Mini Mill

Mini mill

The CRB Makerspace has a LittleMachineShop HiTorque 4190 Deluxe Mini Mill with 3-axis digital readout (DRO). Do not cut steel on this machine.

Hazard level

RED

Warning

Risk of cuts from contact with rotating cutting tools
Flying chips and metal shavings can be hot and sharp
Risk of workpiece or tool ejection if improperly secured
Pinch points between moving table and fixed components
Chuck key left in chuck becomes projectile

Safety

Always wear safety glasses that are ANSI Z87.1 compliant.
Wear appropriate clothing; no rings, gloves, neckties, jewelry, or loose-fitting garments. Tie back long hair.
Make sure you understand the operation of the machine before use. If you are unsure, ask for help—do not “see what happens.”
Remove all tools (wrenches, chuck keys, etc.) from the spindle and table before turning on the machine.
Secure the workpiece with a vise. Make sure the workpiece is held tightly.
Keep hands away from the rotating spindle, cutter, and moving table. Avoid pinch points between the table and fixed parts of the mill.
Clear chips with a brush or vacuum only. Do not use your hands or compressed air to remove chips.
Inspect cutting tools for damage before use and replace dull or chipped tools.
Do not attempt cuts that exceed the capacity of the mini mill or that you have not been trained to perform.
Never leave the machine running unattended.

Instructions for use

Info

Use of this tool requires permission from management and a key to operate. Check out the key from Raphael or authorized personnel before use and return it immediately after.

Do not cut steel in the CRB Makerspace

Verify you are authorized to use the mill and have completed machine-specific training.
Secure your workpiece in the vise or with clamps on the table. Ensure it is flat and cannot shift under cutting forces.
Select an appropriate cutter (e.g., end mill or drill) or tool (e.g. edge or center finder) for your operaction and material.
Install the tool in the proper collet or tool holder and secure it in the spindle. Tighten the drawbar securely. Remove any wrench or spindle lock before starting the machine.
Estimate a suitable spindle speed for your material and tool size using the Cutting Speeds table and calculator below. Set the speed on the mill.
Use the handwheels to bring the cutter close to the workpiece and carefully “touch off” to establish your zero point. Zero the DRO axes as needed.
Plan your cut: choose a conservative depth of cut and feed. Take multiple light passes rather than one heavy pass.
Turn on the spindle and allow it to reach full speed before feeding into the material.
Feed smoothly using the handwheels, watching both the cutter and the DRO. Listen for chatter or overload and reduce depth of cut or feed if needed.
For deeper cuts or slotting, periodically retract the cutter to clear chips and allow it to cool.
When finished, retract the cutter clear of the workpiece, then turn off the spindle.
Wait for the spindle to come to a complete stop before reaching near the cutter or workpiece.
Remove the workpiece, deburr sharp edges, and brush/vacuum chips from the machine and floor.
Return tooling and accessories to their proper storage and leave the mill clean for the next user.

Cutting Speeds

Material	AISI/SAE/ASTM Designation	Feet/Minute
Wrought aluminum	6061-T6, 5000, 6000, and 7000 series	165
Cast aluminum	Sand and permanent mold casting alloys	165
Brass	C33200, C34000, C34200, C35300, C35600, C36000, C37700, C48500	100-200
Bronze	C65500, C22600, C65100, C67500	30-80

Cutting Speeds Calculator

Specifications

Feature	Value
End Milling Capacity	0.6" (16 mm)
Face Milling Capacity	1.2" (30 mm)
Drilling Capacity	0.5" (13 mm)
Table Size	18.1" x 4.7" (460 mm x 120 mm)
T-Slots	3 slots 0.47" (12.0 mm) wide
X-Axis Travel	11.8" (300 mm)
Y-Axis Travel	5.1" (130 mm)
Z-Axis Travel	10.6" (270 mm)
Positioning Accuracy	0.0004" (0.010 mm)
Spindle Taper	R8
Spindle Motor	0.67 hp (500 Watts)
Spindle Speed	100 - 2500 RPM