Diamond Core Drill

Discussion in 'Builders' Talk' started by Doz Stanford, Jul 10, 2023.

  1. Doz Stanford

    Doz Stanford New Member


    Over the past few years I have been working to insulate a mid terrace house built in the 1860's and I have reached the point I need to start installing some condensation vents.

    I have opted to go with the insulated 75mm Passyfier vents which require a 152mm hole.

    The walls are double skinned Luton bricks, no cavity and some of the walls I'll be drilling are rendered outside, some are not.

    I have never drilled out such a hole, although a neighbor that is a retried electrician that has drilled a few tumble drier vents has thankfully offered to supervise my first attempt.

    The advice I need from the good folks of the Screwfix community, is exactly what to buy. I have watched some Youtube videos, read a few posts on this forum and spoken to my neighbor, and have come up with the following list to purchase...

    Drill = Bosch Professional GSB 162-2 RE
    To make Pilot hole all way through = Bosch 2609255436 400mm Masonry Drill Bit with Diameter 8mm
    Core Bit Adapter = Bosch 2608580865 Adapter for Diamond Drill Bit, Black, 1/2-Inch - 240 mm
    Core pilot bit = Bosch Professional 2608597921 PILOT DRILL BIT FOR DIAMOND DRILLS
    Core Bit = Bosch 2608587333 Diamond dry core cutter G 1/2" (152mm)

    Is this everything I need ?
    Have I chosen the right adapter/pilot for the core bit ?

    Renting a drill is not an option, I need in total 5-8 holes and I'll be doing them over a period of time, not all in one go so it would require renting the drill 4 or 5 times.

    Many thanks for any and all advice and comments in advance.
  2. BuildingMad

    BuildingMad Screwfix Select

    That's a lot of expensive gear to buy for that number of holes, when all you need to do is drill a series of holes around a 150mm circle with an ordinary SDS drill with a long 10mm drill bit. Within that circle will be a number of mortar joints that can be drilled away to assist final removal.
  3. Doz Stanford

    Doz Stanford New Member

    I couldn't agree more with the bits being pricy. Two things however put me off using an SDS, one being some posts on this forum, which detailed wrist injury's from using and SDS for such a large hole, one person even claiming a broken wrist from doing so, the other a couple of YouTube videos detail the same. For a smaller hole I'd consider using my 2kg SDS, but for a 152mm I'd rather not risk it... and doing so many I'd probably burn it out.

    Also looking at the second hand prices (for resale after I'm done) I'd get enough back to still make it cheaper than renting or hiring someone to do it for me considering the number of holes I'll need and the timeframe for doing them, I'm doing things at my pace and I don't want to be rushed.

    BuildingMad, do you know if the adapter/pilot/core are a suitable match/fit ?, I believe they are but would like confirmation before purchasing.

    Thanks again for your reply.
  4. Abbadon2001

    Abbadon2001 Screwfix Select

    if you haven't needed an SDS up til now you might be better off buying a Titan with kit for £90 https://www.screwfix.com/p/titan-tt...s-drill-22-piece-accessory-kit-230-240v/4172g

    Ive drilled multiple similar holes over the years and the titan I bought in 2006 is still going...

    I did rent the core drill a few times, and I have a few smaller ones that came with my particular titan kit.

    If its only brick and render, you dont even need anything particularly special ref the core drill , as no concreate involved with hard aggregates in it.

    An 152mm erbauer core drill, arbor and pilot will come in at under £75.
  5. BuildingMad

    BuildingMad Screwfix Select

    You misunderstand.
    I was suggesting a SDS drill used for going around the perimeter of a 150mm diameter circle with a series of 10mm holes.
    Why don't you try it on one hole to see how easy it is, before making your mind up.
    Especially as you already have a SDS drill
  6. BuildingMad

    BuildingMad Screwfix Select

    Forgot to mention, one central hole, draw your circles & work from both sides; saves chunks of plaster & rendering coming off.
  7. Doz Stanford

    Doz Stanford New Member

    Internally, the first room requiring condensation vents has been gutted back to the brickwork, as most of the room have lime render on the walls. I've already repointed the lime in the brickwork and want to get the hole drilled before I frame up, insulate and call in the plasterers.

    I did misunderstand Building Mad, my apologies, however, the prospect of drilling out 15 odd 10mm holes, is not something I want to contemplate. I'm a bit long in the tooth and suffer with arthritis and osteoporosis, the prospect of doing that once is daunting doing it half a dozen or more times... I'll pass, although I respect and thank your effects to save my wallet.

    I have to confess looking further at the SDS drills from Abbadons link, I didn't realise that SDS drills had safety clutches, which is why I naturally went straight to looking at core drills. I also have to confess to not being confident regarding deciphering drill capacity listed on drills as I assume they refer to a drill bit rather than a core bit, such as the drill listed by Addadon only states a masonry capacity of 32mm.

    I have a Titan 15kg breaker that I've had for 7+ years that's removed a huge pond and countless fence posts, so I have nothing against the brand or their products, I just want something that's not going to try to kill me drilling out a 152mm hole and will last long enough to do a bunch of them.

    My SDS is quite old and I'm not averse to the idea of replacing it for something newer/beefier. Any recommendations for one to do the job that has a Safety Clutch/Brake and some anti vibration function ?

    Thanks again everyone, I really appreciate your time.
  8. Doz Stanford

    Doz Stanford New Member

    Bosch GBH 2-26 2.7kg Electric SDS Plus 240V - Screwfix
    Shows the same drilling capacity as the one listed by Abbadon and has Anti-Vibration & Safety Clutch/Brake... would this do ?

