Meet the Machine

Used Mazak QTN-350-II: The Number After the Slash Is the Bed

Two used Mazak QTN-350-IIs can share a chuck, a spindle, a turret and a control and still be very different machines. One turns parts about 24 inches long. The other turns shafts more than 80 inches long. The difference is in the suffix most listings bury.

Our Meet the Machine on the Mazak QTN 200 explains the Quick Turn Nexus family and what the letters mean. This one goes up a size, to the Mazak QTN-350-II, and to the part of the name that matters most on this machine.

Where the 350-II Fits

Mazak dates its NEXUS series to July 2002. The UK trade publication Machinery reported that more than 14,000 Quick Turn Nexus machines had been delivered since that 2002 introduction. The -II is the second generation of the family, and second-generation machines generally run the MAZATROL Matrix Nexus control. Mazak developed MAZATROL Matrix in September 2005.

The 350 sits near the big end of the family. It is the 12-inch-chuck, 4-inch-bar machine, a step up from the 200 and 250 and below the 450. Its successor, Mazak's current QUICK TURN 350, runs the MAZATROL SmoothG control, which Mazak released in 2015.

The Specs Every 350-II Shares

These figures come from Mazak's 2013 QTN Series brochure. They hold for the base machine and for the M and MY versions.

The Number After the Slash Is the Bed

Here is the part most listings bury: Mazak built the QTN-350-II on three bed lengths, and the bed sets how long a part the machine can turn. According to Mazak's brochure:

The metric labels in the last column come from dealer listings, not Mazak's brochure. They line up with the three machining lengths, but read the nameplate to be sure.

Same chuck, same spindle, same turret, and more than three times the part length from the short bed to the long one. A shop turning flanges and short shafts on a 26-inch bed is buying a different machine from a shop turning shafts more than 6 feet long on an 80-inch bed. The long bed needs more floor, and long parts usually need the tailstock and often a steady rest to hold size.

So when a listing says "QTN-350-II" and nothing else, ask for the bed. It is the first question, before the year.

Then Read the Letters

Like the 200, the 350-II came in more than one version. Mazak's brochure gives these differences:

The M and MY have more swing than the two-axis machine, but the maximum machining diameter is 16.54 inches on all three. The milling ratings are Mazak's 5-minute figures.

Read the Control, Too

The control tells you which generation you have. First-generation Quick Turn Nexus machines ran the MAZATROL 640T Nexus. Second-generation -II machines generally run the Matrix Nexus, and Mazak's 2013 brochure lists Matrix Nexus 2 on the 350 MY. If a listing pairs -II with a 640T control, or a year from before the Matrix era, check the nameplate and the control screen before you price it. Our Machining Monday on Mazatrol covers where the conversational control came from.

Kentucky or Worcester

Mazak built Nexus turning centers at its plant in Florence, Kentucky, and its 2011 export announcement named the Kentucky-built QTN-450-II MY. The 350-II was not only a Kentucky machine, though. Machinery reported that more than 450 QTN-350-II M and MY machines were built at Mazak's plant in Worcester, England, and that more than 85 percent of those were exported to Europe. The nameplate tells you which plant built yours.

On Our Floor

We have two QTN-350-IIs, and both are 80-inch-bed machines:

2012 Mazak QTN-350-II/2000 (stock 16898): 26.77 in swing, 12 in hydraulic chuck, 4 in bar, 40 hp, 3,300 rpm, 12-station turret, programmable tailstock, Mazatrol Matrix Nexus control, tool eye and chip conveyor.
Mazak QTN-350-II x 80 (stock 17076): 80 in between centers, 12 in hydraulic chuck, 40 hp, 3,300 rpm, 12-station turret and tailstock.

Both are listed as two-axis machines for long work. Confirm the year, control and options on either one with our team before you buy.

What to Check on a Used QTN-350-II

Confirm the bed and the version. Read the nameplate for the bed length and for M or MY. Then measure what you need to turn.

Check the turret. Index every station and check centerline alignment. A crash can knock the turret out of position.

Indicate the full Z. On a 60 or 80 inch bed, check the ways and the Z axis along the whole length, not just near the chuck.

Test the tailstock. On a long bed, the tailstock carries the long parts. Run it through its travel and check its alignment with the spindle.

Run the spindle. Take it to 3,300 rpm, listen to it and check the temperature. Check the chuck and the hydraulics.

On an M or MY, run the live tools. Spin every driven station and, on an MY, run the Y axis through its full 6 inches.

Record the control and its hours. Confirm 640T Nexus or Matrix Nexus, and check the run-time records on the control.

Who Runs One

The QTN-350-II is a 12-inch-chuck production lathe. On a short bed it suits larger chucked parts and bar work up to 4 inches. On a long bed it turns shafts, rods and tubes that a 26-inch bed cannot reach. Pick the bed for your longest part first, then the letters, then the year.

Resell CNC Take

On a QTN-350-II, read the name from the back. The bed decides how long a part you can turn, the letters decide whether it mills, and the control tells you the generation. A short-bed MY and a long-bed two-axis machine share a model number and almost nothing else a buyer cares about.

Frequently Asked Questions