I saw a couple of Disston crosscut saws at a local antique mall.  My best guess
after consulting the Disstonian Institute web site is that one is a post-1940 D8
(medallion says “Disston USA”, 4 nuts, skew-back) and one is a post-1940 D7 (3
nuts, straight back).  My big question for the list is how much a bow in the
blade matters? Both saws have a distinct bow when you sight down the blade, one
about 1/8” and one more like 1/4”.  Not a sharp bend or kink, but a definite
bow.  The plates are darkened, but do not look heavily rusted or pitted. Any
other tips on what to look for when considering buying an old saw?

The “otherwise” are two back saws that I own that I’m not really sure where they
came from.  Either my grandfather or my father.  One has no medallion (or it is
missing, there is a hole with a missing nut, was the medallion ever used as a
saw nut?), the blade is etched with “CHAMPION”, “warranted high grade spring
steel”, “A tool of real merit”.  A quick googling does not reveal anything.

The other back saw has a medallion that says “Pennsylvania Saw Corp, York PA”.
Googling reveals that it was in business 1938-1979.

I think that both of the backsaws are 1970 or later.  Is it worth attempting to
sharpen them or should I keep an eye out for older saws?  What makes an older
saw better?  Is it that the steel is better quality so the teeth take  and hold
a better edge?  Something else?

thanks,
andrew

There are ways to straighten them and they have been written up on this forum.
I am even lucky enough to have come across a saw tensioning hammer (or a file
cutter’s hammer - much the same) but I still had no luck in the moderate amount
of time I spent trying to do it.

There are so many good, straight saws out there I don't think you should bother
with bent or kinked saws.  Look for saws that are not pitted near the teeth -
easy enough to clean surface rust.  Consider that shorter saws - 22” and 24” -
are really handy in the shop if you aren’t ripping or crosscutting big pieces.

Sharpening is no where near as hard as it looks at first.  You can get an
acceptable sharpening in 30-40 minutes your first try.  And it is not necessary
that all the teeth be identical, just close.  If a saw wanders, a quick stoning
down the length of the teeth on the more aggressive side will fix it.

Most saws were made by the big 3 despite their etches, so almost anything of a
vintage look will be good.  Get one with the number of ppi you would like as it
is a PIA to change it, but easy to follow what is there.

A comfortable handle is very important.  Gluing on a new horn and shaping with
rasps and files in not too demanding and a good thing to practice skills on.

This works unless you live someplace where there are no used tools - here in the
mid-Atlantic we have to be careful not to trip over them
 
Ed Minch

Andrew said “that both of the backsaws are 1970 or later.  Is it worth
attempting to sharpen them or should I keep an eye out for older saws?
What makes an older saw better?  Is it that the steel is better quality so
the teeth take  and hold a better edge?  “

Do you own a pair of calipers, or maybe a 0-1” micrometer?  Measure the
thickness of the steel at the heel and the toe just above the teeth along
the cutting edge, and also along the backside, furthest away from the
teeth.  The best quality saws were taper ground, so that the saw plate was
thickest at the heel along the tooth line, and gently tapering to thinner
steel at the tip and the back.  Modern makers use 1095 spring steel
(basically the same blue steel bands used to band lumber together at box
stores).  Older makers used to also “tension” the steel along the tooth
line by hammering the metal to cause internal stresses to cause it to want
to stay straight.
    Backsaws are different- the saw plate is of uniform thickness, and the
spine pinches the plate and tensions the cutting side (so you can gently
tap the back on the bench if the plate is a bit wavy along the tooth line
to retension it- of course it’s obvious this doesn’t work on newfangled
saws with milled slots with plates that are epoxied in place- this only
applies to rolled steel or rolled brass back saws that only pinch the
plate).  Smaller 6”dovetail backsaws had thinner plates maybe 15 thou, and
large tenon saws up to 40 or 50 thou or so.

To answer to your question, you have to remember that manufacturers made
cheap crap in the old days also, and just because it’s old doesn’t mean
it’s good, and vice versa- just because it’s recent vintage doesn’t mean
it’s crap either.  There were good tools made all over the place, just as
there were cheap tools made for occasional use- stuff made to a price
point.
  I would recommend that you definitely sharpen up the ones you already
have, and use them.  First, as an exercise (it takes practice to learn how
to do anything- you can only practice by doing, not reading about it or
watching videos- you actually have to do it).  It will teach you how hard
the steel is, and you can learn about tooth geometry and set and so on, and
the performance will help you learn to appreciate what “good” means when
you get a really good saw in your hands.
As for bent blades, fixing these takes a lot of experience, and although
I’ve tried to fix some, I’ve only had the occasional success- usually I
leave the bent saws for someone else. A slight bend you may relax by gently
curving the blade over (and old book mentions that you should be able to
bring the toe to the handle!) but only you can judge if it’s useable or
not.   In the olden days, there was always a ‘sawsmith’ in building camps
and lumber camps.  It was a skill set that took years of practice and
learning, don’t kid yourself into thinking you can figure it all out on
your own by watching a few videos and reading old books in a couple of
afternoons.  Manual skills require manual exercises, so definitely start
practicing, but don’t necessarily expect success right off the bat.
 (Otherwise we could have all sorts of basement dentistry and home surgery
clinics all over the place, right?)
Cheers from Waterloo
Claudio

On 2018-01-14 10:41 AM, Ed Minch wrote:
> There are so many good, straight saws out there I don't think you should
bother with bent or kinked saws.

Kinked saws are the devil to fix. Bent saws can be difficult too - but 
sometimes not. But saws that are very slightly bowed, depending upon 
scarcity in your area and the ask price, m_i_g_h_t be worth a try. Not 
in any anteek maul I frequent. So it depends. How much are you willing 
to lose? You can always turn a bad saw into a pile of decent scrapers. 
You do need scrapers?

FWIW

Don


-- 
"You can tell a man that boozes by the company he chooses"
The Famous Pig Song, Clarke Van Ness

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