Tip #34
Planer
Pg. 1-3, Pg. 4-6, Pg. 7-9, Pg. 10-12, Pg. 13-15 (PDF)
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Helpful Planing Tips

Figure 21-7. When you're planing stock to a desired thickness, you need a tool to measure the thickness. Shown here are a combination square (A), depth gauge (B), tape measure (C), outside calipers (D), vernier calipers (E), micrometer (F), and dial calipers (G). All of them will work well when measuring thickness, but dial calipers are perhaps the handiest.

Getting a good, smooth surface begins by making sure the knives are sharp and properly adjusted, the depth of cut isn't too deep, and that the machine is running at the proper speed and feed rate. Here are a few additional tips to help you get the best results:

Accuracy--When you're planing stock to a desired thickness, you'll probably want to measure the thickness many times as the stock approaches the final dimension. Several measuring tools will work well--a combination square, depth gauge, tape measure, outside calipers, vernier calipers, micrometer, or dial calipers (Figure 21-7). If you want a tool that is easy to use and accurate, choose the dial calipers.

Figure 21-8. Check your stock before you feed it inot the planer. The knives should cut with the grain direction. Click on image for larger view.

Wood Grain Direction--Always feed the stock so that the knives are cutting in the same direction as the wood grain (Figure 21-8). If you cut against the grain, the wood may chip out or even be torn apart in the planer (Figure 21-9). The grain direction is usually easy to determine by the look and feel of the workpiece. Looks can be deceiving, though, especially with close-grained woods. If the stock starts to knock or kick back against the infeed roller or you hear wood chipping out, quickly turn the feed rate down to SLOW. If this doesn't help, immediately turn off the planer. When the machine comes to a complete stop, lower the table and remove the stock from the planer. Turn the board end-for-end and try the pass again.

Figure 21-9. If you feed the wood against the grain, you may get a rough, chipped out surface as shown on the right. Feed the wood with the grain to insure a smooth surface as shown on the left.

Knots and Trouble Spots-- Wood with knots, wild grain, or extensive figuring is always difficult to surface and requires extra care. Check that any knots in a board are solid. Warning: Never plane stock with loose or cracked knots. Feed the work very slowly and take light cuts (1/128" to 1/64"). Be especially cautious of kickbacks and stop cutting immediately if the stock will not feed smoothly.

Figure 21-10. It's normal for the planer to cut a small snipe (less than 0.005" deep) in the end of a board as shown on the right. But if you let a board droop when it's fed into or coming out of the planer, the knives may cut a pronounced snipe in one end as shown on the left. Keep the board parallel to the flat on the table at all times.

Sniping--If you let the stock droop when it's being fed into or coming out of the planer, the knives may cut a large snipe at the beginning or the end of the board (Figure 21-10). A small snipe (less than 0.005" deep) is normal. But if the snipes are deep, be more careful as to how you support the stock. Keep it parallel to and flat on the table at all times. Less often sniping may be caused by weak roller pressure. If the planer continues to cut a pronounced snipe no matter how you feed the stock, check the roller springs, following the procedure in the Planer Owners Manual.

Figure 21-11. Damaged or nicked knives will leave long ridges on the planed stock. Inspect each board before you plane it to insure ther are no staples, tacks, paint, dirt, glue beads, or similar materials that will damage the knives. Never plane plywood, hardboard, or any material other than solid wood.

Ridges--Damaged or nicked knives leave long ridges on the surface of the planed stock, running the entire length of the board (Figure 21-11). These ridges detract from the finished surface of the wood and may interfere with the accuracy of your woodworking. The only way to restore the knives so they won't leave these long ridges is to have them reground. To avoid damaging the planer knives, inspect each board before you plane it. Be sure there are no nails, staples, tacks, dirt, paint, or similar materials on or in the wood. If you must surface glued-up stock, follow the procedure described later in this chapter. Caution: If you attempt to surface old lumber with rusted off nails below the surface, painted wood, plywood, hard-board, wood with glue beads, or any material other than solid wood, you will damage the planer knives. Even a bit of dirt on the wood can nick the planer knives badly.

Mill Marks--If the planer makes too few cuts per inch or the height of the knives is inconsistent, the machine will leave unsightly mill marks on the stock. Mill marks are small, parallel ripples that run across a board from edge-to-edge. To eliminate mill marks, try increasing the cutterhead speed (Mark V mounted planer only) or decreasing the feed rate. If the mill marks persist, check the knife positions.

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