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Poor Boy's Split Nuts
by Leif Hanson |
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The screws and nuts
that hold a saw handle onto its blade are getting to be either
hard to find, or are exceedingly expensive. The standard issue
nuts from the hardware store are simple plated steel, and are
not consistent in length in my experience. The brass split nuts
are available, but are limited in supply and quite expensive at
about $5 each plus shipping at the time of this writing.
I
thought to myself that I could make them almost as well using a
few simple tools found in most woodworking shops - and then I
would be able to claim that the saws I make are made entirely by
myself, something I thought would be kind of cool to be able to
do.
Materials and Tools required
The split nuts
themselves will be manufacture from 10-24 (or 10-32) threaded
brass rod (1" long, from McMaster Carr) and plain 9/16" brass
rod (9/16" is a common size on most saws with split nuts, but
I've also seen 1/2" used), both available from good metal
suppliers online (such as McMaster Carr or MSC Direct). Tools
needed are a hacksaw, a drill press, a 10-24 (or 10-32) TPI tap,
a disk or belt sander, and finally a grinder outfitted with a
de-burring and buffing wheel. A jig for making the nuts will be
crafted out of some 8/4 ash, some 1/8" plate steel, and a
threaded insert.
To make the bolts, a
torch (along with all the necessary accoutrements) is necessary
for silver-soldering the nut to the threaded brass. An
oxy-acetylene torch is the best tool for this job - however,
here I am use one of those $50 welding kits that use a small
bottle each of MAPP and oxygen gas. These small kits supply
plenty of heat for the job, and are much less expensive than
buying a full oxy-acetylene rig. If you do a lot of soldering,
this is not very cost efficient method - but for occasional use,
they works fine.
You will also need
some silver solder and flux - I use a brand called "Stay-Silv
45" for the best results. This should be available at most good
welding supply stores.
A Simple Jig, and Making the "Tube"
What's needed first is
a way to drill a hole through the center of the brass rod in
order to thread the nut. The hole must be sized for the size
thread you want to tap, and centered in the rod to be proper.
The only way to do this is to build a simple jig to hold the
brass rod upright so the hole can be drilled into it's center.
You will see the jig in many of the following pictures here, and
I won't go into too much detail on it because of it's
simplicity.
Using a forstner bit
that's the size rod you are using, I drill a vertical hole into
some 8/4 ash, not all the way through, leaving about 1/2" of
wood at the bottom so the rod won't fall through. I then pick a
spot on it's side near the top and drill an additional 3/8" hole
from the side, centered on the previous hole. Into this hole I
insert a threaded insert - this will allow me to use a small
bolt to "lock" the brass rod in place, so it doesn't turn in the
hole while drilling it.
A small piece of steel
mounted on the side of the ash was added when the threaded
insert I used started wanting to strip out of the wood - the
steel is there simply to hold the threaded insert in place in
its hole.
Once the jig is
complete, I take a 7" or 8" section of brass rod, and insert it
into the jig. Using a center finder, I locate the center of the
rod and use a center punch on it to locate it for the drill bit.
I place the entire assembly on the drill press, and drill a
13/64" hole in the center of the brass rod to the drill bits
full depth:
Drilling it to the
full depth of the drill bit is necessary for the next step,
which is tapping the hole for 10-24 thread.
Making the Nut
The next step is to
tap the brass rod using a 10-24 tpi tap:
Tap to the full depth
of the tap - on subsequent nuts, it's occasionally necessary to
drill the center hole a little deeper to accommodate the tap.
Now its time to add
the slot for the nut - you can skip this step if the nut is to
be used for the bolts. I use a hack saw to make the slot:
Cut to a depth of
about 1/8" to 3/16" or so, making sure the cut is level across
the nut - then cut the nut off, making sure you make the cut as
straight as possible and about 3/16" further down the nut than
the slot is deep:
Set the new nut aside
and start the process over, making another then another until
you have as many nuts as you need.
Thicknessing and Polishing the Nut
You now have a rough
nut that is much too thick for use in a saw, and probably not
cut quite as square as it should be. To reduce the thickness and
level off the nut, cut the thread off of an 1-1/2" long bolt
with the same threads, place 2 nuts ( locked together) near the
end (with about 1/8" or so of thread sticking out of the
outermost nut) and chuck the affair into a hand drill. Thread
one of your newly made brass nuts onto the end of the whole
affair and bring it over to the disk sander. Use the drill to
spin the nut, and sand it to thickness:
You have to ever so
slightly cant the assembly to the left to keep the brass nut
threaded onto its holder - otherwise the spin of the disk sander
will unthread it, sending it flying under the nearest bench and
into the most inaccessible spot it can find. When that side is
done, unthread the nut, flip it over, and do the other side in a
similar manner. Keep a pale of water handy to cool the nut so
you can grab it, because the brass gets hot!
Watch the depth of the slot cut into the nut and use it as a
guide - you want the slot to be about 1/2 the thickness of the
finished nut, which should be about 1/8" to 3/16" thick - I
shoot for exactly 5/32" thick. You can put a slight chamfer on
the back of the nut, both for looks and so it seats itself
flatter in the wood when used in case there is sawdust in the
way.
Once the nut is to the
correct thickness, a trip to the grinder where you have a
deburring and polishing wheel installed will give the nut a
finished polish:
From here, its on to make the
corresponding bolt. I used the same slotted nuts for the bolt -
you may wish to use an un-slotted nut and make a shoulder for
your bolt. If that is the case, you can make those by using the
same process above only eliminating the slotting step above.
Making the Bolt
If you choose to use a
shoulder, one can be constructed out of brass bar - simply drill
a hole in some brass bar that is the width of the shoulder you
desire, cut it to length so it will work as a shoulder, with
maybe a final filing to shape. I used a 10-24 square steel nut,
soldered onto the brass rod just below the brass nut:
Anyway, I thread a nut onto the end of some threaded brass rod,
and cut it off at just over 1" in length:
Another option is to
buy the threaded brass rod in 1" lengths, then there is no need
to cut them...
I then silver-solder
the nut onto the brass threaded rod using a torch, some flux,
and some silver-solder:
The threaded rod sticks a little past the nut,
so it's back to the sander to level it off with the nut, using
an additional nut on the same threaded rod assembly still
chucked up in the drill. If you did it all right, it should run
true:
Then its back to the de-burring and polishing
wheel to clean up the face of the nut - you can see some
assembled bolts in this mess:
At this point, the
split nuts and bolts are complete and ready for installation
into your new saw. If you drill the hole to the proper depth,
little filing should be necessary - you will need to file and
polish some on the nut side of the saw for sure, however - as
the bolt will undoubtedly protrude beyond the nut somewhat.
Here's the face of the bolts, installed in the same saw as the
photo above:
When assembling, a little Loctite Threadlocker will also help to
hold the nut in place, but I've not found it necessary.
Summary
While these were made
for new saws, there's no reason this same technique can't be
adapted to make replacement nuts and bolt for vintage screws.
Another fun little project!
Thanks for reading!
© Leif Hanson
norseWoodsmith.com
