16 inch jointer performance questions.

[Gary Grant]

Hello everyone,

I have a Porter 300c belt drive jointer (7.5 hp 3-phase belt drive, 96 inch bed)The bearings are flawless (a nickel will stand on edge all day while running and even during starting and shutting down), the knives are sharp and properly adjusted. When I begin to push a board through it really fights and bounces for the first 2-3 inches and then smooths out and runs flawlessly but then I seem to get the same on the back end of the board as it passes over the cutterhead. I also have a 12" jointer with a Tersa cutterhead and the performance is flawless. I have tried adjusting the tables down to the least cut possible and still get the same issue. The table was coated with Boeshield and then buffed but the wood seems to drag on it. Is this simply a characteristic of this size jointer? Should I get a power feeder? The Porter has a 4-knife round cutterhead. I must admit that I have extreme respect for this machine and simply may not have yet perfected the art of shifting pressure on the board. I do not have this issue with the 12" Tersa.

Thanks in in advance for any and all input!

[Mel Fulks]

Interesting, never heard that one. I've used two knife jointers and three knife but not four. Only thing I can think of beyond table adjustment is your feed rate, four knives need a little slower feed. And low quality knives ( as opposed to genuine high speed ) don't cut as smoothly.

[ian maybury]

Presuming that your 'least cut possible' is the result of raising the infeed table it seems possible that the knives could be set too high above the outfeed table Gary. In that situation the machined lower surface of the board doesn't contact the outfeed table until enough length is cut so that the cantilevered overhang droops down a bit. Which has the effect of stabilising it - but prior to that because there's clearance underneath it it's free to vibrate like a lollipop stick in response to the hits from the knives.

In moderate form it can manifest as a slight slapping or vibrating overtone/harshness mixed into the more normal steady drone of the cutter. It could possibly lead to a less flat jointed surface/poorer finish too. Most tend to just use a set dimension, but this with other signs (e.g. is the machine jointing straight) is actually one way to detect when you have just reached a good knife height setting - coming from outfeed high the sweet spot tends to be the knife height where the slapping is just tuned out. Drop the outfeed table too much and you may start to feel resistance against feeding the wood (depends on how sharp the leading edge of the outfeed table is), and it may start to joint a little convex.

I'm not familiar with the machine, but if that's what's happening and everything else is in good alignment (e.g. is the knife height the same all the way across the outfeed table, are all of the knives accurately set to the same height relative to each other, and is the infeed coplanar with the outfeed?) raising the outfeed table a hair should only be a matter of a single knob or screw adjustment after loosening whatever locking screws are in use.

I've posted before about the effect of the surface finish of cast iron tables on drag. Realistically if the tables are either ground using a coarse grit or the surface milled (as many are these days) a 'toothing' of the cast iron surface will result. So that no amount of waxing or coating will fully or for any decent period eliminate the issue.

Quite a few resist the idea (fear of touching their shiny looking tables?), but one fix can be block sanding with wet and dry silicon carbide paper. Starting with 180 or 200 if they are very rough, and working down to 400 or even 600. The result is not highly visible on a milled table, and should be very regular on even a ground surface if the sanding is done carefully and the surface isn't humped in places. (in which case there are other fish to fry) Mineral/white spirits is a good lubricant. A diamond plate of similar grit works well too if you have one. Then paste wax...

[Mel Fulks]

Good thoughtful info ,Ian. But that machine probably has Mechanite tables,and Porter is real good stuff.

[Erik Loza]

16 inches is a wide jointer with lots of mass under the board and under your hand. If I use a regular jointer after using Tersa (what I'm normally used to), it feels like a car with no shocks.

Maybe just user-itis?

Erik

[peter gagliardi]

Couple other thoughts. How far away from the cutting circle are the bed lips? You want to be as close as can be tolerated from a noise standpoint, and knife crash standpoint. Too much distance enhances the "overhang "effect Ian spoke about.
Also, what is the distance of knife projection? Ideally 1/8" or less from cutter head.
And lastly, are the knives really sharp, and ground with the correct back relief angle?

