Drilling a bath

[John]

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 fibreglass).

Cheers

John

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.

Cheers

John

[Grunff]

A bi-metal hole saw works great. Not one of those horrible split ones you get in a concentric set, one of these:

an arbor:

[The3rd Earl Of Derby]

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.

[The3rd Earl Of Derby]

Missed the important bit. :-)

For gods sake pack the bath with old bed sheets or put a board over the bath.

[Palindr☻me]

Aldi were doing a set of stepped concentric hole drills for not a lot. They still had some yesterday in the Plymouth store.

[Grunff]

They are crap, dangerous, and best avoided.

[soup]

Cone/stepped drill?

:- 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.

[Palindr☻me]

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.

[Andy Hall]

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 anywhere else.

A proper hole cutter should always be used.

[Steve]

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.

Steve

[Palindr☻me]

Ah well, it does appear that lots of people have had problems with step drills and I shall stop suggesting them in future, even though my experience with them has been rather different.

[Grunff]

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.

[The Natural Philosopher]

That actually is not that critical.

Taps have big shoulders and big washers to cover any slightly oversize holes.

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.

[Andy Hall]

undo allen screw and remove drill small rod through the holes in the side and tap gently

[Steve]

I wasn't talking about a step drill, as I said it was one of those crazy clip in hole drills.

Steve

[Palindr☻me]

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.

[Steve]

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 :)

Steve

[the_constructor]

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 appreciated

[biggirlsblouse]

One of those deep holes saws is best, and dont expect the holesaw to be any good when you have finished because a good bath is a very complex compound structure consisting of many layers, some of which are bad for holesaw teeth! I suggest a "deep hole saw because as it finally break through on the other side it is very difficult to avoid the inevitable "plunge" into the surrounding perfect surface to score it!

[Don Spumey]

Interesting observation, could you enlighten me as to what experience you have had in this field?

For my part, I was employed in the bath manufacturing industry for several years, & a 'bog standard' Profix HSS bimetal holesaw was used. Not just for one or two baths, not even for one 'shift' production run, but for three or four runs. Which if my maths serves me right is, an average of 250 baths produced per shift X 3 X 2 (two tap holes) =

1500+ holes drilled. All using a handheld airdrill at a pressure of approx 14psi

Don.