I have never posted here but I lurk here always.. so please be gentle. I have a grizzly 6in jointer that i have been very happy with for the last 5 years. it has been sitting pretty much unused for the last 2 years while i built my house. Well i am back into the shop now and it all of a sudden seems to be cutting real bad. it leaves ripples in the face of the boards. the knives look real sharp and i cleaned them and the bed and rewaxed. but to no avail. any ideas?
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Replies
AJ,
Have the knives sharpened. They have rusted and microscopic and macroscopic areas of rust have eaten away at the cutting edge. Also, you may have caused significant nicks in the knives the last time you used the machine, and had not realized that until you used it recently. Moving each knife slightly horizontally may help until you either get a new set (recommended in order to have a spare, sharp set always on hand) or sharpen this set. You also could hone a temprorary microbevel on each knife, but the answer is to get sharp knives on the machine.
VL
Do the ripples run across the face of the board or with the length of the board?
Did you try checking the knives with a straight edge for height? You can also "joint" the knives by running a sharpening stone over them while they are spinning. Carefully!!!!
I currently have the same type of oscillations you are describing on my planer - I believe the problem is caused by a loose bearing(sp?)in my case.
It is possible that you may have the same problem.
Petmonkey,
re: "You can also "joint" the knives by running a sharpening stone over them while they are spinning."
Is this something you have actually tried? Successfully? Or have you just "heard" about it.
Every few years I have come across this advice which I file into the category of urban myth. I have honed a microbevel onto jointer knives by lightly running a stone over them (side to side) after they have been locked at TDC. I have honed them with a cup hone mounted in a router (which is scary enough).
Even if the operation could be carried out without tradegy, I cannot imagine how the geometry of the situation could correctly put the microbevel on the knife.
This is advice far more dangerous than just about anything I could imagine a worker doing. There is no way this operation can be made safe on a typical jointer. Anything desgined to hold the stone is a jury rig.
Grinding and sharpening operations are carried out on machines that have elaborate and precise mechanisms to hold the work and the abrasive. Rotary abrasive disks are made for that purpose and do not undergo the repetitive pounding and repetitive compressions that a rotating knife head would cause. A bench stone subjected to the stress of a spinning jointer knife assembly could literally blow up.
VL
Venicia The primary object of running a stone across the knives is to joint them to ensure a perfect cutting circle.The size of the micro bevel is microscopic.One is not trying to joint the stone.So one is only dressing 2 or 3 thou.I have done a few times .Personally I find that with a DTI I can set up the knives well enough without jointing.As a way of extending the life of a worn knife to get rid of knotches NO WAY have 2 or 3 sets of knives and send them for sharpening for $!0 or so.But like most things in woodworking if it makes your a.. tight DON'T do it
Jako,
I agree. I don't hone my knives on the machine anymore. Setting them with a magnetic jig achieves an excellent, uniformity. I always have a sharp set waiting. I DO adjust for minor nicks, though, by moving the knives a little sideways.
VL
I don't know whether it's still done with newer machinery, but I had a Delta planer in the 70's that had a sharpening attachment so you could grind the knives in place in the machine. It also had a jointing attachment to allow you to touch up the knives between sharpenings. You could joint the knives until the flat behind the edge was 1/32" wide, then you had to sharpen again.
With a jointer, I raise the outfeed table until it is above the cutting circle. I wrap a 6" stone in paper so it doesn't mar the table, with a little bit sticking out on the end . I put the stone on the outfeed table, turn on the jointer, and gingerly lower the outfeed table until I can hear the knives just touching the stone. I run the stone from side to side until I can't hear it touch any more, then stop the machine and check the knives. If they're all showing a little bit of flat, I hone the face of each blade a little and reset the outfeed table. And yes, I have done it myself, many times. I just did it again to make sure my description was accurate. (A proper question, I may add. A lot of misinformation gets perpetuated by people who haven't tested the methods they recommend.)
