| Planers can be used for a variety of tasks including | | | | machine. Of course, I don't know what your plans |
| milling glued-up hardwood panels, thicknessing and | | | | are for a planer but I'm pretty sure you won't be |
| surfacing lumber and making mouldings. Some of | | | | buying a Cemco any time soon. That still leaves a lot |
| these tasks can be duplicated by other machines | | | | of sizes and types of planers to discuss. |
| such as a wide-belt sanding machine or a drum | | | | A planer/jointer uses the same cutterhead for planing |
| sander. When you have digested the contents of this | | | | as it does for jointing. It looks like a jointer but it also |
| article, you should have enough information to make | | | | has a space underneath the jointer table where you |
| and informed purchasing decision. | | | | insert boards for planing. You feed the boards in one |
| In the "old days" (whenever that was) lumber was | | | | direction on the jointer table, above the cutterhead, |
| simply sawn out of logs and left to air dry. If you | | | | and in the opposite direction through the planer |
| wanted to be able to see the grain so that it could | | | | underneath the cutterhead. This is because the |
| be matched with other boards, it had to be planed. If | | | | cutterhead only spins in one rotational direction. A |
| you wanted it planed, you needed a long bed hand | | | | planer, if it has molding capability becomes a molder |
| plane and a lot of skill. With the invention of the | | | | simply by removing the straight knives and replacing |
| planer, no one needed to plane boards by hand any | | | | them with profile cutters. |
| more and the practice stopped in the name of | | | | Most planers are constructed with the cutterhead |
| "progress." Today, most boards are delivered already | | | | mounted in the top part of the machine and a metal |
| thickness planed and some are even straight line | | | | table with rollers underneath the lumber being planed. |
| ripped on one edge, making things very easy for the | | | | The thickness is adjusted by raising and lowering the |
| woodworker. So, why own a planer? | | | | table with relationship to the cutterhead above. The |
| Thickness planing does not end at the lumber yard. | | | | lumber is driven through the machine by the front |
| Lumber, once edge glued into panels is still uneven | | | | roller or rollers which are usually serrated for better |
| and the boards are never in perfect alignment with | | | | grip. The outfeed rollers are at the same height as |
| each other. Something must take this rough panel | | | | the infeed rollers but they are usually not powered |
| from, say, 1 7/8" down to its final thickness of, say, | | | | and are shiny and smooth. There are some large, |
| 1 ½", smooth both sides. There are two ways of | | | | expensive planers in which all rollers are powered. |
| doing this that I know of: an abrasive planer | | | | There are three types of cutterheads: straight knife, |
| (wide-belt sander or drum sander) or a planer that | | | | spiral and helical. The terms "spiral" and helical are |
| uses knives in a cutterhead. | | | | often used interchangeably although this is inaccurate. |
| A combination of a knife planer and an abrasive | | | | There are strong similarities between the spiral and |
| planer would be ideal but not always affordable. This | | | | helical types but there IS a difference as I will explain. |
| is because planers have a way of tearing chips out | | | | Straight knives are used on most planers in the less |
| of loose grain. They are, however, much faster in | | | | expensive range. For the most part, straight knives |
| removing material than a sanding machine. A sanding | | | | are fine but they do have two drawbacks: they are |
| machine will never tear out chips but it may use up a | | | | difficult to align with each other after changing and |
| lot of valuable production time. So, in an ideal world, | | | | they tend to tear out loose grain more easily. |
| where money didn't matter, you could do most of | | | | Helical and spiral heads get around both problems to a |
| the thicknessing with the planer and then finish up to | | | | large degree. It has been found that a bunch of small |
| the final thickness dimension with the sanding | | | | cutter blades arrayed in a spiral wrap around the |
| machine. | | | | cutterhead will minimize splintering. Helical knives are |
| In fact, if you have the money and need to do your | | | | usually square or rectangular in shape and sharpened |
| woodworking on an industrial scale, there are | | | | on either 2 or 4 sides. They are mounted directly |
| machines with a planer head followed by two or | | | | onto the face of the cutterhead and, thus, require no |
| more sanding heads. I had the chance to use such a | | | | adjustment to align them with each other. To change |
| machine for several years. A friendly competitor | | | | a cutter in a helical head, you simply remove the |
| bought it for his woodworking firm in Hawaii and had | | | | screw that holds it in place. If there are unused |
| it shipped in by ocean freight from the mainland. | | | | edges on the cutter, you can rotate that cutter to |
| This giant machine, made by Cemco, used 880 volt, | | | | exposed the new edge to the wood and then |
| 3 phase motors. A ten HP motor ran the conveyor | | | | replace the screw. You buy cutters by the box and |
| belt and the one planing and two sanding heads each | | | | replace them as needed: Sometime you replace just |
| had 60 HP electric motors. It could plane and sand | | | | a few that have become nicked. At other times, all |
| panels 52 inches wide. In size, it looked like a large, | | | | cutters have been dulled on all sides and it is time to |
| industrial printing press. My friend bought into a | | | | replace them all. |
| sawmill and had Hawaiian Koa wood shipped by barge | | | | The spiral cutterhead is different from the helical |
| from the Big Island to Oahu where he had | | | | head in that Spiral Planer Cutterhead, a whole row of |
| constructed a dehumidification kiln next to the | | | | cutters, connected together in a flexible strip are |
| Cemco machine. Eventually, he over-extended himself | | | | attached to the spiral head, One row at a time. |
| financially and had to close his business. He found a | | | | There are spiral tracks or indentations in the heads |
| buyer for the planer/sander but he had to ship the | | | | that locate the cutter strips. There may be three or |
| huge machine all the way back to the mainland | | | | so tracks on a spiral cutterhead. Helical cutterheads |
| because no one in Hawaii had a use for such a | | | | are much more common than spiral heads. |