shuflid Posted October 10, 2014 Report Share Posted October 10, 2014 I don't think the problem is with my jointer I think it may be operator error. I set the jointer up according to the manual. I tried running a piece of lumber through it. Outfeed table is even with the cutters. After several passes I looked at the board and it was tapered on one end. Don't know what I am doing wrong. Any suggestions. Thanks Dan Quote Link to comment Share on other sites More sharing options...
Tpt life Posted October 10, 2014 Report Share Posted October 10, 2014 Are infeed and outfeed coplaner? Could the board be pivoting to a new plane halfway through? Quote Link to comment Share on other sites More sharing options...
4-Square Posted October 10, 2014 Report Share Posted October 10, 2014 <Outfeed table is even with the cutters <infeed and outfeed coplaner? 99.9% it's one or the other... or both... How exactly did you verify that the outfeed table is flat&true, planer across its width with the highest point of cutterhead arc and co-planer with the infeed table. I believe Marc has a video: Jointer is Jumping. If you work exclusivly hardwoods, oldtimers will insist that the cutterhead arc remain 1.5thou above the plane of the outfeed table. On 99.9%, optimum is between 0.5thou and 1.25thou above. The reasons for this are out of scope. On my setup, optimum is 0.5thou above, but I've got a high-end Euro jointer with the Tersa system... Good luck. Quote Link to comment Share on other sites More sharing options...
Llama Posted October 10, 2014 Report Share Posted October 10, 2014 Recheck your knife settings. They don't have to be off by much to create your issue. Quote Link to comment Share on other sites More sharing options...
Coop Posted October 10, 2014 Report Share Posted October 10, 2014 Agreed, outfeed table needs to be set just a hair below your knives Quote Link to comment Share on other sites More sharing options...
Vyrolan Posted October 10, 2014 Report Share Posted October 10, 2014 If you work exclusivly hardwoods, oldtimers will insist that the cutterhead arc remain 1.5thou above the plane of the outfeed table. On 99.9%, optimum is between 0.5thou and 1.25thou above. The reasons for this are out of scope. I, for one, would love to know more about this...any links to past discussion/elaboraton? Quote Link to comment Share on other sites More sharing options...
Tpt life Posted October 10, 2014 Report Share Posted October 10, 2014 My belief is that this accounts for imperceptible inaccuracy of coplaner tables. The longer the bed, the more likely an imperceptible error is to cause you trouble. Just know that jointing with a hand plane requires protrusion with no negative effect. Quote Link to comment Share on other sites More sharing options...
4-Square Posted October 10, 2014 Report Share Posted October 10, 2014 <My belief is that this accounts for imperceptible inaccuracy of coplaner tables I’ll let folks noodle on it for the weekend… First correct answer gets a set of FWW Rockler Bench Cookies – just kidding… Hint: Why would old timers specify 1.5thou, most current-generation jointers around 1.thou and a monoblock-based unit only 0.5thou? Quote Link to comment Share on other sites More sharing options...
4-Square Posted October 10, 2014 Report Share Posted October 10, 2014 No, no… I’m the product of a very long and expensive education… I don’t need smaller words… I ignored your explanation because it’s wrong, but I didn’t want to point it out… Next time, I’ll know… Thanks. Quote Link to comment Share on other sites More sharing options...
Tpt life Posted October 11, 2014 Report Share Posted October 11, 2014 To the OP, knives wear. Some manufacturers recommend setting knives two or three thou high. Setting knives low will always result in taper. I am trusting that if you set them even, they are even. If your first board tapered, either the board caused incredible wear, or something in the table set up is off. Four and I can debate two to three or one to half, but your options remain verifying the table, and slightly raising the blades. Quote Link to comment Share on other sites More sharing options...
T-astragal Posted October 11, 2014 Report Share Posted October 11, 2014 For one thing, half a thousandth is way too fine to measure without half a thousand dollars worth of calipers and gauges. A fresh ground knife will vary more than that. I'm happy with 5-7 thousandths difference from side to side and blade to blade. There is always a high knife and it can change from left to right. I set the out feed table a tick low. The resulting snipe is imperceivable and the cut is straight. The knife wears down a little too and if it gets below the out feed plane the you start to joint curves. It's hard to push as well. Steve 1 Quote Link to comment Share on other sites More sharing options...
minorhero Posted October 11, 2014 Report Share Posted October 11, 2014 I might be missing something, but the OP said that after several passes the board is tapered on one end. To the OP: do you mean that the thickness of the board is slightly less on one end then the other? If this is the case.. well that is normal for all jointers. It is caused by putting slightly different pressure on the board as you pass it over the blades. The solution for this is as follows, when milling lumber face plane on the jointer one side. When that side is flat you move onto the planer and plane the opposing side. When jointing one edge 90 degrees compared to a flat face, then you use the table saw to cut the opposite edge. This way you will always have square boards. Do not use a jointer on both one side of a board and then again for the opposite side. If you joint two opposing sides of a board you will always end up with a trapezoid. Quote Link to comment Share on other sites More sharing options...
