How straight is straight and what to do if it's not?

[Mark Godlesky]

I bought a couple of handsaws off of ebay with the intention of cleaning them and and teaching myself to sharpen. Obviously one can not examine a saw closely online. Anyway these saws typically have a bow or wave for about the third of the blade near the toe. When sighting down the teeth it looks like the largest displacement is maybe 1/4 inch. They are not kinked, just a gradual curve. WIll this affect the cut? It seems like it would cause you to drift off of your cut line. If so how do you straighten a saw plate?

Thanks.

[Jonathan McCullough]

That's fairly common. I think they get leaned up against a garage or basement wall, and after daily cooling/heating cycles for 50 + years the metal takes on the bowed shape. After cleaning with mineral spirits and sandpaper, I coat my saws thoroughly with paraffin wax and heat them slowly and carefully about fifteen inches above a range flame. Just as the smeared-on wax melts, I rub them down with a cloth and bend them in the opposite direction of the bend as they cool down, sighting down the tooth line and the top. It's okay to get aggressive and bend them almost all the way around--it's essentially high carbon spring steel anyway. They're just barely hot to the touch, like a cup of hot tea, so you only get about twenty or thirty seconds. This always corrects the problem for me. Since you're in AZ, you may be able to get away with putting it in the back of a closed car window in the sun. That's hot enough to melt wax, make a saw uncomfortably hot, but not too hot to ruin the temper of your saw.

Of course if it's a kink, that's different.

[Roy Lindberry]

I bought a couple of handsaws off of ebay with the intention of cleaning them and and teaching myself to sharpen. Obviously one can not examine a saw closely online. Anyway these saws typically have a bow or wave for about the third of the blade near the toe. When sighting down the teeth it looks like the largest displacement is maybe 1/4 inch. They are not kinked, just a gradual curve. WIll this affect the cut? It seems like it would cause you to drift off of your cut line. If so how do you straighten a saw plate?

Thanks.

Some of my saws, I was able to cold bend them in place. Others that were too stubborn, I used boiling water from a tea kettle and that worked great. Also, a stick of wood with a kerf in one end allows you to pry without having your hands on a hot plate.

[george wilson]

I have advised to pour boiling water over the blade and quickly bend it till it is straight. We used to buy our spring steel in coils,and when cold,it was impossible to get the steel to stay straight. Boiling water did the trick,and is several hundred degrees below the tempering temperature,so no harm is done to the steel.

[Andrae Covington]

Try the cold bend first, and if that doesn't work, then one of the hot bending methods. I used George's method to reduce a bow that put the tip about 1/4" out of line. I went through a second round sometime after taking these photos to further improve the kink.

sawbefore.jpgsawafter.jpg

[Mark Godlesky]

Thanks for the input, gentlemen. I'll see how much straighter I can get these saws.