# Spiral Cutterhead vs Straight Knives



## jcecil (May 28, 2008)

I am trying to decide on whether to buy the Grizzly 15" planer with spiral cutterhead or get the Grizzly 20" planer with straight knives. The price is the same, thus the decision between the two. I wanted to sorta poll everybody and see given equal costs if people think spiral cutterhead and less capacity or more capacity is better, most important etc.


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## CedarFreakCarl (Apr 21, 2007)

I've got a Ridgid 13" planer with straight knives and spend a small fortune on blades as well as having to deal with tearout on figured woods. I've also got a 8" Grizzly jointer with a spiral cutterhead. After using the Grizzly with the spiral cutter head, it's a no brainer. I've experienced no tear out on the figured stuff. Also, with the individual carbide cutters, not only do they last a long time, but it one gets nicked, you just loosen it up and rotate it 90 degrees and you're back in business. With 4 edges, they will last a long long time. Just my .02$.


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## Bureaucrat (May 26, 2008)

there is an article on jointers in WOOD magazine this month where they recommend straight knives. "We got a smooth consistent wood surface from the four knives on…" Don't know if that transfers to planers or not


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## mgradwohl (Dec 17, 2007)

It looks like you're making a tradeoff of width (15 vs. 20) or cutterhead (spiral vs. straight).

I have never needed a planer bigger than my 13" Delta, so I'd go for the 15" (still bigger than what I have) with the spiral cutterhead.

I'd much rather have a smaller tool that cuts well, than a wide tool that tears out. It depends on what you build.

Cut quality beats cut capacity in my book. Who cares about a piece of poorly planed wide stock?


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## jcecil (May 28, 2008)

I will sometimes run a glue up through the planer which can get large sometimes. I know some of you might say thats a no no, but I do. Other than that yeah I really don't come across any issues with wide boards. I have been leaning to the 15" but then again I still have that idea that if I bought the 20" I could always upgrade the cutterhead if I wanted to but with the 15" thats a whole new machine to get more capacity.


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## mgradwohl (Dec 17, 2007)

If you get the 20, you can upgrade the cutterhead, that's a good point.

Of course, by the time you upgrade the cutterhead, it'll probably be best to sell the old one and buy a new one. They'll have laser spiral porcelain polishing cutterheads.


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## dsb1829 (Jun 20, 2008)

I really like my spiral cutter on my jointer. Woodjoint does bring a valid point. Spiral heads leave small tracks where the inserts don't quite overlap. They knock off with a single pass of a hand plane, but they are there none the less.

I would err on the side of the bigger tool. You can upgrade the cutter when funds/time allows.


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## roman (Sep 28, 2007)

Cedarfreakcarl…...................I agree with him.

if there are lines after planing with a spiral cutting head then somebody didnt install the knives correctly because the little tungsten steel/carbide four sided knives should overlap each other to eliminate this problem.

I would love a spiral cutting head…..................no tear out on burly, figured, or any other kind of wood.


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## dsb1829 (Jun 20, 2008)

Roman, all of the spiral heads leave track lines. Some are better/worse than others. Some people notice these lines and others don't. I have a Byrd head on my jointer. The tracks it leaves are small and almost undetectable unless you are looking for them. They are there none the less though.


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## lrob (Jan 10, 2011)

I to have the same problem. I have an old 12" Delsaw planner I have been using for 35years and every time I nick the blades I spend a fortune replacing them. I got a hold of some 18" wide boards and want to keep them as wide as possible, the 20" would be great, if I have to replace those knives they must be even more costly. The spiral head could be install later I quess. I wish I had a local Grizzley Distrubtor so I could see the spiral cutterhead in action.


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## Loren (May 30, 2008)

Straight knives are a piece of cake to resharpen with a Makita or similar
wet grinder.

I use straight knives. Spiral does have an appeal, I'll admit, but since I'm
partial to and pleased to use vintage machinery, my options for upgrading 
cutterheads are a bit limited, not to mention costly.

A "real" planer with straight knives generally outperforms the lunchbox 
planers in terms of consistency from part to part. The small planers 
have nicer finishes, but consistency in thickness of parts is less. I'm
not saying every heavy iron planer will out-perform every lunchbox planer.
Uniformity in thicknessing is more important to me than surface quality
off the planer. Your criteria may be different. In any case, I've found
straight knives easy to maintain and do produce the result I'm after.

Some cabinetmakers joint plywood panels, which is very hard on jointer
knives. There's a good reason to do it since it removes deviations in
cabinet panels cause by internal stresses in the panels and removes the
saw marks that usually happen here and there when you're breaking 
up a lot of sheets. With insert cutterheads the jointer knives would 
last longer, especially carbide ones.

