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Surgical wiring SWA through screed

Hey, I said it was slow going.

I've got to work around a kiddos bedtime and work, so I get at most an hour window every day to set up, drill and tidy. Plus fighting the drill overheating.

Hope to be done some time in June 2025/2026 ;)
 
Ok, I'll admit, its glacial...

But I've maxed out my 1m £20 bit...

The 1.2m bit is £100+

So engineering time:
PXL_20250618_201644291.jpgPXL_20250618_201703551.jpg

I think this'll work
 
You made that? What from, and is it hardened?

How did the cost and machining time compare against the time and cost involved in pulling the flooring up then putting it back again?
 
Ivor Windybottom said:
You made that? What from, and is it hardened?
Click to expand...

It doesn't need to be hardened, the shafts of masonry drills are made from a soft steel, only the tip, and the part which fits the chuck, are hardened. In the past, when I've been stuck for a longer drill bit, I've chopped such drills in the middle, and welded a piece of steel in.
 
You could take the floor up, cut a channel through to the hole then blow air through it. Then put all the floor back down and carry on drilling. All perfectly sensible, can't see anything silly about this.

Harry Bloomfield said:
It doesn't need to be hardened, the shafts of masonry drills are made from a soft steel, only the tip, and the part which fits the chuck, are hardened. In the past, when I've been stuck for a longer drill bit, I've chopped such drills in the middle, and welded a piece of steel in.
Click to expand...

I was thinking about the teeth that grip the SDS bit or drill chuck at each end. They must have a lot of torque applied, I'd worry they could round over or push the bit out.

Actually... what retains the bit? Aren't you going to leave the bit behind when the drill is pulled out?
 
I'll admit, failure. But not immediately. I'm kinda stubborn with problems like this and I think I can make it work... So going to keep trying.

1) female end was using grub screws, but they worked loose. Some thread lock should fix that.

2) male end was a cut down 10mm drill bit. Welded in from holes across the width. But the welds failed. Really poor penetration, I can improve technique .

In both cases, the drill bits at both ends bottom out, so the impact is always direct metal to metal.

This was made on a less than ideal machine mart lathe and a knee mill (these are what are going to move into the new workshop).

I can literally put in about 10-20 minutes of work a day at the moment, and it's in a tiny hall that has a door in every wall, Including the front door. I have to leave it clean and usable every day.

The drill can be done for 15 minutes and cleaned up in 5. I've also got about 6 months to do it in.
..
 
OMG they drilled the channel tunnel quicker than this :LOL:
 
Last edited:
Put the SDS bit in the hole and another one behind it, tap tap tap with a hammer.
It will slowly wear away the concrete.

Yes it will take a while but it doesn't seem like you've got much further to go.
 

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