Kinetic Precision - PFG Stones
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Moly Sticks™

Moly Sticks™
Molybdenum truing sticks

for

Diamond Grinding Wheels

 

“MOLY.GG” redirects you to this page. Last update was 12 JUNE 2024

Order the MOLY-2 Moly Stick™ here. All about Shipping and Payments here. Our YouTube channel is here.


  • 3/8-in Diameter x 2-in Length (OD may be ground or as-swaged)

  • Supplied in a plastic cradle to eliminate roll-away and insure durable labelling.

  • 99.95% pure molybdenum pressed, sintered and swaged material

  • Made in USA! Molybdenum from Maine!

(Magnetic steel holder shown not included. You can make one, or hold the Moly Stick™ in a grinding vise.)

“A little Moly goes a long way!”

Molybdenum is used in the truing of resin-bond and metal-bond diamond wheels. To use this technique, you MUST be able to slow your wheel down from typical grinding speeds, such as 5-6000 SFM, to 600-700 SFM (see tables below). This may be accomplished with a VFD on the spindle motor. (Robin Renzetti teaches a method of using the coast-down of the wheel after turning off power, in the event you do not have speed control, in this excellent video. You really should watch the whole video!)

For more information, see the (expired) 1975 Kish Patent:

“… improved results in the form of particularly accurate finishes and minimum wear of the molybdenum tool have been achieved with the grinding wheel operating at slower speeds within a range of from 600 to 700 surface feet per minute. …”

Recommended initial speeds and feeds:

  • Center the wheel on the hub using an indicator to save time, moly, and diamonds.

  • True your wheel at a surface speed of 600-700 surface feet per minute (7-inch wheel would be 380 RPM, though 700 RPM has been proven to be satisfactory). If you use it at full grinding speed, you won’t be truing, you’ll just be grinding Molybdenum. (See tables below.)

    • Downfeed 0.002” for a 150 grit diamond wheel as a starting point

    • Infeed 20 inches per minute as a starting point

    • You may use graphite to mark the wheel at the start of the truing process to make progress more visible.

  • Dress your wheel with a Dressing Stick after truing (Such as McMaster 4563A16). See This NORTON Video to learn how to use a dressing stick. (The Moly Stick™ replaces the truing device shown in the video.)

  • Balance your trued and dressed wheel. You can use the B-200 Balancing Ring if it fits your hub, and the No. BS-8 Balancing Stand if you use 8-inch or smaller wheels.

And, yes, Moly Sticks™ have been used for years in the manufacturing process for PFG Stones® to keep our diamond wheels true! One of these Moly Sticks™ lasts about a year in this process. Your mileage may vary.

Why does this work?

Imagine a little kid running across a mud puddle while wearing galloshes (boots). They run across fast and get muddy. They run across slowly, at just the right speed, and then lose a boot as it gets stuck in the mud. Well, the boot is a diamond, and the mud is the molybdenum.

Another example…

You are holding a bat (baseball or cricket, your choice), and I toss you a 0.45-inch diameter, 0.6-inch length of lead toward you. You swing the bat and send it 100 feet away. Now, I take that same piece of metal, which happens to be a bullet, and fire it at 1250 feet per second at your bat. It goes right through. The bullet is the diamond, the bat is the molybdenum.

These gedanken experiments show what is happening during moly truing. Molybdenum is really efficient at pulling the errant diamonds out at just the right speeds. Too fast, and you are just making really expensive metal dust.

Happy Truing!


Molybdenum Facts

  • Symbol: Mo

  • Category: Transition Metal, Group VI

  • Atomic Number: 42

  • Density: 10.28 g / cm3

  • Discovered: 1778

  • High melting temperature, 2620 °C

  • Low vapor pressure at high temperature

  • Low coefficient of thermal expansion (CTE)

  • Good corrosion and creep resistance

  • Load bearing capabilities at temperatures up to 2000 °C,

  • Excellent thermal and electrical conductivity


Recommended surface speed for molybdenum truing of diamond wheels is 600-700 SFM.

(NOTE: 600 SFM = 3 M/S and 700 SFM = 3.6 M/S)


updated 9 DEC 2024

Our YouTube channel is here.
The KP logo is a trademark of Kinetic Precision. “PFG Stones®” is a Registered Trademark of Kinetic Precision. Two precision ground stones in a red dual-tray is a trademark of Kinetic Precision. “NOZ” and “Perfect Fluid Guide” is a trademark of Kinetic Precision. “Moly Stick” and “Moly Sticks” is a trademark of Kinetic Precision.