Cutting corrugated metal - best tools for the job?

rob w

IMG_20230907_175024.jpg

Hi all,

Looking for the best way to cut back an overhanging corrugated metal roof. It overhangs by about 600mm along a 6m length. I want to cut in situ rather than removing it.

I have a circular saw and have seen it being cut with the blade turned around on it. I also have a small grinder but find it hard to cut the sheets straight/ neatly.

Any suggestions welcome. Would I be wasting my time with a tin snips?

Pic attached for reference

Calahonda52

Getting it supported properly would be my concern as it you cut in in-situ the drop will close the cut and put extra pressure on the blade and will pose a number of risks, depending on the cutting mechanism.

what sort of residual o/hang do you need

10-10-20

What about... and this may be mad altogether - a plunge-saw fitted with a large grinder disk... such as:

https://www.screwfix.ie/p/erbauer-metal-cutting-discs-9-230mm-x-1-9mm-x-22-2mm-5-pack/264ph

Then use a clamped piece of wood as a guide on the affixed portion of the corrugated roof...?

Quandary

If you clearly marked out your cutting line using a nice straight piece of timber then take your time and cut away nice and slowly with the angle grinder(and a new high quality disc). Each sheet should come away easily but have someone there to hold the end steady so it doesn’t drop and pinch your disc. Take your time, make sure both people wear safety glasses.

The Continental Op

Think you will need more than one disc on that. I'd use 1mm wide disks marked as suitable for cutting stainless steel.

I might do it in two hits. First cut off the bulk then a final cut to the required line.

Calahonda52

https://www.boards.ie/discussion/comment/121082060#Comment_121082060

That occurred, maybe with a jigsaw with a proper blade

jmreire

I've done it with a 4" angle grinder and using skinny discs ( several of them in fact ) but I only had an overhang of a foot or so, and did it from the roof itself so had good control of the grinder and disc, while my helper held the cut piece in place until the cut was complete. Goes without saying, safety goggles and gloves are a must. ( people with a fear of heights need not apply) But its not that difficult a job, take your time, and it will work out fine.

jmreire

....

The Continental Op

https://www.boards.ie/discussion/comment/121082633#Comment_121082633

I've worked on several corrugated roofs and tried everything you can think of, sheet saw, snips, angle grinder etc. Jigsaw worked but was a total pain to control, and even with good support was very noisy so please don't forget ear defenders.

TimHorton

https://www.boards.ie/discussion/2058312699/cutting-corrugated-metal-best-tools-for-the-job

https://www.youtube.com/shorts/i7rXMkLG5oQ

The Continental Op

https://www.boards.ie/discussion/comment/121083516#Comment_121083516

That tool is great and I'm sure the OP would be happy if you buy him one ;-)

AmpMan

https://www.boards.ie/discussion/comment/121084255#Comment_121084255

I think I seen niblers in aldi this week.

I just use a 4" grinder like a normal person.

The Continental Op

https://www.boards.ie/discussion/comment/121084266#Comment_121084266

Not all nibblers are equal. The cheaper ones tend to have a bulkier anvil (?) around the the cutter so are only really suitable for flat or gently curved sheets because they don't go around the peaks and troughs of the corrugated iron as well as that Milwaukee one.

CelticRambler

Based on recent metal-cutting experience, I'd use a reciprocating saw with a suitable blade and plenty of support. From the looks of it, you could probably cut one sheet at a time, meaning the individual sections will fall away progressively and not cause any problems (still better to stop the free-falling, though). It should be easy enough to get a nice straight line if you've marked the full length of the line first.

And as the Continental Op says, using any powered saw, it'll be noisy, very noisy.

rob316

Op, I'd get a length of timber, measure what I want to cut plus the offset of the blade on the circular saw. Clamp timber on both ends, few screws in the middle to keep it secure and straight and cut away.

TimHorton

https://www.boards.ie/discussion/comment/121084266#Comment_121084266

Excuse me! , He asked for the best tool for the job and I gave it to him.

TimHorton

https://www.boards.ie/discussion/comment/121084255#Comment_121084255

Excuse me! , He asked for the best tool for the job and I gave it to him.

The Continental Op

https://www.boards.ie/discussion/comment/121089879#Comment_121089879

Slightly cheaper would be paying someone to do it for him.

Lumen

I have a cheap nibbler drill attachment that I bought for galvanized steel guttering. The advantage over any type of saw is supposedly the way it spreads the galvanic coating over the cut edge, so the result is less likely to rust.

The_Bullman

I would not use a grinder. The heat build up with melt the paint at the end resulting in rust which will penetrate up 2 inches from the end of the sheet in no time.

Best tool for straightest cut would be metal cutting saw, followed by reciprocating saw, followed by nibbler. A nibbler will give a good cut and will be least prone to rusting but hard to keep perfectly straight.

rob w

Sorry, Im only getting around to replying to this now - was sick for a few weeks after posting and never got back around to it.

Got the job done at the weekend though - used a grinder and a couple of 1mm discs for cutting stainless. I pre-marked a nice straight line across the roof in advance and went along freehand with the grinder just taking my time. Had a helper just holding the overhang from dropping and it worked a treat in the end. Finished it off with a coating of spray paint along the edge to inhibit rust, so hopefully that does the trick.

Thanks for all the advice and responses - reliable as ever!