Best way to cut Plenums and metal ducting

[ultramods]

I need to cut the plastic plenums that are fixed in position, can anyone reccomend the best way to do this? I was thinking of buying a cheap reciprocating saw like this one:

 

https://www.diy.com/departments/performance-power-700w-220-240v-reciprocating-saw-prs700c/3663602796176_BQ.prd

 

Or should i just use a fine toothed hand saw?

 

 

[scottishjohn]

need a lot more info than that to make a comment 

how big are holes needed , or is just trim what is sticking down in picture?

 

[lizzie]

Installers cut mine off with what looked like an oversized electric carving knife, bit like the thing in your link.  It was a very quick job.

[ultramods]

4 minutes ago, scottishjohn said:

need a lot more info than that to make a comment 

how big are holes needed , or is just trim what is sticking down in picture?

 

 

It's not cutting a hole, the 125mm hole has already been cut.

 

It's trimming the end off the plenum (125mm diameter)  flush with the ceiling so I can then attach the air valve 

 

 

[ultramods]

6 minutes ago, lizzie said:

Installers cut mine off with what looked like an oversized electric carving knife, bit like the thing in your link.  It was a very quick job.

 

Thanks, I was thinking it would make it a lot easier than a hand saw

[Jeremy Harris]

I did mine with a multitool, as it will cut flush to a surface.  I only have the relatively cheap Bosch one, but it seems to be OK (even if a Fein owning guy on site looked down his nose at it a bit).

 

[vivienz]

All the ones in my house were cut with a multitool.

[ultramods]

16 minutes ago, JSHarris said:

I did mine with a multitool, as it will cut flush to a surface.  I only have the relatively cheap Bosch one, but it seems to be OK (even if a Fein owning guy on site looked down his nose at it a bit).

 

 

2 minutes ago, vivienz said:

All the ones in my house were cut with a multitool.

 

Thanks, multi tool does look like a better option is terms of getting a flush to the ceiling cut.

[scottishjohn]

21 minutes ago, ultramods said:

 

 

Thanks, multi tool does look like a better option is terms of getting a flush to the ceiling cut.

its very versatile tool --you need one anyway 

[dimpsy]

https://www.amazon.co.uk/Stanley-015252-FatMax-Reversible-10-inch/dp/B002KHJYBM/ref=sr_1_1?keywords=stanley+dovetail+saw&qid=1558022304&s=gateway&sr=8-1

 

I had one of these which did the job

[Russell griffiths]

Buy a cordless one, so much more manoeuvrable than with a cord. 

[Bitpipe]

9 hours ago, JSHarris said:

I did mine with a multitool, as it will cut flush to a surface.  I only have the relatively cheap Bosch one, but it seems to be OK (even if a Fein owning guy on site looked down his nose at it a bit).

 

 +1 for multitool.

TBH, as the cover fits over, doesn't matter if the cut is a touch rough.

 

Only suggestion (too late for you) is to cut before skimming  - I also did this after and would have had a smoother finish around them if I'd cut after boarding.

[ultramods]

@JSHarris, @Bitpipe can you recommend a cutting attachment please as there are so many to chose from?

[Bitpipe]

1 minute ago, ultramods said:

@JSHarris, @Bitpipe can you recommend a cutting attachment please as there are so many to chose from?

 

I borrowed my sparky's Makita with whatever cutting tool he had on think it was about 50mm wide. The plastic on those plenums is relatively soft and easy to cut, I just plunged the cutter in and out in a circle, took a minute or two for each one.

 

Again, doesn't matter if the cut is perfect as the ceiling fitting covers it up completely.

[Jeremy Harris]

As above, I think I just used the wood blade, like this:

 

BTW, I've found Saxton blades to be good value and better quality than the blades that came with my Bosch multitool.