Jointer tuning woes


Hello group!
I am seeking some advice on a problem I am having with my jointer. Simply put I cannot it to cut a true flat edge. I get snipe at the last few inches of the cut.
Here is a bad ascii drawing of the bottom of the jointed edge:
Front (fed into jointer cutter heads) Rear ________________ __________________________________/
This all started when I had to replace the blades on the unit because the original blades were too dull and beat up. After the blades were replaced I ran into a number of problems with blade alignment, and fitment. These issues are now sorted and the blades are sharp and parallel to the cutter head.
I read a book on maintaining machines which had a section on tuning a jointer. It suggested that this problem comes up because the infeed table is angled downwards toward the end furthest away from the cutter head. I tested this with a straight edge and this was indeed the case, The book says in this case the gibs must be tightened. Did that no infeed and outfeed tables not in plane. Next step: shim the infeed table pushing it upwards until it is in the same plane as the outfeed. Did that using aluminum from a soda pop can.. Now with a straightedge across the table, and the infeed set at the same height as the outfeed everything appears "in plane." But I still have the snipe problem.
I have followed the instructions from the book and still have the same problem, Since this is the first time I am doing this, and since I am not getting the expected results, I do not know if I am doing it correctly.
My problem is I cannot continue my current cabinet project until this is fixed because I am now starting work on rails and stiles for the doors (first time at that too) and everything must be square otherwise nothing will fit.
Thanks for any suggestions you can provide. (no the wife will NOT let me buy an 8 inch jointer).
It is an old Busy Bee 6 inch jointer with spring loaded blades.
Dean
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You may be better off shimming the outfeed table into co-planar with the infeed, as the outfeed doesn't get moved nearly as much. And the snipe you're experiencing could be because the outfeed is lower than the top of the knives. I'd suggest John White's book on the Repair and Maintenance of Shop Tools. Or something like that. The blades needn't be parallel to the cutterhead, but parallel to the outfeed table, which is co-planar to the infeed. Tom
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Snipe _is_ because the knives are high/outfeed low. Tilted outfeed has a different symptom.
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My jointer manual has instuctions to use some hardwood guides. You set them on the outfeed table. When you turn the blades in the correct direction they are supposed to pull the hardwood guides a few millimeters. If th eblades are too high they will pull the guides more than a little bit. If your blades are too proud you will get all kinds of snipe. Of course there are lots of ways to get snipe but blades that are too tall relative to the outfeed table is one way.

Jim B.
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On Tue, 23 Aug 2005 22:08:42 -0400, Dean Hummel

Depending on the method used to set the knives, you may need to raise the out-feed table a small amount. If your tables are "in plane" with each other, the snipe is likely caused by the out feed table being a hair lower than your knives (or one knife). You can test that by lowering your in feed table a small amount (basically get it out of the way) then lay a straight piece of stock, flat on the out-feed table and let it hang over the spindle. By hand turn the spindle backwards to see if your blade(s) nick the piece of stock. Raise the out-feed table just until the blade touch is nonexistent or almost nonexistent. This is kind of a fine line preference situation. You don't want the out feed table too high or your pieces won't be straight but too low will give you snipe. Also, be sure that your test piece of stock is nice and straight when you test.
Mike O.
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Recalling the first time I changed the knives on my jointer, I can say with all sincerity that I Feel Your Pain. As long as the infeed and outfeed tables are reasonably flat (ideally within .003"), you need not lust after a new jointer. Yours CAN be tuned perfectly. Luckily, others have also experienced your frustration and there are many good web sites to help you with this. Here are some of the sites I've found helpful:
http://www.woodcentral.com/bparticles/knife_adjustment.shtml
http://benchmark.20m.com/articles/SettingJointerKnives/SettingJointerKnives.html
http://www.owwm.com/FAQ/JointerTune.asp
http://www.joewoodworker.com/jointerknives1.htm
http://web.infoave.net/~deltoro/jointer.html
http://www.toolnewz.com/0700v1i4/tuning.html
Good luck and stay with it. The results are worth it.
Brad
Dean Hummel wrote:

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In order to work properly, the knives have to be set with a dial gage. If the knives are even a few thousanths high snipe will result.
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Dave W wrote:

But not <necessarily> w/ a dial indicator--a straight edge works just fine.
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Dean Hummel wrote: ...

If this were true, you wouldn't have been able to get a straight edge <before> you changed the knives---the symptom isn't snipe, but either aconcave or convex edge depending on the direction of table misalignment.

