by Roy Bloom, CJF APF and Dave Farley, CF APF
The undercut, sometimes called a hoof gouge, can be used in place of the rasp when clinching. The photos give an excellent view of the steps involved. Like all new methods, the undercut may seem awkward the first few days of use.
I think the undercut gives me a stronger clinch with a smooth finish. The sketches illustrate the results of clinching with and without the undercut. In sketch A, you can see that after clinching, either with a clincher or a hammer, the nail is rasped or filed to eliminate burrs or jagged edges. This process takes material away from the clinch, weakening it. In sketch B you have the nail that has been clinched after undercutting. The undercut provides a pocket to fold the clinch into. The end of the clinch is also resting within the pocket, lessening the chance that it will loosen. Because it is not protruding from the hoof wall it does not need to be filed as aggressively. A sanding block may be all that’s necessary to finish.
I also think that the horizontal mark or scratch that is often caused by the rasp is weakening the wall, a bit like the process of cutting glass by scratching the surface. The undercut minimizes the area disturbed in the clinching process. The undercut requires very little maintenance. If it feels like it is becoming a bit dull just use a small flat file to touch it up. A couple strokes following the angle of the end of the tool is all you need. You need to be sure your undercut has the angles as shown in the photos.
2. Tilt the undercut (about a 45 degree angle) on the second hit.
3. The last blow at a high angle should finish the removal of the pocket.
4. Use the clincher with a very light squeeze to start the clinch over.
5. Now push the clinch back into the pocket produced by the undercut. Do not use a severe pulling motion, just a squeeze and push.
6. Place your clinch block on the nail head and set the nail with the heel edge of your hammer.
7. A light flat blow with the hammer completes the steps of clinching. You’re now ready to sand or lightly file finish the foot.
Sharpening the Undercut
This photo shows the file stroke and angle used to sharpen the tool. A 6” flat file works well for touching up the tool. Sharpening should only require a few smooth strokes following the angle shown in the photo.