Spiral Cutterhead Experiences

Woodworkers discuss the cut quality and performance they've achieved by switching to spiral insert planer tooling. March 26, 2009

We recently upgraded our shop planer from a beaten and battered 15" Powermatic with standard HSS cutters to a new 22" Powermatic with the helical carbide cutterhead. Being just a cabinet maker and not a decision maker at our shop, I did voice my opinion about standard vs. spiral when they were trying to figure it out. Fortunately my arguments swayed them and they went with the spiral cutter and the 7.5hp motor.

I knew we had a massive amount of planing coming for a crew of three people. We are in the process of building 250 8' tall bookshelves for a seminary. They are all built and we are now planing, shaping, and finishing all the trim. We are loving the planer.

So far, six months after getting the planer, we have planed at least eight pallets of lumber. Mostly standard birch, but also a lot of cherry, walnut, hickory, and oak and the blades have not needed a bit of attention. They cut as good as new. They cut cleaner, faster, a LOT quieter, and don't need re-sharpening but once a blue moon (just turn the inserts 90 degrees).

As a side note, we only remove 1/16" per pass. We could do more than that but we do get more grain tearout around the birch's knots and wild grain if we try to hog off too much. If you are hemming and hawing over whether to spend the money on the spiral cutterhead, do it. You may regret it when the bill comes but you will smile the first boardfoot you plane (and ten thousandth boardfoot especially).

Forum Responses
(Solid Wood Machining Forum)
From contributor M:
I find in our case the spiral head only gave a better cut in some of the hardwood that we had tearout in (yellow birch as one example). Otherwise it would not have been worth buying in our case because with most woods the finish was no better with the spiral. Sure the spiral did last longer (and it cost more too) but I would be surprised if you could get much more than the 1/16" depth of cut per pass.

From the original questioner:
It won't eliminate tearout, but it does reduce it a tremendous amount. The six or so pallets of birch we have planed have all turned out remarkably smooth compared to what the older HSS planer cutter left us with, even when brand-new sharp.

If we wanted to we could, and have, remove 3/16" in one pass. You can't run more than 2-3 boards (4-5" wide each) or you slow it down, but it will cut them. It also has more tearout, but still not as much as the older blades.

If you plane much lumber, the carbide will save you a lot of headache. Perhaps it would take a long time to recoup the cost by saving "sharpening money", but also consider the drastically reduced downtime - no need to remove blades and replace them every time you wear out the set.

From contributor F:
My guess is you would have been equally happy with a new industrial planer as an upgrade from your old machine. I recently replaced my new 20" spiral head planer with a 30 +/- year old SCM planer with four knife cutterhead. As far as cut quality and tearout go there is almost no difference. I work mostly with hard maple, though I've done quite a bit of birch of late. The biggest difference for me is I can hog off a lot more material in a full width pass than I could with the new machine. Also the SCM's head is close to a full inch bigger in diameter than the other machines was.

Now having used both I would say spiral heads are the way to go on smaller light duty machines, but not as necessary on bigger industrial machines, especially if you get an on-board knife grinder. Oh and the other benefit of the on-board grinder - you can sharpen your knives in much less time than replacing them, or turning all those little carbide inserts.

From contributor L:
I have to disagree with you on spirals not being necessary on larger industrial planers. I have the SAC equivalent of your SCMI with a Byrd Shelix head in it and it runs great. I can take more material off with it then I could with a straight knife head. It is a PITA when inserts have to be rotated, but I can run at least ten times the amount of material through before having to go through that exercise. They also reduce the load on the dust collector and make a smaller chip besides eliminating tearout. I don't even look at grain direction anymore when feeding lumber through the planer. The difference you're seeing is in the larger diameter cutterhead vs. the smaller one you had before. I have a 125 mm. head in mine.

From the original questioner:
For me the two biggest factors that make this a cut-n-dry issue is the carbide cutters last so ridiculously longer than the HSS cutters and cut quieter. Also, the carbide cutters cut much more cleanly so long as you make sane, logical cuts. I have planed some AAAA curly maple with our machine, and the grain tearout was visible, but very mild and easily sanded with 120 grit on a palm sander. I couldn't do that on curly maple with the HSS blades I don't care how freshly sharpened they were.

As a side note, not all machines are the same. I previously worked at a company that had a much larger planer (25-28" wide if I recall correctly) that had the carbide cutter. I don't recall the brand. But that machine would not plane more than 1/16th off, and this was a bigger machine than the 22" PM we have at the current shop.

I used to use a Grizzly 15" planer that would easily remove 1/8", and the old 15" Powermatic that we just retired would not handle more than 1/32 without bogging down, even with fresh blades. I just can't see why even a new Grizzly should work circles around an eight year old Powermatic.

From contributor F:
It's funny you should mention dust collection because that's something I had almost forgotten about. The carbide head made such light fluffy shavings it would constantly clog up my cyclone (7-1/2 hp Torit) used to drive me crazy. I heard from a couple other guys that they had the same problems. Now with the straight blades no more clogging. It really depends on what kind of work your doing. I can count on one hand the number of times I've used exotics that would benefit from a carbide head. I've done a fair amount of curly maple with the stuff that's just mixed in with my lumber (not good enough to be graded) and haven't had any problems with the straight knives.

