Spiral Head vs Straight Blade in a 15" or 20" planer. Which is better.

[Bob Feeser]

I just ordered a 20" planer and ordered one with the straight blades. I have been using my 12 1/2" Craftsman for about 10 years now and used my Tormek sharpening system with jointer/planer attachment to keep an keen edge on the blades. No down time, and no expense to sharpen, and no waiting for blades. How does that work with a spiral? Do you buy a back up set of blades for $1,000 bucks? I am asking because I don't know. I hear so many positive reviews about the spiral/helix or whatever, and wanted to know about them.
So what are the advantages? And what about cost benefit ratios? You can buy a whole Tormek system with the difference in price.

[Jeff Bratt]

Fine Woodworking (Winter 2012 #223) just did a head-to-head comparison of spiral vs. straight blades for planers and jointers - and they judged spiral to be significantly better. The cutters are carbide, so they last much longer than steel. And each cutter insert has 2 or 4 cutting edges, so this makes it easy to rotate one little insert if it gets a nick without changing the whole blade. And the true spiral blades - with the cutters making a shearing cut on the wood - produced a significantly better milled surface. So they thought that carbide spiral cutter heads were well worth the added cost. YMMV.

[david brum]

I think the biggest advantage is that you don't have to change the blades again. If I recall correctly, FWW figured that the carbide cutters would last 10X longer per side than HSS straight blades. That really means 20-40X longer, since the spiral carbide cutters have 4 sides vs 1 or 2 sides for straight blades. I'm pretty sure that's a lifetime for most casual users.

The other cool thing is that you can plane stuff that would kill HSS blades. For instance, I'm learning to veneer. I screwed up some veneer on one side of a big mdf board. I just skimmed the veneer off until I was down to bare mdf, then veneered it again. I never tried that with HSS blades, but I'm pretty sure that mdf and glue would have dulled them immediately.

[Rick Fisher]

I have a 20" Helical head planer but with 2-sided knives. I would not go back to straight knives unless they where Tersa knives.

The sound difference alone is not worth it. I have had to replace all my knives due to wear, but the amount of difficult wood that was planed would have been a lot of blade changes with old HSS knives..

Its about the best $1000 you could spend as an upgrade.. I would rather have a 15" Helical planer than a 20" straight knifed planer any day..

[Rob Wong]

I have Byrd spiral heads on both my planer and my jointer and would never go back to straight. Like everyone else says, it will last a lot longer, makes a smooth cut with a lot less tearout and is also quieter. Also easy to change cutters when nicked or worn. I've never turned mine once yet.

Aloha,
Rob

[Mike Heidrick]

David, did you scrap the veneer and glue off just to save a piece of MDF?

[Bob Feeser]

Great information. The option is always open to purchase the Byrd spiral head. One thing I realized when I awoke this morning, and that is with a 20 inch planer, and since I have an 8" jointer I can run the boards, lets say on the left side for dimensioning down to size at the faster rate, and then when I shift the feed rate to the slower speed for the final passes I can use the right side, thereby preserving the sharpness of that side for finer finishes.

[Bob Feeser]

Another point in question. I did do some planing on my Sears unit of MDF. I am installing waiscoting in my bedroom and am making it out of MDF since it is going to be painted. ( I started planing down some hickory I had for that purpose, and between the slow tedious task using the Craftsman planer, and the fact that the hickory is always so barky that you have to do thin strips of varying lengths, I spent two days and got one very small pile of wood, so I went and bought 3/4" MDF, problems solved)
Anyhow the point I wanted to make is that in the Shop Fox planer owners manual they tell you specifically NOT to plane MDF or other man made woods of course including plywood. But why does MDF hurt a planer? Any thoughts on that?

[Mark Engel]

The adhesives that are used in plywood and MDF are very hard/abrasive and will dull the knives very quickly. Even carbide knives.

[David Weaver]

Yeah, must be the blades. Plane a piece with a hand plane and note how long the iron stays sharp. That abrasive dust probably ends up everywhere in the planer, but for a cheap lunchbox that you won't do much, and one such that the blades are short enough that you can touch up the bevel on them with a jig or whatever, I'd use it for the MDF and not do it on the good planer.

Using a buddy's planer that was first a 20 inch straight blade planer, and then using it after the spiral head was swapped in, no contest. It leaves a surface that shines with the spiral head - no tearout ever. Same fellow switched out the head on his jointer, you can get it to tear out if you really ram a board through fast in a heavy cut, but if you're judicious, you'll be able to take out *any* imperfection with one swipe of a smoothing plane. The spiral head leaves such a good crisp surface that it hurts to pick up the board because of the sharpness of the corners. it was never like that with straight knives. A heavy cut on a 20" planer can take some magnificent tearout, too. With the spiral, not so.

