Slightly bent back saw - fixable?

[David Weaver]

Well, I purchased my first back saw off of ebay, an old disston with a 12 inch blade with 14 teeth per inch. The seller said straight, and it's close, but it's not straight. At the nose of the saw, there is a bow that is probably a total of a millimeter out left to right - starting about 4 or 5 inches from the nose and continuing all the way out. It's noticeable when the saw is in the kerf - it binds.

Can I use the same basic method as in Bob Smalser's tutorial (striking the saw above the gullets to increase tension on one side and remove it on the other? It isn't a kink in the middle, it goes all the way to the end, so I can't apply that directly, and I'm wondering if it won't work if the metal doesn't have other metal on all sides to "grab" and pull against when I strike it. I can take a picture tonight if needed.

I can see the virtue of buying new saws, though this is the first old saw I've gotten (I've gotten 5 others) that I've had a problem with, but it's also the first back saw.

The teeth weren't properly jointed at each filing, either, but it's not a basket case.

[Zahid Naqvi]

Did you say it was a back saw? in that case it will probably be a little different. It is possible that the curve or bend is only in the "back" and the blade itself is fine, or the other way round.
I am not very knowledgeable about saws, perhaps Mike or Bob can chime in with their opinion. Pictures will certainly help.

[David Weaver]

I'll check tonight. From a brief look last night, the back seemed straight and the blade bent, but it may be a case of the back being bent just a little and the blade bent a lot more.

[Mike K Wenzloff]

David,

In all likelihood, either the back is slightly bowed *or* the back has been pushed down on the saw plate out at the toe.

If the back comes down at the toe, it forces the toothline to be pushed back a bit. But as the top edge of the saw plate is inside the back, it moves less and hence the toothline gets an arc in it.

If the back is straight--any decent ruler will tell you by placing it on one side or both--then all that needs to happen is the back needs pushed up at the toe a bit. How much depends on the arc.

I place a saw in a vise using long enough boards to fully support the saw plate except the end of the saw needs to stick out a coulpe inches. I use a 1" x 1" piece of hardwood I have sawn a kerf into that is long enough it can slip up from the toothline to the bottom edge of the back. Squeeze it snugly against the saw plate and gently tap the end of the wood. This will force the back up.

Use just enough of a hit to slowly move the back up--if it comes off it is a pita to get back on correctly without handle removal. After a tap or two that you see movement on, remove the saw and check the toothline.

Take care, Mike

[David Weaver]

You can see that there is a very slight curve at the front end of the blade. It doesn't exist in the spine (I checked with a starrett straight edge), just in the blade.

Mike, I'm not sure I fully understand your suggestion, but I do think that the back is on snugly and at a uniform height across the length of the blade.

Any ideas guys? Should I screw around with it or just get another saw?

I know the picture doesn't look like much, but it binds in the kerf. I have a feeling I got this saw because the seller didn't want it and thought he'd like to pass it on to some unsuspecting individual while stating that it's straight.

[Leif Hanson]

As Mike suggested, just try to re-position the blade within the back. Sometimes, the way the blade is sitting in the back distorts the blade ever so slightly... If that doesn't fix it, then go on to other things.

As far as it binding - that's possibly not as a result of the bend, but of not having quite enough set in the teeth...