# Forum Home Renovation Structural Renovation  Have you tried cutting colourbond sheet with a blade on back to front ?

## apricotripper

I was told, that a good way to cut sheeting is with an a circular saw with an old blade put on backwards. Not tungsten tipped though.  
apparently cuts through it like butter, with little swarf.  
Wondering how true that is.

----------


## journeyman Mick

Jake,
I've got a purpose made steel blade for cutting roofing. It's a special steel disc with tiny half circles taken out of the rim to form small squareish teeth. It cuts okay, reasonably fast with a bit of a burr but with a huge amount of noise. :Shock:  I'd say that using an old steel blade backwards would be much the same, sending out huge showers of hot sparks and deafening half the neighbourhood. Do you have that much to cut? There should really only be the angled cuts on the gable ends as most/all the other stuff should be supplied cut to size. I tend to just use a pair (or two) of aviation snips. 
Mick

----------


## apricotripper

ta Mick. Your right. don't have much to cut I think. May have to around the doors and windows as well as the gables. I haven't got to that yet.  
I just like the idea of getting a nice straight cut by maybe clamping a straight edge to the colourbond, and runnig the saw along it.  
For those gables was playing with the idea of teking the cladding on, then clamping that straight edge around the knee of the frame and up at the apex, and just with one swoop with the circular saw, while its all up there, make a quick straight cut to do it all in one shot. or forget the straight edge and drop a string line and just do it by eye since its all to be covered with flashing.........better than @@@@ing around with snips. maybe.

----------


## Vernonv

I have used a cheapy fine toothed TCT blade to cut colorbond (works well) and some 1.0 to 1.5 Cees and Zeds :Shock:  (wears very quickly on those). Worked very well but is very noisy, as Mick pointed out. The blade will not be good for anything else after using it on steel, but if you have a half blunt blade lying around ... 
You will need to wear a face shield or goggles ... don't wear normal safety glasses.

----------


## namtrak

I know most people think tinsnips are a pain, but at the end of the day I seem to end up using them anyway. 
Using the old Gilbows is just a matter of technique, and once you get that sorted you can get it to the point where you are almost just tearing the iron like paper.

----------


## Bloss

Two questions here: *Can* you use reversed blade designed to cut timber to cut steel sheet?   :Shock: 
Answer yes.  *Should* you do so?
Answer most definitely no!  :Frown:   :Doh:  
This is wrong on so many levels, not least the safety concerns for you and any around you.  :Shock:  If you want to use a TCT or other powered blade then use one designed for the purpose - there are steel cutting blades and they have specially shaped teeth and so on and there are various tools for the purpose. 
As others have said - for small and DIY jobs snips or even score & snap works well. For cutting along the corrugations score a line against a straightedge using the heel of an old handsaw or better still a TCT score & snap knife as used for fibre sheets. A few back and forth movements (often a single bend will do it) and the sheet will break cleanly along that line. With practice a snip and tear will work well across a sheet. Good idea to wear leather gloves when working with steel sheets like this - I have seen some nasty cuts even with protective gear.  :2thumbsup:

----------


## Andy Mac

Another word of warning about cutting Colorbond with discs, any discs: you may well void the warranty on materials! 
The friction heats up the metal and destroys the rust proof of the coatings. How do I know? My BIL is a trucking contractor for Bluescope Steel, hears all the ins-and-outs from contractors...like those assembling sheds.
He recently went through a huge legal drama himself having a shed built on his holiday block up at Bundaberg. The contractor did exactly as you guys are suggesting, all the sheets trimmed with a grinder. When it came time to sign off on the contract before final payment (BIL goes through everything with a fine tooth comb!), the supplier of the kit was advised about said cutting, and wiped his hands of it!! :Mad:  No warranty at all. BIL won't accept the new shed and wants it replaced, the contractor wants final payment, so its gone nowhere :Annoyed:  
Go the tin snips!!

