From ShopNotes Magazine page 1 © August Home Publishing Co.

Plans N O Ww w w . p l a n s n o w . c o m

®

SetScrew

OutfeedTable

Knife

RetainerKnob

Dovetail

Dovetail

Base

CutterHead

Fence

EnclosedBase

Mounting Pin

Guard

TensioningSpring Infeed

Table

InfeedTableLock

LockNut

Infeed tableadjustmentassembly

Fenceadustment

lever

Gib

JointerKeeping your jointer tuned up pays off in stock

that’s flat, straight, and square.

TOOLS & TECHNIQUES SERIES

TOOL TUNE-UP

I N T H E S H O PT O O L T U N E - U P

Ajointer has two main jobs: toflatten the face of a board, and

to straighten and square up the edge.Sure, you can use it to cut a bevel orrabbet. But the real “meat and pota-toes” work of a jointer is getting stockflat, straight, and square.

That sounds pretty easy. After all,with the long, flat tables and fence ona jointer, it seems like it would be hardto go wrong.

Maybe that’s why it’s so frustratingwhen the wood fibers in the edge of aworkpiece tear out. Perhaps there’s ascoop (snipe) in the end of the board.Or when you sight down the edge, it’sdished out (or there’s a hump) in themiddle.

TUNE-UP. Fortunately, all it takes tosolve these problems is a

simple tune-up. Thiswon’t require any

special tools or

materials. Yet it will make a bigimprovement in the quality of the cut.

The procedure for tuning up ajointer boils down to two main things:getting the tables and fence properlyadjusted, and making sure the knivesare set correctly in the cutterhead.

HOW IT WORKS. Before you makeany adjustments though, it

helps to under-

Tuning up a

Jointer

stand how all the parts of a jointerwork together.

The workpiece is supported by along infeed and outfeed table, seedrawing at left. In between these twotables is a rotating cutterhead thatholds the knives.

If the jointer is set up properly, theknives are at the exact height as theoutfeed table (at the top of their arc).And the infeed table is adjusted lowerthan the knives (usually 1/32" to 1/16").

It’s this difference (between theheight of the infeed table and theheight of the knives) that determineshow much material is removed. As you

make a cut, the knives slice a thinlayer of material off the work-piece which rides smoothly

onto the outfeed table.DOVETAILS. Each table is secured

to the base of the jointer by two pairsof interlocking dovetails, see detail. Asyou adjust the tables up or down, thedovetails ensure that they remain par-allel to each other.

GIB. But over time, the dovetailscan wear slightly which allows thetables to sag. To compensate for this,a flat, metal bar called a gib fitsbetween the dovetails (usually in backof the jointer). Tightening (or loos-ening) the gib realigns the tables.

SetScrew

OutfeedTable

Knife

RetainerKnob

Dovetail

Dovetail

Base

CutterHead

Fence

EnclosedBase

Mounting Pin

Guard

TensioningSpring Infeed

Table

InfeedTableLock

LockNut

Infeed tableadjustmentassembly

Fenceadustment

lever

Gib

Keeping yourjointer tunedup pays off in

stock that’sflat, straight,and square.

From ShopNotes Magazine page 2 © August Home Publishing Co.

From ShopNotes Magazine page 3 © August Home Publishing Co.

T O O L T U N E - U P

Parallel Tables

Adjusting Outfeed Table

It almost goes without saying. To pro-duce a straight edge, the tables on ajointer need to be flat. But there’smore to it than that.

PARALLEL. The infeed table andthe outfeed table must also be par-allel to each other. If the tables slopetoward the cutterhead, you end upwith a hump in the jointed edge, seedrawing and detail ‘a’ at right. If thetables sag at the ends, the edge will beslightly scooped, see detail ‘b.’

Now the tables may not be “off” byall that much. But even the thicknessof a couple sheets of paper is enoughto cause problems.

