helical head cutter life

[Kevin Jenness]

I was in the shop I used to work at yesterday and was checking out the SCMI L'Invincible 24" planer they bought new 9 months ago. This is a custom shop with 6 people on the floor. They just rotated the 140-odd carbide inserts for the first time. A few had nicks, and all had dulled to the point that increased current draw on the cutterhead was automatically kicking the feed motor down to low speed. The job took a couple of hours. For reference, the previous planer was an SCMI S520 with straight knives and onboard grinder which probably got tuned up every 3 to 4 weeks on average. The new unit is unbelievably quiet and is said to do an excellent job. Like most new gear it has electronic controls as well as air adjusted pressure rollers. I didn't ask what it cost.

[Patrick Kane]

Sounds about right, i empirically apply about once a year for small pro shops and upwards of 4-5 for hobbyists. I rotated my cutters after a year of usage, and immediately asked myself, "why?" after running the first board through the planer. Absolutely no difference. I dont buy into the 'knife setting time savings' argument that byrd and others like to use in their marketing materials. As your story notes, it is a LONG process to rotate 200+ cutters. Especially if you are cleaning the cutterhead of debris and using a torque wrench on all the inserts. They are experiencing the direct cost savings, because they had a grinder, but i feel carbide insert heads are a cheaper option over the course of 5+ years. No brainer for a pro shop.

[Jason Evans]

Sounds about right, i empirically apply about once a year for small pro shops and upwards of 4-5 for hobbyists. I rotated my cutters after a year of usage, and immediately asked myself, "why?" after running the first board through the planer. Absolutely no difference. I dont buy into the 'knife setting time savings' argument that byrd and others like to use in their marketing materials. As your story notes, it is a LONG process to rotate 200+ cutters. Especially if you are cleaning the cutterhead of debris and using a torque wrench on all the inserts. They are experiencing the direct cost savings, because they had a grinder, but i feel carbide insert heads are a cheaper option over the course of 5+ years. No brainer for a pro shop.

I buy into the time savings for sure. I switched to a byrd a head on my grizzly jointer and I haven’t turned the blades once in several years. I did replace one the chipped from my mistake with a piece of wood. I use it quite a lot, but not all day. When I had straight blades it took FOREVER to get the new blades perfectly set. Having to stop in the middle of a job and change them sucked. Not sure when I’ll know when to rotate them. I guess when it’s hard to push the wood through.

The straight blades though left a cleaner surface and sharper and cleaner corners when edging.

[Kevin Jenness]

i feel carbide insert heads are a cheaper option over the course of 5+ years. No brainer for a pro shop.

Assuming 10 minutes per month touching up the straight knives plus resetting the knives in the head at least once a year I would say they are already ahead on labor costs. If one were setting the decreased maintenance against the $3k+ it would cost to put a Shelix head in the old S520 it would take over 10 years to break even in my estimate. If they had been swapping knives out though rather than using an onboard grinder your estimate seems correct, even conservative.

I don't know if SCMI offers a Tersa option but it would be interesting to compare the life cycle costs of that vs. a helical vs. straight knives on a new machine. That of course is ignoring the reported reduced tearout with a helical head. I have worked only with traditional knives (HSS and carbide) and Tersa, but I am told the helicals are better in that respect. Most of what comes off the planer is then run through a wide belt so the slight scalloping is not an issue.

[Mark e Kessler]

I think that planer is in the 23-25k range, also with a helical insert the chips are reduced in size as well. If a main concern was tearout and I had a wide belt i would be sharpening my pencil on the cost savings of a helical over straight knife/tersa, of course there are other benefits like reduced noise, the smaller chips and reduced power needed but my gut tells me you are ahead of the game no matter with a helical….

[Patrick Kane]

I buy into the time savings for sure. I switched to a byrd a head on my grizzly jointer and I haven’t turned the blades once in several years. I did replace one the chipped from my mistake with a piece of wood. I use it quite a lot, but not all day. When I had straight blades it took FOREVER to get the new blades perfectly set. Having to stop in the middle of a job and change them sucked. Not sure when I’ll know when to rotate them. I guess when it’s hard to push the wood through.

The straight blades though left a cleaner surface and sharper and cleaner corners when edging.

Hmm, i remember it taking 10-15 mins tops to swap the blades on my 12" griz. It depends on the design of the cutterhead, if you dont have jack screw adjustments, then setting knives becomes a finicky affair. Also, i dont buy into the method of rotating the cutterhead until it moves a piece of wood/ruler a certain distance. Get a dial indicator setup and it becomes pretty simple. However, i have a tersa head jointer now and knife swap is 2-3 minutes at a casual pace. This is where i think over the course of years, its a wash with "time savings". Just a matter of do you want to take 5 year's worth of medicine in one afternoon, or spread it out over 5 years? I do think the carbide helical heads are much more cost effective than Tersa/sending out to be sharpened.

Did you snap a pic of the planer? To Mark's point, that is just about top of the heap. That or the T45.

[Scott Clausen]

I tried the "move the wood" technique and it was a total waste of time. Constructed a jig out of a 1,2,3 block and a dial gauge and was done on the first attempt. Came up with the idea and how to build here on LJ's. Lots of good problem solvers here.

[Mark e Kessler]

Interesting, I have always used the ruler move technique and it has always worked for me but that’s how I was taught by the “old guy” at my first ww job. To adjust the tables for coplaner, twist ect I use dial guages but that is usually a once and done…unless…

[Mark e Kessler]

For me if I had a widebelt I would probably gone straight knife on the planer but without a widebelt the benefit of the helical is to great for me regardless of time savings or not. When I go separates i will probably go tersa on a jointer and helical on planer…

[Keegan Shields]

Don't helical heads require more power over straight knives of the same size machine? Since there is virtually always a cutter in contact with the wood on a helical head, the motor doesn't get the benefit of acceleration between knives like on a 3 or 4 knife head.

Either way, I love the helical heads on my machines.

[Mark e Kessler]

Don't helical heads require more power over straight knives of the same size machine? Since there is virtually always a cutter in contact with the wood on a helical head, the motor doesn't get the benefit of acceleration between knives like on a 3 or 4 knife head.

Either way, I love the helical heads on my machines.

Not sure on others but I believe Felder achieved the lower power by using less cutters and adjusting the layout of the spiral… It is true though that there is cutter in contact with the wood at all times which does make it more difficult to push the wood through a jointer which is also why when I get separates I will more than likely go with a straight knife/tersa head on the jointer

[Thomas Pender]

Have to agree with Keegan’s point. Takes more effort to push things through my helical jointer than my old knife jointer. I attribute that to the constant contact with the cutters. As for turning the cutter heads, I would simply unplug it and get a magnifying glass and look for nicks, chips, or whatever. If it looks suspect, turn it - you can buy them at a reasonable price once you have turned them 3 times (Grizzly sent me a bunch of spares with the jointer) and it seems worth it. Might be good to have a frame of reference from when it was new as far as effort and condition is concerned, but I do love my Grizzly Helical jointer, although making it co-planer was a challenge when I got it.

[Andrew Hughes]

My unscientific research for the increased feed pressure with the insert head is. Very small or even zero forward rake I cannot be the only one that’s noticed the facebevel on a insert. I measured it to be 30 degrees.
Anyone with a straight knife jointer can add a 7or 8 degree face bevel and reduce the forward rake. It will take a lot more effort to push the wood but eliminate tearback. The face bevel acts like a chip breaker.
Im against a insert head for a amateur shop like mine. Because sharp wins every time with woodworking
Good Luck