carbide inserted cutter heads and why I will not change

[Tom Bussey]

I am not saying that there is anything wrong with people spending their money for carbide cutter heads on jointers. And this thread has nothing to do with inserted planners.

It is about why I will not switch.


In the METAL CUTTING industry the rule of thumb for horse power needed for carbide inserts is 1 1/2 horse power per insert. A 3 inserted face mill then requires 4 1/2 horse power to use the cutter efficiently. There are other things that factor in also, like depth of cut and feed rate. The feed rate calculated by chip load per tooth times the number of teeth times the rpm. and to drive the cutter. Therefore, the deeper the cut the more power power is needed to drive both the spindle RPMs and power at the gear box. IN other words the more weight you are going to haul, the bigger the truck you should have. There are a lot of other things that factor in, like how to remove cubic feet of metal the fastest like less depth of cut verses much faster feed rates and modern cutter technologies.

High speed cutters on the other hand are sharper than inserted carbide cutters therefore requiring less horse power. And because the cutter is sharper it also requires less horse power to feed the cutter. And lighter depth of cut requires even less horse power to drive the feed rate. Fact: it is easier to cut yourself installing a a high speed jointer knife than changing a carbide insert on the cutter head.

I hope everyone will agree with me on the fact that a board can not be flattened on a planner. If a board is cupped, bowed, or twisted going in to a planner it it will be cupped bowed or twisted coming out of the planner. The reason being that the pressure rollers and the cutter head flatten the board in the planner but only mechanically. The bow for example return once the pressure is relieved.

The only time I actually tried out a carbide cutter on a jointer i noticed how much more pressure it took to move the wood a crossed the cutter. In other words it takes more downward pressure to move the wood a crossed the cutter. I watch some on TV and it looks like they have their elbows locked when using it. Now, one can remove a cup from a board with this method and if careful a twist somewhat as long not as to much pressure is used, but if you have to apply any downward pressure at all in the bowed section while running it a crossed a jointer then, when a bowed board is flattened on the jointer table during the cut ( the same thing happens as in the planner ) and the bow will return when the downward pressure is released.

My jointer is a 8 inch from Sunhill. It is at least 30 years old. It came with what I believe is a 1 1/2 HP motor. It is possible it could be a 2 HP motor because it is 220 volt but i don't think so. It is snowing right now and my shop is a mile away and unheated and I don't feel like going over to an unheated shop and move the jointer out of its position so I can take the back of the machine off just to find out. MY point is today the inserted cutter head machines are 3 HP not 1 1/2 or 2. And before you jump to conclusions and say the straight knife machines are also 3 HP it is because they use the same motor and pass the extra cost on to you and pass it as an upgraded ( Better) selling advantage.

I indicate my knives in so there is no more difference in height that 2 thousandths in total runout on my indicator. they are also indicated in straight with the outfeed table. In other words I have all three cutters working and I don't have 2 sharp cutters and one dull cutter that is doing all the work. Once my fence is squared to the outfeed table it will remain squared to the table until I change knives.

My depth of cut is .015 ( 2 passes is a 32th. And I use a push stick like on a table saw and can push a board as long as my infeed table is with one hand.

And this is why I will not spend an extra $400 plus for a carbide upgrade for my jointer bit I will spend$275 for a dispozablade system. disposablade.com

[Jim Becker]

Relative to this, in the Tersa world, there are several different knife formulas available, Chromium, HSS, M+ HSS and carbide. They each have "endearing properties". The Chromium, which is the lowest cost, are extremely sharp and really perform nicely in softwoods. The HSS and M+ HSS are more optimal for general use in hardwoods. All three of these types are "sharper" than the carbide. The carbide obviously lasts a lot longer which is nice, considering that they cost a whole bunch more. Carbide are not as sharp as the others initially, but over time, they retain their sharpness longer. Some folks absolutely prefer them. Honestly, I've been very happy with the M+ HSS and have used those for years. Some folks do use multiple formulas depending on what they are doing, but with Tersa (or a quick change system like you mention, Tom), changing is fast and easy. It's also easy to move one or two laterally just a hair to deal with an unfortunate nick.

