Bending jigsaw blades

[Tricky Dicky]

To cut the Celotex floor insulation into joist gap panels, I bought some of these jigsaw blades which should be good for up to 100mm.

Now the jigsaw is not one of my favourite tools so I have never owned an expensive one due to the little use I make of it. What I am finding is go slightly off line and the blade bends out and it is almost impossible to get a perpendicular cut over 1.2m in 75mm Celotex. Some of the reviews mentioned this and I was wondering if the problem is down to the blade having no set therefore not cutting a proper kerf or is it down to the jigsaw?

Richard

[newshound]

Once you put any sideways force on a jigsaw blade it will bend and you won't get a square cut any more.

Cut by hand using a panel saw?

[alan_m]

Isn't this the type of job for a big handsaw?

[JohnP]

newshound [e-mail]> wrote in news: [e-mail]:

A power tool is not the answer to every task.

[David]

Chainsaw?

Our builder got fed up with constantly cutting Celotex one day and just blasted through the sheets with a chain saw.

Quick and effective but it did look as thopugh it had been snowing.

Cheers

Dave R

[Robert]

+1 When I did the loft with 75mm insulation I just used a fine bladed panel saw - easy cutting and not a lot of dust, despite all the "specialist "advice about using special saws or jigsaw blades.

[Dave Liquorice]

bought

+1

+1

Or score and snap. Works at 25 mm not tried 75 mm that might be to thick or require to much force over a too long a distance.

[jkn]

I used an old bread knife - works well.

The best are those with actual serrations, and a mix of serration pitches: f f f f m f f f f m f f f f m f f f f m f f f f m f f f f m f f f f m f f f f m IYSWIM

The more modern wavy edge ones are less good for this.

[PeterC]

I've found that a Stanley floorboard saw is good for fine-ish work. My backsaw was to limited for the cuts and the Stanley is finer and thin but not much kerf.

[Brian Gaff (Sofa]

Hmm, I used to love my jigsaw attachment for my drill. As long as the guide was well pressed to the surface you could cut some lovely shapes with it I found. But oh the dust!

Brian

[williamwright]

Try steering the jigsaw by rotating it slightly in the vertical axis and always only applying force in the exact direction the blade is aligned to. Don't apply any sideways force, which you might be doing instinctively.

Bill

[tabbypurr]

Or do yourself a bigger favour & don't use a jigsaw.

NT

[RJH]

+1 - I've just cut up a load of 50mm celotex for some between joists flooring, takes seconds to do an accurate cut. I've found the best way is not to cut all the way through - do it to about 90% then 'snap' the board and break the uncut foil with the knife. Bit like cutting plasterboard.

[Adrian Caspersz]

[Adrian Caspersz]

This look quick, and less mess.

tape - Perfect Insulation with PIR Board

[RJH]

Looks expensive and convoluted - I just use expanding foam if the fit isn't perfect (which it rarely is in an old property), finishing with aluminium tape. And cut with kitchen knife, as above.

Mind, I can see how all of that kit might be justified if doing it for a living.

[alan_m]

Its another of those demonstration videos on youtube where it is made to look easy because everything is square and uniform.

[Andrew]

I have used those bosch blades for cutting 70mm quinntherm and they worked fine for me.

Another method is to turn the back edge of a hacksaw blade into a sharp knife and make a handle for it. By pulling through the 'celotex' at 45 degrees an accurate cut is easy.

For 50mm celotex a stanley knife with a longer blade is perfect for a clean cut.

[Reentrant]

If you watch earlier Robin Clevett videos on this build you'll see why everything is square and uniform.

[RJH]

He just seems to have a perfect eye for level, square, and everything in between. I like this one:

Sickening :-)