Part Two of handle restoration covers shaping the repair to the correct length, width and contour, and how to finish the repair.
Once you've let the glue-up cure overnight, draw the contour of your new horn onto the repair piece. If you have a matching handle with intact horns, use it to trace the outline on the repair wood. Not a mission-stopper if you don’t. Web sites like www.disstonianinstitute.com have many pictures of vintage Disstons to go by.
Now shape the contours of the repair piece with a saw handle rasp. Tools for Working Wood sells their Gramercy Tools' saw handle rasp for this step of the procedure, and it’s a pretty handy tool to have in your arsenal. If you don't own a saw handle rasp, use a Dremel equipped with a sanding drum. After roughing out the shape with a rasp, I like using my 10.8 Lithium battery cordless Dremel with a sanding drum to further refine the repair piece to shape and appropriate contour. Strongly recommend safety glasses with the bifocal lenses and a dust mask while doing this, not only for safety reasons, but so you can get close in and see in minute detail what you’re doing.
Starting with the coarse and graduating to the fine Dremel buffing wheels, smooth out both vintage and new wood. This softens the edges and helps you achieve a smooth transition between the two pieces, and prepares it for your final buffing with Scotchbrite pads prior to staining and wood treatment. You might find yourself alternating between the Dremel, your scraper, and some fine sandpaper at this point to attain a consistent transition between both pieces. Be careful with the Dremel so you don't wind up sanding a ridge or hollow in the wood. Pop the grain with fine and polish-grade Scotchbrite pads.
Now that you've repaired the horn, it's time to buff out the rest of the handle. If the original finish/lacquer on the handle isn't worth saving, strip it down to raw wood. Often, however, you can save the original finish by gently buffing the handle and judiciously scraping off grime and paint splatters with your scraper. The intent here is to even out the remaining color on the handle in preparation to stain the raw wood marks from the repair work.
Buff the entire handle with 0000 steel wool (or Scotch-Brite equivalent), treat the wood with the product of your choice, such as Murphy's Oil Soap. I like using a wood treatment called Kramer’s Antique Improver, which cleans and preserves antique woods without stripping the original finish. I’ve also found that it assists the final blending of the two pieces to mitigate the ready appearance of a repair. You're done when you're happy.
So here's the end state: the handle's upper horn has been repaired, and with repeated coats of stain the repair should blend over time with the rest of the handle. The through-crack above the lower horn is now secure. Though it is obvious that the handle has been repaired, it is now a far stronger handle and with care, the saw will see another century of use with a comfortable feel in the hand and a renewed ability to saw with confidence.
This above all: have faith in what you’re doing. Repairing a saw handle is not rocket science, but seems a little intimidating the first time you do it. Don’t sweat this. The worst that can happen is that you cut away the repair piece and start over.