ADJUST TABLES. To adjust thetables so they’re parallel, start byraising the infeed table up to the levelof the outfeed table. Then lay a long,metal straightedge across both tables,see Fig. 1.

The goal here is to get both tablesto contact the straightedge uniformlyalong its entire length. That’s wherethe gibs come in, see drawing on pre-vious page. By adjusting the amountof pressure against the gibs, you can

raise or lower the appropriate end ofeach table.

To do this, loosen the lock nuts onthe set screws that hold the gib inplace, see Fig. 1a. Then tighten (or

loosen) the set screws to raise (orlower) the end of the table. When thetables contact the straightedge evenlyalong its entire length, simplyretighten the lock nuts.

Another aggravating problem is whenyou get a heavy cut (snipe) at the endof a board, see drawing.

If the outfeed table is too high, theworkpiece catches on the front edgeof the table, see detail ‘a.’ This causessnipe on the front of the board. If thetable is too low, the snipe occurs atthe back end, see detail ‘b.’

ADJUST TABLE HEIGHT. To preventeither of these things from happening,you’ll want to set the outfeed table atthe exact same height as the knives.Start by placing a straightedge on thetable so it extends over the knife, seeFigs. 2 and 2a. Then raise (or lower)the table until the knife barely touchesthe straightedge.

To check the adjustment, rotate thepulley (or belt) and listen for a “tick.”This indicates the knife is justtouching the straightedge.

1

2

b.

a.

a.

a.

b.

a.

T O O L T U N E - U P

Adjusting the tables on a jointer to pro-duce a smooth, square cut is only halfthe story. The other half is making surethe knives in the cutterhead are sharpand properly adjusted.

HONE KNIVES. If the knives aredull (or there’s a small nick), you canrestore the edges with a sharpeningstone. To hold the stone at a consistentangle, I use a simple guide, see boxbelow. But if the knives have a largenick, a honing guide isn’t the best solu-tion. (You’ll have to remove too muchmaterial.)

SHIFT KNIVES. A better solution isto shift one of the knives in the cutter-head to the side. This offsets the nickby a small amount which results in asmooth cut.

CHANGING KNIVESEventually, the knives will get too dull(or nicked), and you’ll need to replacethem with a set of sharpened knives.(I have a spare set of knives.)

Safety Note: Be sure to unplug thejointer before changing the knives.Also, to provide room to work, removethe fence and guard (or clamp theguard out of the way).

REMOVE KNIVES. The first step isto remove the dull knives. Actually, tomake it easy to keep track of things, I

only work on one knife at a time.On most jointers, the knife is held

in place by a metal bar (gib) and abolt, see Fig. 1a. To remove the knife,loosen the bolts. Then carefully lift out

the knife and the gib.Usually, you’ll find gunk on the

knife, gib, and in the slot in the cut-terhead. So I clean these with mineralspirits. Note: Be careful when youclean the knife. Even a dull cuttingedge can give you a wicked cut.

INSTALL KNIFE. Now you’re readyto install the sharp knife. Start by put-ting the gib back into the slot in thecutterhead. Then slip the knifebetween the gib and the side of theslot. Note: The bevel on the knifeshould face the outfeed table.

With the knife in place, tighten thegib bolts until it’s snug (not tight). Toprevent the knife from twisting, it’sbest to start with the center bolts andwork toward the ends.

ADJUST HEIGHT. The next step isto adjust the height of the knife. Tosupport the workpiece as it slides ontothe outfeed table, the knife has to beperfectly level with the table.

I start by roughly positioning theknife. The goal is to have the “heel”

2

1Setting Knives

b.

a.

a.

Now hold the pulley (to keep the cutterheadfrom rocking) and make a smooth, firm strokeacross the knife. It’s important to remove thesame amount of material from each knife. Socount each stroke and make the samenumber of passes on each knife.

A honing guide makes it easy to “touch up”a dull edge on your jointer knives. Thishoning guide has two sharpening stones thatare sandwiched between wood blocks, seephoto below.

