Help with Jointer Setup

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: A non fixed opposite reference that insures exact results of the piece being : processed. Ask this question, what is it about a TS WITH OUT a fence that : would cause it to produce a cut that is tapered?
Not a great analogy (though I do agree with the general point that getting parallel edges on a jointer is a matter of some luck, and is beter left to other toold entirely). The jointer tables, in theory anyway, provide a reference for a straight edge. Riping on a TS without a fence doesn't give you anything comparable.
    -- Andy Bars
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Andrew Barss wrote:

A straight edge is not the same as a parallel edge. You can make a straight edge quite easily with only a plane. You can even make a straight edge on two opposite sides of the same board. But getting them straight AND parallel is an altogether different proposition. Do the geometry ... without referencing the opposite edge, how will you know if the two edges are parallel?
There IS a way ... but the jointer can't use it.
Bill
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: Andrew Barss wrote:
:> Not a great analogy (though I do agree with the general point that getting :> parallel edges on a jointer is a matter of some luck, and is beter left to :> other toold entirely). The jointer tables, in theory anyway, provide a :> reference for a straight edge. Riping on a TS without a fence doesn't give :> you anything comparable. :> :>     -- Andy Barss
: A straight edge is not the same as a parallel edge.
Indeed it isn't.
All I was saying is that comparing (a) jointing an edge of a board with a jointer (against the reference bed of the jointer) isn't at all similar to freehand ripping on a tablesaw (i..e without the fence).
You can make a : straight edge quite easily with only a plane. You can even make a : straight edge on two opposite sides of the same board. But getting them : straight AND parallel is an altogether different proposition. Do the : geometry ... without referencing the opposite edge, how will you know if : the two edges are parallel?
: There IS a way ... but the jointer can't use it.
As I clearly stated in my original post, I agree that the jointer is not the proper tool to use to create parallel edges.
    -- Andy Barss
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wrote:

With each pass of the board across the jointer knives which are banging against the board that they are cutting, the reference,"you", cannot provide absolute resistance like a TS fence or thickness planer base. There is too much give in your hands and skin to insure a perfectly straight path across the knives. The path may seem smooth and controlled however the resulting taper is proof that some give in your hold is the culprit. The shallower the cut the longer it takes for the taper to "visually" appear.
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Sounds like an operator problem. If you hold to the properly set _limiting_ references, nothing bad will happen.
So just how does a plane work, Leon?
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If you are asking about how a hand plate achieves parallel edges, the user makes multiple passes and not all in the same spot.
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I'm not Leon but am an experienced plane user. It works much the same way as a jointer and it, like the jointer will not in any way ensure that the planed side is parallel to the other side.

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: I'm not Leon but am an experienced plane user. It works much the same way as : a jointer and it, like the jointer will not in any way ensure that the : planed side is parallel to the other side.
Yup.
The jointer plane actually works slightly differently, in that the sole of the plane before and behind the mouth are coplanar (unlike the beds of a powered jointer, where the infeed table is slightly lower than the outfeed), and the blade protrudes down below both (unlike a jointer, where the blades are even with the outfeed table).
This ought to produce diffrent results, I would think, but in practice one can joint a pretty straight edge with a plane. I've never been sure of exactly why!
    -- Andy Barss
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: wrote: :> : A non fixed opposite reference that insures exact results of the piece :> being :> : processed. Ask this question, what is it about a TS WITH OUT a fence :> that :> : would cause it to produce a cut that is tapered? :> :> Not a great analogy (though I do agree with the general point that getting :> parallel edges on a jointer is a matter of some luck, and is beter left to :> other toold entirely). The jointer tables, in theory anyway, provide a :> reference for a straight edge. Riping on a TS without a fence doesn't :> give :> you anything comparable. :> :> -- Andy Bars
: With each pass of the board across the jointer knives which are banging : against the board that they are cutting, the reference,"you", cannot : provide absolute resistance like a TS fence or thickness planer base. There : is too much give in your hands and skin to insure a perfectly straight path : across the knives. The path may seem smooth and controlled however the : resulting taper is proof that some give in your hold is the culprit. The : shallower the cut the longer it takes for the taper to "visually" appear.
Pleae reread what I said, and/or the followup I posted. I am *agreeing with you* that a jointer isn't able to give parallel edges.
But you were comparing (a) trying to get a parallel edge on a board using a jointer to (b) trying to do the same thing on a TS without a fence.
As I said, it's not a very good analogy.
    -- Andy Barss
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What woud be a better analogy?
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: :>
:> As I said, it's not a very good analogy.
: What woud be a better analogy?
I'm not sure. What makes the TS special compared to a jointer (or planer, or router with a straight bit) is that the blade extends back several inches from where it cuts, and it doesn't have a reference straightedge without the fence.
I guess the best I can think of is ripping on a TS (or a bandsaw) with the fence in place, but with the waste side running along the fence. So, you have aboard with one straight edge (call it A), a rough edge B to be trimmed, and you run B along the fence. The resulting trimmed edge C isn't going to necessarily be parallel to A.
Where things get dodgy (or my thinking about 'em does) is when you have A and B already parallel -- trimming it with B running along the fence WILL give you a new edge C which is parallel to A. Jointer is supposed to go the same way (i.e. the "rip on a TS to width plus a hair, trim hair with jointer" approach). But I have a gutt feeling it won't be necessarily parallel to A unless the operator has impeccable technique.
    -- Andy Barss
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wrote:

OK, I agree, you probably have a better analogy here. At least closer anyway ;~)
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What is it about a jointer that would cause it to produce a piece that is NOT tapered?