I have never had anything remotely like a problem doing this. The worst that could happen is having the stone pulled out of your hand, since your hand stays 4 or 5 inches from the cutter. You'd have to make a big mistake to have that happen, but I guess it's possible. I suppose that you could stick your fingers in the rotating cutterhead, since the guard is off, but you do have to have a little sense to work with rotating sharp things, or else you don't do it very long.
The process does work to refresh the edge on the blades, and it does make them all perfectly concentric, resulting in a better finish. It is only a honing operation, not a substitute for sharpening. As I mentioned above, the process is called jointing the knives. I can provide photos if I haven't made myself clear.
Obviously, anyone who doesn't feel COMPLETELY comfortable with this operation should not do it, because they are probably doing something wrong.
Michael R.
Edited 12/7/2003 7:50:22 PM ET by Woodwiz
The powermatic manuals that I have read also recommend this procedure. Let me add one thing from the manual that also increases the safety. Clamp a board across the infeed table to act as a stop for the stone. This prevents the stone from taking off in the direction of the cutter head.
Woodwiz,
OK,
So it CAN be done. (I'm amazed). But that doesn't mean it SHOULD be done. I still think it's very unsafe. My bigger question has to do with the honing that's attained.
I simply cannot understand how using the same physical principles that dull the blade can put a finer edge on it. Driving the blade in a circular motion into wood rounds over the sharp edge. You are telling me that using the same technique into an abrasive stone now improves that dull edge? The angle is all wrong for the microbevel. Not to mention several other violations of sharpening principles.
(shudder)
VL
Thought I would jump in the fray here. I am a safety fanatic and I tried the method of just kissing the knives when the jointer is on. It can be done safely and I learned it from "Sharpening Basics" by Patrick Speilman. By hand works too but it is the difference between hand sharpening and power sharpening.
Jointing the knives while the jointer is running with the proper set-up is what I do when touching them up by hand just isn't cutting the mustard anymore. Last resort for me is to change the knives when all else fails but I learned something valuable here tonight. I plan to invest in magnetic knife holders the next time I change knives.That's always been close to going to the dentist.
My loonie's worth..cheers,
silver
Edited 12/8/2003 2:55:00 AM ET by silver
I could do a long rambling reply on principles of sharpening, relief angles,etc., but the important thing is that it does work better than hand honing. It is safe, if done correctly, and it's recommended by a number of sources including a pretty good manufacturer.
Again, if you are not comfortable with it, don't do it.
Michael R.
Does this "power jointing" need to be followed up with a hand honing to put the proper bevel on the blades? Or is this the final operation?
1) unless the stone is held rigid you will not true the blades.
2) it is a poor way to keep a shape edge on the blades.
Well, since I started it... I'll jump back into the fray.
Some of you guys just slay me. It's the whole "my way or your an idiot" mentality.
Venician - I appreciate your reservations and explanations of your reasons. I was, of course, a little taken aback by your intitial reply to my post regarding "jointing" the knives, but you, in a later post, at least seem to allow for a difference of opinion.
As for that last poster who just flat out said "Don't do it." with no further explanation, c'mon - what's your deal?
It can be done, it is done, and it does work. Is it the best way to get an absolutely perfect micro bevel on your knives? Well duh! Of course it isn't. But what jointing your knives is really good for - is removing very slight height differences in your knife settings. And ya know what? It's the cat's meow for doing it.
Even I can use this simple method to absolutely eliminate any knife height differences. And for those of us using feeler gauges or guides to set our knives - using this approach allows us to eliminate those very slight height differences that creep into the equation.
Like the man said - "If it makes your A*S tight... don't do it!"
Don't like using a TS without a guard? Don't do it.
Don't like making plunge cuts on a TS? Dont' do it.
Don't like using a RAS? Don't do it... but these things can be done and have been done - safely.
Edited 12/8/2003 9:18:22 PM ET by petmonkey
>>1) unless the stone is held rigid you will not true the blades.
