Core drill

[hbooth]

Hi,

 

I'm trying to core a 152mm hole for my soil pipes and using pipe snugs to fit them. I have a 152mm Erbauer drill bit which will do the job but I managed to burn out my old drill when coring the hole. I purchased a more powerful drill from amazon but it a core drilling drill and the thread sizes of the drill and my drill bit are different. I think the diameter is not too much different but the spacing between the threads is way different. Is there an adaptor that I can buy so I can use my drill bit with the drill. The size on the drill is M22 apparently. The size on the dril bit is 1/2" according to screw fix website. I've attached a picture which shows the thread on the new drill(the silver one) vs the thread on the drill attachment for the drill bit(the black one).

 

Any help would be much appreciated.

[markc]

Core bits, especially lager diameter ones really need a water supply to flush away the debris otherwise it collects at the face and puts a lot of strain on the motor, pulling out to clear the cutting dross every few mm helps if doing it dry.

I have done lots of diamond drilling but dont recognise the mount on your new drill/motor, looks like it is missing a chuck

[SteamyTea]

Is the left one a metric fine thread?

https://www.newmantools.com/tech/threadmf.htm

[saveasteading]

Are we talking of concrete here? Mag have steel in it?

I'd recommend hiring a specialist machine complete with corer. This will be diamond or tungsten, and do your core easily. So you will only need it for a day.

 

 

[hbooth]

The left one is the top of the adapter that would then fit into a standard chuck of a drill. This screws into my erbauer core bit which says it's 1/2" thread size on the scewfix website. The one on the right is the end of my core drill machine. The new machine is from Amazon and I stupidly assumed that the thread would just fit my existing core bits which obviously it doesn't.

 

I'm trying to core through block and then brick, both 100m thick. there's the possibility of hitting wall ties too so I#m not sure what effect that will have on my attempt to core the wall. I was considering to hire a machine for a day but for a bit more money I thought I'd buy the new machine from Amazon so I then have it if I need it in the future. I'm sure the new machine is powerful enough to do the job but I need some way to use my core bits with it. The manufacturer has said it's "thread interface size is M22 specification (also known as Rc thread in GB/T 7306.2-2000 standard)" Which really means nothing to me. I'm just hoping I can find someway to use it. Otherwise it will have to go back and I'll just ed up hiring one.

[Gus Potter]

10 minutes ago, hbooth said:

I'm trying to core through block and then brick, both 100m thick.

What about the old schooool way where we carefully chain drill the facing brick on the outside, angle the drill bit so the inner leaf hole is a bit large diameter and then tidy it all up with a long chisel.

 

Takes longer but saves all the hiring hassle and that extra cost of the coring bits, the running about and pressure to return the hire.

 

I would try one in a place where it can't be readily seen and see how you get on. Mind you if you have ten or so to do you may get fed up chain drilling.

 

This has a spin off benefit as when you put to pipe in real life it may not work fall wise and line up with the hole!.. so all that effort getting the hole looking sweet will be a bit of a let down!

 

Try a 120 mm dia hole to start, then line up the plumbing and enlarge if you need a flexible gap around the pipe. A scutch chisel should work here to get a start.

 

 

[Tom]

The fitting in the right, where the core bit screws directly on to the drill without the need for a chuck, is common for a dedicated core drill - so I'm surprised the thread doesn't match the erbauer bit. Might be worth cutting your losses and just hiring a core drill for the day

[SteamyTea]

 

[Conor]

If you can source a 125mm bit, it will be a lot easier than a 152mm. I drilled half a dozen of these through 150mm thick reinforced concrete slabs with an SDS max drill. Would not reccomend. Used pros for the 200mm holes for the 4x MVHR ducts.

Edited October 4, 2023 by Conor

[hbooth]

4 hours ago, Conor said:

If you can source a 125mm bit, it will be a lot easier than a 152mm. I drilled half a dozen of these through 150mm thick reinforced concrete slabs with an SDS max drill. Would not reccomend. Used pros for the 200mm holes for the 4x MVHR ducts.

I want to use the 152mm bit as this is the size required for the pipe snug to fit into the hole and the soil pipe will then jusy push through. I thought it would save some hassle of trying to point up the soil pipe etc. I'm thinking it probably would just be easier to cut the holes smaller and point them up.

 

Thing is I've brought the core machine now and Ideally would like to use it. I just need a 152mm bit that will fit the M22 thread on the machine. Like Tom said above the fitting is common for a dedicated core drill so I too am surprised that the Erbauer core bits do not fit. I'm wondering if there is an adapter to convert the M22 to 1/2" thread and then I can use the erbauer core bits.

[hbooth]

@Tom Do you know where I could buy an 152mm core bit that would fit the machine? I figured the Erbauer bit would jsut screw directly on the machine but obviously not.

[Tom]

Hmmm, no idea sorry. If it was from Amazon I'd just try returning it. eBay often has used Marcrist drills which look bomb-proof

[SimonD]

7 hours ago, hbooth said:

I'm wondering if there is an adapter to convert the M22 to 1/2" thread and then I can use the erbauer core bits.

 

Yeah, you need an adapter. My Marcrist actually came with the adapter even though it's sold as needing one to be bought to use the machine.

[hbooth]

Ok it's going back to Amazon. Thanks for all the help so far.

 

So next question, can anyone recommend a core drill that will work with a 1/2" BSP fitting and capable of drilling 152mm? I'd rather buy than hire but if needs must then I'll hire one.

[joth]

On 04/10/2023 at 07:19, SteamyTea said:

 

 

 

Text book H&S right there

 

[SteamyTea]

5 hours ago, joth said:

 

Text book H&S right there

Shows how easy it really is.

I hope they had an RCD on the extension lead.

[hbooth]

So I managed to core my three 152mm holes. I purchased a Makita 8406 core drill, which is capable of dry coring upto 152mm and it did them with ease. I figured I'll add it here as it may benefit someone else at a later date. I paid £240 for the drill, ok so I could've hired a drill for half the price but I still have a few more smaller holes to core and so it will certainly come in hand in the future.

 

Thanks to all for the comments.

[Thorfun]

4 hours ago, hbooth said:

So I managed to core my three 152mm holes. I purchased a Makita 8406 core drill, which is capable of dry coring upto 152mm and it did them with ease. I figured I'll add it here as it may benefit someone else at a later date. I paid £240 for the drill, ok so I could've hired a drill for half the price but I still have a few more smaller holes to core and so it will certainly come in hand in the future.

 

Thanks to all for the comments.

and you'll probably get half it's cost back if/when you sell it after you've finished with it. i always prefer to buy than hire if i can.