ultramods

Best way to cut Plenums and metal ducting

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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?

 

 

Plenums.thumb.jpg.bfd137033cf2e17d0ff75b37f124d88e.jpg

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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?

 

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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.

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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 

 

plenum.PNG.85b50968216ecdf0ae5de4da4ed4eed6.PNG

 

1582404263_airvalve.PNG.f5718f2876a34a3ec28e5daf3cf92360.PNG

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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

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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).

 

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

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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.

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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 

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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.

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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.

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

image.png.e4ef52689e8f9f54603f1e4fb267e869.png

 

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

 

 

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