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Tool Post Grinder FAQs

How do I determine which tool post grinder will fit my lathe?
The most important steps in selecting the right tool post grinder for your lathe or machine tool are (1) selecting a tool post grinder that matches the swing of your lathe, and (2) selecting a tool post grinder that can be mounted so the centerline of the grinding wheel is at the centerline of your workpiece.  Learn More

How do I determine the swing of my lathe?
Lathe manufactures should specify the swing, so check the lathe specifications and operating instructions. Typically, the swing of a lathe is considered as the distance from the center of the chuck to the top of the ways, multiplied by two.

Should I use a 1 HP or 3 HP tool post grinder?
First, the tool post grinder must fit your lathe (see “How do I determine which tool post grinder will fit my lathe?”) The material to be ground, metal removal rate, grinding operation and grinding wheel employed all impact the power requirement. The more rapidly material is removed, the more power is required. Because so many factors are involved, there is no easy and accurate calculation to determine the power requirements. However, a general rule of thumb is 1 HP for every 1/10 cubic inch of material removed per minute. The following table can be used as a quick reference guide.

Material Removal
(inch3 / minute)















Can I turn the tool post grinder spindle around and grind on the left side? If not, do you make a grinder that will grind in that configuration?
A properly set up tool post grinder always has the motor between the workpiece and the operator, so Dumore tool post grinders are always configured with the grinding wheel to the left of the operator. Dumore spindles are designed so that during grinding the nut tightens on the wheel. It is not safe to turn the grinder around or run the spindle in the opposite direction of what is intended.

Exception: The Series 12 & 25 tool post grinder external spindle for up to 12” wheels (889-0011) is designed to be run in either the clockwise or counter clockwise direction. This is the only spindle capable of safe operation in either direction. The lock washer supplied with the spindle must be installed properly under the wheel nut to ensure safe operation in either direction.

Do I need to oil the tool post grinder spindle?
For all except Series 44 tool post grinders – No. The Series 44 integral spindle tool post grinders do require periodic oiling with Dumore Spindle Oil. All other grinder spindles do not require oiling. If a spindle requires service it is highly recommended it be returned to Dumore for service. Please contact our customer service team.

Can I use the tool post grinder in an application where coolant is applied to the grinding surface?
The Series 57, Series 12 and Series 25 tool post grinders can be used in applications where coolant is applied to the grinding surface. The spindles for these grinders are equipped with water and dust throwers. When the coolant flow is stopped, continuer running the spindle for several minutes to prevent the coolant from working into the spindle bearings. Never allow coolant to flow on a spindle when the spindle is not rotating.

What is the difference between revolutions per minute (rpm) and surface feet per minute (sfm)?
Revolutions per minute (rpm) is the number of complete axis turns per minute. Surface feet per minute (sfm) is the distance any one abrasive grain on the cutting face travels in one minute. In general, wheel speed is usually stated in surface feet per minute (sfm). Machine speed is usually indicated in revolutions per minute (rpm) and most speed indicators and tachometers read in rpm. Learn more about grinding wheel speed and translating surface speed into rpm.