Diamond tip hole saw

[TheJay]

I bought this to make a tidy hole in brickwork.

https://www.amazon.co.uk/gp/product/B09JKJNJXC?th=1

I have an SDS bit with a thread on it that fits. The problem is, it's impossible to keep the bit in the same place when cutting and it goes all over the place.

Any time I have used a holesaw in the past, it comes with a pilot drill bit that keeps it centred. This is so long, it's not possible. Can someone please tell me how I am supposed to use it?

Thanks.

 

[RandomGrinch]

Hi,

You can make the same size hole in an appropriately sized block of wood.
Temporarily attach the block to the wall with a couple of screws.
This will give you a start to the hole without too much wandering around!

 

[Diver Fred]

Start with a short one the same size.

try to keep breaking out the core as drill through - makes it easier on the drill.

Don't forget the drills get very HOT in use so it's easy to burn your fingers.

 

[TheJay]

Thanks, these are both good suggestions. Am I right in thinking the standard way would be using a shorter hole saw of the same diameter?

 

[opps]

Thanks, these are both good suggestions. Am I right in thinking the standard way would be using a shorter hole saw of the same diameter?

Or buy one that has the bar in the middle that will follow the hole drilled using a SDS drill previously. That way you will be able to drill from both the outer and inner face without risking break out.

The fact that it has no slots worries me. If you are going through a 9" wall, how do you remove the core?

I would be inclined to return it for a refund.

BTW, the manufacturer seems to have many products with no reviews.

Amazon.co.uk : Futchoy

 

[Deleted member 174758]

I have an SDS bit with a thread on it that fits. The problem is, it's impossible to keep the bit in the same place when cutting and it goes all over the place.

Any time I have used a holesaw in the past, it comes with a pilot drill bit that keeps it centred. This is so long, it's not possible. Can someone please tell me how I am supposed to use it?

You are supposed to start a deep hole with a shorter core drill of the same diameter (fitted with a pilot), then once you've established the hole swap to the deeper core drill. It's about the safest way and is the standard way

The fact that it has no slots worries me. If you are going through a 9" wall, how do you remove the core?

I would be inclined to return it for a refund.

Likewise. That will just end up clogging up and you'll never clear the debris from inside. Cheap Chinese tat?

Edit: Correction - looked at the brand, "Futchoy". Definitely cheap Chinese tat. European or American brands are far better, and guaranteed quality - so they are less likely to get failed welds, broken diamonds, etc

Most core drill accessory kits have extension bars which will allow you to go through thicker walls by using progressively longer extensions (my set has 3 extension bars). If you must have a single long bit what you need looks like these (note the side slots - the ribbed sides also seem to run a bit smoother IMHO):

I'd also be very wary of using an SDS drill with a core drill bit - a lot of SDS drills either don't have a clutch (generally the cheaper ones) or have a clutch with a very limited torque rating (limiting them to about 63 to 80mm core size). Always use core bits with a long side handle on the drill

 

[opps]

Edit: Correction - looked at the brand, "Futchoy". Definitely cheap Chinese tat. European or American brands are far better, and guaranteed quality - so they are less likely to get failed welds, broken diamonds, etc

I have never seen "wavy" diamond teeth before.

Does that mean it "might" be suitable for use on SDS?

 

[Deleted member 174758]

I doubt it. More likely they are being cheap with the diamonds. Don't think much of the weld quality, either. The thing that makes it suitable is the clutch on the SDS; the maximum safe core bit size is always stated in the manual with most 2kg SDS drills being rated at 80mm or less.

 

[TheJay]

All very good responses, thank you. I am going to return.

I'm not sure about safe core size, this is the SDS drill I have:

Cordless SDS+ Drill 3-Mode | RYOBI | R18SDS-0

Ryobi - 18V ONE+™ Cordless 3-Mode SDS+ Drill (Bare Tool) | Solid and durable SDS drill from the Ryobi power tool range. Buy online today

uk.ryobitools.eu

 

[Deleted member 174758]

That's a cordless, so I wouldn't even try it as you risk cooking your battery or at the very least having to swap batteries every few minutes (with 3Ah batteries, anyway). Even corded SDS drills can get very hot core drilling because you may be running them for 10 minutes or more continuously under heavy load to drill the hole. If your SDS drill is capable of running core drills the manufacturer should state it on their web site and in the manual, as Bosch do here for this model (Max. drilling diameter masonry, core cutters):

The model I picked is a mid-range 2kg-class corded tool but note that it has only 68mm capacity. Cordless models often have much less power and therefore have a lower (smaller) core rating

Whilst you can drill with an undersize SDS you run a greater risk of a snatch (which will hurt, I assure you) and of cooking the drill or batteries

 

[opps]

As above, they don't even mention core drilling in the following.

Cordless SDS+ Drill 3-Mode | RYOBI | R18SDS-0

Ryobi - 18V ONE+™ Cordless 3-Mode SDS+ Drill (Bare Tool) | Solid and durable SDS drill from the Ryobi power tool range. Buy online today

uk.ryobitools.eu