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Diy Advice Needed

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Diamond drill bit and suitable drill from your local hire shop, they charge per mm used. Don't use hammer action though as you will ruin the bit. They will go through Rebars to if there are any in the gravel board. Dry or wet cut depending on the rig hired. It's not difficult with the right equipment. And the removed slug makes an interesting paperweight.

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46 minutes ago, MauriceMynah said:

Thank you all, I should have thought of tool hire we have one not too far away. Sadly I can't take the gravel board down so the holes have to be drilled in situ.


If you use a hole saw with a pilot drill, before you break through, drill from the other side, this should prevent break out.

What I can't understand, no one has asked the reason for doing it lol...

So we await with baited breath.

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If it has has rebar in, you want a wet rig at slow speed.  The aim is to get the concrete paste to do some of the cutting, not too much water and not too little.  Buy/hire a decent quality one and it will do the job.  Be careful - there's some rubbish out there.  Diamond drills have a series of clutches in them, so if it snags it doesn't break your wrist.

Heat is the enemy - if it 'peacocks' going blue, then it's cream crackered.  

Tungsten carbide tipped hole cutters which work on hammer action will work on the concrete but will run into trouble if it hits rebar.  

It's a lot less hassle with diamond.  Just let IT do the cutting.  And don't try to straighten it on the way through - the diamond segment is centred to the carrier core, and is oversized.  It needs to be bigger than the carrier in order to reduce the friction on the metal carrier.  If you try to straighten the cut it will wear the outside of the segment thereby narrowing the diameter allowing friction to build up.

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I used this as a one shot wonder to get through a house wall and concrete garage and it did with no issues which at the price was suprised. Saved hiring.

cheers Grendel putting .com link I could find my orders on uk site lol


We once drill York Minster wall, 2 off 2" holes through 2" foot walls 2 drill 5 hole saws took 8 hours and a 1.5 stop for afternoon service.

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Used a 2ft cold chisel and hammer underneath a floor to go through a 18"wall ,NO power drills then yours truely was the powerdrill ! lol. Just be very careful of the recoil on the drill, you can do your hands a lot of damage ! :facepalm:


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3 hours ago, Viking23 said:

What I can't understand, no one has asked the reason for doing it lol...

I have built a wall to retain earth (A rock garden) which will now have a fish pond at it's foot. There needs to be a number of holes in that wall to accommodate the pipework and electrics for a waterfall, a fountain and a unique filtration system.

This wall was built with two slotted concrete fence posts and 3 12 inch gravel boards one on top of another. It is the third gravel board that needs the holes.

I intentionally didn't say what I was doing and why I needed the  holes because that might have lead people into suggesting other ways to route the pipework. This I wanted to avoid as I know what I need to end up with but I didn't know what tools or how to use them to acheive this.

I guessed that a core saw or whatever it's called would be the answer, but would it have to be water cooled? If so, isn't using a 240 volt drill to drill through a flow of water a tad tricky?

My thanks to Grendel for the youtube clip showing me how to use the tool.

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If you hire some industrial drills, they might be 110 volt, they require a 240-110 Volt transformer, these are usually bright yellow, and come with the hire.

The transformers are wired 55 0 55 so the maximum voltage you will see if you touch a line supply is 55 volts. Safer if you use near water. 

Gravel boards can be manufactured by virtually anybody, some fencing companies have their own moulds. So the quality of the concrete will vary, as will the amount of rebar.

If you have a strong magnet, or a pipe detector, you might be able to chalk where the rebars are, as these could wreck the cutter tool.

Another issue, if you expose rebar, you might allow water entry and thus the rebar will rust, expand and crack the concrete over time.

You may find that the rebar is closer to one side more than the other

So you might be able to drill into pure concrete, the hole will be neater, and  no exposed rebar, but only if the postions of the holes are not critical.

Edited to add... you don't really want to cut the rebar anyway, the horizontal ones especially,  add strength.


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33 minutes ago, Regulo said:

Should have drilled the holes before building the wall. Easy solution now is to order the holes from eBay. Don't buy Chinese ones, the quality is questionable. British holes are far superior.

I shall go to my local wholesaler on Tuesday.

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I suppose you'd all like to know how I found out that Chinese holes weren't all they're cracked up to be? Well, it was like this.
I needed a 30mm hole through my single brick garage wall. I went to B&Q and Homebase, but they wanted a ridiculous price for pre-packed 150 mm long 30mm holes, so I ordered a 3 metre coil of 30mm hole from China. A bargain at £10, p&p included. I was on tenterhooks waiting for delivery, and was surprised when the postie put a small jiffy bag through my letter box. They'd only vacuum packed it! Clever! I'd prepared the wall with a 30mm drill, so cut off a 150mm length of hole from my reel and tried to fit it. But it just wouldn't go in. I was standing there scratching my head, wondering what to do, when my mate Dave arrived. I explained the problem and he said,"Give it here, I'll put it on my lathe and turn it down a few mil for you". Ten minutes later he returned, and we tried it for size. It was still tight, but with a bit of washing-up liquid, and a wooden mallet, we got it in. Just had to trim off the excess with a craft knife, and job done. The rest of the reel is still hanging in my garage, so if anyone needs a bit of over-sized 30mm hole, you know who to ask. In fact, it's in the way, so the whole reel's yours for £5. And I'll throw in the off-cuts. Can't say fairer than that.

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     1.     All pipes are to be made of a long hole surrounded by metal or plastic, centered              on  the hole.

2.     The pipe is to be hollow throughout the entire length – do not use holes that are longer than the pipe.

3.     The I.D. ( inner diameter ) is not to exceed the O.D. ( outer diameter ) otherwise the hole will be on the outside.

4.     All pipes must be supplied with nothing in the hole, in order that water, diesel, gas, or other stuff can be put inside at a later stage.

5.     All pipes should be supplied without rust, as this can be more readily supplied on the boat. Note: Some vendors are now able to supply pre-rusted pipes. This method has been extensively tested and researched by Norfolk contractors and is highly recommended as it will save a great deal of time on the boat.

6.     All pipes over 500cm in length should have the words “Long Pipe” clearly marked on each side and end, so the contractor will know it’s a long pipe.

7.     Pipe over 3m in length must also have the words “Long Pipe” marked in the middle, so that the contractor will not have to look the entire length of the pipe to determine if the pipe is long or short.

8.     All pipes over 20mm in diameter must have the words “Large Pipe” marked on it, so the contractor will not mistake it for a small pipe.

9.     Flanges must be used on all pipes. Flanges must have holes for bolts, quite separate from the big hole in the middle.

10.  When ordering 90° or 30° elbows, be sure to specify left or right handed, or you will end up going the wrong way.

11.  Be sure to specify level, uphill, or downhill pipe. If downhill pipe is used for uphill, the liquid will flow the wrong way.

12.  All couplings should either have left or right hand threads. Do not mix threads; otherwise, as the coupling is being screwed on to the pipe, it is being unscrewed from the other end.

13.  All pipes under 3mm are uneconomical to use, as they require many joints. They are generally known as washers.

14.  Joints in pipes for carrying water must be watertight. Those pipes carrying gas however, must only be airtight.

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If you not too hapy on the drilling side check the cost to have a new gravel board built if they do there own giving them a cut off of pipe to mould in.

Also depending on the size of the pump & litres sod it gallons/min (proper money) look at using a bog standard central heating pump. it's running 24/7 so look at cost. Were running a grunsfos 15/60 but ours is 3300 gallons.

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