pghmyn Posted October 11, 2014 Report Share Posted October 11, 2014 I might be missing something, but the OP said that after several passes the board is tapered on one end. To the OP: do you mean that the thickness of the board is slightly less on one end then the other? If this is the case.. well that is normal for all jointers. It is caused by putting slightly different pressure on the board as you pass it over the blades. The solution for this is as follows, when milling lumber face plane on the jointer one side. When that side is flat you move onto the planer and plane the opposing side. When jointing one edge 90 degrees compared to a flat face, then you use the table saw to cut the opposite edge. This way you will always have square boards. Do not use a jointer on both one side of a board and then again for the opposite side. If you joint two opposing sides of a board you will always end up with a trapezoid.My first question, is the face you jointed flat? Quote Link to comment Share on other sites More sharing options...
shuflid Posted October 13, 2014 Author Report Share Posted October 13, 2014 First of all I would like to thank all the folks that responded to my question. I did some checking and found I was not coplaner. I started adjusting the infeed table with great difficulty. I decided to disassemble the jointer as it was very dirty and made adjusting difficult. I am the third owner of this jointer and I don't believe it has ever been cleaned. Once it is apart and cleaned I will reassemble and set the jointer up correctly. Thanks again. 1 Quote Link to comment Share on other sites More sharing options...
4-Square Posted October 13, 2014 Report Share Posted October 13, 2014 <If you work exclusivly hardwoods.... cutterhead arc above the plane of the outfeed table. <Agreed, outfeed table needs to be set just a hair below your knives <I, for one, would love to know more about this...any links to past discussion/elaboraton? Some elaboration. I looked for a link, but everything I found was so far into the weeds, that no-one would take the time to sift through it... So I'll do a little write up. This is going to be quick/dirty, so it's going to be slightly wrong... Apologies in advance... In theory, the outfeed table of a jointer should be co-planer with the cutting arc. However, superior results may occur with the outfeed table slightly lower than the cutting arc. Why is this, why does it vary by cutterhead design, why does it very by species, how much lower and how do I know if I’ve got it right? And most importantly, does it matter? For the vast majority, it doesn’t matter at all… As long as the outfeed table is slightly below the cutting arc, your fine… Slightly above and you’ll get a taper… Why is this? I’ll give the same oversimplified answer that everyone else does: cutterhead geometry. The problem is ‘cutterhead geometry’ isn’t quite the entire answer… The actual answer is more involved – a lot more involved -- which is why everyone says ‘cutterhead geometry' First things first: If you’re not getting a reference face/edge that’s flat, true and square, then don’t worry about any of this... Get all the macro stuff dialed-in first… All knives at same height, knife arc at same level as infeed/outfeed table across its entire width, infeed/outfeed table co-planer across their entire width, infeed/outfeed tables flat, true and planer along the length, etc, etc, etc. If there is any question about these adjustments, there are numerous videos on YouTube and Marc’s got one on his free-site. BTW: notice I say 'width' several times? I've seen people get infeed/outfeed/cutterhead to what they think is 'co-planer', but only check the center of the three planes... You've got to be solid across the entire width -- yes, it's a lot more work, but that's just the way it is. For me, it's three measures -- back, middle and front -- I know some use more measures, but three is 'close-enough' for me... From this point on, I’m assuming the jointer’s setup properly, everything is planer, all dips are shimmed, the knives are all at the same height, protrusion is set correctly (most forget to check) and that you consistently produce a flat/true face/edge in stock the length/width of the infeed table. If you can’t get consistent results, then stop right here. It makes no sense to worry about micro-adjustments until you’re getting flat/true stock… Same with sharpness: 90% of woodworking problems can be cured with sharp knives, blades, edges, bands, irons, etc. Assuming all the above is true and the outfeed table’s adjusted correctly in relationship to cutterhead’s arc, you will notice a definite ‘suction’ when you try to lift the stock after face jointing… If it’s a tight-grained species, the suction can be considerable. Have you ever used a RoS on tight-grained stock with your DC on maximum? You can lift pieces of stock up to about 6" x 16" x 3/4 (apron for side table w/ drawer) right off the bench – the suction of stock to outfeed table is the same order of magnitude. In other words, it’s very noticeable… If you’re getting noticeable suction, stop – you’re done. No need to read further. BTW: Obviously it’ll be less with open-grained stock, but I mill lots of SQWO and still quite noticeable… Before going on, is this important? It depends. What step in your workflow produces the final reference surface/edge? If you clean-up milling marks with a hand plane or wide-belt sander, then the jointer is there to get you flat&true, not a final reference surface. The other point: how flat/square/true does the reference surface need to be? For the DIY project, not very… For a pattern-maker, you need as good a reference surface as possible. For most, ‘close’ is fine. Now for the counter argument: I joint by sound – I make successive passes until I get a consistent sound… That’s all I need… I then raise the infeed table to a couple thou and make one final pass… If the stock feels ‘stuck’ to the outfeed table, I’m done. If not, then something's wrong -- 99% of the time, the knives are dull. In almost ten years, my outfeed table has been adjusted just once. With a properly adjusted jointer, you don’t have to