----------


## Bloss

> The contractor did exactly as you guys are suggesting, all the sheets trimmed with a grinder. When it came time to sign off on the contract before final payment (BIL goes through everything with a fine tooth comb!), the supplier of the kit was advised about said cutting, and wiped his hands of it!! No warranty at all. BIL won't accept the new shed and wants it replaced, the contractor wants final payment, so its gone nowhere
> Go the tin snips!!

  Thread hijack, but I am not quote sure how they could refuse warranty on those grounds - Bluescope Steel's on guides say: "Use metal cutting discs or shears to cut sheets rather than angle grinder discs"  (http://www.colorbond.com/index.cfm?o...D0B2A398944166). Not sure why that should be so as you can mark & overheat the edge of the material with a cut-off wheel too if you do not use it properly (and how could anyone tell that a _cutting disk_ (rather than a grinding disk) was used in a grinder vs. a saw since the cut made and the disks shape and materials are identical). And the warranty does not mention that http://www.colorbond.com/go/home/res...ages-and-sheds.  
He might note the construction issue he is concerned with and if you later make a warranty claim he could then say that he will not accept the claim, but even so he could refuse only if he could show that the problem for which you are seeking warranty support was caused by that work. The fact of using a tool that is not recommended is irrelevant - it is whether actual damage was caused and as I said only comes into question at some later time _if_ you make claim. The supplier has no grounds and in any case he cannot simply refuse _all warranty_. Contact BlueScope or the fair trade agency.

----------


## Andy Mac

> Thread hijack, but I am not quote sure how they could refuse warranty on those grounds - Bluescope Steel's on guides say: "Use metal cutting discs or shears to cut sheets rather than angle grinder discs"  (http://www.colorbond.com/index.cfm?o...D0B2A398944166). Not sure why that should be so as you can mark & overheat the edge of the material with a cut-off wheel too if you do not use it properly (and how could anyone tell that a _cutting disk_ (rather than a grinding disk) was used in a grinder vs. a saw since the cut made and the disks shape and materials are identical). And the warranty does not mention that http://www.colorbond.com/go/home/res...ages-and-sheds.  
> He might note the construction issue he is concerned with and if you later make a warranty claim he could then say that he will not accept the claim, but even so he could refuse only if he could show that the problem for which you are seeking warranty support was caused by that work. The fact of using a tool that is not recommended is irrelevant - it is whether actual damage was caused and as I said only comes into question at some later time _if_ you make claim. The supplier has no grounds and in any case he cannot simply refuse _all warranty_. Contact BlueScope or the fair trade agency.

  Fair call, except that he works for them! When he talked to his boss about it apparently there was little he could do, as it contravened accepted practice? 
I'm not sure whether a metal blade as opposed to an abrasive disc is the issue, perhaps grinder speed is too fast but a saw isn't. All I know is that if I was putting up a new shed I'd use snips. If it was me mucking about at home with old material (as I tend to) I'd rip into it with a grinder. 
Cheers

----------


## Vernonv

Oldbloss, what it actually says is "Use a metal *cutting saw or blade*, or shears to cut sheets rather than angle grinder discs". The problem of overheating occurs when any sort of abrasive disc is used. What they are referring to is a cutting blade (i.e. saw blade made of metal) and not an abrasive blade fitted to a saw.

----------


## Batpig

Dear Apricot & Guys, 
Thought I might just post this link for a new Cold-Cut saw that GMC must have just released: http://www.gmcompany.com.au/index.cf...oducts&pid=686
Haven't seen it promo'd anywhere yet. You all probably know that even just the blades for things like this are worth a packet, so it might be worth your looking into what this saw costs Apricot, because it looks like it's set up with the right blade. It also looks like it's set up to catch the swarf too, so that the hot bits don't leave little burn marks on your colourbond. Ozito did something like this a couple of years ago, but I'm not sure if theirs could bevel-over like this one (for when you've got normal timber blades in it). 
Best Wishes,
Batpig.

