Kress CNC

MachineInfoBox Kress CNC Portal Mill

Material:	wood, metal
Used with:	endmills
Access Requirements:	CNC Mill Introduction
Tutors:	Sebastian
Similar (More or Less):	CNC router

This CNC portal mill was bought used in 2022 from a maker that build and used it to machine aluminum parts for other CNCs. Main features and specs:

Portal Mill driven by 3 stepper motors (23HS30-2804S)
80kg steel & aluminum build, t-slot table
Spindle: 800w China HF spindle with ER11 collet
Work area: 3000x3600x80mm
Controller: SMC5-5-N-N with jog-wheel
Power Supply: Meanwell 48V 10A
Stepper Drivers: 3x Leadshine DM556

Workflow

This is just an overview and does NOT replace the personal introduction!

create the tool paths in a suitable CAM software (e.g. Fusion 360)
1. post and export the correct G-code flavor
Homhe the machine to zero the machine coordinates
secure your workpiece on the machine's bed
1. if you plan on cutting through the workpiece use a spoil board.
insert the appropriate collet & bit as defined in your tool paths
set your workpiece zero
put on personal protection and turn the spindle on
start your job from the USB stick

Fusion 360 Setup

Import the machine settings file (add GitHub link)
Edit the machine settings. Under "post processor", import the post file (add GitHub link). Make sure to save the post under "local".

The SMC5-N-N-5 processor uses the "mach3" post processor. The one included in Fusion 360 is reported to sometimes cause erratic behavior with this controller. The prepared post on Github is modified to avoid this (add link).

Machine Control

The machine itself is mainly operated by the control panel located on the right side of the machine box and the jog-wheel (SMC5-5-N-N).

The main switch turns on the power for the CNC, the spindle, light and the controller.

Homing the machine: This CNC has no auto-home. Always run the homing operation as first step directly after startup!

Start by homing the machine. If the text „Reset“ blinks red on the screen, press the reset button (1). Press the “Origin Operation“ button (2). In the menu, select „Return To Home“ (3).

Navigation basics:

On the panel, use the XYZ +/- buttons to move the spindle. Always home the spindle at the beginning of your session. If properly homed, softstop settings should prevent the spindle from crashing into the sides of the machine, but navigate with caution. (add info how to change the distance per button press on the panel)

When using the jogwheel, press the button on the left side and then move the wheel. The X1, X10, X100 switch controls how far the spindle moves per click of the wheel. If set to X1, one click is 1/100mm. X10 is 1/10th and at X100 one click moves 1mm.

Zeroing the machine coordinate on the workpiece origin:

The coordinate system. Note that the machine zero point is in the top left front corner of the machine and the spindle moves down into the negative Z direction.
Carefully move down the tooltip onto the reference plane of your workpiece (usually the surface). Wiggle a piece of paper in between the tooltip and the workpiece and move the head down in 0.1mm or smaller increments until you start to feel the resistance and scratching.
Press the „Coordinate Operation" button (1). Press „Z Auto Zero" to set zero of the work coordinate for Z in the current position.
Move the tooltip to the X and Y position that you have set up as your origin in the CAM software.
Zero the work coordinates for X and Y by pressing „X Axis Zero" and „Y Axis Zero" (1,2). You have now fully set-up the zero point of the work coordinates to be in line with the origin of your workpiece in CAM.