Here’s a scenario for replacing your existing planer or jointer head with a Byrd Shelix. As an example, let’s consider a swap in a Powermatic 15-in. planer, about the widest planer available for typical woodworking shop budgets.
It’s pretty easy to say that a carbide edge will conservatively last 10 times longer than a high-speed steel (HSS) edge. Each insert in a Byrd head has four sharp sides, so the total longevity is about 40 times that of a straight HSS blade. Considering that a typical sharpening service will charge from 60 to 75 cents per inch, a 15-in. blade will cost at least $9 to sharpen. For three knives, that’s $27. Now if you sharpen those blades 40 times, the cost will be $1,080 not including the cost of replacement blades, or the time spent taking the blades to the sharpening service and retrieving them after sharpening. A replacement Byrd 15-in. cutterhead will cost $795, so retrofitting a Byrd head could save several hundred dollars in sharpening costs over the life of the cutters, and a bunch of time.
Now let’s consider cutter replacement costs. The number of sharpenings before a standard blade becomes too narrow to use will depend on how much the sharpening service needs to remove to get a clean edge. Typically a sharpening service will remove 0.015 in. to 0.020 in., more if there are serious divots in the edge. Six sharpenings will remove about an 1/8 in., which is about the maximum that most blades could take before becoming too narrow. But for the sake of hedging our bets, let’s assume we can get 10 sharpenings from a set of blades. A set of 15-in. replacement blades will cost $139, or about $13.90 loss each time the blade is sharpened. Forty sharpenings will result in $556 worth of blades. Combine the sharpening costs with the blade costs and you have $1,636 in total costs.
Replacing the Byrd cutters is substantially less expensive. The cutters run $3 each and there are 75 cutters in a 15-in. planer head. So for $225 you can replace all the cutters, a bargain compared to sharpening and replacing sets of knives. Combine the cost of replacement cutters with the cost of the insert head and you end up with a total cost of $1,020. So theoretically there is a savings of $616 with the Byrd head compared to a standard full-width knife head. But the really big factor is time saved by eliminating the need to change knives.
This same formula will work for cost comparison of any type of insert cutterhead. Some cutterheads have only two sharp sides on their insert, so the longevity of the cutters will not be as great, and the HSS cutters will be less so.
Some benchtop planers have insert knives that aren’t capable of being sharpened, so the cost factor for sharpening is moot, but the knives typically cost about $80 (two sharp sides) and the cost factor will simply be replacement of the disposable knives. At a cost of $40 per sharp edge, the savings with a replacement insert cutterhead is even better (10 times longevity for the carbide = 40 sharp edges on disposable knives = 20 sets of blades = $1,600).