----------


## Bloss

> Oldbloss, what it actually says is "Use a metal *cutting saw or blade*, or shears to cut sheets rather than angle grinder discs".

  Yep mea culpa - and I do know the difference funnily enough.  :Blush7:  I cut and pasted the quote from the custom orb site (which does say 'disc' not 'saw') and then jumped to the same list on the colourbond warranty page and didn't notice the one word change. That's what happens when you hurry. The 'over-heating' with cut-off wheels (I use a metal cutting saw blade, but I have occasionally used the thin cut-off wheels too) is overstated as a problem though IMO, but still should follow the manufacturer - they know what's best for their product. 
It's still rubbish so far as this refusal to 'sign-off' on a total warranty for shed goes and that was my point - the only justification for refusal of warranty would be as I said: if the claimed fault or problem were shown to be caused by using an abrasive disc or other installer/user action. For example if the problem was a failing coating finish and it was occurring only or mainly adjacent to a cut & burnt edge then that might well be refused, but a coating failure mid-sheet or at a non-cut edge should be a legitimate claim. In any case a statutory warranty applies regardless of what the guy says, with fit for purpose and duty of care applying - just means that any future claim it might be more troublesome than otherwise. The situation is blurred too because the supplier could then try to force you to seek any warranty remedy from the installer. 
That's why these sorts of jobs should be covered by supply& install single contract or back to back contracts that oblige all parties to install to manufacturers and/or Australian specs. Trouble is we tend to use standard contracts that favour the suppliers & installers not the client and even though this might be a contract for $10K or $20K or more work we do not get legal advice. Fine when it all goes well, but costly if it doesn't.  
Have to say that in my experience this requirement is honoured more in the breach than observance - abrasive cut-off wheels on saws & grinders are widely used in the shed erection and roofing industry regardless of the suggestions they shouldn't be. Doesn't mean it should be that way of course. 
The real point of my post was to use the right tool for the job.  :2thumbsup:

----------


## barney118

Depending on the amount of cutting you intend to do, the good ol hand shears do quite well for small quanties. I agree using abrasive power tools will void the warranty on your product if there are signs that heat has been induced while cutting and therefore corrosion exists down the track you might find yourself in a tough little corner. 
I have hired an electric nibbler with quite a good success but exxy and noisy. I was looking into buyin a set of electric shears but they were also a bit exxy, I wasnt game to use a drill attachment even though I've seen them used in a video.  
I just finished a roof job and used a set of air shear knives $70 bucks, I had acess to a compressor but you can pick them up for $100 bucks. The shears cut a section out of about 4mm which curls up as you go cutting across corro takes a bit of practice but along it no issues at all. No burrs left after cutting just get a good set of leather gloves to use and a decent air hose.

----------


## wonderplumb

Good thread, I dont see how a grinder would void warranty on your roofing, you would need a LOT of heat to burn off the colour let alone the zincalume underneath it. And grinder or not you would still get the 'cut edge protection' qualities from your roof sheets. If the need arises I use those nice thin flexovit 5" blades, but its a hassle using a grinder or shears so I always revert back to the snips.

----------


## kombiman

Also, if you get the blade too hot you may find the teeth coming off and going in random directions.  Having to, in my day job, dig bits of steel out of some poor sap in an emergency department, leads me to say use the right tool for the job.  Says me as I hit me screwdriver with a hammer  :Wink 1:

----------


## Bloss

> I agree using abrasive power tools will void the warranty on your product if there are signs that heat has been induced while cutting and therefore corrosion exists down the track you might find yourself in a tough little corner.

