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Would you like to add information to this article? Interested in writing or submitting an article? Have a question about this article? Scalloping Marks Left by a Helical Jointer Head 
Question
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The lines left by my cutterhead (straight edged inserts) cannot easily be felt by hand. They are more pronounced in softer woods (poplar) than harder woods (maple, ipe), but even in poplar they are too slight to be of concern. I guess my non-expert opinion, without seeing it in person, is that the scalloping you are experiencing is normal for that cutterhead. I am surprised, though, as I thought the quality of cut from a Shelix would be superior to others.
From contributor A: I have a Shelix that I put on my cheap Grizzly 20" planer. The lines are nowhere near that distinct or consistent. I was a little concerned about the slight waviness, but found that they weren't an issue - glue lines right off the planer were acceptable, and wide belt sanding quickly took out the slight irregular scalloping. I'd be curious to know the actual depths of your scallops. Any chance you could use a feeler gauge and measure them? How much sanding does it take to eliminate them? I actually have a custom jointer head on order with Byrd, so I'm wondering if their quality is slipping, or are lines more severe on a larger diameter head? From the original questioner: Here is an attempt to measure the deviation in the scalloped surface. There is about .001 difference between valley and ridge of each scallop. We currently are without a widebelt, so I'm feeling a lot of scraping/sanding is in order. Unlike a few nicked knife ridges to bring down from a straight knife head, we will need to take down the entire surface. Granted we had to really rake a light across the board so others could see what we can feel, but... are we just whining here, or do others feel this is unacceptable?  Click here for higher quality, full size image From contributor P: Personally, I think it is acceptable. Neither planers nor jointers are intended to provide a final perfect finish. Jointers flatten a face, planers machine to thickness. If the scallops are smooth and tear free, you are way ahead. Just think how deep even light tearout penetrates into the wood. Even after running through a widebelt, unnoticed tearout will cause finishing problems, splotching, etc. I really do not think .001 would effect edge gluing. You could run boards for edge gluing through the machine at a skew; that may help in that case. From contributor B: I am a bit surprised by the general tone of the responses here. I know planers don't give finished surfaces, but I don't see anything remotely that poor looking coming out of my old 3 knife Powermatic 100 12" planer. In your shoes I'd be calling the manufacturer asking for either a fix or a refund. Don't mean to contradict others, it just looks unacceptable to me. From the original questioner: Thanks. I do feel a bit discouraged by the results. An indexed shelix head, by most everything you hear, including Bryd Tool (the manufacturer), is the end of all your woes. It has shown a pretty amazing ability to handle figured grain, and the significant reduction in noise is a welcome plus. The scalloping may be my tradeoff for those benefits. However it is not one I expected. So you have an older Powermatic 12"? Want to sell it!? Nice! Without selling your firstborn, it's hard to come by quality, wide jointers these days. From contributor J: I hate to have to say this, but you may be better off with a cheaper insert cutterhead. As I said previously, the finish I get isn't perfect, but it is pretty darned good. I'm surprised you can actually measure the depth of the scallops! My Bridgewood has the normal inserts and leaves fine lines in the surface of the wood. You couldn't measure them; you can only see them in a raking light. Similar to lines you get from straight knives after they've been used a little bit. Other than that, the finish needs only the lightest sanding, though almost everything goes through the sander anyway. I don't know if your head is defective or not, but I would certainly not be happy with the quality of cut you're getting. From contributor J: One thing I forgot. I was thinking of getting an insert cutterhead for my jointer. (Though I don't think it will be a Shelix after this thread!) Would you say the insert cutterhead requires more force to feed boards through? Or is it even a noticeable difference? From contributor G: Completely acceptable. .001 is a number most people can't even relate to. It is 1000 little marks to an inch. It is so small you should be able to sand those lines out by hand in no time at all. If you're getting a quieter shop and good throughput, I would buy a sander. You will find it a very valuable addition to your shop. From contributor P: Well, I got quite curious about this. Since I have an engineering degree and most of my regular day job revolves around designing machine tools, I thought this would be a good candidate for some further analysis. What I found is very close to what contributor B has discovered. I had to make some assumptions because I obviously do not have Byrd's engineering drawings. I assumed the inserts were 15mm, flat on top, straight leading edge. I guessed a shear angle of 10 deg.
What I found is that when you take an insert like this and orient it for shear, the resultant generated profile is a slight arc. Mathematically speaking it is not an ellipse or any pure geometric form, but an arc with a max height of .0014 about .36 in from one side, not in the center of the insert. Byrd staggers their inserts in such a way to deal with this. The best I could do was to get no better than about .00074 arc height. Very close to what the questioner found with his indicator. A smaller cylinder diameter will cause this arc to be even greater, maybe the .001 that was measured. So, there is absolutely no way the Shelix can cut a flat surface. There will always be scallops due to the set shear of the insert. The radius edge did not seem to make much difference. If you want flat, go with a Terminus; that is what I have and it is awesome.