[mreza Salav]

Good points raised. I think it's either (or a combination) of the following: large gap between the tables and the cutter head, knives set a tiny bit too high.

[ian maybury]

:) Just took a look Mel - that certainly is a solid chunk of old iron.

No idea if a low outfeed table issue would show on it in the way i've described (it certainly does on an A3 410 Hammer), but the effect being confined to the start and finish of the cut might well point to something of that sort.

[J.R. Rutter]

Was thinking knife projection as well.

[John TenEyck]

Was thinking knife projection as well.

+2 The outfeed table appears to be too low. I've had it happen on my 10" jointer with the same results you describe.

John

[David Kumm]

Porter made one of the best jointers from a quality perspective you will ever find. The head was balanced and the bearings were open high precision ( 63xx series ). Both could handle rpms up to 6000. knife projection would be my first choice. I'm also assuming there is not a motor problem that causes the head to slow slightly when under load. Whatever the issue, it isn't endemic to 16" jointers or the Porter design, but something that can be corrected. Dave

[Peter Aeschliman]

If it was knife projection/low outfeed, why would this be happening as he finishes the cut? I would think that the cut would just be deep at the end and he'd maybe get some snipe, but it would still be well supported by the low outfeed table.

Gary, does this happen even when you're jointing really thick boards? 8/4 or 12/4 for example? What about narrower boards? I imagine a 1/2" thick and 16" wide workpiece would chatter like crazy while face jointing no matter how well the machine is tuned. Does it do this when you edge joint (I would guess no)?

[David Kumm]

Also check that the tables are co planar. Porter infeed tables could be adjusted for a spring joint and there is some possibility ( small ) that if the infeed is drooped on the outboard end there could be some vibration at the beginning or end. I'm really just guessing because my porter tables are locked down. porter tables are very difficult to adjust due to the spring joint mechanism. I use two dial indicators and an 8' straightedge to get it right. Dave

[peter gagliardi]

If it was knife projection/low outfeed, why would this be happening as he finishes the cut? I would think that the cut would just be deep at the end and he'd maybe get some snipe, but it would still be well supported by the LOWout feed table
Here is why it happens at the end. As the board clears the infeed, which is the only part providing real support, it "drops" off onto the knife of the cutterhead, and because the out feed is lower than the knife at apex, you get snipe, and vibration while unsupported for those few thousandths of an inch.

[jim mills]

Don't mean to hijack this thread, but why would a tersa head perform any differently than a straight knife cutterhead that was properly set up? Especially a 5" dia. head, which that porter probably has.

[Erik Loza]

Don't mean to hijack this thread, but why would a tersa head perform any differently than a straight knife cutterhead that was properly set up? Especially a 5" dia. head, which that porter probably has.

Due to the rake on the Tersa knives, it gives the effect of "sucking" wood down to the cast iron table. At least that's how it feels to me. Much smoother than a standard type jointer head.

Erik

[ian maybury]

Never used them, but the pics show the edge is undercut as Eric describes: http://gabbett.com/tersa-quick-change-knife-cutter-block/

The Hammer equivalent for example is a thin knife ground from flat strip - which gives a cutting edge much like a conventional jointer knife. The mounting slots are raked forward though, which may result in a similar additional 'hook' geometry to the Tersa: http://www.hammer-ireland.ie/ie-en/products/planer-thicknessers/planer-thicknesser-a3-26--260-mm-details.html Somehow i seem to find myself needing to fine tune the knife height on my A3 41 when replacing them. i.e. they drop in close but not quite right. It is a very precisely adjustable system compared to the old style sprung knife deal though.

Do the Tersas drop in without any need for adjustment - even if you look to set the heights to within a thou or two?

[mreza Salav]

with Tersa you just slide them in from the front and turn the machine on!

