I attempted to test-cut a straight line using my new electric jigsaw. Therefore, I clamped a piece of scrap wood and used another piece as guide, marked the cut lines using a pencil and fitted the jigsaw with the blade and cut.
But my cut is like this:
As you can see, my cut is not straight and has some kind of stair-like pattern, so do you think that this blade used to cut is at fault?
Would you recommend this blade for cutting straight lines?
Best Answer
Jig saws are designed for cutting curves.
You can cut straight lines and generally you followed the correct procedure - using a straight edge. Your picture of the cut is pretty blurry, so it's hard to tell for sure, but there are several possibilities:
The piece of wood you used as a straight edge isn't as straight as you thought. Usually one uses a metal or plastic straight edge - one that is manufactured to be straight. Either a ruler, a level, or a specifically designed cutting straight edge.
You didn't follow the straight edge as carefully as you thought you did.
It does appear that your blade has a lower tooth-per-inch count. I'd guess it's between 6 and 9 teeth per inch.
Once you get some practice with the saw, you will get to be pretty good a following your pencil line free-hand (without a straight edge), but it's not likely that you'll ever generate dead-straight lines with a jig saw (especially not free-hand). It's just the wrong tool for the job.
Some additional thoughts:
Jig saws are used for curved cuts, but also for notching or stopped cuts where you need to cut into a board, but not all the way through from one edge to the other. You use it to cut straight in from the outside edge of the wood, straight to the corner, then you nibble away at the turn until you've got enough clearance to make a 90° (or whatever is called for) turn, then make the next straight cut. Continue this for as many interior corners as you need.
None of this is to say that you
Since you've already purchased the jig saw (and may not be able to return it for refund), go ahead and use it. Make some practice cuts to get the hang of how to use it and accept that your cuts will likely never be perfectly straight. If you do need a really neat final cut, adjust your cut to give yourself a smidge (1mm or so) of room to manually clean up the cut using a different technique as noted in Joe's excellent answer.
Finally, it looks like your "option" blade is labeled "extra clean cut". That will help make a nicer cut, but what you really want is a wider blade - one that has more distance between the points of the teeth and the smooth non-cutting side of the blade. This width is what will help the blade track straighter, though it still isn't the magic bullet for straights cuts.
Another, additional thought
Some jig saws have an "orbit" function that causes the blade to move forward and back as well as up and down. The greater the amount of orbit, the faster but rougher the cut will be. This used to be a high-end feature, but seems to have made its way into the mid-range and even some low-end models. Usually, the amount of orbit is adjustable from "lots" to "none". Make sure the orbit function is turned off for a smoother cut