't want to carry too much kit - then it may be worth buying the fancier more expensive bits. Likewise, as Nick says, they are worth purchasing if you are going to be drilling a lot of relatively large diameter shotholes. Otherwise, save your cash and buy the best drill you can afford. If money is no obstacle then buy the best drill and the best bits!

 

[Charlie]

I had a play with these diffrent drill bits today on a lump of limestone I had handy, the Hilti TE-C3X are the best by a country mile.

Not surprising really.

Charlie

 

[nickwilliams]

What size bit(s) were you playing with?

Nick.

 

[Charlie]

I got a set of the hiltis with m8 m10 and m12 x100mm the 3 flute was m10x100mm. the hilti 12mm drilled at least as fast as the fischer 10mm.

 

[AndyF]

Without wishing to sound facetious, I only use cheap bits.

Looked at the prices on one of your links and found the cheap bits I use (screw fix) come at a fraction of the price.

Cheap bits are ok with battery drills (typically 250-350 watts) use them on a 110 volt drill (850 watts for our current drill) and they dont stand up to the work.

The higher power drills make the tip hotter, and we've had a number of cheap bits fail. In one case the tip half broke off, the drill jammed and the drill body flew round and smacked me in the face. Not good.

The Hilti 3X bits are very good, but dont' "clear" as quickly, so you have to pull the drill in and out more to keep up the pace (This is due to not having such a deep spiral goove. They have a higher thermal mass though, and dont overheat.

I like Bosch brand ones best, and any brand "X" made in Switzerland (the Bosch ones are Swiss).

Wickes own brand are also great and clear well.

Avoid the French brands, they have a shallower spiral and are too flexible. The set I bought from "Aldi" was total pants.

 

[pete h]

Without wishing to sound facetious, I only use cheap bits.

Looked at the prices on one of your links and found the cheap bits I use (screw fix) come at a fraction of the price.

Cheap bits are ok with battery drills (typically 250-350 watts) use them on a 110 volt drill (850 watts for our current drill) and they dont stand up to the work.

The higher power drills make the tip hotter, and we've had a number of cheap bits fail. In one case the tip half broke off, the drill jammed and the drill body flew round and smacked me in the face. Not good.

The Hilti 3X bits are very good, but dont' "clear" as quickly, so you have to pull the drill in and out more to keep up the pace (This is due to not having such a deep spiral goove. They have a higher thermal mass though, and dont overheat.

I like Bosch brand ones best, and any brand "X" made in Switzerland (the Bosch ones are Swiss).

Wickes own brand are also great and clear well.

Avoid the French brands, they have a shallower spiral and are too flexible. The set I bought from "Aldi" was total pants.

I think you will find it is not the voltage or wattatge of the drill that counts but the impact energy that maters. The Milwaukee 28 volt is rated at 3.2J and the Bosch 110 multi drill at 3.5J, i use both for work and in tests drilling the same size hole with the same bit (25mm) the Milwaukee held its ground.

 

[AndyF]

I think you will find it is not the voltage or wattatge of the drill that counts but the impact energy that maters. The Milwaukee 28 volt is rated at 3.2J and the Bosch 110 multi drill at 3.5J, i use both for work and in tests drilling the same size hole with the same bit (25mm) the Milwaukee held its ground.

Well yes - probably it would be a function of (impact energy x blows per minutes)

Impact energy spread over a larger diameter bit would be less likely to fail. We usually use 12mm bits.

Those 850 watts can only be transferred via the drill tip, thus the heating effect.

The battery drills are just lower power. The Bosches are 250watts (IIRC) and our ELU is 350 watts. They just dont work the bit as hard.

We never had a bit failure with aour 550 watt B&D, but the 850watt Hitachi we now have eats bits for breakfast.

 

[pete h]

I don't know where you got your information on the power of the Bosch but the one i use is either 800 or 1000 watts will check the tool store tomorrow

 

[AndyF]

I don't know where you got your information on the power of the Bosch but the one i use is either 800 or 1000 watts will check the tool store tomorrow

We had one (albeit quite old now) Infor came from the sticker on the side... 

 

[whitelackington]

We now only use the Hilti bits,
very fast and reliable.
The drills we use are 36volt Lithium
similar output from most makes.