[Malcolm McLeod]

+3 on the low out-feed table. My lowly 6" did same until tuned. First time I changed knives, it took a perfectly flat board and made a perfect chair rocker.

Dial micrometer on mag base is a beautiful thing.

[peter gagliardi]

A note on the Tersa and Terminus head machines- while knife changes are easier for sure, it comes with sacrifice. Namely, knife life. I know people who run the Tersa in pro shops, and I run Terminus. I have asked how knife life was on the Tersa system, and it was described as "abysmal"! I too, with the Terminus system feel knife life is marginal at best. The cut and lack of tear out when fresh, are excellent, but it goes south quicker than it should. Also, the quick change systems don't like deep cuts. The gullet is small, and chip re-entrainment is a real issue, so I limit depth to 1/8" or less.
All that said, I am not sorry I changed!

[Erik Loza]

Peter, just curious. What alloy knives are these guys using, that are dissatisfied with knife life?

Erik

[Peter Quinn]

As have a 12" spiral head in the shop, and I've noticed after somebody processes a batch of something large like 10/4 oak 12' long which happens more than I care for, often the out feed table will be a little low, probably they are letting the heavy stuff bounce off the outfeed table at the end, bad for the jointer, I discourage it, get 2-3 people if required....

Anyway, the symptoms are just as you describe....boards turn into "slappers" at infeed and out feed even on a light cut. On this machine knife projection is fixed, it's a 7Z head or 7 rows of knives, still slaps. Set the outfeed table right....smooth as can be. That's where I'd start. I wouldn't want excessive knife projection but they would have to be pretty far out with full thickness straight knives to cause that kind of problem.

oh, earlier Mel said 4z requires slower feed rate? Must have take. Different math classes. For pretty much any cutter more teeth means you can feed faster and get the same cuts per inch or surface quality. I've found that often you tend to feed slower with more cutters because it's harder to push, but it's not because the head can't handle it. If depth of cut is big the 4z head might swamp the chip ejection system and DC which creates a whole nother problem.....best to improve dust collection which older machines were not great at and take lighter passes. I've seen too many people who seem to think a light 1/4" is an appropriate pass for flattening stock!

[David Kumm]

I really like the Tersa, but I do believe the big steel straight knives dissipate heat and keep an edge longer than equivalent HSS Tersa. Jointers are easy to set so a bigger deal to have tersa on my planer than jointer. Dave

[Erik Loza]

Dave, in Vegas, Martin was really pushing those Kanefusa coated knives. "Tooling supplied by Kanefusa" magnetic decals on all their machines, in fact. I still have not tried them but if Martin is suggesting them over Tersa brand for production use?

Erik

[mreza Salav]

I priced out those Kanefusa blades here in Canada, and they were not much cheaper than Tersa carbide. Don't know how they compare in application

[peter gagliardi]

Eric,
As I understood it, they were using HSS and M2 and they considered both underwhelming.
Having bought and used Kanefusa saw blades, I have to believe the knives would be equally impressive! They are about the quietest and smoothest cutting blades I've ever used. The Japanese definitely know what sharp is!

[Mel Fulks]

Peter..... Yes ,we see that differently. Fewer teeth or blades, with all else equal cut faster. And old 2 knife or 3 knife jointers easily remove a whole inch in one average speed pass. For small shops they stand in for straight -line saws. But we can agree that FACING an inch off is NOT a good idea.

[Erik Loza]

Eric,
As I understood it, they were using HSS and M2 and they considered both underwhelming.
Having bought and used Kanefusa saw blades, I have to believe the knives would be equally impressive! They are about the quietest and smoothest cutting blades I've ever used. The Japanese definitely know what sharp is!

You know, I talk to shops all the time who say, "How come our bandsaw is cutting like crap?". And they have something like ten thousand board-feet on the el-cheapo blade that shipped with the machine. "You guys ever think of trying a new blade?", and then it's like the three chimps who point at each other, plug their ears, and cover their eyes. When it came to trying to stretch out blade/knife life, you would think...

