Best way to cut semi-rigid ducting?

[jayc89]

My ducting should arrive tomorrow/Wednesday and I plan to lay the first couple of runs this week. I'm using 90mm semi-rigid ducting, what's the best way to cut it?

[ProDave]

With a saw.  What other options are you expecting?

[jayc89]

1 minute ago, ProDave said:

With a saw.  What other options are you expecting?

 

A hacksaw was going to be my default. I was making sure I wasn't missing a trick, which has been known...

[ProDave]

A fine tooth panel saw is easier to get a straight cut.

[Iceverge]

If you're careful with a Stanley it works fine as the grooves keep it centred. 

[MJNewton]

1 hour ago, Iceverge said:

If you're careful with a Stanley it works fine as the grooves keep it centred. 

Yeah I'd definitely recommend a Stanley knife - easy, neat and there's no swarf. 

Edited February 14, 2023 by MJNewton

[shuff27]

5 hours ago, MJNewton said:

Yeah I'd definitely recommend a Stanley knife - easy, neat and there's no swarf. 

That's what I used on recommendation of my MVHR kit supplier.  It's pretty easy once you get the hang of it - practice on an offcut.

 

Also good idea to cut the ends that are going into the manifold long initially, then trim them all down more accurately once you're ready to attach them all to the manifold.  I had to do this anyway while waiting for the MVHR unit/manifold to be delivered but it turned out to make the final connection of the 15 ducts into the manifold easier.

[Conor]

You can buy a clipping tool, basically like really big pipe snippers, bit I think you'd need to be doin a lot to get the benefit out of it.

 

I started cutting mine with my right job saw (dulled for pvc pipe, insualtion, cement board etc) but then eventually just used my pocket knife for convenience. Not nearly as meat as can go wayward, but duct is easy to trim.

[crispy_wafer]

Just been at this, started with a Stanley knife, worked but if I wasn't diligent enough then it is quite easy to cut/slice not in a straight line and end up cutting through one of the ridges...  Then I swapped over to a hacksaw blade, and used it to cut on the pull stroke, worked awesome for me, but leaves some swarf on the pipe which needs a bit of a rub, to loosen and clean up.  Try both, one will work for you.

[jack]

It's been ~7 years since we did ours, but I'm pretty sure I used an old bread knife. I found it a lot easier to keep centred in the gap between ridges.

[Dave Jones]

make a simple mitre box out of scrap timber with a slot in it to guide the saw, dead straight cuts every time.

[Tims]

Another vote for a craft knife, quick, easy and clean (if you don't cut yourself instead of the pipe😅). As said above the ridges show you where to cut and it doesn't need to be mm accurate also if you slip and cut into a ridge a little it's double lined anyway.