Making wedges on the jointer

[dusty]

[quote="algale"]When jointing it is absolutely normal for the thickness of the jointed board to be tapered. http://www.newwoodworker.com/jntrtaprs.html
If you take deep passes and/or run the same end through first every pass it will be even more pronounced.
The jointer makes one faces flat]
Thank you for posting this link. I stated earlier that "I respectfully disagreed" but after reading it and rereading it two or three times and really thinking about what was being taught, I have changed my mind.

If anyone is going to refer to this link, I strongly suggest that you also click on and read all of the imbedded links. There is a wealth of good information here.

Furthermore, I do believe that it is entirely applicable to the Shopsmith jointer and planer.

Understand what the jointer and planer were designed to accomplish and do not expect them to do anything else well. They function as a team. Neither one does what the other was designed to do.

A couple of images that might help. These are intended to represent the jointer tables and two squares be used to verify the coplanar relationship of the two tables in a way that I had never thought of. This is a concept that was discussed in the links referenced by algale.

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[ATTACH]26677[/ATTACH]

If the two squares come together with NO GAP, the tables are coplanar. This needs to be done at several locations across the width of the tables to verify the entire table set.

.

[dusty]

I am fortunate to have some milled aluminum blocks that work perfectly for this task (tuning the jointer tables). In the absence of these, however, accurately cut wood blocks would do the same thing.

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[ATTACH]26679[/ATTACH]

[algale]

Thank you for posting this link. I stated earlier that "I respectfully disagreed" but after reading it and rereading it two or three times and really thinking about what was being taught, I have changed my mind.

Ifoq anyone is going to refer to this link, I strongly suggest that you also click on and read all of the imbedded links. There is a wealth of good information here.

Furthermore, I do believe that it is entirely applicable to the Shopsmith jointer and planer.

Understand what the jointer and planer were designed to accomplish and do not expect them to do anything else well. They function as a team. Neither one does what the other was designed to do.

You are welcome. I, however, have come around the other way and think that if the board starts flat and with parallel faces and edges (S4S) it ought to be theoretically possible to joint it without creating a wedge. In all other cases I see wedge-dom (a new word I just created) in a jointed board's future. Do you agree that at least in a case where the board is really flat and has parallel faces it ought to be possibly to avoid the dreaded wedge?

[davebodner]

You are welcome. I, however, have come around the other way and think that if the board starts flat and with parallel faces and edges (S4S) it ought to be theoretically possible to joint it without creating a wedge. In all other cases I see wedge-dom (a new word I just created) in a jointed board's future. Do you agree that at least in a case where the board is really flat and has parallel faces it ought to be possibly to avoid the dreaded wedge?

I don't have enough knowledge or experience to be an authority, but heres my take: just as it's possible to joint a straight, non-wedged edge with a hand plane, it should be possible with a jointer, too. However, in either case it takes a bit of skill in applying the proper pressure. Am I close?

[dusty]

You are welcome. I, however, have come around the other way and think that if the board starts flat and with parallel faces and edges (S4S) it ought to be theoretically possible to joint it without creating a wedge. In all other cases I see wedge-dom (a new word I just created) in a jointed board's future. Do you agree that at least in a case where the board is really flat and has parallel faces it ought to be possibly to avoid the dreaded wedge?

When I said that I had changed my mind, it was not my intent to say that wedges are inevitable.

Furthermore, I don't believe parallel edges are necessary to start with. A single straight edge can be jointed smooth and squared to the face using the jointer.

With one straight edge, the other edge can be made parallel to it either in the planer or on the table saw. Depending on the task, that newly cut edge may need to be taken back to the jointer to get rid of mill marks.

I do concede that a straight and true edge can be turned into a tapered edge without realizing it has happened. If this happens on a properly tuned jointer, it is a matter of technique. The proper technique can be detailed in print but reading that alone will probably not result in one learning how to joint a board. Doing that is a matter of feel. How much pressure to apply downward toward the tables and when to shift or release that pressure is the key factor.

No matter how good your technique, if the jointer is not properly tuned you will not likely get the desired results.

[Owad]

I just pulled out the jointer that came with my older shopsmith and gave that a try. After taking six passes, the taper over two feet is just under a 64th, so it does seem the problem is with the jointer, and not with my technique.

[JPG]

Let us not overlook the purpose of a jointer.

It's primary purpose is to create straight edges.

It's secondary purpose is to make that straight edge 'normal'(90 degree angle) to one face(pressed against the fence). Or some other angle determined by the fence.

If one has a straight edge to begin with, one has no need to use the jointer. If one did, there would be no 'tapering'.

Normally that edge is not straight so the jointer will cut away varying amounts of material along the edge.

If the jointing process removes more material from one end than the other a taper will be the result.

We can blab about technique until the cows come home, but doing so must include differences required due to different shapes of the workpiece. It is possible to joint warped board edges without creating a taper, but that be an isolated result dependant upon the initial shape.