[Keegan Shields]

Tom, variety is the spice of life man… give them a chance!

Here’s how I look at it. The free market is pretty efficient, so if companies like Byrd and all the major manufacturers sell carbide cutter heads on their machines, a great many people must find the feature valuable. I know I do. But it’s cool if you don’t. I would like to try a Teresa style head at some point, seems like it might be the best of both worlds.

I totally agree on boards being harder to feed on a jointer with carbide inserts, having had conventional knives and the segmented cutter head style. But for me, the benefits (no tear out, durable cutters that are tough to nick, easy replacement if damaged) outweigh the downsides (more feed pressure, inferior surface finish, expense).

Maybe when the Tersa patents expire we will see more of those style heads.

[Andrew Hughes]

Its not just the carbide insert that takes more power because of its sharpness. It really the way a insert head cuts into the wood with a 30 degree face bevel.
One way to compare a knife head to a insert head is how a good rip blade on a table saw with a nice hook. Forward rake.
Then compare that to a sliding miter saw with its negative rake blade.
Ive found in woodworking sharp wins every time.

[Jared Sankovich]

Insert helix heads take more power because there is always a knife engaged in the cut, carbide vs HSS makes no difference there. As to Carbide vs HSS sharpness, insert carbide can be finer grain material. I have shaper inserts that I could shave with.

Metalworking carbide inserts are typically negative rake to allow heavy cuts with high removal rates witjnsome level of insert longevity. They also make positive rake inserts that don't take any more power than HSS. It's all a trade off, but when comparing apples to apples I'll take insert carbide over HSS all day long.

[Kurt Wyberanec]

For me, having used both, I too will take inserts every time. I agree it is possible to get a finer finish off a knife, can't tell you the technical reason but others have pointed out some, but tear out is my biggest concern and inserts win for me. That said I have received highly figured lumber from mills that was smooth as glass...I asked about them and they said just straight knives...I couldn't believe it. I know there are helical knives as well which can be good but have never used them myself...I can only imagine that the particular results in mentioning had to be just sharpened or there is something else going on because I know even with brand new knives I was never able to see results like that

[Andrew Hughes]

I disagree Jared.
The increase in power is from the insert making a scraping cut instead of a scooping cut like a knife. If someone wanted too they can add a facebevel to a knife machine. It will lower the effective cutting angle of the hook but watch out it will take more power.
The face bevel will act lot like a chip breaker. I used to have a jointer with a insert head. Before I sold it I studied up.
There actually several helical heads the have carbide inserts that cut without a facebevel. Bryd has done a good job imitating them. Sort of.

[Andrew Hughes]

For me, having used both, I too will take inserts every time. I agree it is possible to get a finer finish off a knife, can't tell you the technical reason but others have pointed out some, but tear out is my biggest concern and inserts win for me. That said I have received highly figured lumber from mills that was smooth as glass...I asked about them and they said just straight knives...I couldn't believe it. I know there are helical knives as well which can be good but have never used them myself...I can only imagine that the particular results in mentioning had to be just sharpened or there is something else going on because I know even with brand new knives I was never able to see results like that
One of the lumber yards I buy from has a planer that’s produces a very good surface. The guys just send wood in just the way it come off the lift. No regards for grain direction.
They also have a sharpening room where I spent time taking to a head guy. Apparently the planer has 6 knives very wide and thick. One guys sets them and joints them. The steel they use isn’t something we can use in our machines because it’s a 1/4 inch thick.
I couldn’t say who made the planer because when i am there it’s running. It’s so loud that a hundred feet away it still hurt my ears. Jointed knives cut pretty close to perfect but are loud.
Im with Tom on this topic I set my knives with a dial indicator as close to perfect as I can. Its sublime how nice t1 cuts when it’s sharp. Hardly any effort most of the time I sit in a chair in front of my jointer and just pass wood right to left.
Maybe I’m using a machine in a slightly higher class then a most. With a 5 inch cutting circle
I do believe some don’t take the time to master one of the most important machines for solid woodworking the jointer.
Good Luck

[Mark e Kessler]

I didn’t read this thread thoroughly enough to really argue one way or the other (except for the fact that carbide inserts for me) but i thought that a helical insert head actually uses less power. I thought I remember several studies demonstrating this and one of them if I remember correctly was from Felder so hopefully Erik can chime in on this.