look at the stock, check with a square, use chalk, scribble tell-lines with a pencil/crayon, etc --- none of that stuff. I haven’t had to check for flat, true and/or square results off the jointer in years… many years... So going the extra mile can have a benefit even if you don’t need the accuracy… BTW: In the good old days, outfeed tables were [mostly] not user-adjustable -- it was all done with protrusion. The outfeed table was shimmed flat&true and coplainer with the cutterblock, then bolted in place... Why can varying the outfeed table height influence outcome? As previously stated, the answer is ‘cutterhead geometry’… The problem is that ‘cutterhead geometry’ hides a lot of detail. It’s important because the geometry determines acceptable design/operating ranges for: knife bevel angle/hook, knife protrusion, angle of attack, cutting arc, cutting geometry and a bunch of other stuff… Which is why everyone gives ‘cutterhead geometry’ as the answer. The other problem is that it’s not exactly the right answer, or at least, not the entire answer. I looked for a good link on this stuff, and found some excellent write-ups, but they were for industrial engineering tracts on cutterhead design featuring pages and pages on cutting geometry and force equations. No one wants to slog through that mess, but it’s out there if you want it. An analogy may help: ice cream -- more precisely, scooping ice-cream from a container. You can dive straight in with a steep angle of attack and a tight scooping arc (the males in our household diving for the goodies at the bottom of the carten) or you can use low angle of attack and a shallow scooping arc (the females in our household - efficient ice cream strategy: more ice cream, less effort). In the macro world, both give equal results – you get desert. But each approach leaves the ice cream container with a different surface. Further, each approach applies a different force (capital F -- Newtonian Force – direction vector and magnitude) to the container: the force vector for the steep/tight scoop is different from the shallow scoop… Similarly, the cutting arc applies force to the surface of the stock – some of the energy is used to cleave fibers and some attempts to push the stock up/off the surface of the jointer (compressing surface fibers in the process). Actually, this is an over simplification and unfortunately slightly wrong. The next layer of the onion accounts for the stock/knife interaction occurring in an arc, so the force vector changes direction in relation to the stock throughout the cut. After that, we get into feed rate, hardness, etc… The bottom of this well is truly deep… Having the knives slightly proud of the outfeed is more closely aligned with the vector trying to push the stock off the table and compressing surfice fibers. Obviously, effective angle of attack and the cutting arc's radius are the prime movers here -- hence, 'cutterhead geometry'. The height-offset changes with cutterhead diameter, knife protrusion, hook, species, old/new growth, etc. But always remember, we’re talking in fractions of thou and for most folks, it doesn't matter at all... BTW: How do I know the knives are dull when I don't feel 'suction' on my last pass (as mentioned above)? If you answer, "Change in Force", you'd be right... Higher percent of energy diverted from cleaving to compressing/pushing. In my case, I mill species between 850J – 1400J, so my outfeed table stays fixed at 0.5thou lower than the knife arc – I found this ‘optimum’ height-offset when I first setup the machine. For my machine and the species I primarily work with, this setting produces the most consistent result. In a decade, it’s only been moved once: I was milling Snakewood (3800J) and had to tap the outfeed table a bit... Not to open another can of worms --- have folks with Asian-sourced 4-post jointers (Jet, PM, Delta, etc) ever wondered why the lower table rollers are on a cam and can rotate through a 6thou ecliptic? Same reason… The factory setting is usually around 3 or 4thou because the typical Janka being milled is around 1000. But it’s user-adjustable for a reason: maybe you work in EWP or maybe in Bloodwood… Here’s a better one: ever get a new set jointer knives and they didn’t perform very well? Did the cutterhead for your model of jointer change over the years? Is the bevel angle/protrusion/hook/etc on the new set of knives correct for the current cutterhead or the previous version? BTW: I’ve fallen prey this one myself – I sat there cursing my old jointer for days until the technician at Delta figured it out for me… I swore-off knives once and forever -- went Tersa and never looked back. Not sure if this helps clarify the subject -- and I apologize for the ice cream analogy -- the more I think about it, the less I like it. Maybe I'll think-up a better one later... <edit> I forgot to answer the question I posted earlier. Why do old jointers generally use more height-offset than newer ones and why do monoblocks usually use less than non-monoblocks? Well, the simple (but not quite correct) answer is our old friend (and pat answer) ‘cutterhead geometry’ … Vintage cutterheads generally had a small diameter with a lot of protrusion to get an effective cutting arc of around 3” give or take... Current-generaiton cutterheads are usually slightly over 3” in diameter and [generally] use around 50thou protrusion for an effective arc of around 3 ½” - 3 ¾”. Monoblock cutterheads average around 8” in diameter (larger units are around 10”) with very little protrusion. So, back to ice cream: you've got a steep angle of attack with tight scooping action on one extreme and a shallow angle of attack with shallow scooping action at the other. But as I mentioned earlier, this isn’t quite the right answer -- however, but it’s big piece of the right answer… 2 Quote Link to comment Share on other sites More sharing options...
Vyrolan Posted October 14, 2014 Report Share Posted October 14, 2014 Some elaboration. That was a very enlightening read. Thanks for taking the time. Quote Link to comment Share on other sites More sharing options...
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