Rottler VR12

Valve Refacing Machine with Centerless Grinding

Machine Operations

Valve Refacing

PDF Resources

VR12 Brochure


Rottler's Centerless Grinding System is able to grind a set of valves to exact same length without adjusting settings.The Centerless System rotates the valve stem on it's own centerline. Precision drive rollers rotate the valve stem and a pneumatic low friction steady rest support the valve stem similar to a precision balancing machine, resulting in extremely accurate valve stem to valve seat run out less than .0002" (.005mm) TIR. The Rottler Centerless System allows a wide range of valve stem diameters to be ground without changing any collets or chucks.Stroking Handwheel - The new design stroking handwheel moves the valve back and forth over the grinding wheel. When operator's hand is removed from the stroking handwheel, the stroking system remains in position until the operator moves the handwheel again. 


  • New Standards - The VR12 sets new standards for Performance Racing and Remanufacturing work. The Centerless Technology eliminates collets and chucks. Valve face is machined concentric to the valve stem for improved sealing, better heat transfer and reduces mechanical stresses on valves.
  • Grinding Wheels - The VR12 is supplied standard with vitrified wheels, grinding oil and diamond dresser. CBN wheels are optional and must be ordered separately. Special wheels available for grinding difficult metals such as Titanium, Inconell, etc.
  • Variable Valve Rotation Speed - allows the operator to adjust surface speed for different diameter valves for best surface finish for a wide range of valve head diameters from small multi-valve to large diesel valves.
  • Variable Wheel Rotation Speed - The Main and Stem/Butt End wheels are variable and are easily adjusted on the control panel to allow different surface speed on different diameter valves for best surface finish on a wide range of valve head diameters from a small multi-valve to large diesel and gas valves. 
  • Canted Roller Drive System - eliminates the need to manually feed valve into or away from grinding wheel during refacing. Canted rollers feed valve against a precision stop which accurately controls valve length on every valve - automatically.
  • Centerless Grinding System - handles large range of valve stem diameters without changing any collets or chucks!
  • Open Sided Pneumatic Steady Rest - No need to switch off the motors when changing valves reducing machining time and increasing life of motors.
  • 9" (230mm) Large Diameter Main Grinding Wheel - Different grit size and bond strength wheels available for grinding different surface finish roughness requirements.
  • Stem/Butt End Grinding - Grind Valve Stem End square to the valve centerline. The V rest allow all valves in a set be be ground to the same distance from valve seat to stem end - essential for overhead camshaft type cylinder heads. Exact amount of material removed from the stem end can be measured with the micrometer adjustment system.
  • Stem/Butt End Chamfering - Grind Valve Stem End with chamfer to allow easy entry to new valve stem oil seals to ensure reliable installation for minimum oil consumption between valve stem and valve guide.
  • Large Valve Capacity - The VR12 Double Dovetail Slideway and micrometer feed system allow large valves up to 15" (385mm) long to be easily set up and ground.
  • Main Wheel Diamond Dresser - The fold away diamond dresser is set to the exact position of the wheel face to dress, just drop the dresser down into place and the diamond is positioned ready to dress minimum material from the main grinding wheel.
  • Base Cabinet - Standard Base Storage Cabinet includes a large 5 gal 20 litre removable coolant tank with replaceable paper filter system. Coolant tank has drain plug and is easily removed for quick cleaning. This large capacity filtered coolant system allows machine use for months and months with no cleaning or maintenance required saving time and money.
  • Large Capacity Coolant - tank and filter system built into standard storage cabinet.
  • Solid Cast Iron Construction - dampens harmonics, eliminates chatter, and maintains accuracy for a long service life.
  • Stroking Handwheel - Stroking handwheel moves the valve back and forth over the grinding wheel.

Standard Equipment

  • Centerless Grinding System includes Pneumatic Steady Rest for Valve Stem Diameters from .160 - .600" (4 - 15mm) 
  • Special Design Drive Roller System to allow grinding of small/short valves without Pneumatic Steady Rest
  • Central Stroking Rotational Handle for easy stroking of valve over grinding wheel,  chuck does not fall to end stop when operator's hand is removed from th ehandwheel
  • Motor Controller converts single phase incoming power to 3-phase motor
  • Variable Valve Rotation Speed from 0 to 230 RPM
  • Digital Display Valve Face Angle Device from 5 to 55 degrees in .1 increments
  • Double Dove Tail Slides for Valves up to 15" (380mm) Overall Length
  • End Stop System to grind valves in a set to equal length from butt end to seat face
  • Butt Grinding and Chamfering Device  including micrometer, adjustable V Nest 
  • Small/Short Valve Butt Grinding and Chamfering Device 
  • Main Wheel  Dressing  Device mounted on the machine
  • Main Grinding Wheel 9.0" (230mm) Diameter, General Purpose (VTRW-10)
  • Diamond dresse for dressing main grinding wheel (VTRW-4)
  • Butt Grinding Wheel 4.0" (100mm) Diameter, General Purpose (VTRW-3)
  • Diamond dresser for dressing butt wheel (VTRW-5)
  • Adjustable Work light
  • Base Storage Cabinet including removable coolant tank and paper filter system, capacity (5) gallons (20 liters)
  • Grinding Oil 7609C 5 Gallons (20 Liters)
  • Filter Paper (20 sheets)
  • Paint Color Code: RAL9002 (Grey White)
  • Electrical requirements: 208-240V, 10A, 50/60Hz, 1Ph 
  • Shipping dimensions: 31 X 36 X 64" H (787 X 914 X 1626mm)                        
  • Shipping weight: 660 lbs (300kgs)
  • Prices (US Funds) FOB -EXW, Kent, Washington, USA


Digital Valve Face Angle Digital display shows exact valve face angle and is easily adjusted by one locking handle from 10 to 50 degrees.


VR12 Machine Specifications American Metric
Base CabinetStandard
Valve Stem Diameter Range (with Standard Chuck)0.138"-0.630"3.5mm-16mm
Valve Stem Length Range (with Standard Chuck)1.970"-10.250"50mm-260mm
Valve Total Length Range2.750"-15.750"70mm-400mm
Valve Face Angle Range10°-60°
Valve Grinding Wheel Diameter9"225mm
Butt Grinding Wheel Diameter4"100mm
Valve & Butt Grinding Wheel SpeedVariable up to 2500 RPM MAX
Valve Rotation SpeedVariable up to 230 RPM MAX RPM
Coolant Capacity (with Cabinet)5 Gallon20 Liter
Valve Grinding Motor Power0.75 HP, AC0.56 Kw, AC
Grinding Oil Pump Power Flow0.025HP - 300GPH0.02KW - 20LPM
Dimensions - Machine36D x 34W x 67" H 915D x 864W x 1702mm H
Dimensions - Shipping36D x 36W x 64" H 914D x 914W x 1626mm H
Machine Weight725 lbs329 kg
Electrical Requirements208-240V, 10A, 50/60Hz, 1Ph
Air Requirements cfm @ 90 psi l/min @ 6 bar
Paint Color CodeRAL9002 (Grey White)