The knife has a nice finish and is ready for a handle. If you look closely you can see the temper line in the steel. Two slabs, or scales, are bonded to "sandwich" the steel and create the handle. I prefer 3/8" micarta for most of my knife handles. I will use stabilized woods as well and the occasional piece of natural wood like cocobolo, rosewood, desert ironwood or lignum vitae to honor customer requests. However, I am not a big fan of the natural woods because of their instability. In my experience, even well cured cocobolo or ironwood can expand or contract based upon climate conditions. Such changes in the wood do not affect the function of the knife, but they can change the feel or aesthetics. Westinghouse originally developed Micarta. It is often seen as an electrical insulator material due to its non-conductive properties. Micarta is almost indestructible and makes for a super tough handle, especially on a working knife, and is very attractive. This knife will be going to an avid hunter. This customer requested red linen micarta with royal blue spacers. Red micarta comes in varying shades depending on the manufacturer. The color of the micarta in the photograph falls somewhere between a true red and a brick color. The blue spacer material is a vulcanized fiber product that is manufactured by several companies in a narrow assortment of colors. In a separate step I have sanded the micarta slabs flat on the surface plate and then bonded them to the spacer material with an industrial grade epoxy. I put the surface plate on top of the two slabs to keep them tight against the spacer and let them cure for 24 hours. When the epoxy is cured I sand the slabs square on my 12" disk sander taking care not to burn the micarta or overheat it, which weakens the adhesive bond. I take a ruler and draw a line from the spine to the front of the finger groove, then tape up close to the line.
I use an adjustable bevel to match the pencil line and then transfer that angle to the protractor fence on my 12" disk sander. I tilt the table to 5 degrees and then sand the two slabs to the correct angle for the front of the knife. The 5 degrees is simply a matter of preference. Sometimes I will use 10 degrees if I think it improves the lines of the knife. It is hard to tell from the photograph, but looking downward from the top of the knife the 5-degree angle goes from tip to handle. If I put too much angle on the front then I will start to shorten sides of the handle. When both pieces are sanded I try and get them into perfect alignment and put them in my bench vice. I hand sand the front angles with a hard block of wood and sand paper going from 220 through 600-grit, then buff with white and red buffing compound to a nice shine. Once the slabs are in place it will be nearly impossible to finish the front of the handle so that operation is always done at this point.
I use "C" clamps to hold the slabs to the knife once I get it properly aligned with the line drawn on the ricasso. Notice that I screwed up my angle just a bit and sanded the slabs just a bit too short. That is why the slab is at an angle to the lines of the knife. Tilting the slabs made them just long enough to cover the rear edge of the tang. Correcting the front angle would have left them too short for this knife. This will not affect the function or appearance. However, if the slabs were wood with a nice grain, the angle might not look right and another set of slabs would have to be used.
The Stock Removal Blade - Part 4 - continued
We will be attaching the slabs to the knife using Loveless style bolts since I prefer a combination of mechanical and adhesive bond. It should be noted that one of the main functions of the bonding agent is to act as a moisture barrier between the slabs and steel. The design calls for a thong-hole tube and an extra 1/8" pin at the bottom rear of the handle. Using the knife as the template, I drill two #18 holes through the micarta, a #30 hole for the small pin and an "F" sized hole for the thong-hole. I clamp the scales together making sure they are in perfect alignment, then use the first scale as a template to drill the second. Now we need to enlarge part of the bolt holes to create the "step" for the stainless barrels of the bolts. I use the step drill and drill through the #18 pilot hole taking care not to go through the handle. I like to leave about a 1/8" ledge of micarta underneath the stainless barrels. You can see how the barrel sits inside of the micarta once we have step drilled.
When both scales are drilled I like to do a dry fit to make sure the fronts of the scales are in alignment. I have not cinched down the bolts so the barrels are still showing on the left side. Any misalignment of the scales once they are on the knife will be painfully obvious. Notice the Corby rivet at the bottom of the photograph. This is another type of rivet/bolt, also called a blind type. When a Loveless bolt is sanded flat it gives the appearance of a bird's eye because of the brass bolt and steel barrel nut. I like the effect, but many others do not. After sanding and contouring the Loveless style often shows a slight thread gap between brass and barrel because of the thread pitch. The handle on the knife in the first photo of Part 1, is attached with Loveless style bolts. With the Corby type all that can be seen is what appears to be a large brass or stainless pin in the handle. The rivet shown here has a 5/16" head. Corby rivets come in several diameters and lengths.
We need to sand the handles now and get them very close to the finished profile before bonding. I attach one handle slab at a time to the knife aligning the slab with the thong-hole tube; rear pin and one bolt, and then clamp it tight. I take a sharp lead pencil and scribe an outline of the slab on the blue spacer material, then remove the slab. I repeat the process for the other slab. I use 50-grit belt and the flat platen to roughly shape the top and rear of the handles, switch to the small-wheel attachment with the 1" wheel to shape the bottom contours, then clean up with a 120-grit belt. I take special care to get real close to the line, but not beyond it. We want a little material left to sand flush with the steel during finishing. I attach the slabs to the knife again for another dry run and to see if I need to remove more material. Mistakes in the handle can be corrected up to this point. Once the handles are bonded there is no turning back. The handles get clamped pretty tight at this point to check for gaps between the scales and steel. If there are gaps then I put a piece of 150-grit paper on the surface plate and sand the slabs until they are dead flat and check again. When I have a nice tight fit all the way around the handle we are ready for the next step.
Everything is removed and all parts are cleaned with acetone. Alcohol also does a fairly good job and can be used in a pinch. Q-tips can get into all of the holes and recesses. Cleanliness is important for a good adhesive bond. Micarta dust or left over oil from sanding can contaminate the epoxy. I use a triangular file to put small divots in the middle of the thong tube and rear pin. This gives something for the epoxy to hold. I sand both with 220-grit sand paper as added insurance. Everything is ready to go. I have found Conap, a clear industrial epoxy, to be an excellent bonding agent. This epoxy has a long pot life giving plenty of time to work and put everything together properly. As a general rule, the longer the pot life and cure time for the epoxy, the stronger the bond.
I mix up enough epoxy to be certain that I will have more than needed. The knife is placed the knife vice so that it can be easily rotated while installing the slabs. I carefully coat every bonding surface, slabs, tube, pin, bolts, threads and handle and put it all together, then tighten the bolts. When the bolts are snug, paper towels or shop rags, dampened with alcohol are used to wipe away the excess epoxy. Excess epoxy will just make the knife more difficult to sand and load up the sanding belts later. The alcohol does not affect the adhesive bond and dries very quickly. When the excess epoxy is removed I lightly clamp the slabs in some of the perimeter areas, especially at the rear, to be sure that we have a tight fit around the tube and pin. I clean up any remaining epoxy and let the knife sit for about 15 minutes, then carefully clean the epoxy that has oozed from the front of the slabs onto the ricasso. We want a tight, smooth, clean fit where the slabs meet the ricasso. When all is clean it gets a final inspection to look for any glaring errors and then is set aside to dry. While Conap is a 24-hour epoxy, I like to let a knife sit for 48-hours before finishing. Some epoxies never seem to be fully cured after 24 hours. I have never had that problem with Conap. However, I got into the habit when I had to substitute "Brand X" after running out of Conap because the other brand (a good brand-name product) did not harden fully in 24 hours. The bottom line is that I tend to ere on the cautious side. In two days the knife will be ready for finishing.