Jointer fence flatness

[JPG]

I wonder if you can do the old hand-tools trick of ganging your to-be-glued edges together in pairs as they pass through the jointer. Then edges that aren't perfectly 90 degrees to the faces will cancel out, come glue-up time.

We be ignoring grain direction here?


I like the conical disk idea. Sorta makes the jointer redundant for 'glueups'!

[BuckeyeDennis]

I bought my SS with jointer in 2011. It was delivered new to the original purchaser in 2003 so I assume it has the newest casting available.

While attempting the first project that required glue up I had unacceptable gaps after jointing . At that point I assumed the front and back beads were not Parallel. To spare all the details I found the beds were parallel within half of a hairs width on a Nat's back end so that meant the fence was twisted or machined incorrectly over its length. Takeing the fence to a machine shop was cost prohibitive.
My work around is, after jointing the edges I run the pieces Through the conical sander. I run the first board face up and the second board face down. This compensates for any variance from 90 deg. in the setup.

The three pictures are of my current glue up project. I am attempting to show the final result after edge sanding with the conical sander.

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Can't argue with those results. Beautiful tight joints you have there!

When I got home from work, I checked the serial number of my jointer. It was manufactured in 1999, so the vintage is not that different from yours.

Next, I pulled out the 4E jointer that came with my 10ER. The only difference I could see in the fence was the position of an auxilary-fence mounting hole, and that a couple more holes had been added to the 1999 version to mount a safety guard.

So then I cleaned off enough of the surface rust to get decent measurements. The 4E fence also had a slight concave bow down its length. But there was no discernable twist. I really don't see how the bow would hurt anything, as a slight "yaw" in the workpiece direction would have no effect on the cut itself.

[BuckeyeDennis]

Hi,

I don't own a shopsmith jointer so I have no advice I can give on that subject.

I have for the last some years started using glue line rip blades, They are towards the top end blades and I have been very happy with the results they provide. (infinitytools.com)

In most cases the cuts are good to go right after the sawing operation and I don't need to use the jointer. If I had to give a number I would say my jointer use is down 90%.

I can't promise you will have the same results but it might be something to think about.

Ed

Coincidentally, I had just installed a brand-new Freud glue-line rip blade for this very project -- someone had given them a great review right here on this forum, if memory serves. I had also realigned the table and fence, and it did indeed "cut like buttah". Nice finish, and not a hint of burning in the cherry.

But now I'm a bit confused. Absent a sled of some sort, isn't it necessary to joint one edge of a board straight for a "reference surface" to ride along the fence, before you can make a nice straight rip cut on the other side with the saw? (Or to edge the opposite side with the conical disk sander, for that matter?)

[BuckeyeDennis]

We be ignoring grain direction here?

I like the conical disk idea. Sorta makes the jointer redundant for 'glueups'!

If I sketched it correctly, to cancel out any jointer angle, the pair of boards should be unfolded "book-match style" after jointing. So if the grain is not straight, it should come together in a V, assuming that both boards are jointed in the correct direction.

And I agree that the conical disk sander makes the grain direction irrelevant. Ideal for figured woods, as they say.

[JPG]

If I sketched it correctly, to cancel out any jointer angle, the pair of boards should be unfolded "book-match style" after jointing. So if the grain is not straight, it should come together in a V, assuming that both boards are jointed in the correct direction.

And I agree that the conical disk sander makes the grain direction irrelevant. Ideal for figured woods, as they say.

Correct sketching. I was 'thinking' the two pass scenario and reversing end to end to make complimentary edges.

[bffulgham]

[quote="JPG40504"]Correct sketching. I was 'thinking' the two pass scenario and reversing end to end to make complimentary edges.]

I did lots of ripping and jointing when I did the panels for the pantry and the charging stationprojects. I would rip the boards then run them thru the jointer with the first board going thru face to the jointer fence and the second face away from the jointer fence. Works like a charm. I did set the jointer depth of cut to slightly less than 1/32" to eliminate tear-out and chip-out. It worked quite well even on the white ash in these projects no matter the direction of the grain.

My jointer fence has a very slight concave bow to it from front to back but I find no evidence of twist to the fence. When the fence is set 90 degrees to the bed, it appears to stay consistent all the way down the length of the fence.

[JPG]

I did lots of ripping and jointing when I did the panels for the pantry and the charging stationprojects. I would rip the boards then run them thru the jointer with the first board going thru face to the jointer fence and the second face away from the jointer fence. Works like a charm. I did set the jointer depth of cut to slightly less than 1/32" to eliminate tear-out and chip-out. It worked quite well even on the white ash in these projects no matter the direction of the grain.

My jointer fence has a very slight concave bow to it from front to back but I find no evidence of twist to the fence. When the fence is set 90 degrees to the bed, it appears to stay consistent all the way down the length of the fence.

I shoulda realized tear out would be 'hidden' in a glue joint anyway!;)

[BuckeyeDennis]

There is no comfort in this at all but if I put a straight edge against my jointer fence I have a gap that begins about at the counter head and extends toward the out feed end for about 3" or 4".

I never noticed this before.

I finally got around to measuring the flatness of my jointer fence. My surface plate is only 12" long, so for a reference I checked my 24" Starrett straightedge against a 24" Lufkin straightedge. There was no discernable gap between any two edges, so I'm guessing that both were straight to maybe 0.001"

Then I placed the Starrett straightedge diagonally across the fence, giving the maximum gap. Using feeler gauges, I measured a maximum concavity of 0.006". It looks worse than it sounds, but I do believe that the twist in the fence was affecting my ability to joint edges precisely to 90 degrees.

Most any machine tool should hold better tolerances than that, so my hunch is that my fence was machined while the cast iron was still "green", and then it warped as the iron aged. That, BTW, is one of the biggest quality problems with cheap Asian machine tools.

Then I called Shopsmith customer service to ask about my flatness-challenged jointer fence. I talked with an extremely knowledge able and helpful lady -- Linda, I believe. It took her less than a minute to find Shopsmith's spec for acceptable flatness on a jointer fence. The spec, unfortunately, is 0.015" max.

So for a fix, I've decided to make an auxiliary fence from an appropriately flat material. I'll use hot glue to make instant custom shims between the auxiliary fence and the jointer fence. These will be permanently bonded to the auxiliary fence, so that the jointer fence doesn't warp it when the mounting bolts are tightened.

Some extra height on the auxiliary fence will also be a plus.

[JPG]

If you are jointing 'edges', how wide are they? How flat is the jointer table over that range?

Side to side concavity is not as important as straight line alignment from infeed through outfeed table.

90 ° accuracy is a function of the fence and technique. hint hint;)

[BuckeyeDennis]

[quote="JPG40504"]If you are jointing 'edges', how wide are they? How flat is the jointer table over that range?

Side to side concavity is not as important as straight line alignment from infeed through outfeed table.

90 ° accuracy is a function of the fence and technique. hint hint]

The tables on my jointer are flat to within my ability to measure them. The fence is the problem. I first noticed that it had a twist when attempting to set it to 90 degrees with a machinist square. When set square back at the quadrant end of the infeed table, it was not square at the cutter-head end of the infeed table. And vice versa.

Against a twisted fence, a flat board can rock. I did, however, discover that I got more consistent results when using the guard in feather-board mode. Presumably because it gave a more consistent center of pressure against the fence.

I happened to be jointing 3/4" stock, but the jointed board edges will reflect whatever angular errors result from fence problems, irrespective of board thickness. Over a 12" wide panel glue-up, I found that these small angular errors wanted to cause significant panel cupping.

So I intend to make the fence flatness problem go away. I just don't need the aggravation!