Is it me or is it the jointer

[algale]

I guess I should have gone to the shop and performed the procedure myself before I referenced it. My BAD.

Like I said, when I do mine, the blade touching the ruler can just barely be felt. It definitely does not pick up and move the ruler an inch or more.

I agree with Dusty. In fact, unless you are trying to make a catapault rather than set up a jointer, I suggest you disregard the 1 inch movement. This website http://woodgears.ca/jointer/knives.html will show you how to do the math and does the math for a 6 inch jointer with an average 2.5 inch diameter cutter head (actually the width of the jointer head shouldn't matter, just the diameter). Any way, a movement of a quarter of an inch would mean the knives were more than 5 thousandths higher than the outfeed.

Now, it just so happens that last night I was resetting knives on a 6 inch jointer I am rebuilding. I won't bother/bore you with how I set my knives, which would be off topic, but after setting them I decided to double check them with a method similar to that described in the thread. Rather than using a steel rule, however, I used a poplar stick about 18" x 1'' x 1". This was in my cut off bin, the result of a rip cut I made some time ago. Before starting, I measured the bottom of the stick for flatness both on the outfeed table and against my Starrett rule.

I laid the stick on the outfeed table with the end of the stick hanging in mid air above the cutter head. Marked the edge of the stick at the very end of the outfeed table nearest the cutter head. Slowly rotated the cutter head. When the stick stopped moving, I made another mark on the stick, again at the end of the outfeed table nearest the cutter head. The two marks were some distance apart. Now, I did not measure this distance last night because I didn't care how far the stick moved]same[/I] amount of distance and I used the two marks on the stick as my reference for checking the other two knives.

But, when I read this post suggesting a 1 inch movement, I thought, "That can't be right" (actually, I thought, "That's NUTS!"). So I went and got my stick from last night and measured the distance between the two marks. The two marks are 7/32nds (0.22 inches) apart. Per the chart (and yes, I am assuming my cutter head on my jointer is the customary 2.5 inches in diameter) my knives are 0.0048 inches above the outfeed table. And I get a nice clean cut with very little tapering -- and yes, I still maintain that unless you start with S4S and have perfect technique (and I have neither), a little tapering is inevitable.

In sum, unless your jointer has like a 12 inch diamter cutter head, 1 inch is too much.

EDIT The stick was 18" x 1" x 1" not 18" x 1' x 1'.

[dusty]

My thanks to you, algale, for posting that reference. There is a massive amount of information there.

I often get off on a tangent and nothing has changed. I have a pet peeve regarding what is no longer taught in many schools - how math can applied to every day activities. I probably remarked at one time, "Why will I ever need to know the Pythagorean theorem"?

Little did I know that one day I might want to know how far that ruler would be moved by the rotating cutter head.

This young wiper snapper has it all together. If you doubt my snap judgement just pay attention to the equipment that you see around his shop. For one thing, he owns a Shopsmith Belt Sander and Power Stand.

PS: Test results to satisfy my curiosity. I just went to the shop to check jointer blades. Result - I need to do some fine tuning. The three blades are close but not the same. With the outfeed table setting proud of the infeed table by .025", the ruler is moved 5/8" every three revolutions of the cutter head (about 7/32" per cutter head).

[pennview]

There are lots of sources for woodworking information on the internet. Some of it is good, some not so good, and it's not always apparent what is correct. For those who bought a Shopsmith new, a copy of the "Power Tool Woodworking for Everyone" book was provided. So, to me it makes sense to look there for instruction on how to set up the Shopsmith jointer.

On page 78 of of the book I got in 1980, under the heading of Machine Adjustment, the book instructs one that "the horizontal plane of the outfeed table must be tangent to the cutting circle of the cutter head." In other words, the cutters must be at the same height as the outfeed table.

In another reference I have, a book that was sort of the bible for woodworkers before there were thousands and thousands of books on the subject, "Cabinetmaking and Millwork" by John L. Feirer, on page 371 it states that "for accurate cutting, the rear table must be exactly the same height as the knives at their highest point." It goes on to explain that if the outfeed table is too low or cutter head too high, you get snipe. If outfeed table is too high or cutter head too low, you get a taper.

