Saw Wave & Kinks

[Eric Gracka]

Hello All:

I have a new Spear & Jackson brass back tenon saw (Model B23-9550B, 305 mm/12", 15 ppi). It seems to X-cut & rip fine. But when cutting at an angle (e.g. regular & rising dovetails), I have major problems - it won't follow my scribed line without binding, or trying to find a new line (which, I think is the grain). So finally, I sighted down the blade, only to discover a wave, about 2/3 of the way from the heel, towards the toe. I removed the handle, put it on a flat bench top (completely cleaned), and tried to bang out the wave with a hammer with a hard rubber end. Of course this did nothing. Then I tried banging it out starting at the heel and moving towards the toe. This put another two waves in the saw. So I hit the saw at the main wave, and the other two waves disappeared, leaving the original wave.

I am afraid of putting the saw in a machinist's vise and trying to straighten it for fear of creating a kink. If I take the saw and bend the blade by hand, it is as straight as an arrow. But, when I release it, it reverts to its former way (i.e. a bow 2/3 of the way down).

Incidently, research shows that it was made in China.

By the way, and I know this comment doesn't apply to my immediate problem, my Disson D8 26" rip saw - no skew (don't know how old it is because the etching is gone, but has the wheat engraving on the handle), is as straight as an arrow.

I can't afford another tenon saw - perhaps a quality panel saw, or Gent's saw might be in order.

Any suggestions please.

Thanks for your considerations for a new woodworker.

[Joe Bailey]

everything you need to know

http://www.badaxetoolworks.com/retension-a-backsaw.html

[Daniel Sutton]

I have used the following link to fix my saws.http://www.wkfinetools.com/contrib/bSmalser/strSawBlade/strSawBlade1.asp

I recommend that you do not use a small ball pein hammer, but a hammer with a larger radius. Also, your anvil surface must be smooth in the area you're hammering or you will get dents. You dont need a london pattern anvil for this exercise, just a hard surface to hammer against.

[Bill White]

A "new" Spear and Jackson?
Check the set of the tooth configuration.
Are you letting the saw do the work, or are ya trying to force the cut?

[george wilson]

I have explained how to eliminate waves from back saws before. I hope you did not hurt the blade by banging on it with a rubber mallet. What you need to do is grip the very front end of the blade in a vise,and tap the front end of the BACK of the saw backwards. This will jerk the blade forward a little in the back,and pull it straight. If you fear the blade slipping again,run a little bead of Loctite down the juncture of the blade and the back. If you don't get the blade jerked straight at first,experiment by gripping the front edge of the blade high or low in the edge of the vise. Personally,I use a smooth jawed machinist's vise,but most are knurled jawed. You can use copper inserts to keep from damaging your saw blade.

If there is still a gentle curve in the blade,DO NOT try bending the back to straighten the curve. What you must do is take a crescent wrench and adjust it to fit the back. Then,torque the back at 90º to the axis of the back. This gentle twist will straighten the cutting edge,and you will not have a curved back to show for it. You may have to grip the front end of the BACK in the vise to stabilize it so you can use the wrench.

Banging on the saw blade can stretch the metal, and then you are in BIG trouble.

I have bought back saws cheap because the seller thought they were ruined by being wavy.

We had to do this to dozens of back saws when we made them in the tool maker's shop.

[Eric Gracka]

A "new" Spear and Jackson?
Check the set of the tooth configuration.
Are you letting the saw do the work, or are ya trying to force the cut?

The S&P manufacture date is stated as December 12, 2002. Although it doesn't say so, I believe (after research), it is made in China. It doesn't even say what kind of sheet metal it is made of. I don't know how to check or set the teeth (other than hammering them flat, passing a file over them, and buying a L&V setting tool).

I am always gentle with my cuts. I scribe a mark on the intended cut and do a couple of gentle draws. Then I start at the front of the wood at a 45 degree angle and draw backwards until I feel a positive cut.

[Eric Gracka]

everything you need to know

http://www.badaxetoolworks.com/retension-a-backsaw.html


I've just read it, and bookmarked it in my computer!

Thank you.

[Eric Gracka]

I have used the following link to fix my saws.http://www.wkfinetools.com/contrib/bSmalser/strSawBlade/strSawBlade1.asp

I recommend that you do not use a small ball pein hammer, but a hammer with a larger radius. Also, your anvil surface must be smooth in the area you're hammering or you will get dents. You dont need a london pattern anvil for this exercise, just a hard surface to hammer against.

I love the link - the procedure seems simple if it works. Being a "newer saw", this procedure seems to be the recipe.

Thank you so much.

[Jim Matthews]

and tap the front end of the BACK of the saw backwards.

I'm not following this.
Could you elaborate?

[george wilson]

Nobody seems to get my procedure!! The front edge of the saw BLADE is clamped in a vise. The back of the saw is not clamped in the vise. It is above the vise jaws. By tapping on the nose of the saw back in the direction of the saw handle,the blade is stretched forward,pulling it straight in the back.

The reason a saw gets a wave in the blade is usually because the saw's blade has slipped back towards the handle a little bit. Since the rear end of the blade cannot slide back(it is screwed to the handle),the blade gets a wave in it. You are jerking the blade FORWARD,pulling it tight again.

[george wilson]

DO NOT GO HAMMERING ON YOUR BACK SAW BLADE!!! That site mentioned above is NOT for BACK SAWS.

Re: The Bad Axe site: I'm sure this method also works,but I must say I prefer my way. I don't have to be concerned that the blade is crammed all the way into the back. We treated MANY saws with my method,and it was quick and easy to do.

[Daniel Sutton]

George, I'll use your method the next time I'm working on a back saw.

[Marko Milisavljevic]

I think you would want to clamp only a small part of the nose - first 2-3 inches perhaps, so allow the rest to expand back into place.

[george wilson]

Yes,just clamp the NOSE of the saw's blade in the vise. About ONE INCH of it. That way,you leave the rest of the blade free to be pulled forward when you tap the front end of the back towards the direction of the handle.

This is not complicated. I have done my best to describe it,though I don't seem to be getting it across.

Your picture is correct,except for just clamping the very front end of the blade,Joe!!:)

[Joe Bailey]

I have deleted my earlier post and now offer this revised rendering (oriented for maximum clarity)

286902

[george wilson]

That is correct,Joe. Except the saw should be horizontal for ease of striking the end of the back. Thank you for posting that. I don't know how!!

[Kees Heiden]

George's method is one method. Sometimes it helps, sometimes it adds news kinks. You can also reposition the back up or down, and you can do this at the nose of near the handle. It is a bit of trial and error until you get it where you want it. Repositioning down is easy with some mallet taps on the back, near the nose or near the handle. Repositioning it higher is a bit more difficult. Clamp the blade in the vice at the point where you want to reposition, and use a stick of wood plus the mallet to move the spine, away from the toothline. Don't be shy, just give it a try, you can only make it better.

This is my (limited!) experience.

[george wilson]

I did mention selectively repositioning the blade in post #5. Everything usually takes some degree of judgement. I did straighten several dozen saws with my method when we were making batches of saws as toolmakers. Every one went to work straight.

Some discretion needs to be exercised depending upon the wave. This applies to any method used. Just don't do anything to cause the blade to become stretched or deformed in any way(like by hammering). Hammering is for non backed saws.

[Bill White]

Thanks. I had no idea that they were being made in China. Go figure.
Hope ya get it worked out.
Bill

[Jim Matthews]

Gotcha.

The idea is the spine is drawn away from the fixed point in the vise,
applying tension to the part that is held, is that correct?