Well, that depends on what you are starting with. If the board already has straight and parallel faces, then a "properly set up" jointer in the hands of a good operator probably won't add a taper, if you're just making a single shallow pass. That is what people that "rip to width, clean up on jointer" rely on.
When you're starting with a cupped/twisted/bowed board and want to flatten both sides, the chances that the two flattened faces will end up parallel is pretty remote. That's why people flatten one side on the jointer, then dimension the lumber on a planer.
...but I'm sure you agree, and the current argument is about the "rip to width, clean up on jointer" process. (Some of the context has been lost by editing.) So why bring in the flattening process? Because I'm sure you'll also agree that the process of flattening will have rather different results depending on how the operator applies pressure, particularly in the transfer of weight from the infeed side to the outfeed side. Especially in the beginning stages when there is still lots of curve in the board - if you push one way to start cleaning up one part of the board, you'll get a different result from what you'd get if you started with pressure on a different point. That's where skill comes in.
...so I would argue (perhaps not strongly) that even when edge jointing the saw-cut face, an operator that doesn't shift and balance pressure between the infeed and outfeed sides runs the possibility of not making an even cut, because there is nothing intrinsic in the design of the jointer to prevent such uneven cutting.
...but I'd agree that this effect would be very small on a single, shallow pass. And I think you'd probably agree that an unskilled operator that takes several passes to both smooth the saw cut and reduce the board width runs a risk of accumulating single unnoticable tapers into a multi-pass noticable taper, because the jointer isn't going to do anything to prevent it.

No, just disagreeing on what to have for a snack.
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Take a piece of any stock that "has not" been edge jointed at all. Run the stock through the jointer "several" times and then measure with a accurate tool(calipers).
In my opinion, you "will" have taper to some degree. I have a highly tuned, well adjusted DJ-20 and I know it will taper a board in a heart beat. It has since the day I got it.
A jointers function is to "face plane" stock and to do some edge work.
Stoutman wrote:

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Oh I don't need calipers to see the taper forming. I had one board that I had to continue to run through several times before it started jointing the trailing edge of the board. By that point, I could visually tell that I had taken much more material off the front vs. the rear. I think I'll go spend some time today fiddling with the outfeed table height and see what I come up with. Cheers, cc
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By doing it "several times", yes, you will possibly accumulate error that can be measured with a caliper. I think the OP is seeing taper with out using a caliper.
If you start with parallel faces you should end up with parallel faces. If you start with a taper you should end up with a taper.

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Not necessarily the case at all, either with edges, or faces. AAMOF, it you happen to have done so, just consider yourself lucky ... this time. ;)
If the board has any edge or face bow the faces/edges can still be "parallel" ... joint one of those faces/edges and you will absolutely NO longer have parallel faces/edges.
Then try to joint the opposite face/edge and you will be chasing your tail with "taper" on one or both ends ... guaranteed.
As Leon correctly stated, a jointer simply should not be used in an attempt to make opposite faces/edges "parallel".
These results can only be guaranteed with, and are jobs for the well setup thickness planer and table saw for the normite, respectively, or the appropriate planes for the neander.
If you do NOT follow this truism, it will eventually bite you in the butt ... guaranteed.
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The practice I have seen on woodworking tv shows goes like joint one edge, rip on TS 1/32" oversize, then go back to the jointer to take that 1/32" off. If the jointer isn't introducing a taper then they should still be parallel.
I don't follow that practice because I know I've got some warp on the infeed table. I can run a square down the length of the fence and it's square at the outfeed side and at the start of the infeed, but not at the infeed just in front of the cutter. I don't do anything about it at this point because a) I can't be bothered because it still makes straight edges and that's what it's supposed to do b) I don't have a straight edge long enough that I *really* trust c) I will probably end up wasting two days screwing with it and not get any better.
-Leuf
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"Leuf" wrote in message

attempt
Yep ... as long as the first step was joint an edge, then rip to width, that should work providing the jointer is setup properly and you're a practiced hand with the machine.
AAMOF, it's not uncommon to do that on panel glue-ups to take advantage of complementary angles by jointing adjoining boards one edge face in, the other face out.
That is not the same as what I stated above, however.
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I have seen that too. I have also seen the shows use a guard when cutting dado's on the TS. Because it is on TV does in mean it is right. My shop teacher would give licks to any one that used the jointer on opposite sides of a board. The TV shows that use a jointer after the TS are using the jointer incorrectly and are not using a properly set up TS. I would not dream of depending on a jointer to bring a board to an exact edge or thickness. If the jointer was intended to make surfaces parallel it would have a gauge like all other tools intended to make surfaces parallel.
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