  Nah - As I said the attempt to refuse warranty and sign-off is a try-on by this guy. The only issue might be an argument down the track on a claim for product failure that could be attributed to use of tools not according to instructions. But that can't be used to 'void warranty' upfront. If the guy being a hard-ass on this was really concerned then all he has to do is sign-off and make an annotation on the document of the issues he is worried about. The rest of the construction and any warranty is simply unrelated to a specific potential future problem arising from edge burn.  :2thumbsup:

----------


## Andy Mac

> Nah - As I said the attempt to refuse warranty and sign-off is a try-on by this guy. The only issue might be an argument down the track on a claim for product failure that could be attributed to use of tools not according to instructions. But that can't be used to 'void warranty' upfront. If the guy being a hard-ass on this was really concerned then all he has to do is sign-off and make an annotation on the document of the issues he is worried about. The rest of the construction and any warranty is simply unrelated to a specific potential future problem arising from edge burn.

  Just had a chat to the BIL tonight, in my shed. Its still in the hands of solicitors. The issue is made more pressing because the shed is already showing signs of rust, and its only a km or so from salt water. And someone up there has peed him off big time, so he's not backing down on anything. If any part of the shed is not to spec he's calling it! 
Cheers

----------


## Bloss

> Just had a chat to the BIL tonight, in my shed. Its still *in the hands of solicitors*.

   :Yikes2:  Gunna be an expensive shed then!  :Cry:     

> The issue is made more pressing because the shed is already showing signs of rust, and its only a km or so from salt water. And someone up there has peed him off big time, so he's not backing down on anything. If any part of the shed is not to spec he's calling it! Cheers

  Coastal construction is always a pain salt just gets on everything.  :Frown:  On the NSW North Coast my Dad & I used to coat all cut edges with a suitable primer & paint as the sheeting was put up which was reasonably successful with colourbond. Even so gal & colourbond in coastal areas often would show signs of corrosion (if not obvious rust) as early as during construction. We found that galvanised materials primed & painted (and then maintained) gave a better long term result than the zincalume/colourbond products even though the manufacturers blurbs suggested otherwise. 
Pity it has gone to lawyers at 10 paces already - lawyers the only winners from that!  :Mad:   :Biggrin:  Look carefully at what you expect from the process and watch the costs. Often it is better to settle or just drop it and spend the money on maintaining the shed (you'll have to do that anyway!) so work out what your limit is on legal costs (vs value of shed and likely result) - and stick to it. These things often turn into p*ssing contests and common sense goes out the window. Good luck.  :2thumbsup:

----------


## Bloss

> Just had a chat to the BIL tonight, in my shed. Its still *in the hands of solicitors*.

   :Yikes2:  Gunna be an expensive shed then!  :Cry:     

> The issue is made more pressing because the shed is already showing signs of rust, and its only a km or so from salt water. And someone up there has peed him off big time, so he's not backing down on anything. If any part of the shed is not to spec he's calling it! Cheers

  Coastal construction is always a pain salt just gets on everything.  :Frown:  On the NSW North Coast my Dad & I used to coat all cut edges with a suitable primer & paint as the sheeting was put up which was reasonably successful with colourbond. Even so gal & colourbond in coastal areas often would show signs of corrosion (if not obvious rust) as early as during construction. We found that galvanised materials primed & painted (and then maintained) gave a better long term result than the zincalume/colourbond products even though the manufacturers blurbs suggested otherwise. 
Pity it has gone to lawyers at 10 paces already - lawyers the only winners from that!  :Mad:   :Biggrin:  Look carefully at what you expect form the process and watch the costs. Often it is better to settle or just drop it and spend the money on maintaining the shed (you'll have to do that anyway!) so work out what your limit is on legal costs (vs value of shed and likely result) - and stick to it. These things often turn into p*ssing contests and common sense goes out the window. Good luck.  :2thumbsup:

----------


## barney118

> Nah - As I said the attempt to refuse warranty and sign-off is a try-on by this guy. The only issue might be an argument down the track on a claim for product failure that could be attributed to use of tools not according to instructions. But that can't be used to 'void warranty' upfront. If the guy being a hard-ass on this was really concerned then all he has to do is sign-off and make an annotation on the document of the issues he is worried about. The rest of the construction and any warranty is simply unrelated to a specific potential future problem arising from edge burn.