Tha being said "most" production shops I know uses carbide Tersas. I really want to give those Kenfusas a try.

Erik

[Kevin Jenness]

We run a Tersa head with M42 knives in a 400 mm Laguna badged Griggio jointer. Our head is licensed by but not labeled Tersa. The knives do not have anywhere near the longevity of the solid M2 knives we run in our other jointers (Invicta DJ20, Northfield 12"), but they are so easy to change out that they are more economical considering labor. When swapping knives we sometimes readjust the outfeed table .001-.002" to achieve a perfect edge joint. Switching to carbide is approximately 5x the cost of M42. We are considering going to 2 carbide knives with 2 dummy knives to extend time between changes without breaking the bank. The hook angle of Tersa heads appears to be about 30 degrees, which is pretty high- not sure why that should be so. When new, the knives do a nearly flawless job except on highly figured material. The Northfield, with an approximately 35 degree hook angle, is a tearout generator on difficult stock. My own Powermatic planer, with 10 degree face-beveled knives in a 20 degree hook head, rivals a Shelix head regarding tearout in figured wood. YMMV.

[Larry Copas]

Due to the rake on the Tersa knives, it gives the effect of "sucking" wood down to the cast iron table. At least that's how it feels to me. Much smoother than a standard type jointer head.

Erik

I had a 12" Northfield and a 12" Griggio with Tersa head. My shop is a one jointer shop so I had a decision to make as to which one would stay. I would surface a board on the Northfield than walk over to the Griggio and run the same board. My experience is exactly the same as Erik described.

I can't speak of knife life with authority as I'm basically a hobby shop. The Tersa knives seem to last fine for me with the usage I give it.

[Joe Calhoon]

I have been using the Kanafusa knives in jointer and planer for a few months now. Too soon to have an opinion. They are less than carbide but still spendy. For sure better than M42 or HSS but I am suspecting carbide might be the least costly in the long run. I have been using carbide Tersa in the S4S machine. They have probably seen 40K bd ft and on the second sharpening. I also have some Leitz terse clone HSS for that machine and they have done well and also on the second sharpening. They are as much as Kanafusa and suspect they are coated. I am seeing some small ridges on the planer Kanafusa after about 500 Bd Ft and that worries me a bit. We are in the middle of a knotty white oak door and millwork project. That should be a good test.

[Mel Fulks]

Joe, some might not get through your terms, M42 is a high speed steel and most of what is sold as "HSS" is only semi high speed steel having about the same hardness ,and much lower heat resistance. What is sold as HSS will often put striations in the first board that goes through the machine, and that is partly caused by overheating the edge even with the cooling fluid going. I don't see changing knives as a big deal,but sometimes I think others are just hoping someone else will do it. I think for small job commercial shops, and home shops M2 leaves a much better finish than "HSS" and no better finish will result from more expensive steel,just more footage before sharpening. Certainly with exotics ,white oak, etc it's nice to have a steel that requires less sharpening or changing in the middle of job.

[ian maybury]

Most of my experience is with machining/engineering, but for sure it's got these days where at the less than premium end of the market the label 'HSS' is pretty meaningless...

[Joe Calhoon]

Mel
Tersa is a little different animal because of the thinness of the knives. I agree with what you are saying in regards to thick knives but it changes with the Tersa. My experience with M42 and the standard HSS with Tersa is not good. I think because of the thinness. Probably fine if you are just running clear softwoods. And I know the old thick M42 would leave a nicer finish than thick carbide knives. Not so with the Tersa. The carbide is just as good or better. The same is true with shapers. The old thick HSS would do better than thick carbide braised. Newer insert with the thin micro polished inserts will give a better finish and long lasting.

Many advances have been made in tooling. Its beyond the reach of small shops but insert tools in Hydro or Shrink fit heads run on molders or machines like the Weinig Contourex leave a finish that is something to see.

