Recently, I tried using my Trion jigsaw with the long S 145/4 FSG blade to cut various notches and trenches in some wooden posts. These posts are 100mm square (4" by 4") in cross-section, made of rough-sawn, treated pine (Pinus Radiata). They had been allowed to dry out over several years, but are not hard to cut across with almost any sort of blade.
The Trion blade made short work of any cuts across the grain, leaving a good straight, perpendicular cut. But I had great trouble using the saw to cut along the grain direction (in the direction of the axis of the post). It was reluctant to make any progress. When I tried pushing harder the blade heated and smoked, so I quickly gave up forcing the issue. I tried various amounts of pendulum action, but it made no obvious difference. Eventually I finished the cuts along the grain with a hand saw, though that was also hard work as I do not have a proper rip saw.
Looking at the cross-section of the S 145/4 FSG blade, it is obvious the teeth - with their alternating points - are designed primarily for crosscutting, not ripping. I suppose I need chisel-shaped teeth, designed for ripping. I had a quick look at Festool Jigsaw Blade Chart, but could not find a solution there (It seems that very few blades can handle 100mm cuts anyway.) I am quite happy to use Bosch blades, rather than Festool, if any are suitable for ripping thick timber.
Before buying the Trion I had made such trenching cuts in a more traditional way, using a circular saw or SCMS, making repeated, closely spaced crosscuts and clearing out the trench with a chisel. That works OK, but produces prodigious quantities of saw dust and takes a while to complete. I was hoping a powerful jigsaw with an appropriate long blade or blades could help me cut out the required rectangular shape more directly. But perhaps that is not so easy to do in practice?
I would welcome any advice on this matter.
Mark
The Trion blade made short work of any cuts across the grain, leaving a good straight, perpendicular cut. But I had great trouble using the saw to cut along the grain direction (in the direction of the axis of the post). It was reluctant to make any progress. When I tried pushing harder the blade heated and smoked, so I quickly gave up forcing the issue. I tried various amounts of pendulum action, but it made no obvious difference. Eventually I finished the cuts along the grain with a hand saw, though that was also hard work as I do not have a proper rip saw.
Looking at the cross-section of the S 145/4 FSG blade, it is obvious the teeth - with their alternating points - are designed primarily for crosscutting, not ripping. I suppose I need chisel-shaped teeth, designed for ripping. I had a quick look at Festool Jigsaw Blade Chart, but could not find a solution there (It seems that very few blades can handle 100mm cuts anyway.) I am quite happy to use Bosch blades, rather than Festool, if any are suitable for ripping thick timber.
Before buying the Trion I had made such trenching cuts in a more traditional way, using a circular saw or SCMS, making repeated, closely spaced crosscuts and clearing out the trench with a chisel. That works OK, but produces prodigious quantities of saw dust and takes a while to complete. I was hoping a powerful jigsaw with an appropriate long blade or blades could help me cut out the required rectangular shape more directly. But perhaps that is not so easy to do in practice?
I would welcome any advice on this matter.
Mark