What is the preferred tool of choice for drilling tap holes in a bath, hole
saw, a ring of tiny holes and join them up? I am thinking along the lines
of a hole saw but I am concerned about chipping/cracking the bath (8mm
P.S. I am doing this for a neighbour and they want to pay me. I have said
"a few beers will do" but they want to pay 'properly' after seeing my two
bathroom refits at home. There is approx 20 metres of tiles and a straight
swap out, with a little bit of a plumbing rejig nothing major. They do not
want to get somebody in to give a quote when they know they will be wasting
his time. Any idea of an approximate cost they would expect to pay (in
Yorkshire) and I will half it, I know it is like 'how long is a piece of
string' but any idea would be helpful.
A bi-metal hole saw works great. Not one of those horrible split ones
you get in a concentric set, one of these:
and an arbor:
If you do use the above items? drill a hole the same size in a piece of
3/8" wood and clamp it to the bath tap area you're going to drill,this will
give you two benefits ie it'll...
1. Help guide the drill through without slippage.
2. Reduce the the chance of cracking/scratching the baths glaze.
They are crap, certainly, but fine for making holes in a fibreglass bath.
They are dangerous, certainly. All tools are dangerous.
But they will make a neat round hole in a fibreglass bath with little
risk of accidental damage to the bath or the person using the tool.
There is a very high chance that the cutters will not be truly round
and that a mess will be made of an expensive bath.
As Grunff says, these are truly a crap tool, whether from Aldi or
A proper hole cutter should always be used.
That actually is not that critical.
Taps have big shoulders and big washers to cover any slightly oversize
The trick is lots of masking tape to avoid accidental gouges on the bath
when it breaks through.
And take it steady at low speeds. Ive got a split ring nested cutter and
whilst it ain't precision, it does produce acceptably round holes in
lots of things.
No special tools are needed on GRP after it has set hard, but
metalworking rather than woodworking tools should be used. It can be
drilled, filed, sawn and polished but not hammered or bent and not
easily punched or sheared. The basic shape cannot be altered and the
resin component shows a tendency to fracture and chip.
I did it a few weeks ago, and tried different bits on the old bath. The
nest-of-drills type was useless, it just didn't hold well while drilling
and wobbled a lot. In the end I drilled a very small pilot hole first and
used a normal cheapo arbor+holesaw, worked really well, drilling a lot of
holes in the old bath helped to get it right.
Only problem was that the holesaw has stuck on the arbor, damned if I can
get it off.
Sorry Steve, when you said "nest of drills", I assumed you meant a step
drill. The "clip in hole" thingy, I tend to think of as a holesaw.
I must admit to still getting readjusted to the problems that people
have had with step-drills. I have been using them for years without any
problem, especially on the likes of fibreglass. Of course on thin metal,
the work does need clamping down with a chunk of sacrificial wood
underneath. And the step-drills are easy to sharpen.
Most hole saws have holes in the side. You hold the arbor in an
adjustable spanner, and stick a screwdriver through a hole in the side.
If it doesn't have holes or flats, grip it with a pair of pump pliers.
I cannot release the drill, if it has a screw its under the nut so using
the hole is out. I've tried every kind of pliers up to mole grips but they
cannot enough grip on the round surface. I think I might ....(i was going
to say blowtorch it)
had a brainwave, stuffed two bolts into each hole, then the molegrips, that
did the trick :)
Other people have suggested tools to use so I will not.
With regards to payment, if you do not want to be paid, why not suggest that
they do something for you instead, even if you can do it, you could always
intimate that you do not have the time so their help would be much
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