Rehanging an Axe Head: Wedge Sizing, Kerf Depth and the Linseed Cure Schedule
Cut the kerf to two thirds of the eye depth, drive a wooden wedge with roughly a 6 degree taper along the long axis of the eye, and leave the tongue standing 1.5 to 3 mm proud after trimming. Fitting is done by removing wood from the haft until the head slides most of the way down under hand pressure, never by driving a tight head onto an oversized tongue. Then cut the linseed with spirits and follow a daily-weekly-monthly schedule for the first year.
By the The Tool Wise Editorial Team
Four numbers hold a hang together: kerf depth at two thirds of the eye depth, wedge taper around 5 to 8 degrees, tongue standing 1.5 to 3 mm proud of the eye after trimming, and a haft at 6 to 9 percent moisture content before any of it starts.
None of those appear in the videos. What videos show is the driving, which is the least important part of the job and the part most likely to split a haft. The work is in the fitting, and fitting is subtractive — you take wood off the tongue with a rasp until the head walks down under hand pressure to within about an inch of its final seat, and only then does a mallet get involved.
Everything below assumes a raw, unlacquered hickory haft and a head with a sound eye. Both tables are the reference; the prose around them is what stops you misreading them.
Getting the old handle out without cooking the temper
The old haft has to come out in a way that leaves the eye clean and the bit hard. Three methods work and one of them ruins axes.
Sawing the haft off flush below the head, then drilling a row of holes down the length of the remaining tongue and driving the pieces out with a punch, is the slow and completely safe option. Twenty minutes, no heat, no risk. This is what to do with a head you care about.
Burning the tongue out is faster and it's what most people reach for. Done properly, only the eye end sits in the coals and the bit is submerged in water or wrapped in a soaked rag the entire time. Done carelessly — head tossed in a fire pit and forgotten — the bit reaches a few hundred degrees and the temper is drawn out of it permanently. You'll see the colour run: straw at roughly 200 to 230 C, brown, then blue somewhere near 290 C. Blue at the edge means the hardness is gone and no amount of oil brings it back.
Epoxy-bonded hafts are their own problem. A Plumb Permabond or any mid-century head set in epoxy will not drive out and will not burn out cleanly. Drilling plus patient chiselling of the softened resin is the only route, and it's a genuinely miserable afternoon.
Fitting is removal
Buy the haft oversized. Every decent replacement haft comes with a tongue deliberately fat, because the maker cannot know your eye.
Slide the head down from the top of the haft, over the swell, until it stops. Mark where it stopped. Then take it off and read the shine — the tongue will show burnished contact points where it bound. Rasp those down. A four-in-hand rasp and a spokeshave do the whole job; a belt sander does it four times too fast and you will overshoot.
Speed this up with layout blue, a soot smudge from a candle, or a pencil scribble on the inside of the eye. Push the head on, pull it off, and the transferred marks show exactly what to remove. Repeat until the head slides down to about an inch above its final seat under firm hand pressure alone.
The final inch is where the interference fit lives. That last inch should need a mallet on the butt of the haft, driving the haft up into the head rather than hammering the head down onto the haft. Hold the haft vertically, head up, and strike the butt end downward against a block — inertia seats the head. Striking the head itself risks the eye and mushrooms the poll.
- Check the head sits square from two directions: bit centred on the haft centreline looking down the eye, and the bit edge in the same plane as the haft looking from the side.
- A haft that binds only at the top or only at the bottom of the eye is contacting the wrong faces. Eyes are hourglass-shaped, wider at both ends than the middle, and the tongue must fill top and bottom.
- Growth rings should run parallel to the bit, not perpendicular. That orientation puts the strongest axis in line with the shock.
- Grain runout of more than about 15 degrees off the long axis of the haft, or roughly one growth line crossing an inch of face per foot of length, is a haft that will break. Reject it before you fit it.
Wedge and kerf specification
Most replacement hafts arrive pre-kerfed and the factory kerf is frequently too shallow. Measure your eye depth — the distance from the top of the eye to the bottom, through the head — and set the kerf at two thirds of it. Deeper than three quarters and you risk the tongue splitting below the eye; shallower than half and the wedge cannot spread the wood where it needs to spread.