>>2) it is a poor way to keep a shape edge on the blades.
George, what do you base these assertions upon?
First, you are just barely kissing the stone with the blades, but allowing the stione to give a little helps in case you are a little heavy handed. As I described before, you lower the outfeed table until you can just hear the blades starting to kiss the stone, then you run the stione side to side until you can't hear anything any more, meaning the tops of the knives that touched the stone are all the same height in relation to the stone and the table. If not all the knives made contact, you just repeat the process until they have all been refreshed, and they are all just about perfectly concentric, and parallel to the outfeed table.
It's a poor way to sharpen blades because that flat area behind the edge can only be so wide without affecting the cut quality, but if it is such a bad way to hone knives between sharpenings, why do both Delta and Powermatic recommend the process?
Do you have some actual data that supports your point of view? I've given mine, and I'd like to read yours..
Michael R
I can provide several good reasons for not using a stone against the spinning blades of a jointer:
1.Blades trued up in with a stone may cut better than they did before the touch up, but that is only because the blades were installed at uneven heights and/or were dull. Touching up the blades with a stone is a poor substitute for sharp blades properly installed.
There are several books and articles on how to set knives, once you learn how to do it properly the process is hassle free and precise. Magnetic jigs are one of the best ways to install knives on a jointer. They can be shop made for just a few dollars.
2. The outfeed table on a jointer works precisely only when it is being raised. When the tables are being dropped, they will move erratically because of the freeplay that is inherent in their design. There is a very real chance that backing down a table with a stone on it can end up with a sudden drop that will jam the stone against the blades leading to nasty consequences.
I have been told one credible story of this technique resulting in the stone exploding and taking a chunk out of the lip of the infeed table where it overhangs the cutter head. I wasn't there, so I don't actually know why it happened, but it is certainly a cautionary tale.
3. The process, even when properly done, will spray tiny hard particles of the stone onto the cutter head bearings, the dovetail ways, and the table height adjuster threads. The grit will cause these parts to wear out much faster than they would ordinarily. Machines that are regularly exposed to abrasive grit have seals to keep the grit out of critical components, jointers have no such protection.
4. The technique throws sparks down into a sawdust filled area, the potential for a smoldering fire, that may not flare up until no one is around, is a slight but real possibility.
John W.
heres the new lowdown. upon further investigation the blades seem to be dull only at the @3/4" strip where i always joint my edges. after bringing in the fence an inch or so my edges are fine again. Thanks for all the great info. I think i will post here alot more. but " cant we all just get along?"
>>1.Blades trued up in with a stone may cut better than they did before the touch up, but that is only because the blades were installed at uneven heights and/or were dull. Touching up the blades with a stone is a poor substitute for sharp blades properly installed.
>>There are several books and articles on how to set knives, once you learn how to do it properly the process is hassle free and precise.
I ran small furniture factories and set up industrial machinery for over twenty years, including all kinds of loose knife cutterheads for automatic shapers, molders, tenoners, and profilers. I think I have a good idea how to set up machines, and have trained a lot of people. I can tell you categorically that there are only two ways to get knives completely concentric. Either grind the knives mounted in a hydraulic cutterhead as it will be mounted in the machine, or joint the knives on the machine. Knives installed with a dial indicator or magnetic jig may be kept within about .001 by a skilled installer, but they will never be exactly concentric. Even insert tooling will have runout because of the clearance between the tool body and the machine spindle. After I joint the blades on my jointer, you cannot see any cuttermarks on a planed surface, just as it is with a high-speed molder with hydraulic cutteheads. You would have to be pretty good indeed to achieve that degree of precision by hand, even with the best of fixtures. Even firmly set jointer knives will move a little every time you adjust the clamping screws.
I repeat, this is a way of trueing the cutting circle and HONING the edges. It is not a substitute for proper sharpening when needed. It is a timesaver, because you can do this a couple or three times beteween sharpenings, and it takes less than five minutes to accomplish. How long does it take you to change a set of jointer knives and set them to better than .001 concentricity? How much does it cost you in time and money to have a set of knives sharpened? Jointing will save you at least 2/3 of that cost.