[Rob Holcomb]

I have a 15" planer. When I bought it, I went with the straight blades. Cost was the biggest factor at the time. It seemed like every month I was taking the blades out to be sharpened and spending an hour putting the blades back in and getting everything set up correctly. Sometimes words would come out of my mouth that normally would not. I hated the procedure so much that I got to the point that I would rather sand more than change out the knives. This past spring, I bought and installed a spiral cutterhead with carbide cutters. I have run 100's of boardfeet of domestics through my planer, light passes on end grain cutting boards, pieces with dry glue left on them, etc. It's been 6 month's now and I haven't had to turn a cutter or do anything. The boards I'm running through it this week have as good of a finish as the ones I ran through it the first time I tried it. Buying the spiral cutterhead was the single best upgrade I've ever done and if I ever need to buy a bigger planer, I wouldn't even look at one with straight knives. The only thing I've noticed that would be on the negative side and it's really more my error rather than a negative is that if I take too deep of a cut, my 3HP planer will stop whereas when I had straight knives it would bog down but run the whole board through. I've just learned to be more careful with my depth of cuts to avoid that problem.

[david brum]

David, did you scrap the veneer and glue off just to save a piece of MDF?

No. I had veneered both sides with shop-cut veneer. My veneer was jointed, meticulously taped and laid out in a nice book match. Unfortunately, it wasn't uniformly thick in a few spots and I got glue pockets underneath the thin parts. Of course, this happened on the show side. It was a learning experience. Anyway, it was nice to be able to remove just one veneered side for a re-do. Running it through the planer was an experiment and I was really surprised at how well it worked.

[Bob Feeser]

So this is the deal. Thanks to you guys I can now see the clear difference making the helix the clear winner. My thinking was centering around the fact that with the Tormek sharpening, I can get scary sharp edges on the blades and get very smooth results. I also was misunderstanding the fact that you can rotate the carbide blades and get a fresh surface right away and not have down time while you sent yours away to be sharpened. Then the final deal breaker for me was realizing what the difference I could expect in terms of tear out. I have some hickory which wants to tear out no matter how soft I plane it in thiness. (Is that a word)?

Anyhow so here is the deal. I will wind up spending only $142 more if I get the planer and purchase the Byrd helix blades later. I know I have to go through the ag of switching them and all but right now dropping 3 grand on a planer is not a great idea. I am purchasing this because I am venturing into a mass production item, and I have to create the sales part of the business also. I did professional woodworking before but only want to specialize in one item now. So with all of that in mind the purchase price of the 20" plus running 40amp wiring is all that I want to spend right now to do my "experiment". I can buy the helix head later. The owners manual is one owners manual for both machines, the straight cut, and the spiral. They even say that the only difference is the cutter head. So for right now I am going to go that way.

Spiral helix rules. When this business works I will upgrade thusly. Thank you for your help. It is greatly appreciated.

[David Kumm]

Bob, keep in mind that if you are really good at sharpening and use the right kind of steel you will still get a great finish. You may need a good method of reinstalling them easily but the cut will still be fine. The diameter of the cutterhead and the angle into the cut, a secondary bevel if necessary, all contribute towards fine tuning a straight knife to perform in difficult woods. I use a Byrd and an ITCH head because I don't know how to do all that but my jointer knives are sent to Bobby at Woodworkers Toolworks and he is a genius at that stuff. The really high end planers have only begun offering spiral heads because they didn't really need them. The spiral is great because it masks the MUCH lower quality of planers these days. The great old Olivers, Northfields, Whitney and Buss planers gave a wonderful finish in the hands of people who knew how to use the onboard grinders and jointers. I'm just saying that your ability to sharpen well puts you at a different level than most and makes the spiral less of an improvement. Dave

[glenn bradley]

These threads often get as polarized a Festool or SawStop threads. That being said, your position on which is "better" will depend a great deal on what you do with them. If I wanted to quickly knock down rough lumber to a skip-planed sort of state I would not really care accept maybe that the carbide would go much longer between interventions. If I wanted as close to a 'finished' surface as possible I would turn to a lunchbox planer designed for such things as slower output with rubber rollers and so forth. Consider what you want your planer to do and then you will be able to decide which is "best".

I moved to spiral heads on my jointer and planer as I work with a decent amount of figured woods and tear out is an issue even with new or newly sharpened knives. Yes, there are a number of acrobatics you can go through to minimize this with knives but, I'm a hobbyist and my shop time is limited by that annoying day job . I like to be able to confidently move material through a machine with a very good expectation of what I will get out of it.

As to cost and payback for the initial outlay; here again your use will dictate the economics. Most quality inserts have four cutting faces and are quite resilient. I just turned my jointer inserts. In the period of time that I had used this initial cutting edge I would have sharpened my way through at least 3 (maybe 4) sets of knives based on my schedule with my knifed machine. This is based on the fact that after a certain number of sharpening sessions, the knives become unusable based on size. Once again, this is based on my use; your use is undoubtedly different. Using this logic I should be good for 12 to 16 sets of knives sharpened to their end-of-life. I added up the cost of the knives and the sharpening sessions based on past history and the spiral head paid for itself, no problem.

I haven't done the math but, I imagine the economics start to wane as the number of inserts rises. They are not cheap (although sources cheaper than the retailer are available) and knives are, relatively. I would still guess that a dozen or so sets of knives (at about $80 to $180 a set depending on quality) sharpened to their service limits would be more expensive than a 20" spiral that might cost around $800 for the same service life. The real test would be that after 6 years or so when it is time for a full replacement set, what's the cost of that and will you get through their life expectancy to get your money's worth out of them? You would have to play that out and judge for yourself.