Segmented cutterheads are becoming quite popular these days but most tools come with traditional straight knives. So it’s very likely that at some point you’ll be looking to upgrade to a segmented head, and thankfully you don’t have to purchase an entirely new machine. Instead, you can just swap out the cutterhead for a new one. The process isn’t all that difficult and this video shows you every step as they pertain to a Byrd SHELIX cutterhead and a Powermatic PJ882 8″ Jointer. While your particular brand of tool may vary in the fine details, the concept is the same and I hope this demystifies the process for you.
As with anything, it depends on your situation. But I can say without hesitation that this kind of upgrade is by no means a necessity. People have been using straight knives for years with great results and because most are made from high speed steel, the initial cutting edge can actually be “sharper” than the carbide inserts found in segmented heads. But a segmented cutterhead, more specifically the SHELIX cutterhead, brings some nice benefits to the party that could make it worth your consideration:
Cut Quality – While you should never expect finish-ready surfaces from any jointer, I find the segmented head produces smooth results for a long period of time. Straight knives are capable of producing an incredibly smooth surface when freshly sharpened, but I find they quickly lose their edge. The carbide inserts of the segmented head start sharp and stay that way for a very long time. In addition, the shearing action afforded by the helical design yields a potentially cleaner cut; a major benefit on highly figured woods or boards with temperamental grain. There’s nothing worse than getting a bunch of tearout on a prized piece of figured stock, knowing you’ll have to waste an additional 1/8″ in thickness just getting rid of the surface flaws. Keep in mind that the “shearing action” I mention is not something you’ll find on every segmented cutterhead. Some cutterheads have inserts that approach the wood head-on so that’s something to look for.
Convenience – In the past I sent my jointer knives out for sharpening about once per year. The cost wasn’t too bad but getting the knives set properly in the cutterhead after the fact was a huge headache. I honestly dreaded the experience. With a segmented cutterhead, the carbide inserts are pre-indexed and never move. So replacing them is as simple as loosening a screw, removing the insert, dropping a new insert in, and tightening the screw. Furthermore, each insert has four sides so all you need to do to expose a brand new sharp edge is rotate the insert 90 degrees. You might find it interesting that I’ve been using a segmented cutterhead in my planer for about three years now and I have yet to turn the inserts even once.
Noise Reduction – The design of a segmented cutterhead results in much less noise, primarily because there’s less metal making contact with the wood at any one time. And with the helical shearing action, the inserts are approaching the wood at a slight angle which means even less metal comes in contact with the wood at once. My tests in the shop showed a roughly 20 dB reduction in noise level while jointing.
I am incredibly happy with the results of the new segmented cutterhead and because I work with lots of exotic and figured wood, I feel it was a wise upgrade. I should mention that if you’re in the market for a cutterhead upgrade, consider your planer first. Since most of my boards will pass through the planer on both sides as a last step in stock preparation, I feel it’s more important for the planer to produce the smoothest cut possible. The jointer would be the secondary upgrade.