Sure the carbide's quieter, but I need ear protection from my cyclone anyway so it's a non-issue. As for the longevity, I can't argue with that. I ran several thousand bd. ft. through my Bridgewood before selling it and never rotated the inserts.

I completely agree that there's a world of difference in particular machines. Personally I'd take a 30 year old Powermatic over a new Grizzly any day of the week, as long as it's one of the industrial models. The 20" I sold was a $3700 Bridgewood, comparable quality to the Grizzly line, not a cheap machine I thought, but a far stretch from the SCM as far as quality. I would guess the new 22" Powermatic is about the same quality given the price, but it does have the benefit of a bigger motor.

I've also used a couple older Powermatic planers, both big boys, they were built well and could chew up lumber all day without a sweat - definitely not comparable to the new machines.

In short I guess I would say that a quality planer well tuned with properly sharpened knives will do the job for most people, they have for over a century now. If youíre using a smaller machine or do a lot of figured woods then sure go for the spiral. I thought when I bought the SCM I would eventually upgrade to a spiral but having used it for several months I no longer see any reason to do so.

From contributor M:
Having owned both types of machines, an SCMI straight knife and now a Cantek, for our application the spiral head is the only way to go. That being said we plane for the purpose of a secondary operation, meaning rough stock surfaced to rip, or surfaced down to mould or resaw.

If you are looking for off the planer glass smooth, high speed steel straight knives are the only way to go because steel can be honed sharper than carbide. The down side being you will only attain that finish for a short period of time. If you want a slightly less quality finish for an extended period of time carbides are it, usually several months for us before turning the inserts. As far as stock removal we can easily take a 1/4-3/8" off of any material if needed with a respectable finish, although that is not required often.

Another huge factor, like the original poster noted, is the noise. The old straight knife planers scream terribly, especially as they start to dull. Lastly that fluffy chip is telling me that you are getting a good cut and that is the by-product of what the spiral head produces, itís a good thing. A bigger collector may be in order. Our machine actually uses a chevron pattern which directs the chips from the outer edges to the center of the hood. If we remove the hose it will literally spray a column of chips several feet out the back of the machine.

From contributor F:
I'm running a 7-1/2 hp Torit, for a one man shop! If that's not overkill already I don't know what is. By the way - how do you like the Cantek? I've seen them advertised but haven't heard any feedback on them.

From contributor U:
I run a Shelix head in my RC63. It works very well for me in part because I run a lot of Jatoba, which will dull out steel knives very quickly. I agree that I never look at grain direction any more, except that as the inserts dull, I actually prefer to cut into the grain - quieter and almost as smooth.

I've not had a clogging problem on any of the three cyclones that I've used with various Shelix heads. Maybe opening another gate somewhere to keep the airflow up through the cyclone would help in that situation. I put a Byrd head in my 12" jointer as well. If I go to a small moulder for S4S, I will likely get Byrd heads for it as well, at least for top/bottom.

From contributor M:

The Cantek we have is a 24" top and bottom straight-o-plane knockoff that has actually served us quite well. Like most import equipment there are certain thing you just say what the heck where they thinking. The design of the heads is pretty cool.

As far as your dust collection the one thing with a true spiral head the chips are directed to the path of the spiral. So material cut to one side of the dust chute may not discharge as easily, which means a little more CFM may be needed. We see this on our moulders that draw more from the side. If you switch the right and left spirals with top and bottom heads you throw the chip away from the dust port and out the front of the machine. A 7-1/2hp system sounds like a lot, but of course there are tons of factors such as open ports length of pipe, and etc. which I am sure you know. I would guess even at that size of collector on a good old SCMI planer pulling some serious chips you are right at that too small threshold.

From contributor F:
I've never used one but always wondered how well those old straight -o-plane machines really worked. Seems like a good concept if most of your stock is not too far out, but does it work well even on the gnarly twisted up boards you get so often? I just saw one go for peanuts a few weeks ago, but they're much bigger than I would need in my operation.

Youíre right - there are many factors to a good DC system, though after reading the last responses I realize we may be on different pages here. I don't get any clogging whatsoever at any of my machines, this cyclone will suck your skivvies off if you get too close! The problem I had when I hooked up the spiral head was at the bottom of the cyclone itself. Because the chips were so fluffy they would clog at the bottom (funnel) of the cyclone which then caused the shavings to bypass the drum and go right into the baghouse. A real PITA as I'm sure you can imagine. I was worried I would have to add a rotary air lock to try to keep things moving, but since switching to the SCM I haven't had that issue again. Hopefully I won't have to worry about it in the future either.

From contributor M:
The concept of the straight o plane is basically you are jointing your wood and planing in one operation. There is obviously limits and if the board is to crooked it will retain some of this. It is impressive to take say 15/16 hit and miss to 13/16 and see how flat the boards lay in the unit. You are right even our import is big and heavy, but two sides surfaced at once and flatter material, you can't beat it.