Tip #38
Molding (continued)
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Molder Knives

Figure 5-3. All of these knives are available for use with the molder head. Buy a few that you can use now; acquire more as you become proficient and your work scope increases. Click on image for larger view.

All of the knives shown in Figure 5-3 are available for use with the molder head. This is quite an extensive assortment, but it isn't necessary to acquire all of them at once. Start with a few sets that will allow you to make a few basic cuts. Other sets can be added as you become more experienced with molder operations and as the need arises.

Figure 5-4. This set of glue joint knives is typical of those which are designed for a special purpose. You can even use part of the profile.

Knives, which come in sets of three matched cutters, are designed like the glue joint set in Figure 5-4 for full profile cuts; that is, the entire width of the knife is used to cut the shape in the wood. The set shown in Figure 5-5 is designed so only part of the edge is used to cut, in this case, flute and quarter-round shapes. However, the full profile may be used if the shape pleases you.

Figure 5-5. This is a sample set of combination knives. Part of the profile is used to form flutes or quarter-round shapes. You can opt to use the full profile if the form pleases you.

Other examples of partial-cut knives are shown in Figure 5-6. The different shapes that each knife will produce depend on how you set up for the cut and, sometimes, how many passes you make.

Figure 5-6. As shown here, combination knives can be used to create various shapes. (A) 3/16" and 3/8" quarter-round and 1/4" bead. (B) Combination 1/4" and 1/2" quarter-round. Click on image for larger view.

Knives, like the drop leaf table joint shown in Figure 5-7, are also available in matched sets. In this case, one set of knives forms the edge of the table, and the remaining set makes the matching cut on the hinged leaf of the table. Examples of three matching joints and two full-profile cuts are shown in Figure 5-8.

Figure 5-7. A typical knife set. These two shapes produce the edges that are required for a drop leaf table joint. One set shapes the table's edge, the other makes a matching form on the drop leaf.

Knives may also be used in combination; that is, different knives may be used on the same piece of wood to produce a particular shape (Figure 5-9). The possible results are limitless, and with a good assortment of knives you could closely duplicate any molding shape that is displayed in any lumberyard.

Figure 5-8. Molder knives that produce these joints are purchased in sets: (A) tongue-and-groove; (B) drop leaf table; (C) flute and nosing. Examples of full profile cuts; (D) glue joint and (E) cloverleaf. Click on image for larger view.

Mounting the Knives--The molder head has three slots equally spaced around its perimeter. Each of the slots has its own prevailing torque setscrew which bears against a steel ball that will seat in the beveled knife hole when the setscrew is tightened. Warning: Be sure the slots in the molder head and the knives are clean. Any dirt that keeps the knives from seating correctly will cause inaccurate cuts and can be dangerous.

Figure 5-9. These shapes are typical of advanced work you can do with the molder head accessory. The shapes of different knives combine to produce the final form. Work like this should be planned in advance, on paper, using the knives as templates: (A) 1" jointer; (B) combination 1/2" and 1/4" quarter-round; (C) ogee; (D) three-bead; (E) groove (part of the tongue-and-groove set).

Hold the molder head so the slot points toward you and loosen the knife retaining setscrew. Tilt the molder head a bit so the ball moves out of the slot and then, approximately centering the knife, slip it into place. Just before the ball contacts the knife, move the knife side-to-side as you tighten the setscrew. This will center the ball in the hole. The knife will adjust itself to the ball and each knife will be aligned as you secure the setscrew. Caution: Do not over-tighten the screws. This will damage the knife, making it difficult to remove. Recheck the knives between jobs. Be sure the knives are correctly seated and that the set-screw is tight. The cutting edge of the knife is always on the side toward the setscrew. When the molder head is mounted on the spindle, the cutting edges will point toward the front of the worktable.

Since the profile of the knife is not the profile cut in the wood, you should keep sample cuts of the knives you acquire. These can be overlaid on a drawing of the shape you intend to produce so you can decide which profile, or which part of a profile, should come into play. Many molder knife profiles are duplicates of classic forms. Therefore, these sample cuts can be used as templates when planning designs, not only for molder work, but also when you are planning projects for lathe turning.

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