Spiral Cutterhead vs Straight Knives

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$.

-- Carl Rast, Pelion, SC

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

-- gjd Southcentral Wisconsin

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?

-- Matt Gradwohl, Upper Cut Woodworks, http://uppercutwoodworks.com/

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.

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.

-- Matt Gradwohl, Upper Cut Woodworks, http://uppercutwoodworks.com/

A lot of it has to do with feed speed. I can slow down my Rockwell 18” wedgebed palner and do figured wood nicely. People rave about the insert heads but don’t really have other experinces to compare it to. I’ve been in the industry for 35 years and rebuild machinery. There is validity to the insert heads but the straight knife heads are better than most know if you know how to tweak them.

-- Few folks really know how to maximize the potential of their tools!

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.

-- Doug, woodworking in Alabama

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.

-- "Good artists borrow, great artists steal”…..Picasso

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.

-- Doug, woodworking in Alabama

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.

-- Remember the one with the most toys when he dies WINS!

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.

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

-- One who works with his hands is a laborer, his hands & head A craftsman, his hands, head & heart a artist

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.

-- www.largewoodslabs.com Apple Creek, Ohio

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

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.

-- McKinney Hardwood Lumber --Specializing in exotic and figured hardwood lumber http://www.mckinneyhardwoods.com -McKinney, TX