5

I recently purchased a bench-top jointer and I think I set up the outfeed table properly according to the instructions that came with it. A straight edge placed on the outfeed table just touches the tip of the cutters when the head is at top dead center.

However, in this question the asker states

I used a ruler to see how many millimetres is the ruler moved. It's moved by 3mm.

Indicating to me that his understanding is that the cutter should actually lift the straight edge and move it slightly toward the infeed table.

This now has me doubting if I set my outfeed table up correctly, or if I've actually got it a bit too low.

  • When setting up a jointer outfeed table, should the tip of the cutter be dead even with the surface of the outfeed table, or should it actually be fractionally higher?
  • If it should be fractionally higher, is the "move a ruler forward by 3mm" a good measure of how much higher it should be?

Or, is the true measure of the accuracy simply jointing two boards and ensuring they come out dead square to each other, no matter what technique one uses to set that up?

3
  • Um, apologies, but how much research have you done on this issue? Or are you asking for didactic reasons, because it makes for a good Q&A to have here?
    – Graphus
    Jan 24 at 14:22
  • 1
    Ummm... the second one, yeah, that's the ticket! As noted, I simply set up following the directions that came with my jointer, presuming that would be correct...
    – FreeMan
    Jan 24 at 14:32
  • Hehe. Although I've definitely read of the lift-and-move-blades thing before (and somehow 3mm seems to be the figure I recall too) if your jointer is working right ever since you set it up the way the manual said to it speaks volumes for whether it's the right setting for it!
    – Graphus
    Jan 24 at 14:43

2 Answers 2

6

When setting up a jointer outfeed table, should the tip of the cutter be dead even with the surface of the outfeed table, or should it actually be fractionally higher?

Ideally, the outfeed table should be dead even with the cutter at the top of it's arc. The trick with the ruler is that it translates a very tiny vertical error into a much more readable horizontal error... if the blade moves the ruler 3 mm, it probably extends less than 0.1 mm above the outfeed table, and that's probably better than being 0.1 mm below the table. Also, being able to quantify the error lets you ensure that it's the same on both sides of the table... if the ruler moves 3 mm on the left side and also on the right, then the blade must be parallel to the table.

I'd put this in the same category as adjusting your rip fence so that it's a few thou farther from the blade at the back of the blade than at the front: ideally, you want the rip fence to be exactly parallel, but a lot of people feel that they can never achieve perfection, so they'd prefer to introduce a tiny error in the direction that suits them best.

If it should be fractionally higher, is the "move a ruler forward by 3mm" a good measure of how much higher it should be?

I think I addressed the "should" part above, so let's just talk about how good the test is. The idea is that when you're very close to the edge of a circle, the circle looks almost like a straight line, and the ratio between the length of a chord and the distance from the midpoint of the cord to the edge of the circle becomes quite large. The ruler here is a line intersecting the circle that is the blade's path; the distance that the ruler moves is the length of the cord, and the vertical distance that the blade lifts the ruler is the distance from the ruler to the edge of the circle. Let's say the blade traces a circle of diameter 65 mm and the ruler moves 3 mm; then the height of the arc is about 0.035 mm, which isn't nearly enough to worry about. So I think that the ruler trick does give a very good indication of the height of the blade above the table.

1
  • 1
    Excellent points and the math at the end helps a lot.
    – FreeMan
    Jan 25 at 13:25
3

Doesn't make any sense to me why you'd have the blade higher than the out feed table. Since it would then always be cutting 'that much' more than what your gage says you are cutting off. Including if you put your infeed table at '0'.

For me personally, it makes sense that if I have a nice done joint and I set the intable to 0, and I run the board again, it should basically 'burnish' the edge , certainly not cut another 3mm off of it.

I also don't see how having it higher by more than a whisker, would actually make flat boards, since the outfeed table being lower, should put a slight curve in the board, depending on your technique. The point of having the blades even with the outfeed table is to have immediate support for the board with the 'missing' wood.

Mine is set so the the blades just catch a straight edge on the outboard table.

EDT: And to get a 'slight' curve for glue ups, pushing down a little harder in the middle on a last pass tends to give me a nice tiny bow that works well for clamping and gluing you really don't need much, and I only want it on one board of the two (at least it works great that way for me!)

4
  • 1
    I agree and that all makes sense. Having not really done any research on setting up a jointer before I set mine up, and simply trusting in the instructions, I was surprised by the info posted in the other question and was looking for confirmation that what I did was correct. +1. I'll wait a bit for others to chime in before accepting anything...
    – FreeMan
    Jan 24 at 16:58
  • "Doesn't make any sense to me why you'd have the blade higher than the out feed table." Yup. This is just a passing reference in a Fine Woodworking vid on shimming to fix a sagging outfeed table, but it plainly states the conventional setting.
    – Graphus
    Jan 24 at 20:29
  • 1
    In previous question blades not set at 3mm above outfeed! Blade moves ruler 3mm horizontally when head is rotated by hand.
    – Volfram K
    Jan 25 at 9:08
  • @VolframK I'm glad you pointed that out. Somehow I missed that and it does make a huge difference...
    – bowlturner
    Jan 25 at 13:33

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.