Helical cutter head problem

[Robert Chapman]

I just bought a new Jet jointer and a Powermatic planer with helical cutter heads. Initial impression was that the helical heads gave a very smooth cut with little final sanding needed. I'm doing a table of birdseye and curly maple. After planing I finish sanded the top with 220 grit and stained/finished. That was when I saw the marks left by the planer. The marks go the lenght of the board and are very slight parallel ridges - I could not see them until I had on the satin finish - but they are definetly noticable. I sanded them out and now the top looks fine. It takes a lot of sanding because the ridges are very gradual across their height. I get the marks from both the jointer and planer. Is this typical of helical cutter heads? If not, what can I do to correct this problem? It seems like the old strainght knife cutterheads needed less sanding to get a really smooth surface. Thoughts? Suggestions?

[Jason Beam]

There was an article in one of the wood mags in the last 3-4 years that saw exactly what you've reported, too. Seems normal, as I can tell. :)

Sugguestions? Get friendly with a hand scraper :)

[C Scott McDonald]

Seem to remember a thread here about that. maybe to much pressure on the rollers I don't remember.

[Mike Spanbauer]

it's normal, just have to sand them out.

It doesn't take that much time to run on up through the grits, but the finish can fool you into thinking nothing is needed.

Another fast way to remove them if you've a smaller work piece is a card scraper (I can scrape as fast as I can sand usually, but it's a matter of thumb stamina).

mike

[glenn bradley]

If you do an SMC "Google" search on the word 'scallop' you will get a few threads on this. Some folks report them and some don't. I can force them if I run the material way faster than I should through my jointer (that's me; I just had to keep trying to see if I could make it happen). On a planer it could be more of a problem as some do not have speed adjustments. On your jointer, take it slow and I would expect them to go away. I'll assume there are some adjustments associated with the problem as various degrees from "none" to "ouch" are reported. Maybe someone who has had the problem and been able to reduce or eliminate it will chime in ;-)

[Mike Spanbauer]

Glenn,

I've not seen a Byrd head that can produce cuts without extremely slight scalloping. What I implied in my response and have experienced is that even if you can't feel the ridges (I can NOT feel them on mine) they are visible in a raking light with certain species.

It's the nature of the cutting motion, I don't believe ANY of the segmented heads avoid this.

mike

[Joe Jensen]

The light marks are normal. If you start with 120 grit they sand out very quickly. Using every grit from 120 to 220 will make quick work of it.

Just remember the tearout you used to get with straight knives, and how tearout takes WAY more time to sand. :)

[Adam Grills]

If you do an SMC "Google" search on the word 'scallop' you will get a few threads on this. Some folks report them and some don't. I can force them if I run the material way faster than I should through my jointer (that's me; I just had to keep trying to see if I could make it happen). On a planer it could be more of a problem as some do not have speed adjustments. On your jointer, take it slow and I would expect them to go away. I'll assume there are some adjustments associated with the problem as various degrees from "none" to "ouch" are reported. Maybe someone who has had the problem and been able to reduce or eliminate it will chime in ;-)


Glen,
Feed speed does not correct or change this, it is the nature of the cutter head. It is better to have a slight sandable scallop than have tearout that you can/ can't fix with alot of work.

I am running a Bryd head and have the line/ scallops. IMO never go from planer to P220 grit! I go from P120 and up and they disappear fast!

Adam

[Robert Chapman]

Thanks guys - I gues that there is no such thing as " just a 220 grit sanding". Should have known that it was too good to be true. It is true that the tear out is really minimized - even with highly figured birdseye maple.

[David DeCristoforo]

This is the problem with the current generation of so-called "spiral" insert cutter heads. A "true" helical head has continuous knives that wrap around the cutter head. It is these cutter heads upon which the reputation of helical heads is based. Unfortunately, these proved hideously expensive to manufacture and required dedicated machine mounted sharpening attachments. It was not long before the segmented "insert" cutter system was implemented. This was much more economical to produce and also eliminated the sharpening problems. Unfortunately, these heads do not perform at the same level of their more expensive predecessors. It is almost impossible to produce a perfectly clean surface with segmented knives. It's just the nature of the beast. There is little you can do since there is no way to adjust the inserts and there are so many of them that even if you could adjust them, you would probably need a week to do it!