Deepen a short kerf with a hacksaw. Cut on the centreline and take your time; a kerf that wanders off centre spreads the tongue unevenly and one cheek of the eye ends up carrying the whole hang.
Head class Nominal eye, length x width Typical eye depth Kerf depth Wooden wedge taper Cross-wedge call Proud height after trim Hatchet, 1.25-1.75 lb 1 1/2 x 1/2 in 1 1/2 in 1 in, about 66 percent 5-6 degrees, wedge 3 in long tapering from 3/16 in None needed; a single wood wedge is enough 1.5 mm Hudson Bay, 1.5-2 lb 1 5/8 x 9/16 in 1 5/8 in 1 1/16 in, about 65 percent 5-6 degrees None; the shallow eye punishes a steel wedge 1.5-2 mm Boy's axe, 2-2.5 lb 1 5/8 x 5/8 in 1 3/4 in 1 1/8 in, about 65 percent 6 degrees, wedge 4 in long tapering from 1/4 in Optional round steel wedge at 90 degrees 2 mm Cruiser double bit, 2.5-3 lb 2 x 5/8 in 2 in 1 5/16 in, about 66 percent 6 degrees Wood only. The symmetrical eye spreads evenly and steel adds nothing 2 mm Felling axe, Michigan or Jersey, 3-4 lb 1 3/4 to 2 x 3/4 in 2 to 2 1/4 in 1 1/2 in, about 68 percent 6-7 degrees, wedge 4 1/2 in long tapering from 1/4 in Round steel wedge optional; drive it last and only if the wood wedge leaves slack 2-3 mm Splitting axe, 4-6 lb 2 x 13/16 in 2 1/4 in 1 1/2 in, about 66 percent 7 degrees Round or diamond steel cross wedge recommended; splitting shock is worse than chopping shock 3 mm Splitting maul, 6-8 lb 2 1/4 x 1 in 2 1/2 in 1 5/8 in, about 65 percent 7-8 degrees, wedge 5 in long tapering from 5/16 in Steel cross wedge, yes. Overstrike shock will loosen a wood-only hang 3 mm Broad axe, 5-8 lb 2 1/4 x 1 in 2 1/2 in 1 5/8 in, about 65 percent 7 degrees Wood only if the haft is to be removable for regrinding; steel if the hang is permanent 2-3 mm Pick mattock, 5 lb 2 3/8 x 1 1/8 in, oval 2 3/4 in No kerf. Slip-fit eye, head seats from below Not applicable Not applicable; the taper of the eye holds it Not applicable Measure your own eye rather than trusting the class row — nominal dimensions vary by maker and by decade. Use the percentage column, not the inch figure, if your eye depth differs from the table. Wedge stock should be the same species as the haft or softer. Hickory wedges in a hickory haft work fine. Poplar, basswood and soft maple wedges compress slightly under the drive and grip well. Oak wedges are hard enough to split the tongue if you get enthusiastic.
Glue is optional and the argument about it never ends. A thin smear of hide glue or wood glue on the wedge faces adds holding power and still lets you remove the haft later with heat and patience. Epoxy in the kerf makes the hang permanent and makes the head a nightmare for whoever owns it in thirty years. Skip the epoxy.
Stop driving when the sound changes. A wedge going home rings progressively higher and then goes dead — that dead thud is the wedge bottoming or the tongue refusing to spread further. One or two more taps past that and you're splitting wood you can't see.
The linseed cure schedule
Raw hickory drinks oil. That's the entire point — a saturated haft resists moisture swings, and moisture swings are what loosen hangs. The mistake is treating linseed as a finish and putting three coats on in a weekend. It's a cure, it takes a year, and the first coats have to be thin enough to penetrate rather than sit on top and gum.
Use boiled linseed oil, not raw. Boiled contains metallic driers and cures in a day; raw linseed can stay tacky for a week and never really hardens. Cut it with mineral spirits or turpentine for the early coats.
The end grain at the top of the eye and the exposed kerf are the two places water gets in. Flood those separately and repeatedly.