  I stand corrected Old Boss (to a point) . I spoke to Steel direct today to enquire a bit more for my own warrantly certificate I need to get hold of. The first response I recieved was dont use cutting discs they generate heat etc.... I followed up with Chapter 7 of the installation states "we recommend that you use a power saw with a metal cutting blade because it produces fewer damaging hot metal particles and leaves less resultant burr than does a carborundum disc." You can interpret this a number of different ways, it doesnt state that you cannot use carborundm discs or it doesnt say they recommend them either. 
 In short "we recommend the use of cold cutting saws such as the Makita 4130 unit with the appropriate tungsten blade" 
What is the definition of "appropriate tungsten blade" If I went into Bunnings what would I look for, I'm thinking a circular saw blade suitable cutting steel?  
In short your warranty is bound by the use of the appropriate Aust Stds and BSL technical bulletins at time of installation.  
I have to admit the installation instructions are crap with regard to defintions, how would you look like in court if you had a claim... 
have a look at the following attachments.

----------


## Bloss

> I
> What is the definition of "appropriate tungsten blade" If I went into Bunnings what would I look for, I'm thinking a circular saw blade suitable cutting steel?

  Just trying to help not having a go - I come across a bit blunt sometimes!  :Smilie:  And yes you are right - there are special TCT steel cutting blades made by Irwin & others. They have different tooth shape and rake etc and will be clearly labelled 'metal cutting' and will list ferrous & non-ferrous metal cutting capability on the pack. Bunnings usually carry them in 185mm (71/4") as most saws designed specifically take that size. They are not cheap (around $100), but there is no alternative really. 
They are the same type of blade used in the Triton Steel Cutter http://www.triton.com.au/product.php?id=36 (a great machine albeit with some limitations, but perfect for my needs and I got mine for $130 with a spare blade!) in which they will cut through up to 50mm _solid_ steel bar (I have been using it for RHS and it is brilliant). 
I use an Irwin metal cutting blade in a 185mm saw for colourbond & galv iron sheeting and it works fine so long as you have the sheet secured well. For cut-outs and tight cuts I use snips or if a lot to do a thin metal cutting wheel in a 125mm grinder.

----------


## manofaus

***don't forget that the grinding sparks will embed into the colorbond and rust later. As we know rust stains even zincalume sheets.*** 
My uncle is a roofer and he has shears by makita, but mostly he tears the colorbond sheeting with tinsnips. its magic to watch when he is doing a a 4 point hip roof.
Like he says though, if you are planning all your cuts properly should end up under flashing anyway. Most of the trouble happens when you fit and then cut.
But I guess if you do it every day you learn a few tricks.

----------


## barney118

I certianly wouldnt want to be going to court over these sort of issues on a personal front rather than a buisness front as old boss mentioned you have to weigh the costs up vs fixing it anyway.  
After writing a few contracts in my time and been on the other recieving end when the insurers wont pay out (luckly for me it, the experienced gained is somewhat valuable at a price of course). It is amazing when you dig deep into terms and conditions you end up finding that the legal people have thier own definitions compared to your interpretation, hence the wording is all so important, from this blog you can see how the manufacturer recommends one thing but there is a legal side of it too, they have left themselves open a fair bit by not defining a few things. 
Old boss the beauty of the forums allows others to learn from other peoples mistakes or find know how to do something better. A quote from my old boss _"A bloke who has never made a mistake has never made anything".  My motto is learn from your mistakes._ 
The air shears did a great job for me, my existing zincalume was cut with an "angry grinder"  :Biggrin:  and it did show some decent corrosion and the burn marks were evident, in saying it had been up for a number of years and protected under flashings, I wouldnt like to see an edge cut leading into the gutter done like this. 
I have a full set of hand shears since doing my roof, I love the l/h ones and curved ones, and I am amazed at what you can do with them when it comes to flashings,guttering, whirlybird installment.

----------