[glenn bradley]

Glenn,

I've not seen a Byrd head that can produce cuts without extremely slight scalloping. What I implied in my response and have experienced is that even if you can't feel the ridges (I can NOT feel them on mine) they are visible in a raking light with certain species.

It's the nature of the cutting motion, I don't believe ANY of the segmented heads avoid this.

mike

I agree Mike. At that slight degree, straight knives do it too. After all, the knife (or insert) is not moving parallel to the face, it is arcing toward and away as it passes,eh? Like you say, sometimes it is so slight that it is as good as invisible. I don't think many of us expectto go right from the machine to finishing but sometimes it sure "feels" that way ;-) What I meant by "forcing them" is that I can make them more apparent if I try hard enough.

[Mike Spanbauer]

Yeah, I finished my first piece off the head thinking it was perfect... urm... oops. Thankfully it was a minor piece for my son and it'll be beat up fast enough that the finished surface won't be recognized :)

Although, there is NO way you'd get me to go back to straight knives after using a byrd.

David does bring up the one odd blade type that had a very short life, which was the blade that literally wrapped around the head creating a shearing cut (one continuous knife, that wrapped around the head about 20-30Deg). They didn't last too long as they were all HCS and HSS due to the flexibility. - talking about the replaceable knife versions. Then there were the super expensive grind on machine spiral heads that David mentioned... 'spensive OUCH.

There is one other type, just for completeness that we haven't mentioned here which is the long segmented cutters that Northfield and other *uber* class machines possess. Rathern than the 4 cutting surface inserts you find on the "economical" versions, the segmented cutters were MUCH wider such as 1-2" each and had 2 cutting edges. I've never seen the production surface from that machine, but I suspect it doesn't have ridges... of course, it costs 2-5x the price of the Byrd for a comparable size.

mike

[Chip Lindley]

Robert? Do these marks extend across the width of your board (corresponding to knife marks?) or form corrugations down the length of the board? Just trying to visualize, since I am giving the purchase of a helical head much consideration. Thanks!

[Joe Jensen]

Robert? Do these marks extend across the width of your board (corresponding to knife marks?) or form corrugations down the length of the board? Just trying to visualize, since I am giving the purchase of a helical head much consideration. Thanks!

The ridges are about 1/2" apart. They are so slight that you can't feel them, and often can't see them unless the light is just right. The are very easy to remove with 120 grit, and IMHO they are no worse than the small ridges that ran across boards off my straight knife cutterhead. If you finish a piece right off a straight knife planer you will see ridges across the board about 1/64" apart.

[Stan Urbas]

The way guys talk about how great these things are, I thought I was the only one with that problem. I thought I could "adjust" the problem away, but no go. So now I only use my spiral head on problem wood, like figured maple. For most others, like cherry, pine, oak, hickory I go back to the regular planer blades and keep them sharp. When I do use the spiral on figured maple I start sanding at 80 grit and work my way up.

[Rick Fisher]

General uses a head called the Magnum Head. The promote is not causing scallops. It uses a wider blade than the Byrd which is made in Germany.

The replacement cutters are $5.50 each and only 2 sided, so the cost is much higher than operating a Byrd head.

I have one, it has never scalloped but it has, on occasion caused very slight tearout in maple. (when the grain changes sharply).

The tearout is nothing like a straight knife, but its there.

I kinda think its one or the other. Tear out or scallop. I think it probably better on some wood and not as good on other wood.

Its a nasty looking thing too.

http://i335.photobucket.com/albums/m455/jokerbird_photo/Planer.jpg

If you work figured maple, the Byrd head is likely the best there is. Sanding is just a fact of life.