Stage Coats BLO to solvent Interval Soak then wipe Dry at 21 C and 50 percent RH What you should see Prep None None Before coat 1 Sand to 180-220 grit, wipe with spirits to lift dust and mill glaze 1 hour Dull, open, slightly fuzzy surface that darkens instantly when wetted Soak coats 1 to 3 1 part BLO to 1 part mineral spirits One coat per day 30 minutes soak, then wipe every trace off with a dry cloth 24 hours Oil disappearing into the wood within minutes; almost no sheen after wiping Build coats 4 to 7 2 parts BLO to 1 part spirits One coat per day 15 minutes soak, wipe dry 24 hours Absorption slowing; a faint satin appearing on the swell Finish coats 8 to 12 Straight BLO One coat per week 10 minutes, wipe hard until the rag drags 48 hours Surface starting to hold a low sheen; wood feels dense rather than oily Eye and kerf 3 extra applications, any stage 1 to 1 for the first, straight thereafter Alongside the schedule above Stand the axe head-up and flood the top of the eye; leave 20 minutes 24 hours End grain drinking visibly; top up until it stops taking oil Year one Roughly 12 Straight BLO Once a month 10 minutes, wipe dry 24 hours Colour deepening toward amber; grain sealed Thereafter 2 to 4 per year Straight BLO Start and end of each working season 10 minutes, wipe dry 24 hours A haft that never goes grey or fuzzy and never needs rewedging Follow the interval column, not the coat count — the schedule is once a day for a week, once a week for a month, once a month for a year. Below 15 C or above 70 percent humidity, roughly double every dry time. Wipe every coat off. Oil left standing on the surface skins over, stays gummy underneath and eventually flakes. A properly oiled haft feels dry to the hand and slightly warm-looking, not slick.
Skip anything that shortcuts the schedule. Soaking a whole haft overnight in a tube of oil is popular online, and what it mostly achieves is a saturated swell, a slow cure and an axe that leaves greasy prints for six months.
Linseed rags start fires
This is not a footnote. Boiled linseed oil cures by oxidising, oxidation is exothermic, and a crumpled oily rag in a bin has enough surface area and enough insulation to run away to ignition on its own. No spark required. Garages burn down this way every year.
Lay used rags flat on concrete outside until they're stiff and dry, then bin them. Or drop them in a sealed metal can of water. Never ball one up, never leave one in a pocket, never throw one in with sawdust.
Checking the hang before you trust it
A hang can look perfect and still be wrong, because two of the four things that matter are geometric rather than mechanical.
Sight down the haft from the butt with the bit pointing away. The cutting edge should bisect the haft. If the bit sits off to one side, the eye was fitted crooked and every stroke will glance.
Stand the axe on a flat bench, bit down, resting on the cutting edge and the butt of the haft. On a correctly hung felling axe the edge and the butt both touch and the haft's centreline points at or very slightly ahead of the edge. That relationship is the hang angle, and it's the difference between a bit that enters square and one that enters heel-first and skates.
The Hang Rating grades exactly this: head weight, balance point, hang angle and haft geometry. A rare head hung badly rates worse than a plain one hung right, which is the whole reason we score the hang rather than the maker.
- Balance point: on a well-hung 3.5 lb felling axe the assembled tool balances roughly 2 to 4 inches below the eye.
- Give the head a firm rap on a wood block after 48 hours. Any movement, any click, means the wedge is not home.
- Recheck at one week and one month. Fresh hangs settle, and a wedge tapped once more at week two often never needs touching again.
- A haft that has gone loose in dry winter air can be re-wedged. It cannot be fixed by soaking the head in water, and anyone who tells you to leave it in a bucket overnight is describing a repair that lasts until Tuesday.
Heads that are not worth rehanging
Some heads are done and it's better to know before you spend a week on the finish.
A crack in the eye wall, even a hairline one running from the eye toward the cheek, will open under wedge pressure and open further under use. Retire it. A poll mushroomed into a ragged skirt has been used as a hammer against hardened steel for decades and the metal at the rim is work-hardened and brittle; the skirt can be dressed back, but the head has been abused and the eye is often distorted with it.
A bit ground so far back that the cheeks are thicker than the bit is long has lost its pattern. It'll still split, so hang it on a straight haft and let it be a splitter. And a head that's lost more than about a fifth of its stamped weight is telling you the same thing in numbers.