From contributor R: Funny, as some say acceptable, and some would suggest going with something else. I say let’s see first what Byrd has to say. For laminating, in my opinion, I agree this is not acceptable. But for surfacing and/or planing a plank prior to assembly, in my opinion, it may look disappointing, but acceptable, and surely it is as easy and fast to remove as you would get out of a regular planer knife that leaves nick marks, which you would see going from any regular sanding steps prior to attacking your finishing steps! This type of head will/should give you more advantages and opportunity than pain! I hardly get a perfect assembly joint, glue-up and/or matting faces, that does not need little sanding. Any assembly needs some little sanding prior to attacking your finishing steps. In my opinion, with a half decent orbital sander and a regular pre-finish hand sanding job, you should see those go away. If not, than you can say it is not working right!
From contributor O: I have a Shelix 8" head on a jointer and I get nothing like you're showing. To me it seems like there is a problem with the head. I hope the Shelix Corp. can straighten it out for you. This should not happen. From the original questioner: Wow, contributor P! That's some serious analysis. I'm not familiar with Terminus. Now you have my curiosity up. Thank you all for the input. I have sent all pictures shown here to Byrd Tool over the last couple of days for their input. I have not gotten a direct response as of yet. I have a suspicion that with this style head, you get what you get. You take the good - no tear-out, quieter, with the bad - scalloping. From the original questioner: Well Byrd finally got a hold of me. They said that .001 is within their specs but that it looks worse than that. I think they're assuming the raking light makes it look worse than it is. Indeed I did everything I could to show the problem so you all could discern my situation. Byrd asked me to send them a couple of the sample boards that were in the pictures. They are sent. We should know in a week or so what their take is on it. From contributor U: I run a Shelix head in my 12" jointer and 24" planer. I know exactly what you mean about being disappointed by the scallops. You just spent a pile of money and thought it would be like straight knives, only better in every regard. But over time, my original concerns have faded away. For me, the benefits of the Shelix outweigh the very minor surface deviation. Quiet, fast, extremely little tearout. Those marks sand off very easily even with a ROS and 150 grit. Unless you are face laminating, and concerned with visible glue lines, it shouldn't be an issue. How often did you get away with going right from machine surface to final product before?
From contributor Y: What about edge jointing for panel glue-ups? Do these scallops create a more visible glue line? From contributor U: Regarding edge gluing and glue lines - I have not tried it, so I don't know. I have two jointers. The Shelix head is in the one that is setup with a feeder for facing boards. I don't edge joint on it. I did notice that the scallops were greatly reduced after I rotated the inserts, cleaning the inserts and seats as I went. It would only take some machining swarf/grit under a small percentage of inserts to make scalloping more prominent. Also, the cutterhead diameter plays a role in my experience. My first Shelix was in a 3" diameter planer head. It has more scalloping than the 4" jointer head, which has more than the head in the RC-63.
From contributor F: We have two of the Grizz 10 inch jointers with their index head and the finish is nowhere near as pronounced as you show. Check your insert seating, table alignment. As contributor J says, it is very important that the insert seat is clean and seated correctly. Even if it is factory new, I would check these two conditions, as sometimes you will get a Monday, Friday product even from Byrd. From contributor A: I don't agree that Byrd heads leave a surface too irregular for lamination, but would appreciate some input from the technical experts on the subject. Assuming regular or semi-regular undulations of .001", would this significantly weaken the bonds, given the recommendation for glue joints seems to be about .004"? Especially if one sends boards through a planer at an angle, or is careful to offset surfaces straight through a jointer, these little undulations shouldn't be a problem, right? My experience, making butcher block and end grain blocks gluing right off the Byrd head, has been positive. You really need a magnifying glass to see the difference between glue lines coming from straight knife head and those from the Byrd Shelix head. I was very worried about this, and tested it before making the switch. From contributor E: Okay. So color me totally impressed by the responses this question/concern has garnered. This is what this community is all about, in my opinion. I have to say, I looked at the indexable cutterhead scenario, and could not (then) justify it. I did, however, start to back-bevel the knives in my surfacing machinery, and the results are vastly improved, especially on figured solids. Maybe that's too old school, I dunno? I do not have to contend with volume. But the money I saved got me into digital readouts for everything - planers, sander, and ts... and a few rather choice Festools. ;) Have you reviewed the related Knowledge Base areas below? 
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