On a planer for me helical insert carbide all.day.long., on a jointer it’s questionable, it is pretty difficult to face a wide board on a jointer with a helical and for me its a prep machine so for separates i would do helical on planer and probably straight knife on jointer but on a j/p it’s a compromise so helical.

[Jared Sankovich]

I disagree Jared.
The increase in power is from the insert making a scraping cut instead of a scooping cut like a knife. If someone wanted too they can add a facebevel to a knife machine. It will lower the effective cutting angle of the hook but watch out it will take more power.
The face bevel will act lot like a chip breaker. I used to have a jointer with a insert head. Before I sold it I studied up.
There actually several helical heads the have carbide inserts that cut without a facebevel. Bryd has done a good job imitating them. Sort of.

If you look at the helix heads the effective hook angle is nonwhere close scraping. It's close to the same as a gib head. The only difference being one is bevel up and one is bevel down.

[Jared Sankovich]

Maybe I’m using a machine in a slightly higher class then a most. With a 5 inch cutting circle
I do believe some don’t take the time to master one of the most important machines for solid woodworking the jointer.
Good Luck

5" heads work a lot better than anything smaller just based on the tangential nature of the cut. They still will tear out more than a 3" diameter helix head. Not suprisingly 5" diameter heads running carbide straight knives on a shear single seem to be able to cut anything regardless of grain direction.

[Andrew Hughes]

The Felder machines I’ve seen looks like one or maybe two rows of inserts going around the head.
Bryd head have a lot more inserts. For instance my jointer had 6 rows of nine 8 inches wide 3 inch cutting circle. I think it’s the reason handfeeding wood was unappealing to me.
My planer has a bryd head and while it does what it does the thing that bugs me is very small bite I can take from rough lumber. I think it’s 3/32 max. Because of the face bevel it’s really a scraping cut.

[Andrew Hughes]

5" heads work a lot better than anything smaller just based on the tangential nature of the cut. They still will tear out more than a 3" diameter helix head. Not suprisingly 5" diameter heads running carbide straight knives on a shear single seem to be able to cut anything regardless of grain direction.

I sometimes pass wood at a angle if the boards are thin. I’m remember reading Insert heads like bryd have the insert set at a 7 degree angle with a slight radius on the edge. I’ve not been able to determine the hook angle of the inserts seats. My guess is 45 degrees. If the inserts were not carbide they would dull fast from the scraping cut.

[Keegan Shields]

Segmented cutter heads almost always have a cutter in contact with the wood. So the motor is under a constant higher load. Straight knife cutter heads allow the head to accelerate between knife contacts. I suspect this also impacts the HP requirements, although I don’t have any empirical data.

Interesting points about scraping vs cutting angles between the two systems. I would think a true helical cutting head would need less additional HP given the lower effective cutting angle that is presented to the wood than straight segmented heads.

[Mark e Kessler]

It all comes down to the engineering of the head, I think my AD941 helical head is 4"-5" dia maybe 63 or 83 cutters, can't remember think the max cut is 5mm. Does it matter if it's a scraping cut, what is that and how do you determine it and if it even matters one way or the other?

I now remember that Felder claims 20% power reduction but can't find it and not sure if that number is against a byrd (which are known to require a lot more power) straight knife (3 or 4?) or other helicals on the market or an average. that's the problem with making claims like "20% less", "significant reduction" those are more akin to marketing terms to obfuscate the information to make it more palatable to a pedestrian.

I like to be armed with all the technical details and specs that I can to come to the best choice but the end result is what matters and the helical wins for me, this is my experience with Felders Silent power head. long life with consistent results for the duration of that time, reduced chip size, QUIETER (I was yelling that, lol), superior finish, almost never any tear out and I almost never pay attrition to feed direction and reduced power consumption. I would imagine its the same for the SCMI, Martin and Hermance version

[Jared Sankovich]

Segmented cutter heads almost always have a cutter in contact with the wood. So the motor is under a constant higher load. Straight knife cutter heads allow the head to accelerate between knife contacts. I suspect this also impacts the HP requirements, although I don’t have any empirical data.