>>2. The outfeed table on a jointer works precisely only when it is being raised. When the tables are being dropped, they will move erratically because of the freeplay that is inherent in their design. There is a very real chance that backing down a table with a stone on it can end up with a sudden drop that will jam the stone against the blades leading to nasty consequences.
I don''t know what kind of jointers you have been working with, but on every one I have used, the adjustment on the outfeed table is pretty tight, and takes a deliberate effort to move the table up or down, and the possibility of any slippage is very remote at best. If you are really worried about that, most jointers have a locking mechanism for holding the bed in place, and you could snug that up a bit to provide the amount of drag you want. Your comment may hold true with lever type adjustments; I haven't used them enough to judge.
At any rate, what is this jamming the stone against the blade? Even if you forget to raise the outfeed table and run the stone out over the blade, all it does is make a nasty noise, bounce, and chip up the stone. Not nice, but not major either. Worst case, you buy a new stone and send the blades out to be sharpened.
>>I have been told one credible story of this technique resulting in the stone exploding and taking a chunk out of the lip of the infeed table where it overhangs the cutter head. I wasn't there, so I don't actually know why it happened, but it is certainly a cautionary tale.
Rumors and hearsay. I speak from direct experience. Yes, you could break a stone if you really screwed up, but you will be behind the cutterhead, not in front of it, and the times I have screwed up, the results have been as I described above. You don't sem to understand that we are talking about the slightest of touches between stone and knife.
3. The process, even when properly done, will spray tiny hard particles of the stone onto the cutter head bearings, the dovetail ways, and the table height adjuster threads. The grit will cause these parts to wear out much faster than they would ordinarily. Machines that are regularly exposed to abrasive grit have seals to keep the grit out of critical components, jointers have no such protection.
Every jointer I have ever worked on except for ones with babbit bearings has had sealed ball bearings. Open bearings wouldn't last at all.
I have never seen a jointer where any of the surface of the ways was exposed in use with the infeed table set for zero cut. Worst case, some grit gets on the top 1/2 inch out of eight inches or more, and gets blown or wiped off when you are done. These aren't exactly reciprocating parts, and wood can be plenty abrasive, too, especially the ones with a high silica content.
Can you name a jointer where the height adjuster threads are hit by shavings? I can't.
4. The technique throws sparks down into a sawdust filled area, the potential for a smoldering fire, that may not flare up until no one is around, is a slight but real possibility.
I don't know about you, but I try to keep my machines fairly clean. Although I have never seen this operation throw sparks, good housekeeping does overcome this objection.
The biggest real objection I can think of is poking your fingers into a rotating cutterhead. That would be nasty. Done correctly, your hands never get within several inches of the cutterhead, but it is still a very real danger to the inattentive or inexperienced. So once again I say, if you are not comfortable with it, don't do it. But I don't think it is necessary to keep inventing reasons why you shouldn't do it. The reason I just mentioned is a plenty good one.
Michael R
The 20 inch General 330 thickness planer has a honing stone that can be mounted over the cutterhead and very slowly wound down into the revolving cutterhead to joint the knives.This can be done until the flat is about 20 thou.then it starts to burnish the wood At first it is a bit nerve racking but the trick is to realise the stone barely kisses the knife
I like it! I lot of dangerous jobs get much easier when you can get the machine to hold the tool for you.
That sounds like the kind of setup I had on that old Delta industrial planer.
Thanks for the specific replies to the issues. I will add this to my list of things to do in the future. I have been and will continue to joint many bf of lumber for my house project and look forward to spending less time (not zero) sharpening and more time working.
I agree whole heartedly with your assertions. They make perfect sense to me. Going to the store for a pop can be very dangerous if not done correctly. One false slip of the steering wheel could cause a head-on collision with another car. Yet we drive our cars all the time in spite of the dangers. I would underscore your advise that this is something for people that understand the process and are comfortable in its' execution.
