Expert advice for professional installers on drilling porcelain tiles. By Richard Hazell of 365 Drills



Background:



Richard Hazell standing outside the house at 7am. Cold. And holding an internal light.


Recently I was asked to drill 150 holes into very hard porcelain tiles in four bathrooms over a weekend. This was an excellent opportunity to test our kits to destruction so I looked on it as a live exercise.



Below are my experiences:
I decided to road test our product under the harshest of test conditions to make sure you - a professional tiler - can be totally sure I have experienced the worst a job can throw up. I also did it for myself because often I meet trade buyers in warm comfy rooms who want to pick holes into our kits. I want to be prepared. No surprises.


Property: The site was a new build with four bathrooms on four floors. One in the basement, One by the front door, one on the bedroom floor and one in the roof space.
General Conditions: The weather was bitter cold with sleet and rain.. There was no heating. Windows were fitted but external doors, garage and basement were open to elements and so working in freezing conditions meant thick layers of clothing. T-shirt. Jumper. External jacket and hat which obviously restricted my movement.

Most pipes can be bashed through in a less than elegant way

Working conditions. There were a mix of guys from chippies, electricians and plumbers competing for space, materials and basic utilities such as electric and water. In addition to the internal fitters there were guys outside working on a concrete pour with routine deliveries from cement trucks and others. Inside the rooms were dirty, poorly lit and had multiple power cables running from room to room. Each room had a mix of tools, materials, packaging and rubbish from old newspapers to unwashed coffee mugs. T


here was one outside portaloo but no tea or coffee facilities.



A Dewalt radio played in the background and at certain times a loud sporadic burst of singing could be heard from one contractor to certain songs. His most popular "She's so lovely" By artist "Scouting for girls". shouting : "She's flirty, turned thirty Ain't that the age a girl gets really dirty?" (repeat). and insisting the song was written about Ulrika Johnson.



Fixtures of mirrors, first fix electric's onto very hard porcelain tiles


Morale: Was low from some of the thirteen people as they were working the weekend, it was dark with a lack of natural light and everyone was keen to be gone by 2pm each day. Morale was affected because the project was running at a loss for the contractors due to problems with the basement.


My timing estimate was that 150 holes would be 3 mins per hole or 450 mins of drilling or 8 hours of actual drilling times. This worked out to be accurate and equated to four hours of drilling per day. I was originally informed all areas would be pre-marked for me and I would simply drill the holes. However on arrival I was told contractors would mark the holes as I went. I asked if they could mark at least 12 holes per time.






First problem (for the contractors) was the drill noise. So they went off and marked holes in different bathrooms while I continued to drill. This meant following them from bathroom to bathroom so I had to travel light and carry everything from one room to another. This proved to me that equipment should be as portable as possible. I used a small paint kettle for water with a small sponge and put drill bits in my pocket. The heaviest item was the battery charger so I left that in one spot and went back to it for a recharge when I got a flat.


They were also keen to ensure the holes I drilled first were for heavy stuff like shower doors, sinks, cabinets and toilet pans so that they could do their job of fitting them. The problem (for me) came later because access to other holes was restricted by the fittings.



So I had to take them back off the wall. For example I had to remove the loo pans, sinks and cabinets. It was easier to remove the items. Of course this added to (my) time on site. In hindsight it would have been more efficient to drill all holes first and then fit.






In order to test the durability of drills I did the opposite of the advice we give on site. I Drilled fast, applied pressure and used a minimal amount of water. Under the heaviest load the 8mm lasted about 5 to 6 holes before giving up.



This is in line with our quoted pack life. So I am now confident that there is some redundancy in the drills if used correctly. But at least we can back up the 2-6 hole life with real field tests.