[Mel Fulks]

Joe,thanks for your reply with additional info,I didn't realize you were referring to TERSA. Your posts carry deserved weight and I was just concerned about the small and home shop guys who often think they are buying HSS when they are really buying semi high speed. I know smart small shop owners who bought widebelt sanders to remove tear out they would not have had without dishonest "high speed" quotes. I'm aware of hydro lock type stuff but never seen it.

[David Zaret]

so far in my travels, i'm seeing relatively positive results with the tersa kanefusas. i'm probably 1000 bdft in on the first edge, mostly hardwoods, and they still seem pretty sharp. compare that with M42s, where i can blow through an edge in a few hundred bdft if it's really hard stuff, or a little more if softer. i still have my eye on carbides though, and after seeing joe's post above, i might pull the trigger.

the last machine i had was a minimax and i had a byrd head made for it. it was a huge improvement over the straight knife head that was on it, but from a quality point-of-view, in my opinion, nothing touches the cut of sharp tersas. the cut quality is just exceptional. but, the life of standard knives is weak.

joe - where and how do you get your carbide tersas sharpened? thanks.

[Joe Calhoon]

joe - where and how do you get your carbide tersas sharpened? thanks.


http://www.kyocera-unimerco.com

[Larry Edgerton]

I had the same Porter Jointer up until a couple of years ago. I did have a time getting it tuned but once there it stayed. Knife projection was more than normal but the knives were THICK! The tables on mine could be slid forward and back to get the table very close to the knives so that was not a problem. Not all of them I have seen had this feature but you could check.

I agree that the Tersa knives seem to have a shortened life. But they are so easy! I have gone to carbide recently and so far am happy with the results. Still get a better than average finish, which surprised me. I was expecting less but they seem to be just as good as the M42. It is my understanding that the carbide can be of a tighter grain structure because it does not need to be braised. Can't say this is a fact but it is something I have read several times.

[Larry Edgerton]

I priced out those Kanefusa blades here in Canada, and they were not much cheaper than Tersa carbide. Don't know how they compare in application

mreza, I found the best price for tersa carbide up in your neighborhood. I ended up paying about 140 US after the exchange rate for 520's. Some place in BC, I can look it up if you like.

[Erik Loza]

I had no idea anyone re-sharpened Tersa knives.

Erik

[peter gagliardi]

I don't know about Tersa, but Terminus advertises one sharpening. Of course then you technically get into resetting the machine to do it correctly. I have had some success without resetting though.

[mreza Salav]

mreza, I found the best price for tersa carbide up in your neighborhood. I ended up paying about 140 US after the exchange rate for 520's. Some place in BC, I can look it up if you like.

I buy my blades from tersaknives.com which are in BC. Their pricing is the best I've found (and good service).

[Mel Fulks]

Since just several thousandths difference between height of knives and outfeed table make a difference as to whether a jointed edge is straight, has snipe, convex edge,or concave edge ,my guess would be you could hone TERSA knives a little but not ,remove nicks without making out feed table adjustment necessary. On two jointers used in employments I made a magnet gauge to set knives. Both machines were old iron and the out feed tables were adjusted by a wheel,not a lever. I determined how much a complete turn of wheel lifted table,then filed notches on circumference edge representing 2 thousandths. Those notches were about 3/8 of an inch apart. I made a position pointer from sheet steel much like those commonly seen on various machines. My magnet gauge was made so that I would first drop out feed table to correct line
labeled on wheel that allowed installing knives in a vertical position. After all three were done I would turn wheel elevating
table position to "0". No further adjustment needed. One of the machines had indexing holes in cutter head end and that
made the alteration quite precise. While not applicable to all jointers I think that is a good system for low cost sharp knives and quick special adjustment.

[Joe Calhoon]

I had no idea anyone re-sharpened Tersa knives.

Erik

Its only worth it for the carbide. I did have my coated Leitz knives resharpened by them and that worked out. Kanafusa say theirs cannot be sharpened. Because of the cost I may give it a try.

