One lesson any mechanic or handy man will clearly remember was the first time they snapped a bolt by over tightening it. This is often preceded or followed by stripping or cross threading. Mine was a reverse threaded peddle in a bike crank. Lessons to this day I heed as I wade my way through life.
I think over time, for those of us who enjoyed turning wrenches, it started with bicycles, gravitated to dirt bikes, and eventually cars. Learn early the concept of torque; it’s a kin to heat in the kitchen. You want as much as possible but too much varies from problematic to deadly.
So my point with all this is PLEASE BE CAREFUL when working on these old saws. Consider that most splits are 100+ years old and it’s impressive they’ve held up so well.
Most of the threads would be made using a screw plate of hardened steel and the soft brass would be turned into the plate similarly to how a dowel plate works. The threads used were simpler than later Glover style saw screws.
With that in mind it’s important to use proper fitting drivers. This is preindustrial revolution hardware you’re dealing with. One size for sure will not fit all. For more information on making a split nut driver see previous post on making them.
So before you bear down on the next screws make sure the fit is good. When tightening, remember your goal is to prevent the handle from moving. Tighten it some, then check and tighten more if need be. If It loosens that’s not the end of the world. If it snaps, it might be…
However, if the latter just happened there is still hope. Been there, done that comes to mind. Provided the break is clean below the threads you’re looking more at a candidate to be silver soldered or brazed. The difference being is the metal used as the filler and the point at which it melts. Since brazing requires more heat than soldering, acetylene gas mixed with air is commonly used. However if you can use a butane torch this is a low cost alternative. That said, more research is recommended as this is not my area of expertise.
That’s about as technical as I’ll get with it as I’m lucky enough to have a friend mentioned in earlier posts, David Latouche. He routinely brazes metal for work as well as teaches on the subject. Double bonuses, he agreed to help fix a few saw screws as well as go over the basics.
To start it’s important the area being brazed is clean. It’s also important to check or figure out how the two pieces properly fit back together. Good glasses or magnification can help. You’re looking to match the score marked on one side to the other. The better the fit the easier it will be to stabilize it when heated.
Because David routinely brazes he already has a work area set up with fire bricks used in ceramic kilns and a small container of mild acid/etch type cleaner called “pickle” that we used to submerge and clean the pieces before brazing. The solution was strong enough to clean the oxidation at the break but mild enough that it didn’t affect the patina on the outside. That said the heating process often results in raising the copper in the metals to the surface resulting in a pink hue around the area. The amount largely correlates to your skill and the break in general.
With the parts clean it’s time to get down to the business at hand. The breaks on mine were easy enough to line up. I then applied some flux and cut a very small piece of solder. David uses a simplified version of a Third hand tool to apply pressure and hold the parts together while applying heat.
After watching him fix one I was ready to try my hand. I’ve done my fair share of copper pipe repairs and soldering so it’s not completely foreign to me. The big difference being is how you heat the area and apply the flux. This was a bit trickier than soldering or sweating a pipe. Brazing done correctly uses the heat to wick the solder into the joint where the flux was applied. The flux attracts it and therefore the location and amount are more critical.
The goal is to get the area up to temp without heating the entire piece. Once the piece is done it’s dropped into water and checked. It’s still soft and if needed can be bent a little. Often you’ll find split nuts bend quite a bit as the plate shifts in the handle over time.
When done I’m happy to say we fixed all three, 2 label screws and a split nut, and they will now see a second chance in a future restoration. At this point the weather outside had turned a bit nasty with snow and ice on the roads so I gathered my things and headed home.
What we’ve learned:
• Always use the proper size driver when working with any fasteners.
• Apply enough pressure to tighten but not so much to strip or break.
• Always apply torque progressively smoothly.
• Fear not; often broken screws can be fixed.
Joe Federici— saw advocate
°Remember Jr. Sawyers, be mindful when playing with your nuts!