Planing Difficulties
The species of wood, as well as condition, will affect planing ability. The harder the wood, the more difficult it will be to plane. Below, we have included below, a list of wood characteristics you may encounter when planing. The following descriptions of defects will give you some possi- ble answers to problems you may encounter while planing different materials. Possible solu- tions follow the descriptions.
Chipped Grain—Usually a result of cutting against the grain, or planing wood with knots or excessive amount of cross grain. Chipped grain can also be caused by dull knives or misaligned chipbreaker. Often, chipped grain can be avoided by slowing down the feed rate and by taking shal- low cuts. If those options do not work, inspect your lumber and determine if its grain pattern is causing the problem. If the wood does not show substantial crossgrain, inspect your knives for sharpness and inspect the chipbreaker for proper alignment. See the Adjustment Section.
Fuzzy Grain—Usually caused by surfacing lum- ber with too high of a moisture content. Sometimes fuzzy grain is a characteristic of some woods, such as basswood. Fuzzy grain can also be caused by dull knives or an incorrect grinding bevel. Check with a moisture meter. If moisture is greater than 20%, sticker the wood and allow to dry. Otherwise, inspect knife condition.
Glossy Surface—Usually caused by dull knives taking shallow cuts at a slow feed speed. Surface gloss will usually be accompanied by overheat- ing. Often, lumber will be scorched and eventual- ly damage to knives will occur. If knives are sharp on inspection, increase feed speed or cutting depth.
Snipe—Occurs when board ends have more material removed than the rest of the board. Usually caused when one or both of the bed rollers are set too high. Can also be caused by the chipbreaker or pressure bar being set too high. However, small amount of snipe is inevitable.
Snipe can be minimized by proper adjustment of the planer components, but complete removal of snipe is extremely unlikely. More likely, you will be able to reduce it to a tolerance of .002". If snipe under that level is a problem, consider plan- ing lumber longer than your intended work length and cut off the excess after planing is completed.
Uneven Knife Marks—Uneven knife marks can occur when the chipbreaker is set too high. Inspect cutterhead bearings if re-adjustment of the chipbreaker fails to remedy the situation.
Chatter Marks—Usually caused by incorrect chipbreaker and pressure bar setting heights. Chatter marks can also be caused by running a narrow wood piece through the planer at either the right or left end of the cutterhead. Chatter, like uneven knife marks, will show in the form of a ''washboard'' look. Chatter marks are more likely to be inconsistent in appearance than uneven knife marks.
Wavy Surface—Caused by poor knife height adjustment, a wavy surface appears when one knife is taking deeper cuts than the rest of the knives. Remedy by resetting the knives to a toler- ance within 0.003" of one another.
Pitch & Glue Build-up—Glue and resin build-up on the rollers and cutterhead will cause overheat- ing by decreasing cutting sharpness while increasing drag in the feed mechanism. The result can include scorched lumber as well as uneven knife marks and chatter.
Chip Marks—Occur when chips are not properly expelled from the cutterhead. The knives catch the chips and drag them across the lumber being planed. Chips tend to be random and non-uni- form (as compared to chipped grain). Can be caused by exhaust blockage or too much room between the cutterhead and chip deflector. Using a dust collection system in combination with the planer can help reduce chip marks. Inspect the chip deflector and readjust (as described earlier in the text).
