Cutting curves in fibre cement

[denis]

Does anyone have experience in cutting curves in fibre cement, e.g. villaboard / hardiflex?

I am looking to cut some scalloped trim in the pattern shown in the picture. Any suggestions?

Cheers

Denis

[Canetoad]

Hi Denis
used to do a few of those found a 100 mm grinder with diamond blade made it easy if a bit messy

[silentC]

Yep I've found that freehand with the 4" grinder is as good a way as any. You can clean it up with a rasp, chisel or even a hand plane. Maybe you could try a jigsaw. Haven't given that a go myself but with the right blade it should work.

[denis]

Thanks Canetoad, SilentC. Is there any trick to doing it with a grinder? Do you cut along the line or grind away the waste up to the line? Probably a silly question but I just bought an angle grinder recently but have never used it.

Denis

[silentC]

You'll need to get a diamond blade, which is like a thin disk of steel with diamond dust on the edges. Then you can cut into the sheet, rather than trying to grind it away. See how neat you can do it. If it's a bit rough, cut shy of the line and then clean it up with a rasp.

For the shape you're looking at, it might really be worth giving the jigsaw a go if you've got one.

[rod1949]

I'd be inclinded to use a jigsaw and use a carbourndem coated blade.

Another way is to cut a template appropriate to and use your router (if you have one).

[denis]

I'd be inclinded to use a jigsaw and use a carbourndem coated blade.

Another way is to cut a template appropriate to and use your router (if you have one).

Thanks for the suggestions Rod. I do have a router -- what kind of bit would I use?

[rod1949]

Thanks for the suggestions Rod. I do have a router -- what kind of bit would I use?

You would have a choice of at least 3 types of bits ie;

Straight bit - used in conjunction with the template guide that fixes into the base of the router and run against the curves template you make. or

A Flush Trim bit or Pilot Panel bit, with these the template guide that fixes into the router is not required, as both these bits run directly against the curves template.

You need to remember that with using a router you will not get the fine/small peaks at the top of each curve as you would if a jigsaw was used.

[chrisp]

I've never tried using a router on FC sheet - and I don't think I'd like to try. But if you do could you let us know how it goes and please post some pictures of the router bit afterwards :eek:

[rod1949]

I've never tried using a router on FC sheet - and I don't think I'd like to try. But if you do could you let us know how it goes and please post some pictures of the router bit afterwards :eek:

Neither have I, but depending on how much has to be done a TCT bit should be ok. However I would imagine, subject to how hard and fast the router is pushed into the sheet, that the top and bottom edges of the cut would be a bit fluffy (if you know what I mean).

[denis]

Think I'd be a bit nervous using my regular flush trimming bit on fibre cement. I have seen references to cutting FC with a spiral saw or cutout tool, which I suppose are about the same as a router. I have come across references to special solid tungsten bits for this purpose -- on the internet, but not in the shops.

Denis