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In part 1 I looked back at the videos for Jet and Powermatic and the idea of including helical cutterheads in stationary woodworking machines in place of three-knife or four-knife heads. Also, the variations on noise levels were shown with changes in decibels readings.
Next, what about costs associated with each cutterhead? Let’s look at the Grizzly G0593 (with 40 carbide inserts in its head) compared to the G0586 (with a four-knife cutterhead). Both are 2hp machines with the only difference being the cutterheads. The additional cash outlay is $330 and that buys you the spiral-head machine. That might seem excessive, but I think it’s very reasonable if you look into the total costs over time.
Each insert has four sharpened edges, so in a sense, you would need three sets of knives (plus the set that comes with the tool) to gain equality with the inserts. The additional sets of knives are $50 per set or another $150.
If you would prefer to look at the process of sharpening the blades when they dull versus purchasing new sets, my local cost to have jointer knives sharpened is $5.75 per knife up to 18″. That’s $23 per set of four and the three additional trips to the sharpening service would be $69.
So, you think you’re way ahead? How about the fact that the knives are high-speed steel (HSS) whereas the inserts for a helical head are carbide? The HSS knives will dull much more quickly than the carbide inserts. I’m not sure how many more times you’ll need to sharpen the HSS knives. That’s going to depend on the amount of lumber you run over the tool. At Popular Woodworking we feel confident saying carbide last four times longer than HSS, so you’ll incur an additional $276 ($92 x 3) in sharpening fees. That puts the total invested in sharpening only at $345. And we’ve yet to discuss the value of your time in replacing the knives or trips to and from the sharpening service.
Next, let’s take a look at another difference. When a nick shows up in the knives, you loosen the locking screws, slide the nicked knife to one side then tighten those screws. All the while you’re hoping that you don’t change the height of the blade in relation to the other knives. With a nick in a carbide insert , outside of the trouble of simply finding that nicked cutter , you’ll loosen one screw, turn the insert 90Ã?º and tighten the screw. Time is a consideration here too.
In my opinion, the average woodworker who works in a home shop might never have to replace the carbide inserts. With the inserts staying sharp longer and rotating the inserts for three additional uses, this becomes a possibility , barring a catastrophe. If you do need to replace the inserts completely, the Grizzly G0593 that we’re using in this discussion has 40 carbide inserts. Total replacement costs for the 40 inserts is $80 (that’s less of an expense than having the HSS blades sharpened four more times).
Given the fact that a helical cutterhead is quiet, stays sharper for a longer period of time, allows for a quick fix of damaged inserts and is only higher in initial costs not long-term costs, if I were purchasing a new machine there would have to be a great deal for me to buy the old cutterhead design. I’ll choose the helical cutterhead with the carbide inserts. How about you? Is the supposed extra cost stopping you?
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I don’t even worry about turning the boards the correct way to eliminate chipout. I just run it through the jointer and planer without even checking. With figured wood the grain is goind 3 or 4 different directions at the same time so why try to turn it around through the tool. Get a tool that solves that problem.
There are not ridges on my Grizzly, but if you use a piece of chalk and lightly rub it over the surface you will see some irregularities. A light sanding with sandpaper and it’s all removed. The 4 rows of cutters ar alligned so that two rows 1 & 3 are in the same place and the other two rows 2 & 4 pick up the wood between the cutters 1 & 3. There is some overlap but no missing spots where the wood was skipped.
Remember the wood is moving and the cutters are not touching the wood at the same point in the rotation.
I bought mine because i have a lot of figured wood and the older type flat blades leave a lot of chipout on the surface. I don’t have that problem with the carbide cutters. Problem solved.
I’ve read other articles that talk about the surface not being perfectly smooth after using a jointer, etc, using the carbide inserts. The article stated that there are small ridges left behind where the inserts are not perfectly aligned. Is this information incorrect?
I bought the G0586 w/ 4 knife cutterhead. I am overjoyed with the performance of the 4 knives. I also bought their knife grinder and an extra set of knives. Now, I am not a professional in the field of woodworking but, an avid homeshop woodworker (Chippendale & Queen Anne if you please ;^) anyway with the $$ that I saved I bought the grinder and knives (also an extra set for my G0453 15" planner).
I bought the Grizzly 8" jointer with carbide inserts and am I glad I did. I had a friend give me a board to plane and he left a broken off screw in the wood. I turned two cutters and was back perfect again. Grizzly states that even the oil under a cutter can raise the height to give you uneven cutting so make sure that you remove all stray articles from under the carbide cutter.
I was so pleased that I purchased the 20" carbide planer also. A happy camper.
Carbide inserts are a major pain. It takes FOREVER to find the bad one, and when you do, you cannot always just turn it 90 degrees. If you do, the "new edge" protrudes higher than the worn edges of the other inserts.
In addition to this, inserts do not always want to sit flat in the recessed area that they are supposed to sit in. There is a build-up of dirt, etc., and then you have to fight to make it "just right. This means that you may have to search for that insert 2 or 3 times, if you think you have it, you try it, and realize that the surface of your wood is not smooth, search for it again, etc.
You also have the problem of the screw heads being rounded out, and not wanting to be removed. And when you try and remove used screws, they are always filled with dirt, dust and pitch. They become a battle, and you have to battle with dozens of screws, just to get a complete set of new, even edges.
Lastly, you sometimes have an insert crack and break, and this causes sharp metal to fly where ever the decide to go. If you use such inserts, PLEASE wear safety glasses and use other safety precautions!
(I have worked full time in the woodworking industry for 23 years.)