I'm no expert when it comes to saw nuts. This is the way I've come to
understand it:
Early split nuts were cast in one piece. Many early handsaws including
all pre-1876 Disstons have this type of split nut.
The first improvement was Washburn's 1867 patent for improved split
nuts. These were wrought and assembled from two pieces of material. I
don't think Disston ever used this patent, rather, they continued to
cast their saw screws in one piece. Some early Peace saws have this
type of saw screw.
The second improvement was Munger's 1869 patent for two-piece split
nut type saw screws. Again, I don't think Disston used these. I have
several Peace saws with this type of saw screw.
In 1876 Disston patented an improved saw screw that was cast in one
piece and used a screw head rather than a split nut. I don't think
other saw maker's used this patent. I don't think Disston cast the
patent dates into these saw nuts.
The final improvement was Glover's 1887 patent for an improved saw
screw- the one we see on most post-1900 saws. It is wrought rather
than cast, in one piece making it strong and cheap. Soon, all saw
makers adopted it.
Some sawmakers continued to use split nuts well after the Glover's
patent improved nuts we widely adopted. Peace, for example, used split
nuts on his lower-end models like the Darlington, until at least as
late as 1895, perhaps longer. Spear and Jackson used split nuts on
some low-end models until at least 1915 (date based on a description
found in a S&J catalog reprint). I assume this was due to cost- the
new Munger patent screws must have been more expensive, even if they
were a superior product.
As far as maintenance goes.. If a saw has absolutely virgin split nuts
and a loose handle, I don't try to tighten them. When the handles were
finished the nuts were filed flat, leaving a nice fit and finish. This
also reduces the depth of the slots making them hard to grip with a
driver. If you do manage to turn the nuts without caming out, the
screw is never likely to be flush with the handle again, and it will
look monkeyed with. Instead, use a very thin shim or better yet, try
to add some very thin oil to the slot in the handle. Sometimes this
will make it swell enough to regain a good grip on the saw plate and
spine.
If the saw nuts have been tightened already, then there's no harm in
trying to do it again. I use a brace with a split nut bit to make sure
I have a good grip and enough torque. Some screws will break off,
others may blow-out the wood surrounding the nut if you aren't
careful, so go slow. It's good to have lots and lots of spare split
nuts.
Earlier this year I sold a nice mid-1800s split nut backsaw to a
Galoot. Before shipping it I made sure the handle was tight. When he
received it a week later he mentioned that the handle was too loose to
use and sent it back. I received the saw and sure enough, the handle
was loose. I threw it in my repair pile and didn't think about it
again until a few weeks later. When I picked it up again the handle
was tight as could be. The difference in humidity between my shop and
his led to the handle shrinking and loosing its grip on the blade. A
little linseed oil fixed this problem for good.
Hope this helps,
Josh
On Aug 2, 2010, at 6:50 AM, Ed Minch wrote:
>
>>
>> GG
>
> I undoubtedly have this wrong, but I think that Disston invented the
> saw nut as we know it now in 1875, so any Disston with split nuts
> is older than that, but from other makers could be younger too.
> Imagine the confusion a hundred years from now when 22nd century
> gilutes come across a "modern" split nut saw.
>>
>> I don't know much about Spear and Jackson, so I was doing some
>> Googling and found a reference that S&J stopped using split nuts
>> between 1850-1860.
>
> Ed Minch
>
>
>
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