STONES. If the knives only need a bit ofwork, I use the 400-grit stone. But for smallnicks, the 180-grit stone is best. Just be sure

to follow up with the finer grit. Either way,apply a few drops of oil to the

stone as a lubricant.USE. To use the

honing guide, set iton the knife so thestone rests againstthe bevel, see detail.

Honing Guide

From ShopNotes Magazine page 4 © August Home Publishing Co.

T O O L T U N E - U P

of the knife project about 1/16" abovethe cutterhead, see Fig. 1a.

LEVELING SCREWS. To accomplishthis, you may have to raise or lowerthe knife. This is just a matter ofturning a pair of leveling screws topush the knife up, see Figs. 1 and 1a.Or, to lower the knife, turn the screwsthe opposite way and tap the knifedown with a wood block.

All it takes is a slight turn to adjustthe leveling screws — maybe just aneighth of a turn. The important thingis that the knife projects the sameamount at each end.

GAUGE. To check the adjustment,I use a simple gauge. It’s just a scrapthat’s laid on the outfeed table so itrests on the knife, see Fig. 2a. (Besure the scrap has a straight edge.)

To use the gauge, make a pencilmark on the scrap that aligns with thefront edge of the outfeed table. Nowrotate the pulley (or belt) so the edgeof the knife “catches” the scrap anddrags it forward, see Fig. 2b.

The actual distance it travels isn’tcritical. (I adjust the outfeed table asneeded so the scrap moves about 1/8".)Now make a second mark on the scrapthat aligns with the outfeed table, seeFig. 2b. This creates a reference that’sused to check the opposite end of theknife.

To check the adjustment on this

3

4

5

Magna-SetIf you change jointer knives fre-quently, a Magna-Set will allowyou to do it very quickly.

The Magna-Set consists of twoplastic bars that rest on the out-feed table and a pairof metal rods that con-nect the bars, seedrawing at right.

MAGNET. To posi-tion the knives levelwith the outfeed table,there’s a magnet ineach bar, see detail.The magnet holds theknives at the correct

height while you tightenthe gib bolts.

Note: Reference lines on thefence make it easy to position theMagna-Set.

end, align the first mark with the out-feed table and rotate the pulley again.Ideally, the knife will drag the scrapthe same distance. If the second markaligns with the outfeed table, it meansthat both ends of the knife are set atthe same height.

At this point, it’s just a matter oftightening the bolts securely. There’sonly one problem. As soon as youtighten them, the knife creeps up.The trick is to anticipate this move-ment. This is a trial and errorprocess. But after a few tries, you’llget a feel for how much the kniveswill move.

To adjust the remaining knives,simply repeat the process. Then adjustthe outfeed table so it’s level with thenewly installed knives, refer to page3.

TIME. So just how long does all thisactually take? Well, on a good day, Ican change the knives in an hour. Butto be honest, it may take longer. I’vespent as long as four hours setting theknives. (For information about a knife-setting jig that speeds up the process,see box below.)

FENCE, GUARD, & BELTOnce the knives are set, there are justa few more things to check.

SQUARE FENCE. First of all, afteryou reinstall the fence, don’t forget

to square it up to the table, see Fig. 3.Otherwise, you’ll end up with abeveled edge instead of one that’ssquare to the face of the workpiece.

GUARD. You’ll also want to checkthe guard. For safety, it’s importantthat there’s enough tension on thespring that the guard swings all theway back against the fence at the endof a cut, see Fig. 4. Note: Check yourowner’s manual to see how the ten-sion is adjusted on your guard.

V-BELT. The last thing to do is toadjust the tension on the V-belt.The V-belt doesn’t have to be“drum tight.” To reduce theamount of vibration that’s trans-ferred to the jointer, I leave it looseenough to squeeze the belt togetheras shown in Fig. 5.

From ShopNotes Magazine page 5 © August Home Publishing Co.