That's because as someone else noted snipe is owing to the outfeed table being low compared to the cutting diameter of the knives. In particular, you first need to make sure all knives are at the <same> height as even one being a little high will cause a problem.
Second, since you're getting snipe, the outfeed table is low. Simple fix is to raise it very slightly, take a test cut. Repeat until symptom <just> goes away.
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Yup, and dial indicators are for folks that spend more time setting up the equipment than using it. 1) If you are sure the tables are co-planer. (and) 2) If you are sure the knives are square and even (Then) 3) Set your in-feed table for a pretty healthy cut like maybe 1/16th" to 1/8th" doesn't need to be precise. Take a known square scrap about 10" long and run it through the jointer about 3" and shut the jointer off. Then as Duane was saying just bump up the out feed table so the outfed cut on your scrap lays perfectly flat on the surface of the outfeed. If you want a precision measurement use a feeler gauge. 4) Go back to work a little practice and you can change out knives set your depth in a few minutes
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Update:
Thanks for all the replies. the web sites Brad pointed me to were very helpful. What I learned.
- Shim the outfeed relative to the infeed not the other way around,
- I referenced John White's book in my initial attempts to fix this problem.
- If the outfeed is too low this can also present problems. Turns out that was the case as the knives were not touching the straight edge when it was set on the outfeed table.
- When the straight edge is set on the outfeed table the blades should scrape the straight edge but not move it. This actually gives an audible indication; if the blade is not parallel you can distinctly hear a difference in the scraping sound.
- I used a Magnaset jig to set the blade height. The magnets on the front of the jig are too small to guarantee that the blade remains in place. Since they are connecting to the tip of the blade the cross sectional area of the blade is too small for the magnet to hold it firmly in place. The magnets that sat on the outfeed table were fine.
- The springs supporting the blades were throwing the alignment off when I used the magnaset jig. I have removed them.
- Had to recalibrate TDC. Was out by about 1/8 inch.
Result. No snipe. Much smoother surfaces. No more tapers across the board due to different knife heights and the scalloping is gone too (also due to different knife heights.)
Still not perfect though. Fence is a hair off 90 degrees, and even when the infeed table is cranked up to the max, the jointer takes off a hair. This probably means the outfeed should be lowered slightly and the blades reset yet again.
But for the moment I can live with that. Will run some test boards through and see how they come out.
I can definitely say that if or when I buy my next jointer I will look carefully at the blade changing mechanism (or maybe just give up and buy one of those carbide helical cutter heads. :)
Thanks for all the advice, keep it coming!
Dean
Dean wrote:

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On Wed, 24 Aug 2005 22:46:55 -0400, Dean Hummel wrote:

Sounds like you are 99.9% there. I use a large steel block (ground square) to set my fence against for perpendicular. You could do the same with a 2-4-6 block or a large magnetic v-block set on end from a machine shop supplier. "Shop grade" is accurate enough, so just about any discount supplier will do. The magnetic block also has the advantage of being hands-free while tightening but I prefer to know that the block I use will move and reveal any error, however small, if I miss the mark of true perpendicular. Your 'call' on that point, though. I worked as a machinist for several years (prototype, tool and die-making), so I tend to be a bit of a snot when I first set my machines up for a cut. I reset the miter head on my table saw whenever I first use it for the day. I hold a known-accurate framing square against the blade, release the miter clamp, cock the miter face and push it against the other leg of the square. Tehn I tighten the miter face. Next I pull the miter face away from the square a few inches and then bring it up to it again to check the first setting lest I have accidentally moved the square while tightening the clamp. All this takes about ten seconds and assures that I at least start with a good square cut.
If you are going to use a square to set your jointer / saw blades etc., get a good machinists square because it will sit vertical for you and because it will hold 'true' through many uses. A woodworking try-square does not have the same repeatability and can not be relied upon for this level of accuracy. The extra precision and repeatability are, to me, worth the price of admission.
Ignore the markings on the jointer itself. No matter what make of jointer you have, direct comparision with a solid right angle will be more accurate than whatever scale shipped with the machine.
For the utmost in accuracy (to the extent your jointer can hold a setting), cock the setting tool (block or square) so that the surface hitting the adjustable face of the jointer is an edge, not a flat. You can then sight along the edge with a light behind it to achieve accuracies unlikely by any other means. And you can do so reliably and repeatedly.
There are probably a hundred or even thousands of other machine setup tricks for the woodshop that I am not even aware of but I know for a fact that the ones I mentioned above do work and are reliable.
Bill
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