diamond core drill best practices

[Ouch77]

Hi all,
Any tips and advice for diamond core drilling?

I'm in the process of putting a series of holes in the walls of my house for pipework for my extension, I'm using an Erbauer core drill set, with the 52mm size, and a Bosch PBH3000 sds drill (obviously not in hammer mode) with a max speed of 1450rpm - I'm drilling through some pretty tough local (Newport) brick . It's currently taking me over an hour. with occasional 2-3 minute breaks to allow me to stretch and let the drill cool off a bit. Any thoughts or suggestions as to how I could reduce the time/increase the effectiveness? Should I be letting the drill cool down more frequently? How much pressure should I be applying? Continuous or pulsed pressure? etc..

Thoughts welcome..

 

[johnny2007]

More pressure will only result in slower coring.
Keep just a little pressure which will help keeping the tool straight and go slow, not at full rotating speed.
Make sure your sds has a clutch, otherwise your wrists might get twisted.
A coring drill is always best, but I have used my makita sds and the clutch engages effectively if the bit jams.
In fact, it engages earlier than the clutch on the coring drill.
Don't know about other brands of sds though.

 

[opps]

Hi all,
Any tips and advice for diamond core drilling?

I'm in the process of putting a series of holes in the walls of my house for pipework for my extension, I'm using an Erbauer core drill set, with the 52mm size, and a Bosch PBH3000 sds drill (obviously not in hammer mode) with a max speed of 1450rpm - I'm drilling through some pretty tough local (Newport) brick . It's currently taking me over an hour. with occasional 2-3 minute breaks to allow me to stretch and let the drill cool off a bit. Any thoughts or suggestions as to how I could reduce the time/increase the effectiveness? Should I be letting the drill cool down more frequently? How much pressure should I be applying? Continuous or pulsed pressure? etc..

Thoughts welcome..

I don't understand how the sets provided with an integral drill bit are supposed to work.

I have core bits but the arbour has a rod rather than a drill bit. I use a long SDS bit to drill through the brickwork, and then use the core, drilling from both inside and outside to prevent break out.

Are you predrilling with an equally sized SDS bit first? If not, the SDS bit that they have in the arbour is going to have to try to drill in rotary only, meaning that it may be that which is slowing down the job.

 

[Ouch77]

@johnny2007 - my Bosch has a clutch, so no worries there. I guess the issue is what speed is considered slow. My drill has a 2 speed gearbox, as well as the trigger speed controller, so I usually run it on the lower speed (1450rpm) but usually flat out.

@opps I tend to pre-drill, my set comes with an 8mm masonry tip, on a tapered stock, which sits in the arbor. Though to be honest I tend to remove the inner drill when I'm in a couple of inches, as it frequently binds up, also my 8mm sds isn't as long as my walls are thick so I tend to run out of hole, as it were.

 

[Deleted member 174758]

1450rpm is not that slow. I looked up the speed recommendation for a 52mm core - Duro (a well known supplier) quote 1250rpm, with the additional recommendation that speeds should be reduced when drilling abrasive materials. So maybe just lower the speed to around 900 or 1000rpm

 

[Notch7]

Hi all,
Any tips and advice for diamond core drilling?

I'm in the process of putting a series of holes in the walls of my house for pipework for my extension, I'm using an Erbauer core drill set, with the 52mm size, and a Bosch PBH3000 sds drill (obviously not in hammer mode) with a max speed of 1450rpm - I'm drilling through some pretty tough local (Newport) brick . It's currently taking me over an hour. with occasional 2-3 minute breaks to allow me to stretch and let the drill cool off a bit. Any thoughts or suggestions as to how I could reduce the time/increase the effectiveness? Should I be letting the drill cool down more frequently? How much pressure should I be applying? Continuous or pulsed pressure? etc..

Thoughts welcome..

Maybe not so much on smaller sizes but on anything over 75mm, I find it cuts better to rock ever so slightly up / down and side to side, and applying pressure at each new position.What it does is cut just a part of the circle each go.

 

[Ouch77]

1450rpm is not that slow. I looked up the speed recommendation for a 52mm core - Duro (a well own supplier) quote 1250rpm, with the additional recommendation that speeds should be reduced when drilling abrasive materials. So maybe just lower the speed to around 900 or 1000rpm

maybe I'll back off a bit. Erbauer don't really state a speed, which is irritating.

