Planer knife settings

[Greg Snyder]

Hi, I am in the process of restoring a old Crescent 18" planer. It came with some new knives, but not installed and I was wondering how high they should stick above the drum? Basically how thick of a cut should it take? I have a manual from the OWWM web site but it references a gauge that came with the planer that I dont have. Once I know how high they should sit, I can take are of setting them even to the table. Thanks

[Steve Jenkins]

I always used a dial indicator and set the knives .035 above top dead center.

[Joe Von Kaenel]

Greg,

They make a Jig for lack of a better word to set up planer blades
Several companies make them. "PLANER PAL". These make changing planer blades easy. Hope this helps.

Joe

[Frank Guerin]

I always used a dial indicator and set the knives .035 above top dead center.

Steve. I believe your saying .035 above the infeed table but I'm guessing.

[Chip Lindley]

I believe the poster is referring to setting PLANER knives. No infeed table here. .035" would refer to height of the knives beyond the diameter of the cutter head, at the top of arc.

[Frank Drew]

On the older machines I've used (those without knife-setting jigs), we let maybe 1/16" of the flat part of the blade below the bevel show above the cutterhead gibs. In other words, the bevel shows but not much more of the rest of the knife than you have to while still securing the knife well in the cutterhead.

However, the thickness of the cut is determined by raising or lowering the table, not by how much knife projects from the cutterhead.

[Steve Jenkins]

What Chip said. Both planer and jointer I set at .035 above top dead center of the cutterhead. To find top dead center place the dial indicator on the table with the feeler against the cutterhead between the knives then slide it crosswise to the cutterhead back and forth and you will find the lowest spot on the arc. this is dead center. Actually with a planer it is bottom dead center and with a jointer it's top deadcenter. Same thing just different reference.

[Greg Snyder]

I did some research over at the OWWM website and found some references to setting them around .100 to .125 high. It seems that if you had them at .035 that would limit your maximum amount of wood removal per pass. I am not sure about that, but this is a big, old, 5hp planer so its not laking any power or mass. I do have a set of the planer pals that I am going to use once I set them up for the correct height. Thanks and happy new year.

[Steve Jenkins]

Just for grins once I set my jointer for a 1/2" deep cut and it did fine with the knives set at .035. I was straightening a piece of 1x6pine jointing the edge. I took one pass each direction from center then reset to about 1/32 cut and did a full length pass and bingo a straight edge. I'm certainly not saying that I would recommend doing that. The infeed table on my jointer will drop down about 3/4" or so.

[Tom Veatch]

...It seems that if you had them at .035 that would limit your maximum amount of wood removal per pass. ...

Not at all. It does limit the maximum thickness of shaving that can be taken with each blade pass, but that's not the same as the maximum material removal per pass.

Think about the geometry of cutterhead relative to the work. It's as if a table saw blade were several inches wide. The "cutter exposure" on a table saw blade is much smaller than the maximum depth of cut that can be made.

[Tony Joyce]

The more the knife projects beyond the cutterhead the louder it will be. Less projection equals quieter. You may not be able to tell such a minimal difference, but when you project a cutter on a moulder head 1/2"-3/4" further out than a straight knife the difference in noise is very noticeable.

The projection will not limit how much stock you can remove in a single pass. Hanging the knife out farther will only make it louder and more prone to chip out. The head itself acts like a chipbreaker.

The short answer is the closer to the head the knife projection is the better.
Just my .02 based on my experience.

Tony Joyce