Interesting points about scraping vs cutting angles between the two systems. I would think a true helical cutting head would need less additional HP given the lower effective cutting angle that is presented to the wood than straight segmented heads.

Interestingly regarding thr true helix heads (Newman Whitney quiet cut) that is not the case. The invicta 63 came in 2 versions the D version had straight knives and a 10hp motor. The N version had the Newman head and needed a 15hp motor because of the head.

I just measured one of the "spiral" insert shaper heads I have. The hook angle is 12.7 degrees. My Newman jointer (original head) is approximately 23 degrees.

Insert head
474502

[Joe Calhoon]

Tom, variety is the spice of life man… give them a chance!


Maybe when the Tersa patents expire we will see more of those style heads.

Keegan, the Tersa patent expired a few years back and many clones available now. Leitz, Kanafusa and a few more. Options for coated HSS from some also. I’m happy with my Tersa and use mostly carbide and coated HSS. No plans to change but if I did I would be taking a hard look at the spiral inserts some of the better mfgs are doing now. Did straight conventional knives for many years and would never go back to that.

[Kevin Jenness]

Does it matter if it's a scraping cut, what is that and how do you determine it and if it even matters one way or the other?


It does matter, a lot. If you want details the best discussion of wood cutting I have seen is in Hoadley's "Understanding Wood", well worth the investment. The effectiveness of a cutterhead is probably influenced by rake angle more than anything. You won't actually find true scraping cuts, what Hoadley calls type 3 chip formation, in a woodworking cutterhead (an exception being the obsolete "French" shaper head), but you will find different rake or attack angles. The lower the rake angle the less the chip is lifted up, the less tearout is produced, and the more power is required to make the cut. The seat carbide inserts are held in and their sharpening angle determines the rake angle, much as in a bevel-up hand plane.

[Mike Kees]

So many variables in this conversation. I think that a very large majority never experience the difference that really good HSS makes. I was very fortunate to get this education early from an older guy that ran a sharpening shop near me. He sold me on using HSS with high tungsten 14 %minimum and 18% preferably. I think 18% is T1. Anyway got my first set of knives for my Delta DC380 planer and could not believe the cut quality and how long they lasted and lasted.... I now own a 16'' Italian jointer with a 4-5'' diameter head and four knives, it cuts very well with very minimal tear out only in really nasty grain. My planer is a 20'' Cantek with a segmented carbide head. Any minimal tearout from the jointer is erased by this planer. It leaves very faint lines that sand out easily. I will not replace my jointer head because to me it would be a large sum (3000 plus) wasted . My jointer flattens faces of material before it heads to the planer, finish surfaces are not it's job.

[Mark e Kessler]

Thanks Kevin, i have the book - I don’t know why I said it that way , maybe trying to be a smart$$$ i guess I don’t see how it comes into play with most cutter heads from reputable companies of a higher order. If i was in production running x1000’s of bfdt then I would be super concerned. But glad you brought up the clarification because it can matter.


It does matter, a lot. If you want details the best discussion of wood cutting I have seen is in Hoadley's "Understanding Wood", well worth the investment. The effectiveness of a cutterhead is probably influenced by rake angle more than anything. You won't actually find true scraping cuts, what Hoadley calls type 3 chip formation, in a woodworking cutterhead (an exception being the obsolete "French" shaper head), but you will find different rake or attack angles. The lower the rake angle the less the chip is lifted up, the less tearout is produced, and the more power is required to make the cut. The seat carbide inserts are held in and their sharpening angle determines the rake angle, much as in a bevel-up hand plane.

[johnny means]

"Elbows locked while using", isn't really data, now is it. Your reasoning also has plenty of other issues with assumed facts.

[Erik Loza]

My understanding is that spiral heads require less HP to drive due to the shearing angle of the cut. If you think about it, only one insert is cutting at any given moment, as opposed to an entire full-width knife. Also, the low projection of the knives/inserts contributes to this. You're not "hogging" with a spiral or Tersa head so the cut is inherently smoother.