[Robert Chapman]

Joe - the ridges are like corrugations down the lenght of the board. I would still recommend the helical cutter. Just have to sand more than I hoped [my least favorite woodworking task].

[Joe Jensen]

The way guys talk about how great these things are, I thought I was the only one with that problem. I thought I could "adjust" the problem away, but no go. So now I only use my spiral head on problem wood, like figured maple. For most others, like cherry, pine, oak, hickory I go back to the regular planer blades and keep them sharp. When I do use the spiral on figured maple I start sanding at 80 grit and work my way up.

80 grit WOW

You must have WAY different ridges than I do. I can't imagine needed to go below 120. I can remove them in less than a minute on a door with 120...joe

[Cliff Rohrabacher]

I recall a thread here about this same issue. If I recall correctly, it boiled down to a question of whether the cutterhead was a true helical or just a round-ish carbide insert cutterhead.

I'm runnin fumes here but, I think the deal was that in the world of helical cutterheads not all are created equal. Some are true helical and some just look like it. The true helical ones cost a fair bit more.

[Cliff Rohrabacher]

Ohh that's a purdy cutter head da Griz gots there.

Nice universal grind on the carbide too. Took a brave engineer to specify that I bet.

[Mikail Khan]

I have a Grizz 1033X planer and a Grizz 609X jointer. Both have different types of spiral heads.

The planer inserts are set in a helical pattern, they are set at an angle to the feed direction and have a slightly curved edge (I think it is Byrd Head). The inserts measure 0.588" accross the middle and 0.576" along the sides. So the curve on each side is about 0.006" high. The planer leaves ridges that have to be sanded out because of the curved edges of the inserts.

The 609X jointer has a Grizz head (I think). The inserts are set in a helical pattern. Unlike the planer, the inserts are set perpendicular to the direction of feed and have straight edges. The jointer does not leaves ridges like the planer does beacuse the inserts are not curved. Light sanding is still required because of my poor technique which leaves ridges when I change the position of my hands.

MK

[Sean Rainaldi]

I have a Grizz 1033X planer and a Grizz 609X jointer. Both have different types of spiral heads.

The planer inserts are set in a helical pattern, they are set at an angle to the feed direction and have a slightly curved edge (I think it is Byrd Head). The inserts measure 0.588" accross the middle and 0.576" along the sides. So the curve on each side is about 0.006" high. The planer leaves ridges that have to be sanded out because of the curved edges of the inserts.

The 609X jointer has a Grizz head (I think). The inserts are set in a helical pattern. Unlike the planer, the inserts are set perpendicular to the direction of feed and have straight edges. The jointer does not leaves ridges like the planer does beacuse the inserts are not curved. Light sanding is still required because of my poor technique which leaves ridges when I change the position of my hands.

MK

I was comparing the two could not decide.

So from what you are saying, it sounds like the grizzly head for the 15 inch planer at 100 bucks less than the byrd would provide a better finish than the Byrd, although the Byrd might last longer.

Anyone agree or disagree?

[Karl Brogger]

I've got the wrap around the head style knives in my planer. I think its a model 15 Powermatic. In any case, I can't find anyone to sharpen them. The new knives are about $100 a set. I wish the little insert cutter head was available when I bought mine, the maintenance would be much less. I don't know what just the head costs but it might be more economical just to replace the head.

As far as I'm concerned nothing that comes out of a planer is finished. Its a rough tool, for rough work. Not that it can't be accurate, but for instance when I build drawers, the material is planed to +1/16", thrown through the widebelt to thickness (80g/120g/180g), then sanded with an orbital with 150g.

The big Northfield planers don't actually leave that great of a surface, even with the small knives. But they will hog off a 1/4" at full width with out too much complaining. Most commercial shops can't justify the $30k price tag on one. But it will be the last planer ever required by that company. I'm a little biased, they're made in my home town, the high school had a sweet wood shop, mostly Northfield Equipment too.