On the left is a clean hole that was drilled without breakage. On the right the hole has just started. In the middle the hole is being formed


After 150 holes I feel qualified to comment on drill tequnique. Over the weekend I adapted my technique The best way to drill is in bursts. Apply pressure to the drill bit then back off. Keep the sponge under the drill and withdraw it from the hole to cool it then push it back in hard against the tile for a few seconds. I found pulling the tip back until it was just at the edge of the hole but not completely out was the key to keeping it cool. Another must is not to break the core.



This is the delicate part in the middle of the hole. If you snap it off its a bugger to poke out the core fragments. If you do manage to drill without snapping then it pulls out nicely in one smooth action. Word of warning is the core has a tendency to snap at about 90% into a tile. So you eject a broken plug then drill the final 1mm. But its this that gets stuck in the barrel and is a pain to poke out.



The secret is not to move the drill too much. Hold as steady as you can. Believe me after 150 holes fatigue sets in so I found myself holding it in some funny ways. For example at waste height I pushed the drill with my hip and pushed the trigger with my wrist not finger. At the end of two days every bone in my body ached from cold, bruising and bumps. I think I had the equivalent to tennis elbow on my thumb from holding the drill for so many hours



Fitting items can restrict movement. This loo pan stopped the fixing of a loo brush on to the left tile. So it was refitted to the right tile


Final thoughts: At the end of the experiment I have a number of suggestions. If you drill aggressively change the cores every five holes because you can waste time getting the maximum life out of a core. It takes ages on hole 6.



ry and stick with 8mm which give much more bite than 6mm. Its better to dump the rawl plugs supplied with the fittings and change to your own rawl plugs which are cheap enough to buy in bulk from many retailers.



If you are going to drill that many holes then perhaps use a drill that has a button to keep it on. My figures were raw from the trigger. Dont be afraid to start off the holes dry. I used an old knackered core to start off most of the holes. Just dip it on a wet sponge to cool it.




Most fixing come with a cap to disguise hole drilling. If you are good enough then the caps can be removed...


I actually enjoyed my weekend and the guys on site were all good people. Having experienced the pain and the concentrated conditions myself I really appreciate what goes on in a job. One thing I was surprised at was the drill plate. I had put nice little thumb groove into the plate to indicate where to press it. But to be honest the plate can be held in any area. It was interesting to discover how little tile the plate needed to grip. I had that plate in all sorts of angles and working heights.
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.With regard to the guide Richard, I have found it beneficial to run the drill through the guide hole prior to it's first use as it has less drag on the guide when you first start, therefore helps to keep it in place. Also, bit picky this, would be nice if your guide holes had "centre lines" on the outside of the holes to help alignment. Small point I know but I would find that useful.

Grumpy

Excellent idea and just goes to prove we never have it 100% right. Always room to improve.

The idea of dots on the plate to guide it came up in the past. I mulled it over and for some crazy reason dropped it in favour of keeping the design simple.

But I think center lines are something to put back to the top of the modification list.

Next time I have the injection mold in bits I will add them. Doesnt have to be much bigger than a standard witness mark.

Also for me its "metal off" so as an engineering procedure its fairly straight forward to do. My problem always starts when we need to go "metal on" which means drilling out plugs etc. Expensive and not so elegant.

I'll add cross-hairs (centre lines) as soon as we need to do any mods.
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With regard to the guide Richard, I have found it beneficial to run the drill through the guide hole prior to it's first use as it has less drag on the guide when you first start, therefore helps to keep it in place

When we first looked at the drill cores we found slight tolerances approx of 0.05mm. In the first prototype some cores rattled and others were a tight fit. So we modified the ports into a "V" shape.

In the finished model for example the 40mm hole is 40.05mm at the top and and 39.95mm at the base.

When you first put a core into the cone it nicks out a fraction of a mm of plastic in the first second of drilling to form a perfect fit for that particular core.

All ports now have a bevel or chamfer on the edge. A second benefit is the bevel makes it much easier to guide the drill cores into place.

What tool is best to mark you`r cuts on porcelain

Depends on colour I think.

Black tiles I use masking tape and pencil.

Natural stone I just use a pencil.

Thanks it will be masking tape then