Making wedges on the jointer

[Owad]

I really appreciate all the help.

[dusty]

I really appreciate all the help.

Can we then assume that you are no longer making wedges when wedges are not wanted? If not, then we have not helped at all.

[Owad]

I took a 12" long board and measured the width at the 1, 6, and 11 inch marks, then took six passes on the jointer. These are the widths after each pass:

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Pass   1     6     11
 0   3.451 3.457 3.451
 1   3.426 3.440 3.450
 2   3.391 3.414 3.451
 3   3.357 3.387 3.427
 4   3.324 3.363 3.412
 5   3.290 3.336 3.392
 6   3.257 3.308 3.370

Do those seem reasonable? Here it is again, showing amount removed with each pass:

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          1       6      11
Pass 1	.025	.017	0
Pass 2	.035	.026	0
Pass 3	.034	.027	.024
Pass 4	.033	.024	.015
Pass 5	.034	.027	.02
Pass 6	.033	.028	.022

After the first two passes, I noticed it wasn't removing any material from the end, and began to keep a better grip on it, though I tried not to press down on the infeed table. While most of the board was smooth, the last two or three inches of the board was a bit rough after every pass, which suggests to me that there's something wrong with my technique.

[dusty]

Theoretically, the same amount should removed for each pass. So yes, something ain't right! Furthermore, it seems that the same amount should be taken off the entire length of the work piece. When deliberately cutting tapers on a jointer, more is taken off at the outfeed end. Looking at your test results, it appears to be somewhat the opposite. I am a little confused by the numbers.

Jointing short (12" long) boards is something I try to avoid. Do this with about 2' long (or longer) pieces to see if you get similar results.

Infeed table is set for what depth of cut?

Are all three cutter blades set the same?

What is the "accuracy standard" that we want to achieve?

Realizing that we are working in a "wood shop" and not a "machine shop", there needs to be some reasonable standard or performance against which we test our production effort.

When performing machine alignments, I use a self imposed +- .005" standard. Anything within that range is considered perfect (for a wood shop).

When cutting and measuring wood, I use a bit looser standard; I strive to achieve milling accuracy to within 1/64" (.016"). As my machines and I get older, I find that these standards may have to be relaxed just a little bit. The 1/64" marks on my rulers have gotten closer and closer together. Cutting exactly where I measured isn't always the way it works.

[algale]

Was the board flat on the bottom and top to begin with and with parallel faces?

[dusty]

I have used my jointer for many years and have always been very satisfied with the performance. I still am.

But, as a result of this thread, I decided to start from scratch and check out my jointer. Some question have been asked (and even responded to by me) that have now peaked my curiosity.

If my measuring techniques are suitable for this task, my jointer tables are not flat. At least not as flat as I would have said.

[ATTACH]26675[/ATTACH]

There appears to be a shallow cup right in the center of my outfeed table and a low corner on the infeed table. The deviations are slight (.002" to .003" but more than I expected.

My flatness gauge is shown here being used on the Main Table but I use it for many different applications. On the jointer table, I can zero the gauge anywhere on the table but then when I move it around on the table(s), I see variations of .002" to .003".

[dusty]

I love fun projects like this.

I was just out in the shop making jointer dust and while doing so I made a couple observations.

Accurate measurements of the width along the length of a jointed board are dependent upon the edges being square to the face. This is especially true if one measurement is made with a board facing up and the next measurement is made with that board facing down.

Meaningful measurements should all be made with reference to the same surface.

Measurements taken repeatedly at the same location will deviate from one another based on the proficiency of the operator to use his digital caliper. The end of the board that I have been using changes 1 or 2 thousands each time I measure it. Seldom do I get the same measurement as the last time I measured it.

This little experiment has shown me that the work I do is not as accurate as I once thought it was.:eek: It must be that dip in the jointer table.

[Owad]

Was the board flat on the bottom and top to begin with and with parallel faces?

Not quite perfectly, as you can tell from the initial measurements, but it was a milled board from Lowes. It looked flat with a straight edge, but I didn't use anything like a dial indicator on it.

[Owad]

Jointing short (12" long) boards is something I try to avoid. Do this with about 2' long (or longer) pieces to see if you get similar results.

I don't have a spare board of that length right now, but I'll give that a try.

Infeed table is set for what depth of cut?

About 1/32. I didn't fine tune it.

Are all three cutter blades set the same?

I put a straight edge on the table and checked all the blades at both ends and the center. They all barely scrape the straight edge and are at least as consistent as I would be able to make them without a dial indicator.

[algale]

Owad,

I'm going to link to a post I did some time ago about how I used an article in FWW to make "test bars." These are cheap and easily made out of plywood and drywall screws. Once made, you can check your jointer tables to see if they are coplanar (when set to zero depth).

Let's make sure the jointer is set up right.

http://shopsmith.net/forums/showpost.ht ... ostcount=1

Al