Bottom line, both technique and board geometry determine if tapering results.

P.S. Yes improper alignment of the cutter to the outfeed table alters every thing.

[fitzhugh]

Wow, this is timely!
I've got to reread this and read through the linked pages (and their links, as ordered, I mean politely suggested) before asking too many dumb questions...
but I will ask one for now:
I'm confused by the references to using the jointer with tables co-planar. Doesn't that mean you are relying only on the degree to which the knives protrude above the outfeed table (and in this case, the infeed)? While mine protrude a tiny bit based on the "move the straightedge 1/8" method I'm at the computer to read up on jointers because I just read comments about setting jointer knives so they are exactly the height of the outfeed table (using glass on the outfeed w/ micrometer to see if the knives start touching glass)
... reading through old FWW's - FWW 105, april/march 1994 p6

So, by co-planar you really do mean co-planar, with the tables all lined up and at the same height, not just deeply and truly parallel but possibly at different heights, right?

Sorry this is worded in a confusing fashion - I'm supposed to be in home in bed with a nasty cold, not home at the computer and certainly not home in the shop. Don't let swmbobsbsapuwewIwntmsaw* know I'm not.

*...because she brings soup and puts up with enough when I'm well not to mention sick and whiny, of course. What, didn't you know that? you a ludite or somethn? ok, seriously, it's time to retreat to bed again. Only, have to say first how much you all suck for talking about things I really want to read about when I'm too hazy-headed to follow. And I can't just read in bed on my phone because I dropped IT in the toilet.

[JPG]

Wow, this is timely!
I've got to reread this and read through the linked pages (and their links, as ordered, I mean politely suggested) before asking too many dumb questions...
but I will ask one for now:
I'm confused by the references to using the jointer with tables co-planar. Doesn't that mean you are relying only on the degree to which the knives protrude above the outfeed table (and in this case, the infeed)? While mine protrude a tiny bit based on the "move the straightedge 1/8" method I'm at the computer to read up on jointers because I just read comments about setting jointer knives so they are exactly the height of the outfeed table (using glass on the outfeed w/ micrometer to see if the knives start touching glass)
... reading through old FWW's - FWW 105, april/march 1994 p6

So, by co-planar you really do mean co-planar, with the tables all lined up and at the same height, not just deeply and truly parallel but possibly at different heights, right?

Sorry this is worded in a confusing fashion - I'm supposed to be in home in bed with a nasty cold, not home at the computer and certainly not home in the shop. Don't let swmbobsbsapuwewIwntmsaw* know I'm not.

*...because she brings soup and puts up with enough when I'm well not to mention sick and whiny, of course. What, didn't you know that? you a ludite or somethn? ok, seriously, it's time to retreat to bed again. Only, have to say first how much you all suck for talking about things I really want to read about when I'm too hazy-headed to follow. And I can't just read in bed on my phone because I dropped IT in the toilet.

YES

There was much misuse of the word co-planer.

Only when the infeed and outfeed tables are at the same height are they co-planer.(share a common plane)

And yes the blades must be at the same height as the outfeed table all across the front end of the table.

At all times the planes of the tables need to be parallel. Thus all points on either table are offset vertically the same from all points of the other table.

It works in that once on the outfeed table the fresh surface created by those equal height blades becomes the reference for all cutting that follows(assuming no interference from the infeed table).

It is the invalidity of that assumption in some instances that creates a result different from a straight surface.

Get Well!!!!!!

[fitzhugh]

It is the invalidity of that assumption in some instances that creates a result different from a straight surface.

Get Well!!!!!!

Thanks!
and you are fast enough you caught me before I waddled back to bed
So I'll re-read this and consider reading co-planar as parallel when that makes more sense.

Now, about those knives and the outfeed table. The way I learned to do it (that way it sounds like I learned decades ago in my apprenticeship and not last week or so via google and this forum) I set the tables close enough to co-planar that I couldn't tell otherwise with tools on hand (straightedge) and then set the knives so they moved a light straightedge by exactly (in theory) 1/8" at each end and center. That was explained as compensating for the rebound from compressing the fibers, in contrast to metalworking where compression is insignificant at this scale and the knives would be set at the same height as the outfeed table.

Those are two different things. Perhaps they are close enough that they are nominally the same and get equivalent results, but I doubt it.

Any thoughts? Oh, and is this hijacking enough I should take it to another thread?

Now I really want to get in the shop. I'll print out the threads to read and take them back to bed with me instead. Just got dust devil cyclone and hoses and bucket so I can actually use my shop with shopsmith and still breath so I'm already frustrated at getting sick. Got a just tuned planer and an I thought I'd just gotten it tuned until I saw this thread jointer, some finally finished sharpening them hand saws, and a bunch of presents to make out of some wonderful cherry and walnut. So I have to get well.