[beeg]

In another reference I have, a book that was sort of the bible for woodworkers before there were thousands and thousands of books on the subject, "Cabinetmaking and Millwork" by John L. Feirer,

I have that book and never found a use for it.

[pennview]

Beeg, maybe you could give it to a new woodworker. At 928 pages, there's lots of info in the book that someone just starting out would be interested in.

[JPG]

Using that write-up as a guide would indicate my knives are still a bit too low. Using the ruler method, mine advances only about 1/4" for each blade. The write-up indicates it should move 1".

That writeup clearly states that at the completion, the outfeed table is raised to the height of the blades.

That ruler movement was with the outfeed table lowered.(not something we can do with a rigid outfeed table).

The last paragraph relates to jointers with non-adjustable outfeed tables.

[dlbristol]

Our old friend Pythagorus can be found in a lot of places. What amazes me is that the whole of trigonometry , could be and is taught as. being based on the concept of rotating a constant length and recording the ratios of all three sides of the resulting triangles. And yet it is a bit of a surprise to see it in this setting. When I taught, I always looked for these types of applications. I have to admit I just saw this one for the first time. I have a friend who still teaches, he will have a copy of this one by Tuesday! And I learned a lot about the jointer as well, at no real cost and on my schedule! Love this forum.

[JPG]

]It seems to me that pressure on the infeed table too long would cause more to be cut from the trailing edge[/b]. This is opposite of what I was experiencing. Also, no trailing edge snipe here.

The opposite happens.

When the infeed end is pressed against the infeed table, the registration to the outfeed table is lost. The leading end can float above the outfeed table. This causes the blades to take too deep a cut, but at some point the workpiece will 'rock' and cause the trailing end to rise thus cutting a thinner cut at the trailing end. You end up using the infeed table as a reference at the leading end, and the outfeed table at the trailing edge.

Now if the blades are raised above the outfeed table and the infeed is set to the desired depth of cut on the leading end, the leading end will rise even further above the outfeed table. With the blades raised higher the ciut after the workpiece 'rocks' will be deeper than before and will probably reduce the amount of tapering.

Keep in mind that the 'rock' I alluded to will raise the trailing end off the infeed table, thus it cannot 'fall' off the end of the infeed table and cause snipe.

I believe the absence of snipe with the blades raised above the outfeed table asserts the existence to the rocking movement.

It should prove interesting to determine if the jointed edge is straight and not bowed out in between the ends.(tapered at both ends)

[JPG]

I have that book and never found a use for it.

I just acquired that book and although 'dated', it has a wealth of information. I paid $2 for it at a habitat thrift store.

Already it has corrected some misconceptions I have had(yes Charlese it identifies the difference between a plough and dado cut with a 'dado' blade).

As mentioned above the jointer setup is clear and concise.

An earlier post had a link that really nailed the proper adjustment and warned us of the existence of bad, incorrect advice.post 18 I recommend reading all the jointer info inside that link.

Finally that 1" movement was with the outfeed table LOWERED considerably. FWIW that increased the accuracy of the measured ruler movement by increasing its distance(when the table is finally raised to the height of the blades, that distance is 0).

[algale]

That writeup clearly states that at the completion, the outfeed table is raised to the height of the blades.

Great catch, JPG. I did miss that, in paragraph 7 of his write up, http://www.woodcentral.com/bparticles/k ... ment.shtml, he does in fact actually state that one must reset the outfeed level with the knives after all the adjustments are made with moving ruler:
[INDENT]All that remains is to set the outfeed table level with the knives. If you don't, then you will gouge board ends or taper the edges. Worse, you may get convex or concave profiles. Use the ruler for this. Adjust the outfeed table until it just barely contacts each knife across its length. [/INDENT]

So the one inch movement of the ruler was simply a convenient unit of measure and was used (as I used my measuring stick) to ensure that all knives were at the same height and were also level.

On the other hand, unless I have missed it, the web resource I cited http://woodgears.ca/jointer/knives.html does not contemplate a further adjustment to the outfeed table after adjusting the knives slightly proud of the outfeed table using the moving ruler trick.