>>Thanks for the specific replies to the issues
A lively discussion does tend to bring out all the sides of an issue, and helps to test one's thinking. As long as people stick to the issues and stay civil, I think it's a lot of fun. I always seem to learn something or pick up a good idea from these "debates", and hopefully others get exposure to various points of view, also.
Michael R
It is interesting to read your comments in the discussion on jointer blades.
Especially the point that all blades wriggle under final tightening of the screws.
I wondered if I was the only one to endure that frustration.
Further, by way of interest, I have a Delta Rockwell book circa 1937 that shows how to joint the knives but I was always nervous about the idea.
Ken
I give my views, you give yours.
There appear to be no people sharpening up their circular saw blades, drill bits, or router bits that way. In fact, when sharpening your router bits you remove the "wear" along the relief. A reasonable person might ask why if this technique works it has it not spread to similar machinery.
"Why do both Delta and Powermatic recommend the process?"
Perhaps you should ask them why it works. (I used to stone the "wear" off my jointer blades, but the blades were stationary.)
>>There appear to be no people sharpening up their circular saw blades, drill bits, or router bits that way.
Of course not. A reasonable person would only have to look at the geometry involved to see why. There are no long, straight edges to joint, and even if there were, The machines don't lend themselve to that kind of operation.
>>In fact, when sharpening your router bits you remove the "wear" along the relief.
In fact, router bits are sharpened by removing mateial from the face, not from the profiled edge.
>>Perhaps you should ask them why it works.
The question was, of course, rhetorical. I know why it works, and several other people have corroborated that opinion from atual experience. I ask you again, Upon what basis do you make those assertions. Do you have experience of facts to back them up, or are they just unfounded opinion? If there's somthing you know that the rest of us don't, please don't keep it to yourself.
Michael R
I gave you several examples that show tool builders and professional sharpeners, guys who know something about sharpening tools, don't do what you are suggesting.
Feel free to do what you wish.
I hate to beat a dead horse but...
I never once indicated that jointing the knives is ideal for sharpening. In fact, I don't even know if knives could be sharpened in that manner. What I am saying is this:
Jointing the knives provides for an easy, straight forward, simple to understand method to make sure that your jointer knives are perfectly concentric.
Perhaps the reason that this process is recommended and used for the jointer is because it just happens to be a process that works with the jointer.
Just because a process works with one machine, does not mean that it has to work with all machines. The initial post - I seem to remember, dealt with wavy material. One of the causes of wavy material is uneven knives. It is that issue I was referring to.
Another reason for wavy material could be dull knives (although not in my limited experience). I was not indicating that jointing the knives would fix any problems associated with dullness. Dull knives need to be sharpened and jointing them is not the best way to do it.
However, if you feel like you have a knife that is just slightly off... by all means spend 15 to 20 minutes setting and resetting your knives - OR, just joint the darn things and be done with it in 15 to 20 seconds.
>>Does this "power jointing" need to be followed up with a hand honing to put the proper bevel on the blades? Or is this the final operation?
I hone the face of the knives lightly, just for drill, but I don't think it is really necessary. No further work is necessary on the back of the blade.
As long as the flat on the top of the blade is less than 1/32" wide, it doesn't really affect the cut. If it gets wider than that, it begins to affect the cut and the knives should be sharpened conventionally.
If you look at a well used saw blade or set of planer knives, you'll see a shiny band of metal just behind the edge, before the resin buildup starts to show. Wood is compressed a little as it cuts, and it flows back behind the cutter, rubbing that narrow area, hence the need for relief angles. In practical terms, with a cutter turning 5,000 RPM or so, a concentric strip behind the cutting edge, a few thousandths of an inch wide doesn't make any difference in performance, because a dull knife compresses the wood even further, reducing the quality of the cut, and leading to a washboard appearance.
