New Saw - Rehab Question

[Patrick Tipton]

Greetings Gentlemen:

I purchased this brass backed backsaw from an online auction site for a pretty reasonable price. I love the looks. The handle is nice with a few small love nicks. The blade is lightly rusted and should clean up well. I was surprise, though, to find a kink in the blade - of course the seller didn't disclose it. The blade is not creased, but does have a cup near the teeth. The cup itself feels "un-tensioned", ie very little stiffness as opposed to the rest of the blade. The brass back is close to straight with just a slight bow in the middle. From reading the various rehab posts on the site, I am hoping I can pull it straight, but I am wondering about the cupped area? These pictures aren't great, but hopefully give you a bit of an idea.

Suggestions most appreciated.

181341181342181343http://www.sawmillcreek.org/images/misc/pencil.png

[David Weaver]

First thing I would try on that saw is to lift the front of the spine an eighth or so and see if it makes a difference. There may be no tension on the blade because the toe of the back is pushed down on it.

If that doesn't work, check the back with a straight edge on both sides (it's not going to be perfectly flat, but hopefully it will be straight) and where the plate meets the back. If it is straight, it might be worth replating it. All you need to do to do that is get calipers and measure the thickness on the plate in a couple of places, take the handle off of it and pull the back free - that'll give you an idea what you'd need for a plate.

Last i checked, a plate with the teeth punched was in the $20 range from mike wenzloff, and if you don't want to sharpen and set the teeth, only a little more for them to do it.

That's really an attractive little saw, nice split nuts, nifty medallion, brass back and a tote that is clearly hand done with good crisp lines for a beech tote that old. The english saws really put the american saws (post-disston's initial hand done totes) to shame for design and character.

Who is the maker, btw? I have two old saws, a whittles and a nurse, and neither one of them is perfectly straight, though they are certainly straight enough to use now. That'll be a dovetail saw, right? As long as it's close to straight when you're done, it will work very well.

[george wilson]

I just jerk the blade straight. Re read my recent post on straightening a backsaw.

[David Weaver]

George, is the jerk you're talking about twisting the spine like you said before (which has helped me three times now), or is it something else? How recent was the post?

[george wilson]

Gad!!! I've repeated this several times. Torture,torture!!!:) You clamp the front edge of the saw BLADE in a vise horizontally,and tap the front edge of the BACK. This pulls the blade back straight. If it has a mild curve,clamp the saw upside down by the back at one end. Adjust a Crescent wrench(or make a wooden wrench like I do,to not mar a NEW back). Hold the wrench vertically,and gently twist the back in a sideways direction to straighten the cutting edge. This will make the edge straight without bending curves into the back,which looks bad.

Sorry,my left eye is driving me nuts. Feels like it has sand in it from surgery. Writing is an effort.

[David Weaver]

Yeah, I had the first trick before, and I soaked the second one off of you. I was wondering if there was a new one. Straightening saws is not my favorite thing to do - it would be more tolerable if my eyesight was worse. Just looking for more tricks.

[Paul Incognito]

I just got a saw in the same condition as Patrick's. Straight back but has a spot in the blade that appears to have no tension.
I tried both the tap and the twist techniques and neither worked. I think it's time for a new plate.
I'm curious to see how these tricks work for you, Patrick.
Paul

[Patrick Tipton]

Thanks for the comments. I am heading to the shop in a few minutes and will try to jerk it straight. The saw is a marked "A Rosling, Sheffield" and "Cast Steel". The blade is 12 inches and filed crosscut.

I will let you know how I make out later today.

Regards, Patrick

[george wilson]

Paul,I suggest you keep trying to straighten the blade. All is technique.

[Paul Incognito]

Thanks for the vote of confidence, George. I've tried just like you describe and no luck.
How hard do I have to hit the back? I'm a bit leery of slaming it too hard. I've hit it pretty hard with a wooden malett but don't want to go full force for fear of doing more damage.
The blade on my Groves is like Patrick describes his, a spot at the teeth that appears to have no tension.
Thanks,
Paul
PS, sorry Patric, I don't mean to hijack your thread.

[george wilson]

It could be that the DIRECTION of your blows is not correct. Are you striking the back in a downwards direction,straight in line with the back,or what? I need to know more about where your lack of tension is,exactly. I'm pretty sure it can be corrected,but haven't seen it,of course.

[Paul Incognito]

George,
Thanks for the help. The lack of tension is at the teeth, in the middle of the blade. I can take the teeth and just push them from side to side.
In trying to jerk the blade straight, I'm hitting the front tip of the back straight in line with the back, towards the handle.
If it makes a difference, it's a 10" Groves.
Paul

[Patrick Tipton]

Paul - no problem, we are all trying to learn here;)

So I tried to retension the blade by striking it straight back from the front. I didn't hit it hard, but I did hit pretty solidly with a dead blow hammer (several times) and it didn't fix my problem. Looking at the back, I can't see any evidence that the blade has moved any direction or is otherwise loose from the back.

