Stock Making index

Part 6 Shaping the forearm

Our first step in this part is to clean up the stock from the grip area back to the butt plate.  I start with a flat Microplane and begin smoothing the flat areas, feeling for high spots as I go. With a round Microplane, I clean up the areas next to the thumbhole ridge, making a smooth continuous transition from the ridge to the butt.

Working with an orbital sander, and manually with 80 grit paper, I carefully remove the marks from the Microplane, being careful not to change the contours I just worked so hard to achieve.

Stock blanks are like a box of chocolates. You never know what you’re going to get. As you get deeper into the carving, you can uncover some fantastic grain and figure, or you can uncover unwanted knots and voids. A fancy knot doesn’t necessarily bother me, as that is just the way nature makes wood, but a knot that leaves a void has to be dealt with cosmetically.  A simple trick is to mix some sawdust from your wood with a little yellow glue and use the mixture to fill the void. You can use epoxy for larger voids, but this one is small enough for the yellow glue.

Mix the sawdust and glue to a consistency of Play Doh, more dust than glue. Use a putty knife to force the mixture into your void. Don’t just skim over it, pack it in tightly.

Let the repair dry for at least 30 minutes then sand it smooth. It will still be a knot, but the void will be gone.

The next step is to taper the forearm. I like the look and feel of a tapered forearm. I taper the blank from full width at the thumbhole to about full width minus 1/2 inch at the front of the forearm, depending of the diameter of the air tube. To mark the blank, I place a piece of 1 inch Delrin, the diameter of the Marauder air tube, into the air tube cut, and using a flush cutting trim saw and a precision thickness gauge, I make two small cuts that can be seen when I turn the blank upside down. The flush cutting trim saw has its teeth set in one direction only, so it won’t damage my expensive thickness gauge.

I made a fixture for tapering blanks from a piece of Melamine shelving, using stove bolts and wing nuts for clamping. The bottom of the clamping slots are relieved for the heads of the stove bolts to allow the fixture to sit flat on the table saw. The smaller slot fits the square of the stove bolt and keeps it from spinning while tightening the clamps. I set the table saw fence to the width of the fixture so that the saw blade is flush with its edge.

By aligning the saw cut at the front of the blank, and the side of the blank at the thumbhole, with the edge of the fixture, I get exactly the taper I want.

The angled hand hold on the fixture allows me to keep pressure against the fence while feeding the blank through the blade. The saw blade is fully raised for this cut, so care must be taken using this procedure.

Once one side is cut, I reverse the blank and taper the other side.

Using a sanding block and 80 grit paper, I remove the saw marks from the angle cuts.

Moving now to the router table, I cut a radius on the bottom edges of the forearm. This is accomplished by using a inch roundover bit and a starting pin. The starter pin screws into the aluminum router plate. The fence is not used for this operation. The blank rides on the inch bearing on the cutter, and the starter pin. Using a starting pin is the only safe way to make this cut. Always feed the stock into the rotation of the bit with the blank against the pin, and remember the rotation is counter clockwise when the router is upside down. In other words, feed the stock AWAY from you when on the LEFT side of the cutter, and TOWARDS you when on the RIGHT side of the cutter.

Because the blank rides against the bearing of the cutter, I have to be especially careful when I get to the holes for the manometer and the mounting stud. I just leave the cut a little fat in those places, and clean it up later.

Using the Microplanes and 80 grit paper, I clean up the areas around the manometer hole, and the trigger guard.

The final cut on the forearm is made with a large thumbnail bit. I switch to a router plate with a larger insert opening, and set the depth of the cutter so that there is no “cuticle” on the cut. I then adjust the fence to leave a small flat on the top of the blank.

I clean up the cut with a sanding block and 80 grit paper. We now have two shaped stocks ready for sanding and finishing.

In the next installment, we will complete the sanding, and finish the stocks with Tru Oil.

Part 7 - Sanding and Finishing