Jointer Infeed and Outfeed Tables Not Straight? How to Diagnose and Fix the Problem

A jointer can only produce a truly straight, flat surface when its infeed and outfeed tables are properly aligned. Even a high-quality cutterhead cannot compensate for tables that are twisted, sagging, warped, or no longer coplanar.

If your jointer starts producing boards that are slightly curved, tapered, or difficult to joint straight, don't immediately blame the knives or cutterhead. The tables themselves may need attention.

This guide explains how to determine what is wrong and what you can do about it.

1. Are the Tables Actually Warped?

Before making any adjustments, determine whether you have a table alignment problem or an actually warped cast-iron table.

Always unplug the jointer before performing any inspection or adjustment.

You will need a long, reliable precision straightedge. Ideally, it should span a substantial portion of both tables.

Raise the infeed table until it is approximately level with the outfeed table. Place the straightedge across the tables and check several positions:

• Along the fence side

• Along the operator side

• Through the center

• Diagonally across the tables

Use feeler gauges to measure any visible gaps.

This simple test can reveal several different problems.

2. Flat Tables That Are Not Coplanar

This is one of the more common situations.

Each cast-iron table may be perfectly flat when checked individually, but the infeed and outfeed tables do not lie in exactly the same plane.

For example, one corner may be slightly high, or the end of one table may drop away from the straightedge.

In this situation, the tables themselves may be fine. The jointer probably needs table alignment rather than table replacement.

Depending on the jointer design, correction may involve adjusting:

• Gibs

• Dovetail ways

• Parallelogram table mechanisms

• Table mounting points

• Shims

Make very small adjustments and recheck the tables after each change.

3. Jointer Table Sag or Droop

Another possible condition occurs when the outer end of the infeed or outfeed table sits slightly lower than the area near the cutterhead.

When a straightedge is placed across both tables, the tables may appear to form a very shallow V.

The opposite condition can also occur, with the outer ends slightly higher.

Even a small error becomes important because jointer tables are relatively long. A small angular difference can affect the straightness of the finished workpiece.

On some dovetail-way jointers, gib adjustment can influence table alignment. In other cases, carefully positioned shims may be required.

Parallelogram jointers generally use a different adjustment system, so always check the manufacturer's instructions for your particular machine.

4. Check for Table Twist

A table doesn't necessarily have to bow vertically to cause problems. It can also be twisted.

This is why checking only the centerline of the jointer isn't enough.

Check both sides of the tables and then check diagonally. If one corner is consistently high or low compared with the others, you may have a twist or mounting/alignment problem.

Again, determine whether the table itself is twisted before attempting to correct it through the adjustment mechanism.

5. Check Each Table Individually

This is an important step.

Place your precision straightedge on the infeed table only and inspect it in several directions.

Then repeat the test on the outfeed table only.

If each individual table is flat but they don't line up with each other, you have strong evidence of a coplanarity or adjustment problem.

If the straightedge shows a consistent gap across an individual table itself, the cast-iron table may actually be bowed or warped.

That requires a different solution.

6. What If the Cast-Iron Table Is Actually Warped?

If you confirm that an individual cast-iron table is genuinely warped, avoid trying to straighten it by force.

Do not hammer, bend, heavily clamp, or heat a cast-iron jointer table in an attempt to straighten it.

Cast iron is relatively brittle and can crack. Improper attempts to straighten it can also make the table geometry worse.

Depending on the severity and value of the machine, practical solutions may include:

• Professional inspection by a machine shop

• Precision surface grinding or machining, where appropriate

• Replacing the affected table

• Replacing the machine if repair is economically impractical

For an older or valuable industrial jointer, professional re-machining may be worth considering.

7. Don't Overlook Simple Causes

Before concluding that you have a damaged table, inspect the jointer carefully.

Look for:

• Sawdust or debris trapped around sliding surfaces

• Rust or contamination on mating surfaces

• Burrs or damaged edges

• Loose fasteners

• Improperly adjusted gibs

• Excessive gib pressure

• Wear in dovetail ways

• Uneven machine mounting

• A distorted or unstable base

Sometimes what appears to be a warped table is actually a much simpler mechanical problem.

8. How Accurate Should Jointer Tables Be?

The closer the two tables are to being truly coplanar, the better.

As a practical reference, getting the tables within approximately 0.002–0.004 in. (0.05–0.10 mm) over their working length is a reasonable target for many woodworking jointers. Precision machines may justify even tighter alignment.

Don't focus only on a single measurement, however. What matters is that both tables are individually flat and properly aligned relative to one another.

9. Check the Outfeed Table Against the Cutterhead

After correcting table alignment, the relationship between the outfeed table and the cutting circle must also be checked.

This is critical.

If the outfeed table is too high, the workpiece may stop or become difficult to feed.

If the outfeed table is too low, it can cause snipe—an excessive cut near the end of the workpiece—and may also prevent the jointer from producing a consistently straight surface.

With straight knives, the knife height must be correctly established relative to the outfeed table.

With a helical cutterhead, follow the cutterhead and machine manufacturer's setup procedure for establishing the correct relationship between the carbide cutting edges and the outfeed table.

Table Alignment and Cutterhead Performance Work Together

A premium cutterhead can dramatically improve the cutting characteristics of a jointer, but the cutterhead is only one part of the machine.

A properly designed helical cutterhead with carbide inserts can provide advantages such as a smoother shearing cut, reduced cutting noise, longer cutting-edge life, and easier individual insert replacement.

However, even the best cutterhead cannot correct inaccurate machine geometry.

For the best jointing results:

Flat tables + coplanar alignment + correctly positioned cutterhead = straight, consistent jointing

If you've upgraded your jointer with a Sheartak helical cutterhead and are experiencing an unexpected cutting problem, checking table alignment should be part of the troubleshooting process.

Need Help Troubleshooting Your Jointer?

If you're unsure whether your problem is caused by the tables, bearings, cutterhead installation, or cutterhead setup, take several clear photos with a long straightedge positioned across the infeed and outfeed tables.

When contacting Sheartak Tools, also provide the brand and model number of your jointer.

The more accurately the machine geometry can be identified, the easier it is to determine whether you're dealing with a simple adjustment problem or something that requires mechanical repair.