Thorfun Posted March 24, 2022 Share Posted March 24, 2022 tomorrow's job is to make a start on drilling through the dense concrete blocks in the basement walls to allow the MVHR ducts to be run. I have an SDS drill and some diamond core bits. will be using the 117mm bit for our 92mm ducting. my question is is it one hole per block or can I put 2 in a block? they're standard blocks so are 440mm wide so I could fit 2 holes next to each other and still leave 'some' of the block intact but it just feels like they'll be like Swiss cheese. I'm only going through non-load bearing walls btw. any advice before I make a mess in the basement in the morning/maybe afternoon depending on how my day job goes? Link to comment Share on other sites More sharing options...
PeterW Posted March 24, 2022 Share Posted March 24, 2022 Really not advisable to use a 117mm core bit in an SDS - they are not made for it and there is no slip clutch on an SDS drill so when it catches on something in a dense block it will spin and break your wrist or smack you in the face … Go hire a core drill unit and do it properly. 1 Link to comment Share on other sites More sharing options...
Thorfun Posted March 24, 2022 Author Share Posted March 24, 2022 6 minutes ago, PeterW said: Really not advisable to use a 117mm core bit in an SDS - they are not made for it and there is no slip clutch on an SDS drill so when it catches on something in a dense block it will spin and break your wrist or smack you in the face … Go hire a core drill unit and do it properly. Ok. Noted and will do. how about number of holes per block? Able to advise on that? Link to comment Share on other sites More sharing options...
Mr Punter Posted March 24, 2022 Share Posted March 24, 2022 I have done lots of cored holes in concrete blocks with a Makita and a Dewalt SDS drill. I did do plenty of wrist strengthening exercises over the years and these must have paid off... Easy 2 per block. 3 would be fine, but not more than half the block removed horizontally over, say, 3 blocks. 1 Link to comment Share on other sites More sharing options...
TonyT Posted March 25, 2022 Share Posted March 25, 2022 No comment on quantity of holes, but I wouldn’t use anything that didn’t have a clutch, it’s an accident waiting to happen 1 Link to comment Share on other sites More sharing options...
Russell griffiths Posted March 25, 2022 Share Posted March 25, 2022 I brought a cheap £45 drill from screwfix as I didn’t want to bugger up my expensive drill, did 7 holes through 150mm concrete in an icf house and I couldn’t kill it, I really tried. Make sure it has a clutch and put the side handle on. If you don’t mind the mess set up a hose and dribble water on the core bit. Keeps the dust down also. 1 Link to comment Share on other sites More sharing options...
Thorfun Posted March 25, 2022 Author Share Posted March 25, 2022 3 minutes ago, Russell griffiths said: I brought a cheap £45 drill from screwfix as I didn’t want to bugger up my expensive drill, did 7 holes through 150mm concrete in an icf house and I couldn’t kill it, I really tried. Make sure it has a clutch and put the side handle on. If you don’t mind the mess set up a hose and dribble water on the core bit. Keeps the dust down also. interesting idea. was looking to hire a core drill at about £50 per week but if I can buy a cheapo then that might be an option. will take a look at screw fix, thanks. Link to comment Share on other sites More sharing options...
Thorfun Posted March 25, 2022 Author Share Posted March 25, 2022 7 minutes ago, Russell griffiths said: I brought a cheap £45 drill from screwfix as I didn’t want to bugger up my expensive drill, did 7 holes through 150mm concrete in an icf house and I couldn’t kill it, I really tried. Make sure it has a clutch and put the side handle on. If you don’t mind the mess set up a hose and dribble water on the core bit. Keeps the dust down also. like this https://www.screwfix.com/p/erbauer-erh750-3-4kg-electric-sds-plus-drill-220-240v/232fv ? says it has a safety clutch Link to comment Share on other sites More sharing options...
Conor Posted March 25, 2022 Share Posted March 25, 2022 I drilled dozens of big holes with my titan sds drill. The slip clutch is essential. Also borrowed sparks core drill. Not a whole load of difference tbh. It's really tough work. Set yourself up on a proper platform so you can keep the drill level and your weight behind it. Ladder is no use. Oh the dust. The dust. Wear all the masks. For the holes through the 200mm RC walls I hired a guy... Best money spent!!! 1 Link to comment Share on other sites More sharing options...
Mr Punter Posted March 25, 2022 Share Posted March 25, 2022 I have never had an SDS that doesn't have a clutch. I doubt you could even buy one as I would think the seller would risk being sued. Link to comment Share on other sites More sharing options...
PeterW Posted March 25, 2022 Share Posted March 25, 2022 The issue on SDS is the clutch is designed for the torque on the maximum bit size, not the torque you will apply using a core bit. The maximum in masonry with that Erbauer for example is less than 30mm in masonry - Whilst the leverage on a 117mm will be lower, the chance of it snatching with a core drill is much higher, especially on blocks where you have no idea what is inside them. 36 minutes ago, Conor said: Set yourself up on a proper platform so you can keep the drill level and your weight behind it. Ladder is no use. This is imperative - ladders are asking for an accident. Link to comment Share on other sites More sharing options...