If you're not after speed and consistency from part to part your criteria
for what you want may be more flexible. Lower noise, for example,
may be more important to you.


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## Pop (Aug 6, 2007)

What exactly are we talking about here? There spiral cutter heads that use segmented straight knives such as a Powermatic model 15S. Then there are so called spiral heads which are really helical heads such as the Byrd/Powermatic model 15HH. I have the Helical head Powermatic 15HH plane. I have no small tracks on my planed wood. With the helical head it would be quite impossible since there are 2 rows for every 1 row in a straight blade plane. The purpose for the 2nd row is to fill the voids in the spacing of the cutters in the 1st row. There is no place on the cutter head were a blade is not present in the planing process.

Pop


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## WoodLe (Sep 29, 2010)

I have a 15" spiral cutterhead planer and just love it. I sold my 15" straight knife and never regretted it. I planed some character hickory lumber for a set of kitchen cabinets and was impressed with how smooth it came out even with all those knots and 'character'. I don't think my old planner could have come close. But if you don't do much with character or figured woods, you probably will get by with a straight knife. If I was to choose, I would pick the smaller planner with the spiral cutterhead.


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## Danderson (Jan 19, 2011)

Here is a great blog in Popular Woodworking about the total cost of ownership of 4 knife vs helical cutterheads (specifically as it relates to the Grizzly G0593 vs G0586 jointers.

http://blogs.popularwoodworking.com/editorsblog/CommentView,guid,1bef51c2-ced3-41a5-84e4-f75517f81f64.aspx

I hope this helps.

-Dan


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## McKinneyMike (Feb 11, 2011)

The three things that a spiral cutter head has over a straight knife bladed head in general are:

1) Spiral/Helical head is very quiet by comparison!
2) No tearout when planing figured or difficult to plane species of lumber
3) Much easier to maintain, but does require thoroughly cleaning insert seats when replacing or indexing cutters.

I bought one of the first Byrd helical cutter heads back in early 2001 as I needed a solution for planing figured hardwood lumber. I was sold from the moment that I turned the planer on for the first time after changing the cutter head but when I ran the first piece of curly qtr sawn White Oak thru the planer, I was in heaven. This is without question the most difficult figured wood that I have ever handled and I have had or sold about every variety in existence over the years. 
The expense is tough to swallow for a hobbyist woodworker, but if you value your ears, it is well worth the cost in the log run.


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## pvwoodcrafts (Aug 31, 2007)

I have a Grizzly 20 in planer and an old 221 powermatic 20 in. planer. I upgraded both to the byrd head and have never regretted it. I would spend $200 a year for each planer to sharpen straight blades. I get nearly 2 years out of each side of the carbide inserts. The way I see it it will pay for itself in under 6 years. Other benefits are: noise level drastically reduced, No tearout even on glued up curly maple panels despite grain direction. It's a no brainer for me


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## richgreer (Dec 25, 2009)

I know some will disagree with me on this but I read a very good article about the power requirements on a spiral head versus straight blade jointer. According to this article, the spiral head requires more power to do the same work.

Why? With straight blades the motor gets a micro second to recover between each hit by a blade. This allows the head to have a slight hammering effect. With a spiral head the head is constantly cutting with no breaks to recover.

According to this article, the difference in power requirements can be noticeable.

FWIW, I am very happy with the straight blades on my jointer (and planer).


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## Pop (Aug 6, 2007)

I have never been so happy to see a machine go as when I swapped my straight blade planer for my helical head planer. On the power question, the machine needs the rest between a full contact of a straight blade. The helical never fully contacts the wood with more than a 1/2 inch carbide tooth at a time. It would seem to me that this would require less not more power with less strain on the motor.

Pop


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## WoodLe (Sep 29, 2010)

A lot of websites say that a true spiral shear cut cutterhead uses LESS horsepower. Just google it for yourself.


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## Pop (Aug 6, 2007)

Thanks WoodLe, As I was pointing out a straight blade applies force to a 12 or 15 inch point on contact with the wood. A helical spiral only contacts the wood in 1/2 inch increments. Yes it would require less power. These 1/2 inch index cutters have 2 more advantages. 1. They make less noise. 2. They produce a small chip instead of a long twisted chip that clogs up dust collection equipment. I was told by the engineer in charge of dust collection R & D at Delta that the worst chip in a woodshop to clog up dust collection equipment was the long spiral chip produced by a straight knife surface plane.

