Week 7. Group / Computer-controlled Machining

This is group assignment page for West harima student :

Student

• Koharu Takeda

group assignment

• do your lab’s safety training
• test runout, alignment, fixturing, speeds, feeds, materials, and toolpaths for your machine

machine

• The Original Machine made by Fab Lab West-harima

• I use Digico-MILL48 Version 5 (100mm square steel frame version), is completely original machine, was produced from planning, designing, manufacturing to installation, with the founder of Fab Lab West-harima and his friends.

Digico-MILL48

machine	description
processable materials	Wood.Processable materials (Wood, Processable materials (Acrylic, Polycarbonate, PVC, etc), aluminum)
Work area	About 1300 mm(w) x 2500 mm (L) x 150 mm (H)
Feed rate	1-3000 mm/min
Spindle speed	max 18000 r/min

Keyboard operation of XYZ Axes

Tool Name

Operating Procedure

1 Switching control on and off

2 Homing (machine hardware origin setting)

• Since Homing is very slow, you can save time by manually moving it closer to the X-Y-Z- limit switches before pressing the Homing button.
• Pressing the Homing button will automatically detect and set the machine origin.

3 Mounting an end mill

• Select collet and attach

• Install end mill

  Note

  • Depending on the type of endmill, endmills should chuck more than 10 mm.
  • Length end mill after attached = “Material thickness + more than 5mm”

• Secure with wrench

4 User origin setting (set to the decimal point position set in the data)

！！！Always match the origin set in the data with the origin setting of the machine. Otherwise, a serious accident will occur.

• Move the tip of the end mill attached to the spindle to the XY position of the user origin

• Press ZeroX,ZeroY

5 Z origin setting (using probe)

• Probe installation

• Press the touch probe (button)

6 Confirmation of cut-out material range

• Make sure the area to be cut out is inside the board
• Also make sure the toolpath is free of nails, etc.

7 Set dust collector

• Set dust collector part on the spindle.

• Connect the cyclone parts and the hose to vacuum cleaner.

8 Importing Files

• Import and open G-code files saved on a PC
• File extensions that can be imported (for Mach4 settings in FabLab Nishi-Harima)
  • .nc
  • .tap
  • .txt

9 Start

In case of emergency, if machine action has any strange behavior, press the emergency stop button to stop.

Our Lab’s Safety Training

I had safety training at Fab Lab West-harima, and Fab Lab West-harima.

I learned that Large CNC Machining is a machine that can cause injury, blindness, death, and even fire due to mistakes. As safety measures, We learned to be aware of safety precautions, clothing, machinery, materials, emergency procedures, and many other items.

1.Safety Precautions at West Harima

• During Operation, do not enter within 1 m of the machine while it is in operation, as bits and materials may break and scatter during cutting.
• Never approach the cutting path during machining.
• Do not work alone when working Always work with at least two people in all processes, including material fixing and machine operation.
• Never operate the machine unattended. Operate under operator supervision at all times during operation and be ready to respond to emergencies.
• Understand that rotating tools are a fire hazard because of the friction and heat they generate. Also, be sure to take measures to extinguish flames.
• Know the location of the emergency stop switch. If any abnormality (unusual noise, unexpected behavior, etc.) is sensed during machine operation, immediately press the emergency stop switch to stop processing.
• Always turn off the main power to the machine when performing work that directly touches the machine, such as fixing materials, changing tools, or adjusting positions.
• Do not climb on machinery, materials or spoil boards to prevent falls
• Do not cut material without making sure the material is securely fastened to the work surface. Understand that there is always a risk of flying broken material.
• Check the condition of consumables and do not use consumables that are worn, warped or distorted. (end mill, spoil board, etc.) *To avoid damage and fire hazard
• Do not operate when tired or sleepy.
• Do not get the main unit or power supply part wet.
• Do not disconnect or insert cables while the power is on, as this may result in the destruction of the equipment. When unplugging or plugging in cables, be sure to do so with the power turned off.
• When an accident occurs, do not deal with a small group of people, stop the machine, and call for help.
• Confirm emergency contact information, etc., and promptly contact the relevant authorities in the event of an emergency. (fire department, emergency services, hospitals, etc.)

