# Forum Home Renovation General Odds & Sods  Fibro cement board

## Laurence

I plan to construct a cover for our firefighting water pump from fibro cement board. Could someone tell me how to to cut it (eg is there a blade that will fit my angle grinder, or my circular saw) please? Also, are there special screws or is it best to use nuts and bolts to plate the sides together. And, are there important things I need to know/do/not do?
Thanks
Laurence

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## Jon

Laurence, 
two methods that I know to cut fibro.  A score and snap knife the same as laminex etc, or much better, a fibro cutter which you could get from any hardware store.  I have know idea of price.
I think you should try to avoid cutting with power tools because of the dust, but don't quote me on that. 
For joints, you will need to use wood or steel to screw into or bolt through as the fibro can't hold a screw. 
Jon

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## Thommo

Hi Laurence,   the way I cut it is with a diamond cutter blade on your angle grinder.
It does it pretty quick, and yes it does produce a bit a dust.  Just make sure you cut it outside and wear the right equipment.

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## Justin

When I laid a heap of fibro as a substrate for floor tiling, I used a fibro cutting blade on my triton workbench in ripsaw mode. It worked well, but the dust was really thick. 
If you don't have a triton then of course you could just use a circular saw freehand or against a guide. Cutting outside may be the go on account of the dust issue.  
Cheers,  
Justin.

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## ChrisH

James Hardie recommend several methods including "score and snap" knife, and a special fibre cement blade in a circular saw. I recently did gable ends and dormer window cladding in Hardies Chamfer, a profiled weatherboard. Initially I used a special fibre cement blade in my Hitachi 7 1/4" saw. It has only 4 teeth.  I followed the (detailed) instructions provided, and got great easy cuts. After about 100 cuts the sat threw off a tungsten carbide tip and got really hot in a few seconds. The saw disc went all soft and floppy from the heat. As I am 2 hours drive from the shop to get a replacement, I pulled out the trusty old score and snap knife. I finished the job using it, and still haven't used the (warranty) replacement blade.  
These boards are 9 mm thick and needed to be scored several times on both sides to get a neat cut, but it was still easy. 
For very heavy fibre cement sheet boards I would use the cutting disc with the following precautions (which I did myself) 1. Use a good dustmask, goggles and earmuffs.
2. do it out in the open to minimise your saw breathing in dust, which I imagine wouldn't do the motor any good. 
3.Use a guide to make sure the saw cuts dead square. If you turn the saw even slightly in the cut then the teeth of the saw will rub against the edge of the cut, which heats them up and off they fly! (this was explained to me when I took back the first disc, but they gave me a replacement anyway.)
Info about cutting fibre cement is on james hardie's website, ot they will send out booklets on each of their products at no charge. 
Chris.

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## Justin

Well, it looks like the James Hardie website is exhibiting to all and sundry that they have absolutely no knowledge whatsoever of the material that they are attempting to manufacture and sell ! 
Someone from this BB better get an email off to them quick smart, advising them of their unsafe, inefficient and unworkmanlike methods...........

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## soundman

Reality check.....  
Untill recently james hardy industries were the countries largest manufacturer of asbestos products.
This speaks volumes for their atitude to user safety. 
If you are stupid enough to prefer working in a cloud of fine gritty dust be my guest. 
But for thinner sheets the score & snap method is great for long straight cuts. 
for cut arrounds the old favorite fibro cutter is quick clean & quiet.  
If you realy feel the need to use power, cutting a wet cutting machine such as a brick saw for planks or a quick cut(concrete saw) is worth consideration. Particularly if the material is thick compressed flat sheet. 
Remember the material is Fibre Reinforced Cement. 
By cement they mean cement.

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## ChrisH

I have the fixing manual for Hardies external cladding range. 
Here is what it says:
Section 7, working instructions: 
-Score and Snap... gives instructions on using a score and snap knife. >>>This method should only be used where sheet edges will be hidden behind jointers and corners. This method is NOT recommended where cut edges will be exposed.
-Hand Guillotine: Same warning about exposed edges.
-Fibreshear tool by Toolex - edges can be exposed.
- Hand sawing - only suitable for very short cuts. Use an old hand saw in short forward jabbing motion. 
- Power saw with fibre cement blade, eg Hardiblade - gives an acceptable edge for exposed cut edges when saw is run along a clamped batten to give a straight edge. 
User must wear goggles and a dust mask, preferably a disposable cartridge type. All operations must be carried out in the open and dust extraction equipment must be fitted to the power tool. Refer to safe working practises in section 8.  
Section 8 gives a description of silicosis of the lungs and its causes. It recommends using a wet saw such as Makita 4101R or 4107R. It warns about dust exposure during cutting and during clean up afterwards.  
The claim that Hardies don't understand their own product is a bit rich. The only methods that give a neat enough cut to be left exposed to view are the fibreshear (expensive) or a power saw cut (warnings and safety advice are clearly given).
Hardies were bastards over asbestos but there are times when a saw cut IS the best choice, it is NOT a demonstration of ignorance or anything of the sort. You just have to take the appropriate precautions, which Hardies explain in detail.
Chris.

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## Justin

O.K, it looks like subtlety is wasted in this particular forum, so I'll spell it out. I was not, repeat was not, claiming that Hardies don't understand their own product. 
What I was doing was having a humorous dig at the post subsequent to my first one, which so diplomatically referred to my methods (aka those recommended by James Hardie) as unsafe, inefficient and most unworkmanlike. Also reference made to the "no knowledge whatsover of the material blah blah blah" 
Mental note to self : use plain, non-subtle, non-cryptic english in future posts......

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## ChrisH

Sorry Justin I didsn't pick up on your subtlety. 
We are in furious agreement about the self appointed experts. I guess we were making tha same point, I just thought you were making the other point... ( I was v. tired at the time...)
Best wishes.
Chris.

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## Little Festo

Hello Laurence, 
I had to put up some lining for a wet area several months ago. I used a fibro cutter and it was suprisingly quick and easy. You should check to see if the supplier can cut it size for you as some do.  
BTW err on the side of caution re your health. I've had to attend a few post mortems where cause of death was lung cancer , it's not very pretty. Also seen patients suffering from it as well - BE CAREFULL. 
All the best  - Peter

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## soundman

Back to the original post.
Laurence mate.
Score & snap knife will be fine & cheapest for your little shed. 
Cobsidering its a fire fighting pump a steel farme would ne the go.
Knuts bolts & washers (big washers).
Drill the holes carefully with a masonry drill. 
Better still go with corigated iron & angle.
Have the corro cut to size. 
cheers

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## ChrisH

Hey Doorstop
If you're ther REAL Chris H
What does that make me...
The UNREAL Chris H?
(sounds good to me) 
From a really truly Chris H.

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## Laurence

Thanks to everybody for their replys/information. 
Project completed - used score and bend successfully (and will in the future), didn't relish the idea of lung destroying dust clouds everywhere. 
Regards
Laurence

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