Chipper Knives for Morbark, Carthage and Precision Husky
Replacement knives for North American whole-tree and debarker-fed drum chippers. These machines run harder and dirtier than a mill yard chipper: bark, grit and the occasional fence staple. The knife has to survive impact first and cut second, and that changes the steel and the edge angle.
Two, three or four knives — and why the count changes the blade
A whole-tree drum usually carries two to four knives per drum, bolted through pockets machined into the shell. Fewer, heavier knives take a bigger bite per revolution and see higher shock load; more knives give a finer chip at the same drum speed. The knife count is set by the drum, but it decides what you should specify:
| Knife count | Load per knife | What to specify |
|---|---|---|
| 2 | Highest — deep bite, blunt impact | Tougher grade, 9CrSi or 6CrW2Si at the upper hardness, 40–42° edge |
| 3 | Medium, the most common | Standard chipper grade, 38–40° |
| 4 | Lowest per knife, finer chip | Standard grade, 35–38°, watch edge straightness |
Morbark builds both drum and disc machines, and the disc chipper knife is a different animal: shorter, usually with a countersunk fixing, and it works against a bed knife on the disc face rather than an anvil in a drum. If you are ordering for a disc machine, say so — the two do not interchange.
Steel and edge angle for bark and grit
Carthage and Precision Husky knives usually run 6CrW2Si or 9CrSi in the HRC 57–62 band. On clean softwood you can sit at 60–62 and get long life. On bark, pallets and urban wood we pull that back to 57–59 on purpose: a blade that dents and can be dressed is cheaper than one that chips and has to be scrapped.
The anvil gap decides chip quality more than the knife
Clearance between the knife edge and the bed knife or anvil is normally set at 0.5–1.5 mm and checked with a feeler gauge after every knife change. Open it up and you get oversize chips, stringers and a hammer mill working overtime downstream. Close it and the knife hits the anvil. Most “the knives are no good” complaints we receive trace back to this gap.
What to send
| Send this | Detail |
|---|---|
| Machine model and drum diameter | Morbark, Carthage, Precision Husky model number from the plate |
| Length × width × thickness | mm, or inches — we work in both; state which |
| Fixing | Countersunk angle, through-bolt diameter, hole pitch, number of holes |
| Feed | Whole trees, logging slash, pallets, land clearing |
| Current knife life | Hours or tons between changes |
Send your knife drawing or sample photo
Frequently asked
Do you make knives in inches to US drawings?
Yes. Send the drawing in inches with the tolerances as drawn; we grind to the inch dimensions rather than converting and rounding.
Can you match the hardness on my current knife?
Tell us the grade or send a failed knife and we hardness-test it. Matching an existing spec is safer than guessing when the machine has a history of a particular failure.
How many knives should I keep as spares?
One full set per drum plus one set in reserve. A chipper stopped for a knife change costs far more per hour than the blades.
Related: Chipper knife overview · Bruks, Vecoplan & Pallmann · All machine brands
Send your Morbark, Carthage or Precision model
Model plate photo plus the old knife size is enough to quote. One piece minimum.
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