Getting the King Kn 64 Running Again
I've been around enough of these units to know that most people don't read the manual until something is already broken. The King Kn 64 is no different. It's a precision knurling and threading unit, and the manual that comes with it is accurate but terse. I learned that the hard way when my first one started throwing inconsistent thread pitches on 3/8-inch stock. The manual breaks down into roughly six sections: setup and alignment, tooling installation, routine lubrication schedules, troubleshooting charts, parts diagrams, and torque specifications. That's it. No fluff. The parts diagram alone saved me two hours of guesswork once, because the knurling wheel retainers use a completely different thread direction than the rest of the assembly. Left-hand thread on the left side, right-hand on the right. I missed that on my first rebuild and managed to cross-thread the holder before I caught it. Most of the issues I see come from skipping the alignment check. The King Kn 64 mounts to a lathe carriage, and if the knurling head isn't perfectly perpendicular to the workpiece axis within about .002 inches, you're going to get chatter, uneven knurl patterns, and premature tool wear. I used a dial indicator mounted to the carriage and checked runout at the tip of the knurling wheel before every job for about six months straight. Once I stopped being lazy about it, scrap rates dropped by roughly 40 percent.
Another thing nobody mentions enough: the lubrication intervals in the manual assume clean, dry shop conditions. If your shop runs humid or you're cutting with soluble oil coolant that splashes into the head, drop the relube interval in half. I was going by the standard 50-hour recommendation and ended up with a seized feed screw after about 200 hours. Replacing that screw set me back around $180 and a half day of teardown.
The Practical Maintenance Routine
Here's what I actually do, and it aligns pretty closely with the manual's recommendations but with a few adjustments from experience. Every 50 hours: Check the knurling wheel engagement depth. The manual says to back off the feed until the knurling pressure gauge reads between 15 and 25 pounds during cutting. If you're reading above 30, the wheels are too aggressive or your stock size is slightly off. Every 100 hours: Remove the head cover and inspect the gear train for metal shavings. Light machining dust is normal. Chunky steel flakes mean something is wearing prematurely. I keep a small magnet on hand to pull ferrous particles out of the gear oil before reassembly. Every 500 hours: Full disassembly of the feed mechanism, clean with solvent, and repack with ISO 68 spindle oil. This takes about 45 minutes if you have the right screwdrivers and a clean workspace. The King Kn 64 Maintenance Manual lists a torque of 18 foot-pounds for the head mounting bolts. I trust that spec, but I also recommend a thread-locking compound on those bolts if you're doing heavy stock removal. Vibration from hard knurling will loosen them over time regardless of the torque value.
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A Specific Problem I Ran Into
About a year ago, the cross-feed on my unit started binding at about the three-quarter travel point. The manual's troubleshooting chart pointed to worn gibs, but when I opened it up, the gibs were fine. The real issue was a tiny burr on the lead screw that had formed from a single instance where I'd knocked the threaded end against the bench. It was so small you'd miss it without a magnifying lens. I used a fine Arkansas stone to dress the burr and the binding went away completely. Took about ten minutes total. This is the kind of edge case the manual doesn't cover because it can't possibly list every way you can damage the thing. The King Kn 64 is solid but it's not built for production-line speed. The manual acknowledges this by recommending a maximum continuous duty cycle of about 15 minutes before allowing a cool-down period. Push it longer and you'll heat-expand the housing and lose your alignment. I've also noticed that replacement knurling wheels are proprietary and run about $65 to $90 per pair, which adds up fast if you're doing a lot of different material types. There isn't a universal aftermarket option that fits without modification. For light maintenance work and hobby-level production, this unit is more than adequate. If you're running multiple shifts per day, you'd probably want to look at a dedicated production knurling station instead. The King Kn 64 is designed for the machine shop that uses it occasionally, not the one that depends on it every hour.
Getting the Manual
The King Kn 64 Maintenance Manual is available through the original equipment manufacturer's website, usually under the support or documentation section. You'll need the serial number from the unit's nameplate to get the correct revision. There are also third-party reproductions floating around on industrial parts websites, but those sometimes have errors in the torque values from older revisions. Cross-reference any numbers you're unsure about with the serial-number-specific version. I keep a printed copy in my toolbox drawer alongside the parts diagram. It saves me from digging through files on a laptop when I'm already standing at the lathe with grease on my hands.