With no success tapping the back, I took the saw to my anvil with great trepidation. I have done a little body work and know that pounding metal isn't easy. Per the instructions in the FAQ's above, I did a little tapping with a light ball peen hammer. The good news is that the blade is now tensioned. The bad news is that it is less straight then when I started. It now has an "s" in the blade. I wish I lived closer to one of you experts, 'cause I would plead, watch and learn. Given that I am too far away for that, I am going to head back to the shop in the morning and peen a bit more. Worse case, I will reuse the back and insert a new blade and learn to file teeth from scratch.

Before I started hammering, in looking at the blade, it really did look like one side was stretched and that it would be really hard to shrink enough material to get the saw straight. If it wasn't a saw, I would have grabbed my torch and shrunk the metal using heat. This bend is probably sufficiently complex to fix that it is beyond my current skill level, but I am going to give it hell anyway.

Pictures will follow tomorrow.

Thanks for all the suggestions.

[Paul Incognito]

Patrick,
I figured the same as you...if I can't get it right, the worst case is getting a new saw plate from Wentzlof.
I'm going to keep trying though, I certainly can't make it any worse.
BTW, George, I did have success straighteing hand saws using your method. Worked like a charm.
Paul

[george wilson]

Paul,it sounds like you might need to carefully clamp the saw in a wooden jawed vise teeth down,in a corner of the vise,and gently tap the back upwards a bit,just above where the slack part of the blade is, and by degrees,carefully checking the tension at the toothed edge as you go. Hold the saw at 45 degrees,and just clamp the slack part of the blade in the vise. You will in effect,be pulling the center part of the blade down from the back. You'll have to tap under the edge of the back with something like a small brass hammer.

The process is all about being careful and checking as you go.

If you get the blade tight again,better run a little medium Loctite along the edges of the back,so the blade can't slip loose again. I really don't think you need to throw the blade out. A new blade could do the same thing if it isn't held properly by the back.

[Paul Incognito]

I finally got a chance to do some work on my saw. I either got it fixed or screwed things up beyond repair...you be the judge.
First I took the handle off. With a clear view, I could see that the blade wasn't seated fully in the back at the handle end. So I clamped it in a vice and used George's instructions, except that I hit the back end of the back. That drove the back down tight onto the blade and straightened the plate out pretty good, eliminating the spot that seemed to have no tension. Then I clamped the bottom of the back in the vice to try and close that up a bit tighter to hold everything in place.
It seems to be have worked. The only caveat is that the screw holes no longer line up with the handle when it's seated properly on the blade/back. Drill new holes in the plate?
Also, the split screws are pretty buggered up, anyone out there think it would destroy any of the saw's "vintage appeal" if I replaced them?
I'm pretty happy to have gotten this straightened out. A big thanks to George for his willingness to share his experience.

Paul

[george wilson]

I guess you'll hae to drill new holes. Use a small masonry drill,and run it very fast. About 2000 RPM. I'd run some loctite down the blade so it can't slip loose again. Can you put the handle back in place,and run the drill through the holes?

Another good way to make holes is to punch them of you have a Butcher's punch. If not,a flat nose punch right over a hole of the same size is how a blacksmith would punch them. Chance you could crack the blade if you don't do it right,though. Don't use a tapered punch. Masonry drill works fine. The carbide tip burns the temper right out of the blade,and goes on through. You can drill holes in a file with one. You need to be careful to not let the drill get too hot,though,or the tip will melt the brazing loose. No trouble to drill a thin saw blade,though. The handle is difficult to get back off if you drill the holes in place,though. The burr really hangs on.

[Paul Incognito]

George,
Thanks for the help.
Yes, I was planning on drilling through the handle so that the holes will line up. I'll use a carbide tip masonry bit as you suggest.
Then I'll sharpen her up and see how she cuts!
Paul

[Patrick Tipton]

I had a similar experience. First, when I received the saw, I noticed that the handle was loose on the blade. The split nuts weren't really tight, but they were tight enough that they should have been holding the blade. I then took the handle off the saw and the back off the saw plate.

From the marks on the saw plate, it looks like the back slipped off the rear portion of the saw plate many years ago. I went ahead and ordered a new saw plate because, while I think putting the back on correctly would likely fix the un-tensioned portion of the plate, there are a few rust pits near enough the teeth that I would like start fresh. I have never had the pleasure of filing, setting and sharpening teeth from scratch so this is a great opportunity to learn. Pictures to follow.

Regards, Patrick

[Paul Incognito]

Cool Patrick,
I'm interested in hearing how you make out with that.
I'll post some pics of my saw after I'm done.
Paul