Michael R
Venicia, I think my method of honing is similar to yours. Was wondering how you lock the knives at TDC? I use a small wood wedge tappped in at the back of the cylinder but have wondered if there's a better way. Then I lay an old plastic drafting template on the outfeed table to protect the cast iron and work a wet stone across the knives. Before I do any of this, I have to set up a magnetic gooseneck work light, put on my headband magnifier for my old eyes and put a towel on the floor for my old knees cause it takes a while. The spinning method may work for some but I picture a knife digging in and pulling the stone and my hand into a spinning blade. Letting go of the stone in time isn't a game I want to play.
I tried the cup hone method, following instructions in a FWW article but it also was too fast and furious for me.
Ian
>>The spinning method may work for some but I picture a knife digging in and pulling the stone and my hand into a spinning blade. Letting go of the stone in time isn't a game I want to play.
When you lower the outfeed table, it is so gradual that the blades just barely kiss the stone. There is no tendency to pull. The knives can't dig into the stone; it's harder than the blades. Second, this is all done with a very light touch and a very light grip. No possibility of "pulling" anything.
The biggest danger would be getting distracted and sticking you fingers into the cutterhead for some reason completely unrelated to the process, and that is a very real danger. But if you pay attention and keep your hands out of the way, the process is safe and takes less than five minutes. It won't take out nicks, just refreshes the edge.
Again, if you don't feel perfectly comfortable doing it, then by all means don't. I'm just trying to give info so people can make informed decisions.
I didn't see the article in FWW, but I may try to make a fixture for actually grinding my jointer knives in the machine. The jig on the Delta planer just used a piece of spring steel as a stop, and you could lift it out of the way to advance to the next knife. On a jointer, I would drill and tap a couple of small holes in the bed so the stop could be put in exactly the same place, once I had the setup just right. I would try to grind the backs of the knives, not the faces. Sure would save a lot of setup time changing knives.
Michael R
Iancummins,
I used to clamp the pulley on the cutterhead.
Another way is to make a block whose width is the same as the measurement across the inner edges of the belt. The block has an arc in its end that mates with the circumference of the pulley. The block is snugged up against the pulley and a clamp is placed across the outer surfaces of the belt, clamping the belt against the block and around the pulley.
VL
I've had to buy new blades for my old craftsman 6 1/8 jointer. They were only 20 bucks from amazon, but I was kind of at a loss on how to get them accurately installed. So I purchased a book from FWW titled "Care and Repair of Shop Machines: A Complete Guide to Set Up, Troubleshooting, and Maintenance" which is very has a whole section dedicated to calibration and repair of a jointer with simple to make, inexpensive tools. It was the best 14 dollars I've spent in a while. The whole book clearly tells you infallable ways of calibrating and maintaining all of your major shop machines. I now have my table saw cutting so accurately it's scary. It's amazing what a scheduled maintenence routine will do for your shop.
Hope that helps.
Fred
HI AJ
I've read some of the replys. It sounds like you have what we call washboard occuring. This happens when at least one of the knives is higher than the rest. The way to tell is to run the board on its edge and run it slow. You may have been doing this with out thinking about it two years ago. Runing the board slow should produce a good cut.
Now how to fix the problem. First I do not recomend the honing stone approach. I have see it done, its dangerous and does not do very go job. I'll leave out the details. Have the knives sharpened. Before you install them hone them as if it was a chisel edge. Lay the blade on its back flat on the jointer table. Hold the stone in your hand move the stone not the blade .BE CAREFULL. Next install them using a dail indicater for this purpose. They should be installed level with the out feed table. There are many methods of setting knives find what works for you. Don't forget to unplug the tool first.
Cliff
Yippie! the perfect reason to sell it and move to the next size! tell me aren't you secretly envious of those jointers that are as big as an aircraft carrier? (I know I am) Well if your wife had a microwave that went bad on her, she'd just throw it away and buy another wouldn't she?
there you have it reason and the logic it will take to convince your wife! ;-)
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