Royal Master TG-12×8 Thrufeed Centerless Grinder

Royal Master’s TG-12×8 series of centerless grinders packages a very robust platform in a compact footprint. The Thrufeed TG-12×8 is ideal for everything from guidewires down to .002” up to larger diameter bar stock. Piece parts can be ground up to 3” in diameter all while holding sub micron tolerances. Materials ground can be from plastics to carbide and PCD, using the straddle bearing design on both spindles, and the Starrett surface plate granite machine bed, it is built for accuracy and performance.

Thrufeed grinding is a fairly basic centerless grinding principle that many machines have in their portfolio. But where the TG-12x8 differs is the engineering designed into the system results in a superior machine that is worthy of the Royal Master name.

Designed from the ground up over 15 years ago the system boasts many impressive applications to its, these are all pedestrian for this machine. The TG-12×8 thrufeed machine is in its wheelhouse where more demanding applications are required and where machine design equates to a part that is less then 1 micron straight and round from a machine “ out of the box”

Grinding a screw extractor at he show is a cool part, but the history of the machine is even more impressive. Grinding bar stock is old news, PCD, Ceramics and carbide been there and done that. One of the most impressive applications we have done is an 8000 parts per hour.

The grinder is equipped with the Granite Bed, 4 handle sizing dial with .0001” indicator, dovetail and gib with hard chrome and Turcite coatings and over the wheel diamond dressers tracing a template to dress the Norton Quantum grinding wheel. All of this to make for a low cost centerless grinder.

Available in Infeed, Thrufeed, as well as Hi-Accuracy and CNC versions, this machine has a capacity of 3” (75mm) in diameter. It offers a grinding wheel diameter of 12” (300mm) and a regulating wheel diameter of 8” (203mm), both wheels are 8” (203mm) wide.

The grinding wheel spindle design has three sets of class 7 ABEC angular contact Timken bearings inside a larger headstock with an outboard self centering bearing set for a twin grip design. This design gives the grinding wheel spindle superior accuracy. The regulating wheel, with its 2.25” (57mm) diameter spindle and Timken bearings allows for the most demanding applications to be ground with zero deflection. The 8” (203mm) diameter regulating wheel allows for closer tolerance with larger diameter work.

The machine sits on our 8” (203mm) thick Starrett surface plate quality granite. The granite bed forms a perfect platform for such a robust spindle design. The granite known for its rigidity and thermal properties provides a superior platform to other machines on the market that have thinner cast iron beds, and makes it as strong as those who have machine platforms twice the physical size of the TG-12×8.

We added stepper motors and ball screws to our dressers for programmable traverse rates as standard equipment. With this new platform, wheel dressers are offered as Air Sensing, Automatic dressing, over the wheel CNC as well as Rotary Diamond Disk CNC platforms. On the TG-12×8 we upgraded our regulating wheel servo drive with 170 foot pounds of continuous torque, with a 10:1 gearbox.

No matter what your thrufeed application is the 12×8 is a perfect machine for grinding it!

The TG-12×4 Thrufeed system is:

12” Diameter Grinding Wheel 8” wide, 8” Diameter 8” wide Regulating wheel

Variable Frequency Drive on grinding wheel spindle for super abrasives or maintaining constant surface footage when grinding.

Outboard bearing on grinding wheel for an extremely ridged design allowing for high stock removal rates on hard materials

Infeed and Thrufeed Grind Capability

Password protection on operator interface

Programmable Infeed Cycles can be saved and recalled with unique file names from a library

5” of Ram Bed travel allowing for removal of Grinding Wheel

High volume feeding available such as bar feeders or step feeders. One application yielded 8000 ppm on a 1.5” long part.

The Highlights

Grind parts down to .002” Diameter up to 3.0”
Run a Conventional abrasive grinding wheel or vitrified CBN wheel that is diamond tool dressable.
Run at higher spindle speeds to maximixe thruput, for example at 9000 surface feet per minute with multi-grit stages across a vitrified CBN wheel face
Step Feeder automation is efficient to feed the beast up to 8000 ppm
The grinder is equipped with a standard Starrett surface plate Granite Bed

Spindle Design engineered with Timken for the most robust system. Confirmed by FEMA Analysis by Timken engineers
Stepper motors and ball screws to our dressers for programmable traverse rates as standard equipment
Regulating wheel servo drive with 170 foot pounds of continuous torque, with a 10:1 gearbox
10HP Main Motor with Optional 15hp

Engineer Deep Dive

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