SimonD Posted March 25, 2022 Share Posted March 25, 2022 53 minutes ago, PeterW said: The issue on SDS is the clutch is designed for the torque on the maximum bit size, not the torque you will apply using a core bit. The maximum in masonry with that Erbauer for example is less than 30mm in masonry - Whilst the leverage on a 117mm will be lower, the chance of it snatching with a core drill is much higher, especially on blocks where you have no idea what is inside them. + 1 to this. I burned out an SDS drill clutch and when it went the drill nearly broke my arm against a joist. Instead of trying to save money on a cheapo sds drill I went and bought a proper core drill with proper bits. I don't even have to have all my weight behind it, just a firm press, to chew through concrete blokes. The bit set I have has an extract function so it hardly ever binds on the grounds. It's a revelation. Link to comment Share on other sites More sharing options...
Thorfun Posted March 25, 2022 Author Share Posted March 25, 2022 this one https://www.jewson.co.uk/p/hand-held-diamond-drill-JTH3063A has a built in water feed. I could just hire it for a week, stick it on my account and be done with it. thanks for all the answers, I'll have a think about it all and work something out. going to leave this job until next week now as well so I'm not rushing to do it. 1 Link to comment Share on other sites More sharing options...
Thorfun Posted March 28, 2022 Author Share Posted March 28, 2022 thanks all for the advice. hired a core drill this morning, used a platform rather than a ladder and have drilled 8 holes so far (107mm) and, even though the drill is bloody heavy for this weedy middle-aged man, it seemed to go through pretty easily. 2 Link to comment Share on other sites More sharing options...
Bitpipe Posted March 28, 2022 Share Posted March 28, 2022 Very impressed you got those holes so close together. No idea if that's a good idea or not I remember doing our MVHR through the timber frame, had made no provision for penetrations in steels or frame so was totally winging it. Had to take out a few noggins to get all the duct in, house still standing... 1 Link to comment Share on other sites More sharing options...
Thorfun Posted March 28, 2022 Author Share Posted March 28, 2022 42 minutes ago, Bitpipe said: Very impressed you got those holes so close together. No idea if that's a good idea or not well, I figured that that top row of blocks has nothing at all sitting on it so if that block collapses then it won't affect anything! I was actually quite tempted to just take the whole block out but I paid good money for the core drill and wasn't going to waste it. 😉 2 Link to comment Share on other sites More sharing options...
Pocster Posted March 28, 2022 Share Posted March 28, 2022 I have a core drill . It’s a slow and messy job . In the end I bought a really decent masonry drill bit and simply multiple holes I.e stitched the hole out . Was less effort and certainly less dust . Link to comment Share on other sites More sharing options...
Thorfun Posted March 28, 2022 Author Share Posted March 28, 2022 35 minutes ago, pocster said: I have a core drill . It’s a slow and messy job . In the end I bought a really decent masonry drill bit and simply multiple holes I.e stitched the hole out . Was less effort and certainly less dust . yes, it was slow (although not as slow as I thought it'd be after reading your experiences!) and very dusty (which isn't really an issue for me as I'm in the dungeon and nothing else is down there) but wasn't that bad at all. I managed to do 10 holes today and have another 9 to do tomorrow. I could've easily done it all today but I also have a day job that takes up most of my time! I'm going through dense concrete blocks and used a Screwfix/Erbauer 107mm diamond core drill bit (https://www.screwfix.com/p/erbauer-diamond-core-drill-bit-107mm/1121v). what was it you were core drilling again? 1 Link to comment Share on other sites More sharing options...
dpmiller Posted March 29, 2022 Share Posted March 29, 2022 the only holes I needed in block were the soil pipes, MVHR vents, and cooker hood duct. The soils I did with a TCT core drill, the others I stitched. All done with a Dewalt cordless SDS and no hassle? Link to comment Share on other sites More sharing options...
Pocster Posted March 29, 2022 Share Posted March 29, 2022 13 hours ago, Thorfun said: yes, it was slow (although not as slow as I thought it'd be after reading your experiences!) and very dusty (which isn't really an issue for me as I'm in the dungeon and nothing else is down there) but wasn't that bad at all. I managed to do 10 holes today and have another 9 to do tomorrow. I could've easily done it all today but I also have a day job that takes up most of my time! I'm going through dense concrete blocks and used a Screwfix/Erbauer 107mm diamond core drill bit (https://www.screwfix.com/p/erbauer-diamond-core-drill-bit-107mm/1121v). what was it you were core drilling again? I bought cheap core bits - that was probably the issue Link to comment Share on other sites More sharing options...
Thorfun Posted March 29, 2022 Author Share Posted March 29, 2022 21 minutes ago, pocster said: I bought cheap core bits - that was probably the issue I'm not going to lie to you, my arms hurt! I did the final 9 holes this morning which took about 90mins and by the end of it I was covered in dust and could barely lift the core drill. but it's done now and I have lovely pretty round holes. 🙂 1 Link to comment Share on other sites More sharing options...
Pocster Posted March 29, 2022 Share Posted March 29, 2022 4 minutes ago, Thorfun said: I'm not going to lie to you, my arms hurt! I did the final 9 holes this morning which took about 90mins and by the end of it I was covered in dust and could barely lift the core drill. but it's done now and I have lovely pretty round holes. 🙂 You need to man up 💪💪💪💪💪😂 1 Link to comment Share on other sites More sharing options...
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