Engraving Tools, End Mills & Cutters
Spring Loaded Engraving Tools
Vacuum Chucks & Pumps for Workholding

Feeds and Speeds for Armor Mills and Armor Drills & Broken Tap Removal Tips

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Reference the below tables for general Feed and Speed Rates

• Table 1 - Armor Mills
• Table 2 - Armor Drills
• Broken Tap Removal Tools - Tips

Armor Mills are designed for use with rigid cnc machines when cutting or engraving granite or other hard materials.

Control of the depth of cut, the spindle speed, and the cutting feedrate is critical to achieve maximum tool life.

Cutting granite or other extremely hard materials may not be possible with the use of a hand operated tool or the life of the tools may be significantly reduced.

2L inc. has tested the armor mills on granite with a rigid cnc machine and a rigidly held workpiece. 

Feedrates are below:

• Please note as with all machining, it is important to take appropriate safety precautions.
• Use of coolant is typically recommended  and will extend the life of the tool bit.
• The sample of granite shown below was machined at the specific feeds and speeds listed above in the table. The Armor Mills successfully machined for 30 minutes at the above conditions to complete the sample.

Note: Consider the above feeds and speeds as a reference point. Variations in the above table may be required depending on material being machined and cutting conditions.

To remove broken taps and drills, it is recommended to feed the tools by hand (hand wheel on lowest feedrate) until the tool has plunged far enough into the broken tool to encounter a stable cutting condition.

In other words, as the tool begins cutting into the uneven jagged surface of the broken tool, feed extremely slowly to prevent the tool from walking which will put high side loads on the cutting tool and lead to breakage.

Once the tool is fully into the cut and seems stable, feeding with the cnc control at the above feeds and speeds is possible.

Stones such as granite and marble have different machining properties among different varieties and even at different spots within the same piece of stone.


RPM = (SFPM x 3.82) / D
IPM = (No. of teeth) x IPT x RPM
 

RPM= Spindle Speed.
D = Diameter of tool.
IPR = Inches per rev.
IPM = Inches per minute.
IPT = Inches per tooth.
SFM and SFPM = Surface feet per minute.

Please note as with all machining, it is important to take appropriate safety precautions.

Note: Consider the above feeds and speeds as a reference point. Variations in the above table may be required depending on the material being machined and cutting conditions.
 

Use of coolant is typically recommended and will extend the life of the engraving tool bit.

To remove broken taps and drills, it is recommended to feed the tools by hand (hand wheel on lowest feedrate) until the tool has plunged far enough into the broken tool to encounter a stable cutting condition.

In other words, as the tool begins cutting into the uneven jagged surface of the broken tool, feed extremely slowly to prevent the tool from walking which will put high side loads on the cutting tool and lead to breakage.

Once the tool is fully into the cut and seems stable, feeding with the cnc control at the above feeds and speeds is possible.

Stones such as granite and marble have different machining properties among different varieties and even at different spots within the same piece of stone.

RPM= Spindle Speed.
D = Diameter of tool.
IPR = Inches per rev.
IPM = Inches per minute.
IPT = Inches per tooth.
SFM and SFPM = Surface feet per minute.

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Armor Mill™

Use the Armor Mill when the tap or drill is broken off below the surface of the workpiece or when the broken tap or drill has an uneven top surface that would cause the Armor Drill tip to walk or deflect.  These tools are manufactured in house with a Premium, Ultra Fine, Nano Grade, Solid Carbide for maximum tool strength.

Order Armor Mills Here

Armor Drill

Use the Armor Drill when the tap or drill is broken off above the surface of the workpiece or when the broken tap or drill has a flat top surface that will not cause the drill tip to walk or deflect. These tools are manufactured in house of a Premium, Ultra Fine, Nano Grade, Solid Carbide for maximum tool strength.

Order Armor Drills Here

It is recommended that both the Armor Drill and Armor Mill tools be used in rigid machines (machining centers, knee mills, lathes) with the parts held securely. Using the hand wheel at the lowest speed, feed very slowly and keep a steady feedrate. Peck or stop frequently to remove chips from the hole. If the part needs to be drilled with a hand drill, operate the drill at faster rpms, use a strong, steady force, and keep the drill as straight as possible. It is important to prevent the tools from walking or deflecting, especially when first contacting the uneven part surface.

As with all machining, it is necessary to take appropriate safety precautions.