Cutting fibre cement board

[Prof]

Hi guys,

What a great idea this forum is..

You don't always find what you're looking for in advice on the DIY section of Bunnings website..

My question is...What's the best type of power tool to use for cutting a large diameter hole in fibre cement board?

[Kermit]

Would this do the job @Prof?

https://www.bunnings.com.au/trojan-fibre-cement-sheet-cutter_p6010345

[Prof]

Unfortunately no Kermit...
I should have mentioned that it's a round hole..

[fredgregg]

I used a tile hole saw

[Prof]

Is that different from a normal hole saw?

[Andy_Mann]

@Prof, if you're to be cutting circular holes, then a carbide/diamond tipped jigsaw or reciprocating saw would seem ideal, but there's a problem. The dust is nasty stuff, check out post #8 by Peter Kelly:

http://www.sawmillcreek.org/showthread.php?199310-Blades-for-cutting-Hardie-(fiber-cement)

You could try to vacuum the dust while cutting, but you'd need a vacuum with a HEPA filter (expensive), & that's able to contain the dust completely for disposal, or you're back to square one. Even then, you'd still have to remove the contamination from the nozzle, hose, & filter compartment.

Wet cutting would be ideal to contain the dust, but instead of using a Wet/Dry Vac (more problems than it's worth), let the residue run into a disposable bag/container that can be sealed & disposed of safely.

Sorry if I sound like a drama queen, but it's you, & your family's health that could be at risk.

My suggestion would be to wet, then scribe & snap your eave panels to length, leaving a gap between them, that you can fit with a panel that's safer, & easily cut to install your fittings.

[Brad]

Tile holesaw would have a diamond edge.

https://www.bunnings.com.au/p-n-6-piece-ceramic-tile-holesaw-set_p6370115

57mm is the largest size in that kit. You can get larger sizes in tungston teeth at bunnies.

I might end up in the naughty corner but you can look here too.

http://www.gasweld.com.au/catalogsearch/result/index/?cat=0&dir=asc&order=relevance&q=Diamond+Coated...

[Prof]

Thanks guys for all your help and suggestions..

I must say I'm very surprised at how dangerous this stuff is!! I always thought that fibre cement was a safe alternative to asbestos! It sounds like it's just as bad!!

Getting back to the job at hand...I'm planning on cutting out a circular hole approx. 30mm. in diam. to run speaker wires and HDMI cable into the next room.. and a large rectangular cut out out for an aircon..both in existing interior walls..

fredgregg &Brad..A diamond tipped hole saw sounds like the best way to cut the 30mm. hole..
I looked at Bunnings and Gasweld sites and they have wet cut saws, which would work fine if the sheet was lying down..but what about a vertical wall panel..Wouldn't any moisture applied get down into the panel and possibly cause some swelling?

Andy_Mann.. I think your idea of using a reciprocating saw with a diamond blade might be the way to go for the aircon cut out..This cut out will be on an exterior wall which also has fibre cement brick wall cladding on the outside..

[Brad]

I would wet cut any holes before you do your final fixing while the sheet is down.

For the aircon I would be tempted to use fill pieces rather than cut a hole, few extra joins but you can avoid dust by snap cutting the sheet.

Fibre cement is safer in that you can snap cut it where any damage to asbestos releases fibres.

[Andy_Mann]

@Prof for drilling the 30mm hole on an installed vertical panel, either a carbide tipped, or diamond coated hole saw would be fine, but I wouldn't recommend doing it dry.

For a cheap hack, set up your hole saw as normal, but before you fit it to your drill, scrounge a cheap stubby holder, make a small cross cut in the centre of its base & slide it onto hole saw shaft. Grab a spray bottle of water & dampen the inside of the stubby holder, & also where you're about to drill (it doesn't have to be saturated, just moist).

Partially drill, & hold a damp cloth under the stubby holder to collect any dribbles, as you'll need to repeatedly remove the hole saw to remoisten the hole site.

Repeat the process until you're done.

Then rinse the hole saw thoroughly under a tap, & thoroughly rinse the basin/trough. The hole saw's safely ready for another day.

Rather than rinse the rag, put it in a pastic bag, tie the bag securely, & drop it into your rubbish bin.

I'll get back to you on the cut out for your air-con later.