Drill power for core drilling

[Handyman]

What's the minimum drill power I can get away with for diamond core drilling up to, say, 50mm? Same question but for 127mm? (I will only consider buying Bosch, Dewalt, or Makita brands).

 

[Hitachimad]

The Makita 8406 core drill with capacity of 6" is about 800watts.

One thing to remember, although a core drills motor is smaller than some standard type impact drills, they are geared differently so produce much more torque for the same size motor.

I can recomend the Hitachi DC120v, although they say 5" max, it easily copes with a 6"

 

[Handyman]

Point taken, Hitachimad, about gearing, but what I want to do is buy a normal drill suitable for 95% of my tasks, but is also suitable for the occasional core drilling. I don't want (= can't afford) to buy two different machines.

 

[seaangler]

when using a diamond core bit you need high torque , a good bit of power and a clutch (which will stop YOU spinning if the core bit jams)
this doesnt come cheap the bosch GSB22-2RE is one of the cheapest quality ones available but you are still looking around the £170 mark
You can get away with a sds drill on the smaller size cores (up to 50mm) but its not advisable to go much bigger

 

[Hitachimad]

Point taken, Hitachimad, about gearing, but what I want to do is buy a normal drill suitable for 95% of my tasks, but is also suitable for the occasional core drilling. I don't want (= can't afford) to buy two different machines.

What drills do you already have? Do you have an sds already?

That bosch one looks like just the ticket for general work and occasional cores.

 

[Handyman]

I do not have an SDS drill (yet). My trusty old Bosch 750w hammer drill must be 20 years old, but the bearings are wearing out (and it really has been abused), so I thought I'd replace it with a GSB20-2RE, and maybe buy an SDS model later on.

I don't want the thing to be too heavy for general use, and the GSB20 seems nearest replacement to what I've got, but if I can use it for light duty core drilling, then that would be a bonus.

GSB22 is obviously more powerful, but also heavier and more expensive - especially if I'm going to by an SDS later, but if I have to go to this level in order to do core drilling, then I might rethink. Might be better to hire core drill as and when required.

(Does the GSB22 have a clutch?? Can't see this in the spec)

 

[Hitachimad]

1010W input motor
- no load speed 0-800 0-2100rpm
- collar diameter 43mm
- weight 2.8kg
- max drilling capacities 16mm in steel, 40mm in wood, 22mm in masonry, 110mm diamond core
- vibration control
- forward/reverse rotation
- safety clutch
- 12 months manufacturer's warranty

Yes

 

[seaangler]

it does have a clutch but it isnt as sensitive as on the makita 8406 for instance , not a great problem though - just withdraw the core bit now and then to clear the dust (the dust can cause the bit to jam)

the 12 months warrentry is correct BUT if you register any bosh blue drill on-line then you print yourself a 3 year warrentry

 

[iaith]

I bought a B&Q 850w rotary hammer drill a couple of years ago , I've only ever used it for mixing plaster which it dose well.
The other day I needed to drill two 110mm holes through a normal double skinned brick wall .I didn't have a core drill so I used the B&Q drill with a diamond core bit. I don't think the drill has a clutch so it must have been the gears grinding when the drill got stuck but basically it done the job fine, and even after all that gear grinding it still mixes plaster perfectly. it cost £60 several years ago ,I think they're only £30 now. thats cheaper than hiring a core drill.

 

[Hitachimad]

Probably the motor, if you jam a drill without a safety clutch it takes a few seconds and the bugger will get red hot.
Do it more than a couple of times and the mindings will be cooked.

 

[Hitachimad]

Probably the motor, if you jam a drill without a safety clutch it takes a few seconds and the bugger will get red hot.
Do it more than a couple of times and the mindings will be cooked.

The last thing you want is to be drilling a hole for a customer and it dies midway!!

 

[Handyman]

I only buy Bosch tools, and Bosch blue where appropriate. I can't be bothered with any cheapo machines. I've been tempted in the past on a couple of occasions, and then regretted it ever since. So, it has to be Bosch for me. (My abused 20 year old Bosch hammer drill is the DIY green variety )

Going back to the GSB variants, I'm going to have another look at these models. Is the GSB 20 really a waste of time for core drilling, even if only needed occasionally??

 

[gcol]

I will only consider buying Bosch, Dewalt, or Makita brands.

Ok, fair enough.

I only buy Bosch tools, and Bosch blue where appropriate.

Hmmm, well which is it?

Personally, when it comes to major power tools that are used frequently, I buy Makita.

 

[Scrit]

I don't think the drill has a clutch so it must have been the gears grinding when the drill got stuck but basically it done the job fine, and even after all that gear grinding it still mixes plaster perfectly. it cost £60 several years ago ,I think they're only £30 now. thats cheaper than hiring a core drill.

The only problem with it not having a clutch is that it can catch and throw you off the ladder or even sprain your wrist - not good! Larger cores require a low geared drill with a clutch on safety grounds.

Scrit

 

[iaith]

OK guys. I'm not suggesting that anyone should go to B&Q to buy power tools, I did years ago but since then I've learnt the error of my ways. I used the B&Q drill out of desperation, I was expecting it to get jammed and then burn out, I could then throw it away and buy something decent, but the drill didn't behave at all the way I was expecting, when it did get stuck there was a definite clicking sound like a ratchet or maybe gears slipping.