Also, my experience as far as white-knuckling boards is the exact opposite of what the OP is describing. The old skool jointers definitely required you to put more pressure on the board. With Tersa or spiral, you almost get this suction-type effect as the board moves over the cutterhead. Difficult to explain but I can't see how anyone would say a traditional jointer machines a board more smoothly than one of these more modern designs. Just my thoughts.

Erik

[Alex Zeller]

I bought my PJ882-hh so it wasn't a choice. Had I bought new I wouldn't have gotten carbide inserts. I rarely go from the jointer to a sander so all I'm looking for is flat. It's only 2hp but when sending a board near 8" wide through it I can feel the resistance. I can't say that the motor bogs down at all though even when taking 1/8" off on one pass (not that I do that very often). That being said the original owner said he never rotated the inserts and I haven't yet so maybe after 8 years they are starting to loose their edge. Even though I always wear hearing protection I do like it being quieter.

[brent stanley]

Hey Alex, I've been using a Byrd head in a jointer for years and the problem I run into is cutter dullness sneaking up on me. It happens so slowly that they are very dull by the time you rotate them. I just did this the other day and it made a world of difference. Be extremely meticulous about cleaning everything and using the proper torque when you rotate and I expect you'll notice a difference after 8 years on that side.



I bought my PJ882-hh so it wasn't a choice. Had I bought new I wouldn't have gotten carbide inserts. I rarely go from the jointer to a sander so all I'm looking for is flat. It's only 2hp but when sending a board near 8" wide through it I can feel the resistance. I can't say that the motor bogs down at all though even when taking 1/8" off on one pass (not that I do that very often). That being said the original owner said he never rotated the inserts and I haven't yet so maybe after 8 years they are starting to loose their edge. Even though I always wear hearing protection I do like it being quieter.

[Rod Sheridan]

I didn’t read this thread thoroughly enough to really argue one way or the other (except for the fact that carbide inserts for me) but i thought that a helical insert head actually uses less power. I thought I remember several studies demonstrating this and one of them if I remember correctly was from Felder so hopefully Erik can chime in on this.

On a planer for me helical insert carbide all.day.long., on a jointer it’s questionable, it is pretty difficult to face a wide board on a jointer with a helical and for me its a prep machine so for separates i would do helical on planer and probably straight knife on jointer but on a j/p it’s a compromise so helical.

The Felder Silent Power head uses less power than our straight knife head.

It also uses less power than the Byrd head…..Regards, Rod

[Keegan Shields]

Thanks Jared. I didn’t know that was the case.

[Phil Gaudio]

I was doing some jointing/planing yesterday with a Minimax 16" J/P with the Xylent insert cutterhead. Cherry stock was just under 16" wide (5 feet long) . I have the jointer set to about 1/64". It does not take all that much force to move a piece like this across the cutterhead, and certainly the force required is nowhere near the level that would make me think about going with a different knife setup. I think its a function of how much of a bite you take and how sharp the cutters are.
https://i.postimg.cc/Hxd1DMMG/IMG-3235.jpg (https://postimg.cc/Z97M6Cjj)

[james manutes]

Interesting debate . I had never heard of Tersa cutterheads , so I did some reading . I guess your never too old to learn something .

[glenn bradley]

When I read these types of threads I can't help feeling like someone is trying to justify not having something for some reason. That's OK, we all do things differently. I keep a small drill motor at my otherwise power-free workbench. This worls for me but I don't necessarily think anyone else has to do the same.

With the widespread positive use of insert heads they are obviously doing their job. I will chime in with the wear factor sneaking up on you. The tell tale for me is increased resistance (just like with other types of cutters) and a poorer result than expected (just like with other types of cutters) :). It is also a challenge for home shop or one man operations to determine wear using the calendar. This is especially true if you do little production work and mostly do custom stuff; the burn rate of material through the machine just isn't consistent enough over time. Watching for cut quality has worked well enough that I don't feel the need to put an hour meter on any machines ;).

As mentioned above, the load on the motor is actually less for some insert cutter heads. Angle of approach, rake, and so many other contributing factors that require a little more science than comparing a Ford to a Chevy and declaring empirical data. Like adding a cyclone to a system not designed for one, adding an insert head to a machine not designed for one can give sub-optimal results. Both of these actions can result in eventual comments or declarations of inferior performance. The range of tolerance, expected load and too much stuff that others know so much more about that I do go into these things. Love them or hate them at your discretion ;).