 

[cdbe]

They can be slow, I spent a hour and a half on a recent 110mm one. If you chain drill round the hole with a 5mm sds bit after you've got it started that will help.

 

[Exedon]

If your using standard plain core drills it can be steady,
The ones with the dust extraction groove are certainly quicker.
Better still a dedicated drill intended for coreing,
I've a marcrist drill and use there pc850 cores they are intended to work with percussion on (not sds) really quick less than 5 min for a 110mm through class B bricks.

 

[opps]

@opps I tend to pre-drill, my set comes with an 8mm masonry tip, on a tapered stock, which sits in the arbor. Though to be honest I tend to remove the inner drill when I'm in a couple of inches, as it frequently binds up, also my 8mm sds isn't as long as my walls are thick so I tend to run out of hole, as it were.

Paying a tenner or twelve quid (?) for a long SDS bit might be prudent. At the moment it sounds like you might be deviating as you core drill. That will increase the pressure on the wall of the core drill and slow things. The rod ensures the you follow a straight line, or in your case the arbour SDS bit. That said, an SDS arbor drill bit is only 8mm at the tip, the fluted apart will be slightly smaller (thereby possibly allowing deviance).

With your current set up, you WILL have breakout when you get through the wall, given the inability to drill from both sides.

I still don't understand why they have SDS bits in the abor though given that that the core is rotary only.

I guess it is a case of Screwfix/Kingfisher buying cheap Chinese rubbish and the person responsible for sourcing the tat not understanding how it should work. If I am wrong I hope to be corrected, that way I learn something new.

Sorry, I am not expecting you to be able to explain why there is an SDS bit in the centre, I am hoping that someone with more experience than either of us will be able to elucidate/educate us.

Regards

 

[cdbe]

Mine doesn't have an SDS bit, it has a masonry bit with a taper to fit in the core holder (the little thing with the thread). One of my sets comes with a steel guide rod (like a drill bit with no tip or flutes) which also has a taper, I assume the idea is that you hammer through without the core fitted, then fit the guide rod and core. My set has two "core holders", an SDS fitment and a hex fitment for a standard chuck - the drill bit and guide rod are interchangeable between both. Many SDS drills have a rotary setting (no hammering) for diamond cores.

 

[Deleted member 174758]

I still don't understand why they have SDS bits in the abor though

The only setup I've come across like that was a cheaper TCT core set a number of years back. I had just such a set for kitchen fitting for a short while between getting tired of paying his to hire a diamond core drill and cores and actually biting the bullet and buying some

I fully agree with you on the topic of piloting all the way with a long SDS bit then using the core from both sides - this stops you from spalling away the surface of the brick if drilling from the inside out and makes for a neater job in general

 

[Deleted member 174758]

Many SDS drills have a rotary setting (no hammering) for diamond cores.

I'd say that in view of the fact thst many 1st generation SDS drills (which all lacked rotation stop) either lacked or only possessed rudimentary clutches, the rotary only setting was more for the drilling of tiles, etc where the hammer action is likely to break tiles. Products, like SDS auger bits, SDS chucks, etc are later innovations designed to make an SDS drill (originally a bit of a one trick pony) more versatile. The clutches on most SDS drills have got better, but are, in any case, limited to something like 50 or 60mm max diameter, and SDS drills also lack the long side handles of true core drills which are needed for large diameter cores (I started with a 1st generation Bosch SDS which was my pride and joy at the time)

 

[Notch7]

Using a large core drill on a drill without a clutch is dodgy. There was a case of an electrician working next to a lift shaft, the drill snagged and he went down the lift shaft. Brown Bread.

 

[Ouch77]

This is the kit I'm using:
Screwfix/Erbauer core drill kit

I wouldn't entertain using the pilot drill for much, given it's only a taper fit. I'm drilling into underfloor cavities, so tidyness isn't an issue, though previous holes have turned out quite neat, I assume its a feature of these tough brick I'm drilling as if they don't seem to spall much under 'abrasion' drilling, only hammer drilling.