2.Work Clothing

• Wear protective equipment such as earplugs, dust masks, goggles, etc.
• Wear appropriate work clothes (e.g., JIS-compliant work clothes) and safety shoes.
• Wearing jewelry of a shape that can easily get caught in the rotating parts of the machine is prohibited.
• When there is a risk of the operator’s hands getting caught in the rotating parts of the machine, the wearing of gloves is prohibited.
• If you have long hair, tie it up and put it in a hat, etc. (to prevent it from getting caught)

3.Pre-operational check

• Check for visible abnormalities such as loose screws, scratches, etc. (Especially check Z-axis screw)
• Confirm that safety devices (sensors) are working properly
• Confirm that protective functions (emergency stop button, etc.) are working properly
• Check the machining path (machining route)
• Confirm that there are no fixed screws in the machining path (machining route).
• Check machining origin setting
• Check condition of consumables (end mills, spoil boards, etc.)
• Check endmill chuck tightness (If loosely tightened, it will fly off.)
• Check dust collector tightness (If loosely tightened, it will fly off.)
• Do not touch the endmill blade (remove dirt with a toothbrush, etc.)
• During processing, a large amount of sawdust is generated. Before processing, a dust collector should be connected and operated. Also, sawdust should be disposed of
• Check that the material is securely fastened to the work surface (if the workpiece is not securely attached, it may fly off during processing) alt text
• Check if the material is appropriate for processing by CNC (see below for appropriate materials)

4.Material conditions

• Materials that do not have or may not have embedded nails, screws, or other metal fragments
• Materials that do not contain moisture or humidity
• Material without warpage or warping
• Materials that can be safely fixed and processed with screws, clamps, etc.

5.the machining origin

• Pay attention to the machining origin, especially the origin of Z-axis. If it goes too far, it may penetrate to the CNC main unit.

6.Chip Load

• chip load (inches per minute): ~ 0.001-0.010” = (feed rate / Spindle Speed / number of flutes)

• chip load (mm per minute): 0.0254 - 0.254

• In case of Fablab West Harima

• Basically refer to tool datasheet
• recommend chip load (mm per minute)（0.05) (on the advice of the user’s fitter or chair craftsman)
• Depend on material, the chip load is different. Need experience.

7.Plunge Feedrate

• Plunge Feedrate is “Speed of Z descent”.
• In the event of an emergency, it is important to set the speed at which the emergency stop button can be pressed if there is an irregularity in the operation of the machine.
• In case of Fablab West Harima
• Plunge Feedrate：100mm/min -300mm/min

8.Cut Pitch (Cut Depth)

• In case of Fablab West Harima
• Basically refer to tool datasheet
• When using an end mill larger than 3 mm, Cutting Pitch (Cutting Depth) should be half the diameter of the end mill (1/2D).
• Strictly prohibit cutting at reckless depth of cut just because it takes time

Test

Measured the 12mm cardboard.(Measured value=12.5mm)

Using Kerf Check Parts Generator,enter the values you want to test (start-width,pitch,gap,number-of-kerfs,blade-diameter) and click and download the SVG file.

“Kerf Check Parts Generator” created and customized by the following two people.

Customize : by Atsufumi Suzuki / FabAcademy 2022(Kamakura)

Original : by Doyo Daisuke / FabAcademy 2018(Kamakura)

This time we use 12mm thick board. Then set the width from 12.5mm to 13.5mm.We made this svg data into a toolpath with Fusion360. Then started cutting.

End mill used: 8mm flat end mill

Machine cutting done.

Lots of sawdust remains. This is due to the fact that the cover of the dust collector, which my uncle made himself, is falling apart.

Cut the tabs with han saw.

Now test the best gap for building furniture etc.

This case 12.7mm gap seems the best.

Result
Actual thickness	12.5mm
Best fit size	12.7mm
Clearance	0.2mm

It is important to proceed with individual assignments based on this clearance.

Instructor informed that as this is made of wood, it easily changes the thickness flatness etc. due to humidity and temperature. Besides if we bought less expensive boards, the size probably varies. So the figures we got this week are not always right.