Can't cut straight

[23tony]

I regularly have all sorts of problems cutting with a jigsaw. Recently, I was cutting some notches in some sheet lumber that I wanted to cut square, and even in the (only) 1-1/2" from the edge, I ended up with a big curve and not at all straight cut.

It seems like the blade bends as I'm cutting so it never actually goes where I'm trying to go. To get it slightly straighter I end up turning the tool 20-30 degrees off the cut line to compensate.

I have the same problem when cutting curves, but if I stay WELL clear of the line it's easier to compensate for.

I've tried varying my cutting speed (faster, slower, MUCH slower) but that didn't help. What am I doing wrong?

 

[Tim Sherwood]

Tony I used to have this problem too. Turned out that when I was leaning a little to watch the line, I was putting sideways pressure on the saw. That causes the blade to bend in the cut and wander away. Does this problem happen when you're using an edge guide? That kind of problem can sometimes happen with a dull or bent blade.

 

[bob vaughan]

The teeth on one side of the blade are sharper than the other or are have a more pronounced set. That happens some times.

 

[Mike Davis]

The teeth on one side of the blade are sharper than the other or are have a more pronounced set. That happens some times.

Turned out that when I was leaning a little to watch the line, I was putting sideways pressure on the saw. That causes the blade to bend in the cut and wander away.

Both of these have happened to me.

 

[Henry W]

Both of these have happened to me.

...sometimes simultaneously...

But seriously - can you tell us what jigsaw you are using.?
I had 2 or 3 cheap-o B&D saws, then maybe a Craftsman that was a minor step up, before I bought a used (old!) Bosch. Only THEN did I understand that a jigsaw could be used to cut contrallably. The newer model saws with a support bearing right behind the blade are a huge improvement in cutting accuracy. But side pressure and misaligned views still can cause issues.

 

[Oka]

I have run into this more than once, I'll add to both Tim and Bob's statement, besides their points you can not muscle a jig saw cut like you can a drill bit or circ-saw cut. As a friend showed me the most pressure to exert is to push down and keep the saw table positively engaged without wobble. Then as you guide the saw through you have to let the saw motor do the work of cutting.

 

[FredP]

I have run into this more than once, I'll add to both Tim and Bob's statement, besides their points you can not muscle a jig saw cut like you can a drill bit or circ-saw cut. As a friend showed me the most pressure to exert is to push down and keep the saw table positively engaged without wobble. Then as you guide the saw through you have to let the saw motor do the work of cutting.

+1000! As with any tool you have to let the tool do the cutting. Same with Sanders. Bearing down on the sander does not make it work faster. It causes other issues when you force the tool.

 

[JimD]

One of the few tools my father gave me was a jig saw. I think it might have been a black and decker. It worked terribly. Would hardly cut anything. Then I got a Bosch I still have. HUGE change. I could cut a 4x4 post with a jig saw! I still have and regularly use this saw to cut wood and metal. If I cut in a straight line with it I have to angle it a few degrees or it will not follow the cut line. I volunteer at my church where they also have a Bosch jig saw. It cuts about the same way. Slight angle required. But if you do that it will cut straight. On straight cuts, the blade stays vertical.

When cutting a curve, especially if it is tight for the blade I'm using, the blade will sometimes tilt. Using a smaller blade so I do not have to force it to follow the curve helps. But even a well supported blade can tilt. It is cantilevered from it's supports and it isn't a heavy piece of metal.

There are probably other good jigsaws but I am sticking with Bosch. They work and are reasonably priced. But a jigsaw is not the ideal tool to cut a straight line. It will do it with proper technique but whenever possible I use a track saw or circular saw. But a notch is a good case of needing to use a jigsaw, or if possible a bandsaw.

 

[23tony]

Thanks for the tips. Definitely try to let the tool do the work - but it also sounds like there might simply be some quality issues at play.

Not sure about the differences from one side to the other on the blade, it's happened with several blades - but worth looking into.

Had the problem with two: One was a Skil - frankly, I've come to expect not-so-great quality from them. The other is a cordless Porter Cable.

Despite the problems I have, it's still a useful tool, so maybe I'll look into something of better quality.

 

[Phil S]

Here is a trick that I learned from two different craftsman - one from Germany, the other from Romania. They both cut holding the saw under the piece and followed the cut line on the top watching the protruding blade. Takes some getting used to but the cuts are much better

 

[bob vaughan]

Jig saw. Saber saw. do those terms mean the same thing in this conversation?
The fact that a tool maker calls their corded tool a jig saw doesn't mean its the same thing as, say, a Swiss-made Bosch 1581 saber saw with a new Bosch-made blade installed.

Trimming with router jig would be more precise with only the inside corner to deal with.

Even the best saber saw with the best blade is only going to be so precise and never like a band saw as mentioned above.

 

[Oka]

Yes Both are the same. The names are used interchangeably. The jig saw was an evolution of the fixed scroll saw to a handheld version. The term "Sabre saw" mid 1900's was also used to describe a sawzall (reciprocating saw), but that moniker was lost in favor of the popular Sawzall. I think marketing drove the terms to their present meanings.... just a guess.

 

[23tony]

I've seen the "hold underneath" technique, maybe I should try that. Didn't think of a router, that definitely could have made things easier.