[Mark e Kessler]

I find it interesting that the OP basically made a declaration of independence from carbide and we all bit while he is MIA.... lol

good topic discussion nevertheless.

[Zachary Hoyt]

I've read discussions about the benefits and drawbacks of insert cutterheads many times here on Sawmill Creek, but so far my interest has been purely academic. I'm too much of a cheeseparing skinflint to pay for an insert cutterhead or a machine that has one. For what I do straight knives work pretty well most of the time, and when they don't I work with a power sander of one kind or another to reach flatness or consistent thickness without tearout.

[Warren Lake]

Jared what insert can you shave with. Ive never seen any with an edge that is as sharp as high speed steel can be. Sharp is not the be all and end all sometimes super sharp will still chip out on certain woods and having a secondary bevel will cut more like a wedge and cut cleaner. A molding company guy told me that many years ago. We always honed high speed steel before it went in and its dangerous at that point.

[Jared Sankovich]

Jared what insert can you shave with. Ive never seen any with an edge that is as sharp as high speed steel can be. Sharp is not the be all and end all sometimes super sharp will still chip out on certain woods and having a secondary bevel will cut more like a wedge and cut cleaner. A molding company guy told me that many years ago. We always honed high speed steel before it went in and its dangerous at that point.


474594
The Freud Rp inserts are sharp enough. I'd expect others as well, but it's hard to hold them and try...lol

[Darrell Bade]

I find it interesting that the OP basically made a declaration if independence from carbide and we all bit while he is MIA.... lol

good topic discussion nevertheless.

I assumed the OP was a salesman for dispozablade system which he mentioned ......... lol

[Frank Pratt]

The Freud Rp inserts are sharp enough. I'd expect others as well, but it's hard to hold them and try...lol

I showed my grandkids how sharp my chisel was by shaving my face with it. Worked great except for the cuts that ran down my cheek from the edges. I didn't even feel the cuts. Grandkids were not impressed.

[Ronald Blue]

I installed a helical head Grizzly brand head on my Jet J/P last fall. The inserts are very sharp and have a mirror finish to them. I paid close attention while handling it because I have no doubt they will cause blood shed if careless. Are they as sharp as HSS? Probably not but they are close. I have no complaints with the power needed, finish left, or effort it takes to push a board across.

[Alex Zeller]

I remember reading that carbide can't be sharpened as well as HSS. But in a short amount of time the HSS will start to loose it's edge while the carbide keeps it's edge. The nice thing about woodworking (and the choice of tools) is that two people can look at the same project and decide two very different ways to accomplish the task.

[Brian Holcombe]

On the jointer and planer I prefer Tersa carbide. They’re extremely sharp (when new) and leave a nice finish. Tersa us easy to change and a nick can be resolved by bumping a knife over slightly. This is better than trying to rotate one insert in a group which is not advisable.

I use a fair amount of insert carbide in other aspects of the shop and brazed carbide where inserts aren’t available.

It’s been my experience that most people run their inserts much longer than they should, they’re usually very dull by the time they are rotated.

It also helps to take them out and clean them if they get gummed up for any reason.

I have a couple HSS cutters left in the shop and I’m always looking for a way to replace them with carbide.

[Tom Bussey]

("Elbows locked while using", isn't really data, now is it. ) You are right, but it does shows how incompetent the person is. Your reasoning also has plenty of other issues with assumed facts.) Hog wash I see a lot of that on You tub. When you see that , if the board is bowed going a crossed the jointer is is bowed when it comes of just like the planner. If carbide cuts with less power then why are the machines now 3 horse power instead of 2 like my 25 year old jointer?

I am not trying to justify anything as someone kind of claimed. I posted the reasons I will not change over from straight knives to an inserted cutter head on a jointer. And I came to that conclusion from for what I observed and from trying out a inserted cutter head.

I never claimed that inserted cutter heads were bad. Again I only stated my reasoning to not switch over and I would like to think that my reasoning for me is just as valid as your reasoning is for you to buy one.