I have a handsaw that refuses to cut in a straight line. If I mark a vertical line on a piece of timber and try to cut along it, the cut diverges from the line and curves to the left. No amount of sideways force will make the cut follow the line. If I attempt to compensate by angling the blade slightly to the right at entry, it still curves to the left.
There is nothing obviously wrong with the saw. If I lay the blade flat on a flat surface, it doesn’t seem to be visibly warped in any way.
Can a saw be faulty in this way? If so, what exactly is going on? Or is it something I am doing wrong?
Yep, it’s possible.
That’s also possible.
The teeth on a hand saw aren’t perfectly straight. Instead they are slightly set to the side. They also alternate, meaning that if the first is set to the left, the next is set to the right, the third is set to the left, the fourth to the right, etc. This allows the saw to cut a slightly wider channel than the width of the body of the saw blade, which prevents the blade from binding as you cut deeper.
If the set isn’t balanced due to damage to one side of the blade or bad sharpening or whatever, then the blade is going to want to drift sideways a bit as it cuts.
If you have another hand saw to try, that will tell you if it is your technique that is throwing it off to the side or if it’s a damaged blade that is throwing it off.
How flexible is the blade? Larger handsaws often require a particular technique to get a straight cut that has to be learned for each saw. When I want a really straight hand cut, I generally use a pull saw because the push motion tends to case anything larger than a tenon saw will tend to flex on the push.
Stranger
It’s quite flexible. It’s this style of saw (maybe not this exact design):
811861_1.600x600.jpg (600×600) (comtecdirect.co.uk)
Yeah, try reducing the force on the forward stroke and see if that helps. It’ll probably seem like you’re generating less force on the rear stroke because you can’t bear down as well but the blade isn’t going to want to walk around on you.
Stranger
Are you sure it’s not a left-handed saw? (Intended as a joke, but the more I think about it…)
I’m a fan of pull saws, I’ve been using the same one for probably 10 years. I’m no carpenter but I do a few projects now and then requiring finer precision than what cheap power saws can do, and the pull saw is more intuitive than a regular saw to me. I feel like pulling any kind of object towards you, when there’s contact with some kind of work surface, allows greater control than pushing it away from you. I think this even applies to pens and pencils.
I have one knife that my ex, who was left-handed, favoured (everyone has a favourite kitchen knife, right?), and now when I use it it pulls the wrong way for me (right handed). (We did not bother sharpening our knives). Other knives are fine.
Could be the same thing’s happened to your saw, or maybe it was machine ever so slightly wrongly, and that tiny bias has meant it’s leaned ever further to the left over time.
If you can sharpen it or have it sharpened, that might eliminate the problem.
While the saw could be an issue, don’t discount the possibility your arm movement isn’t as smooth and linear as you might think it is. If you were a world class pool player you might get the sort of ergonomic analysis that would show that at a certain flex point one muscle over-exerts and pulls just that little bit too much, but you could well be doing that without even realising it.
Having used pull saws as @Lamoral says above, you rely less on variable muscle effort and can focus more on maintaining a straight line with a softer draw.
Carpenter tips: With proper grip, your index finger should point out along the handle, not be curled around the grip. The saw should be angled at about 45 degrees not 90, so that you can keep it aligned. You can also try the old trick of scribing the line with a knife to give the saw something to follow. Light pressure, let the saw teeth do the work. If you are ripping rather crosscutting, the grain can affect the saws path.
But its probably the saw. I would say just try with another saw, but I have lots of saws.
As a carpenter, if I want a straight cut I use a saw guide. Not so practical with a hand saw, but just to say that entropy is stronger than ego.
The saw is cutting more on the left. It follows its own path. It could be that the tooth set is off. But more likely it is duller on the right side. One old trick carpenters used when they did not have time to sharpen and set a blade is to gently file the sides of the teeth to the left. We even do this on powered bandsaws to make them cut straight. Lay the blade on a flat surface with the left teeth facing up. Place a fine file flat on the teeth. Gently stroke from handle towards the tip. Try it out and see.
