my celotex cutting 'invention'!

..Annoying really,as i came up with this today when I'm nearly done with insulating my barn conversion roof(between and under rafters),but it works brilliantly for me.

I got an extra long jigsaw blade ( that was rubbish for cutting thick timber,wandered all over the place)

Took it to my bench grinder, ground all the teeth off,and created a bevel on both sides so it was sharp like a knife..and gave it a try....

Bloddy brilliant!!...very clean smooth quick cuts..and best of all,no dust!! Yes,the blade wandered a bit,not totally square,but if you take it easy,it's not bad at all,especially as i like to cut my pieces a bit small and foam the gaps after fitting, so a totally square cut isn't needed. ...then i fixed a bit of thin-ish ply to the base plate of the jigsaw,about 200x200,and i got a much more square cut, as I'm using 'seconds' boards that have an irregular surface,here and there. The blade will cut up to 150mm,my boards are 75's,looking foreward to trying it on 100mm boards when i insulate the floor...

Now I'm waiting for some clever sod tell me there's a much better way to do it....but is there another 'dust free',way??