    Looking further at other drills, I think the spec listing for that drill might be wrong...

    Just looked at the Bosch and Makita sites and looking at the SDS drills they state are suitable for 152mm cores (Bosch GBH-8-45 D) and (Makita HR4511C) are both more expensive than the Bosch core drill I mentioned in my first post :/
    Last edited: Jul 10, 2023
  9. The Happy Builder

    The Happy Builder Screwfix Select

    Quite seriously, you could end up with broken bones, personally I have been badly bruised.
  10. longboat

    longboat Screwfix Select

    If you already own an sds drill just use that.
    Yes, it may burn out but then again it may not.
    If it does, buy a new one.
    I drill quite a few core's (40 - 160mm) every year and still haven't seen the need to buy a dedicated machine that costs £500+ when my makita sds, or even more commonly my makita combi drill does the job just fine.
  11. longboat

    longboat Screwfix Select

    Weakling! :p
  12. The Happy Builder

    The Happy Builder Screwfix Select

    As you get older you generally get more sensible and just say no instead of doing jobs that involve drilling big holes through granite rubble walls or one and a half brick wall.
  13. Pauld21323

    Pauld21323 New Member

    I've recently drilled a 152mm core through a solid brick double skin wall which was ok but not the easiest thing physically. Personally if I had arthritis etc to contend with as well I'd go the stitch drilling route. I did it with a titan SDS and an erbauer core and just cut a bit, bashed out the middle then cut a bit. Take the time to get a comfortable position if you core it as you'll be in it for a while.
    Abbadon2001 likes this.
  14. H Bell

    H Bell Active Member

    I would buy a cheaper core drill bit. You can get a cheap Chinese set for about £60. You are only drilling 5 holes so you don't need an expensive bit. The drill, well, that's always useful, but the bit isn't, the moment you have finished the job it's bin material.
  15. Truckcab79

    Truckcab79 Screwfix Select

    Titan SDS/breaker. Can’t recall the model but the bigger of the two. Erbauer core drill set or look on eBay for Rennie Tools core drills. All you need. Don’t chain drill them. Will take you forever and looks awful. I know it’s hidden behind the vent but looks amateurish.
    Abbadon2001 likes this.
  16. H Bell

    H Bell Active Member

    Never tried a 152mm but I did drill four 200mm once. My heavens, the wrist strain was high! The drill was a powerful core drill, but it didn't have a safety clutch, so you just had to be really fast on the on/off if it jammed. The worst part though was that there was no safety on the on/off of the drill at all. When you pulled the drill out of the wall, it was full of brick, so pulled towards the floor. This often activated the drill. To say it was dangerous was the understatement of the year. It convinced me that 200mm was probably beyond the safe limit for a hand-held drill. It was doable, but there was little about it that was safe. 152mm should be OK, but I would be hesitant to recommend it to anyone who has to drill five of them.
  17. FlyByNight

    FlyByNight Screwfix Select

    I use a well looked after Bosch GBH2-26 that is around 16+ years old - a predecessor to the one linked too. The very important capability is A CLUTCH with any core drilling. Mine has interchangable chucks - SDS or Hex and I prefer Hex for cores.

    As for your Core bit - look at the Marcrist ones stocked by SF - there is a 152mm. https://www.screwfix.com/p/marcrist-diamond-core-drill-bit-152mm/6374f all my cores are Marcrist (except 2 which are £5 clearance items).

    Almost any adapterkit will be OK, Bosch, Marcrist or even Erbauer (which look suspiciously like Marcrist, but may not be). You will need an extension.

    After putting the pilot right through, go through the render on the outside and at least 10-15mm into the outer brick before going back inside and working from there. Keep the pilot drill in place, it will not drill but should keep you straight.
  18. Doz Stanford

    Doz Stanford New Member

    Hello again everyone and thank you all for your replies, I am most grateful for all the contributions.

    H Bell, I have two options.

    The first would be 5 to 8 holes that are 152mm using 75mm Insulated Passyfier vents.
    The second would be 5 to 6 holes that are 132mm using 100m non insulated Passyfier vents.

    I suppose if I went with option 2 I could just use a can of insulating expanding foam between the duct and brickwork and cut and foam the internal PIR insulation as close as possible on the internal wall.

    I would appreciate any thoughts on either of these options, as to which is best.

    After reading the input given I've swapped the core bit on my shopping list to the Marcrist and after further reading of similar posts on this forum I am going to go with the Bosch Professional GSB 162-2 RE, I'd just rather be safe than sorry and go a little overkill as I've still got so much work left to do before winter sets in, I've got a SF discount voucher that will bring it down almost £50 which makes the price a little easier to swallow.

    Will these parts be ok with said drill and a 1/2" Marcrist core
    To make Pilot hole all way through = Bosch 2609255436 400mm Masonry Drill Bit with Diameter 8mm
    Core Bit Adapter = Bosch 2608580865 Adapter for Diamond Drill Bit, Black, 1/2-Inch - 240 mm
    Core pilot bit = Bosch Professional 2608597921 PILOT DRILL BIT FOR DIAMOND DRILLS

    Again, thank you everyone for taking the time to help.
    Abbadon2001 likes this.
  19. FlyByNight

    FlyByNight Screwfix Select

    I cannot see why you feel the need to go for that GSB drill - what are your reasons?

    What is your existing drill?

    You will still need a standard size adapter as well as the 240 extension.
  20. Truckcab79

    Truckcab79 Screwfix Select

    You’re over-complicating this. There’s a reason they make 152mm core drills. Buy the SDS and core drill of your choice and get drilling. You won’t find anyone who does this for a living chain-drilling multiple holes or messing around with other ways to achieve the end result.

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