Pop


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## aewd (Mar 23, 2011)

This is an easy one. After using both the standard three-knife cutterhead and the spiral replacement (1/2" inserts) for 5+ years each on my 8" Woodtek jointer and 15" Woodtek planer, this is what I know:
Each face of the carbide squares stays sharp for at least six months, even with heavy use. Four turns means at least two years before replacement. 
Turning the knives, including cleaning the knives and seats takes a little over an hour to do both machines. I've turned them without cleaning once without ill effects. That took half the time. 
Try face planing or planing heavily figured maple uphill with even the sharpest long steel knives. Even with a slow feed on the jointer and low speed on the planer, it is a crapshoot. The little cutters, however, do a perfect job, one month in, three months in, five months in. 
The spiral cutters are MUCH quieter as well. 
While I've never used standard carbide knives so I can't comment about them, compared to steel knives, there is no comparison whatsoever, as far as cut quality, changing time, and noise. I would venture to guess that anyone who has used both would say the same. I hope I never have to change, adjust or have sharpened another standard knife again. 
Two things though-the cutters can leave those very slight steps, and with hardwoods, you MAY need to step down a grit to start your sanding. And the cutters, when finally replaced, aren't cheap-nearly $4.00 ea from Woodworker's Supply. Anyone know of a cheaper source??
But I will never go back.


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## Stationarycopper (Apr 12, 2012)

I do not know if anyone is still interested but here is the updated link for the article Danderson posted over a year ago…..
http://www.popularwoodworking.com/article/are-helical-cutterheads-the-answer-part-2


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## Porosky (Mar 10, 2009)

spiral. end of discussion.


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## pmayer (Jan 3, 2010)

I have a 18" woodmaster with spiral cutterhead. The cut quality is amazing, and even more impressive is the noise reduction. Average sound level when planing is about 82 db, compared to 92 with same machine using straight blades.

If I had to choose between spriral cutterhead and 3" capacity I would take the spiral cutterhead. There are workarounds for cheating more capacity out of your planer, but when you take a divot out of your table top with a regular planer knife, you have your work cut out for you.


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## thebigvise (Jun 17, 2010)

Byrd-Shelix helical all the way.


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## rustynails (Jun 23, 2011)

I have a 8'' jointer and a 15'' planner both with the spiral cutterheads love both of them compared to my old straight knive machines.

Hands down the way to go…

Richard


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## Bobsboxes (Feb 8, 2011)

I have 15" spiral planer and 8" spiral jointer. They are way better than knives, I have had 3 knife planers and will never own another, they are money eaters, I have had my spiral planer for over 4 years and use it every day in winter, and have yet to turn carbide cutters. I was going thru 3-4 sets of blades a year, around 150-200 dollars a year.


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## pmayer (Jan 3, 2010)

On the power requirements topic, I have seen strong opinions on both sides of this debate. I spoke with engineers at both Grizzly (where I got my jointer) and Woodmaster (planer), and they both indicated that spiral cutterheads required less power than conventional cutterheads. In use, I don't see the jointer struggling at all with a spiral cutterhead, but at the same time I have never used that jointer with standard knives. The planer can not cut as deeply with a spiral cutterhead, but I believe that is a result of the low cutting angle rather than a power issue. In my own unscientific comparison of a standard cutterhead vs. spiral cutterhead on my planer where I have both cutterheads, I believe that there is more resistance/drag with the spiral cutterhead.


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## DocSavage45 (Aug 14, 2010)

Great thread. I'm getting the feel that there are more pros than cons to a spiral head planer. If I am doing figured woods, it seems a no brainer. I have a luch box delta that has been discontinued. Haven't run hardwood through it yet. Will use it until I can afford a larger more efficient machine. Read somewhere that going from straight knife cutter to a hellical cutter is more expensive. since I'm tight with my money ( who isn't these days) I'll probably go w/carbide cutters on a grizzly machine.


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## ChrisCarr (Jun 19, 2010)

Im looking to buy a new jointer in the next year and am thinking about getting a grizzly with a spiral. I also like the parallelogram jointers, since there longer, simpler in maintenance and easier to fix since you dont need shims to get the tables right.


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## Brad_Nailor (Jul 26, 2007)

I have owned the Steel City 13" spiral head planer for about a year and a half and I really like it. It definitely does everything discussed here..It's quiet compared to a similar straight knife planer..It excels in planing curly, figured woods..It leaves a really nice almost 150 grit sanded feel to the planed lumber. As far as "tracks" discussed here, I can see some planer marks if I hold the boards up to a raking light, but it's nothing I can actually feel with my fingers, and nothing a light sanding with some 150 grit wouldn't take care of. In comparison to other smaller planers, and even larger straight knife planers the planer marks left by my spiral cutter head are nothing compared to the knife marks, tear out, and sniping I would get when the lumber dealer would plane stuff for me. I have a small Rigid jointer, and they actually make a Byrd/Shelix spiral cutter head for it..only it costs more than I paid for the whole jointer! Once i get into a shop with more room I want a long bed 8" with spiral cutterhead..


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