How to Set a Jointer Outfeed Table to Knife Height
What's inside
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A jointer’s outfeed table should sit level with the knives at their highest point of rotation. Set it too low and the board’s trailing end dips as it leaves the cutterhead, producing a snipe or a tapered cut. Set it too high and the board catches on the table edge or rocks over it. The adjustment is small—often just a few thousandths of an inch—but careful setup makes a noticeable difference.
Contents
What you need
Use a straightedge long enough to span the cutterhead and outfeed table, plus a way to turn the cutterhead by hand. A precision steel straightedge is a good choice; a known-flat, straight piece of hardwood can work for a rough check, but it may flex or move with humidity. A feeler gauge helps measure small gaps. A dial indicator is useful for precise adjustments, but is not required for a typical shop jointer.
A precision straightedge is worth considering if you also set planer beds, saw fences, or machine tables. For occasional jointer adjustment, a sound straightedge and feeler gauge are usually enough.
Unplug the jointer before touching the cutterhead or knives. Remove the fence if it blocks access. Clean pitch, dust, and chips from the tables and cutterhead; even a small chip under the straightedge can throw off the reading. Do not use your fingers to check knife height.
Set the knife-height reference
Lower the infeed table below the outfeed table so it cannot interfere with the measurement. Rotate the cutterhead by hand until one knife is at its highest point. On a straight-knife jointer, place the straightedge lengthwise so it rests on the outfeed table and extends over the knife. Use the knife’s cutting edge as the reference—not the cutterhead body or the lowest part of the bevel.
With the knife at top dead center, the straightedge should just touch the edge. When you turn the cutterhead slightly by hand, the knife may move the straightedge a small amount. Many jointers are adjusted so the knife moves it about 1/16 to 1/8 inch, depending on the machine and its manual. Follow the manufacturer’s procedure if it specifies a different amount. The main goal is consistent knife height across the cutterhead and an outfeed table level with the knife at its peak.
Adjust the outfeed table
Check the relationship near both ends of the cutterhead, then at the middle if the straightedge allows. If the knife lifts the straightedge noticeably, the knife may be too high. If there is a visible gap at the knife’s peak, it is too low. Adjust the knife first if your jointer has adjustable knives; changing the outfeed table to compensate for uneven knives can hide the problem and leave the machine cutting poorly.
If the knives are correct but the outfeed table is low or high, adjust the table using its handwheel, locking levers, or adjustment screws. Make small changes, then lock the table and measure again: locking hardware can shift the setting. Repeat the check across the cutterhead. A table that is correct at one end but not the other may be twisted, dirty at a mounting point, or out of alignment; it is not fixed by raising the whole table.
Choosing a measurement method
| Method | Best for | Trade-off |
|---|---|---|
| Straightedge and feeler gauge | Routine checks and basic setup | Affordable and simple, but depends on a genuinely straight edge and careful positioning. |
| Knife-setting jig | Replacing or matching straight knives | Speeds up repeatable knife setup; a jig must fit the cutterhead and may not set the outfeed table by itself. |
| Dial indicator | Fine adjustments and diagnosing uneven height | More precise, but costs more and takes practice to mount and read consistently. |
A jointer knife-setting jig can make knife changes less tedious, especially on a jointer with multiple straight knives. It is not a substitute for checking the outfeed table. For occasional maintenance on a small machine, a straightedge and feeler gauges are often the better-value setup.
If your jointer has a helical cutterhead
Carbide-insert heads do not present one continuous knife edge, so the straightedge test used for straight knives may not apply in the same way. Check the jointer manual for its table-height procedure. Some designs use a reference insert or a specified cutterhead position; others require a dedicated gauge. Do not assume that a method for a straight-knife head will give a reliable result on an insert head.
If an insert is damaged or sits proud, it can leave a ridge or chatter marks even when the tables are aligned. Clean the insert pocket before replacing an insert, and tighten screws to the manufacturer’s specification. A feeler gauge set is useful for measuring small clearances, but it cannot correct a loose insert or a twisted table.
Verify with a test cut
After tightening all locks, reconnect power and joint a straight, flat board with a consistent feed. Keep pressure on the infeed table at the start, then transfer pressure to the outfeed table as the board passes the cutterhead. Do not press down hard over the knives; that can mask a setup problem and affect the cut.
Inspect the board with a straightedge. A consistent taper from one end to the other often points to an outfeed table set too low or high. A short dip at the trailing end suggests the outfeed table may be low, though poor pressure transfer or a bowed board can cause a similar result. A board that catches as it moves onto the outfeed table may indicate a high table edge. Recheck the measurement before making another adjustment, and change the setting only a little at a time.
If the table will not hold its setting, check the lock, gibs, and adjustment mechanism for looseness or wear. Correct height matters, but a secure table and evenly set knives matter just as much for a clean, repeatable cut.