[Larry Edgerton]

Joe, I went to the carbide because I had to plane about 2000 ft. of Makore, almost as bad as Teak on knives. Glad you nudged me into it, they are still planing well today, where with M42 I would have burned up a few and had nothing.

I had a tube full of dull M42's, have thought about having them sharpened but was wondering if it would really be worth the cost/time. It would throw off the thickness indicator I imagine as well, but I could get around that if it was worth while.

What is the cost per knife?

Thanks, Larry

[Larry Edgerton]

I buy my blades from tersaknives.com which are in BC. Their pricing is the best I've found (and good service).

Yup, thats the place. I was buying from Global but they did not seem to want to deal with small potatoes like me.

[Joe Calhoon]

Joe, I went to the carbide because I had to plane about 2000 ft. of Makore, almost as bad as Teak on knives. Glad you nudged me into it, they are still planing well today, where with M42 I would have burned up a few and had nothing.

I had a tube full of dull M42's, have thought about having them sharpened but was wondering if it would really be worth the cost/time. It would throw off the thickness indicator I imagine as well, but I could get around that if it was worth while.

What is the cost per knife?

Thanks, Larry

Larry,
I bet you will get 5000 or more before turning the knives.
Wow time goes fast, i looked in my checkbook and it was 2010 when I had these resharpened. For $300 they did 8) 270mm knives and 8) 160 knives. half were the Leitz coated HSS but the cost is the same. There is a possibility it might have only been 4 of the 160. To long to remember.

I still think carbide is the best solution for the mix we do. Jury is still out on Kanafusa. Bottom line is it costs money to plane and shape wood in a pro shop. You just have to figure the best balance for maintenance labor, knife cost and surface quality.

I keep all my old knives and inserts. A large shop owner told me the carbide is worth a little money at recyclers. I don't know if the HSS is.

[David Zaret]

i talked to the unimerco guys yesterday - turns out they are in my back yard. for 530mm carbide tersas, sharpening is ~$35 a knife. they also will sharpen HSS and M42, cost ~$33 knife (again, 530mm). he said that they have a huge grinder, and that "the carbide's start at 10mm, and they have about 1mm to work with - past 9mm in width, they are done. most people get two or three sharpening out of a set, depending on how bad they are."

obviously it doesn't pay to sharpen HSS/M42 - i paid ~$80 for a new set of 4.

he said they actively evaluate the knives when they come in, and do the bare minimum to get them sharp.

based on the feedback in this thread, my next set is going to be carbide, and i'll probably leverage the exchange rate and tersaknives.com pricing and buy from there. unimerco told me they sell the same knives (distributor for same manufacturer) and they were much more expensive. but for sharpening.. seems like an excellent option.

--- dz

[mreza Salav]

i talked to the unimerco guys yesterday - turns out they are in my back yard. for 530mm carbide tersas, sharpening is ~$35 a knife. they also will sharpen HSS and M42, cost ~$33 knife (again, 530mm). he said that they have a huge grinder, and that "the carbide's start at 10mm, and they have about 1mm to work with - past 9mm in width, they are done. most people get two or three sharpening out of a set, depending on how bad they are."

obviously it doesn't pay to sharpen HSS/M42 - i paid ~$80 for a new set of 4.

he said they actively evaluate the knives when they come in, and do the bare minimum to get them sharp.

based on the feedback in this thread, my next set is going to be carbide, and i'll probably leverage the exchange rate and tersaknives.com pricing and buy from there. unimerco told me they sell the same knives (distributor for same manufacturer) and they were much more expensive. but for sharpening.. seems like an excellent option.

--- dz

So you'll have to adjust your tables after sharpening your Tersa blades? 0.5mm smaller radius of cutter head is quite a bit...

[David Zaret]

...as i had to do with the kanefusa knives, as they were slightly larger than the stock M42s. no big deal...