Computer-Controlled Machining

Group assignment requirements

The group assignment for this week is the following:
- Complete your lab’s safety training
- Test runout, alignment, fixturing, speeds, feeds, materials and toolpaths for your machine
- Document your work to the group work page and reflect on your individual page what you learned

Large format CNC router machine specs

CNC Machine Overview

The CNC machine we used is the ShopBot PRS5 Standard, celebrated for its versatility and efficiency. It offers an excellent combination of speed, precision, and a generously sized cutting area, making it ideal for various applications, including furniture crafting, signage production, and prototyping.

The machine is equipped with VCarve Pro design software but is also compatible with other CAD/CAM programs, providing flexibility for diverse design and manufacturing requirements. Its ability to adjust critical parameters such as spindle speed, feed rate, and cutting depth ensures consistently accurate and high-quality cutting results..

Available Features and Key Settings

• Machine Name: ShopBot PRS5 Standard
• Spindle Maximum Speed: 18,000 RPM
• Machine Bed Size (Work Area): 96” x 48” (2438mm x 1219mm)
• Toolpath Generation Software Used: VCarve Pro (included with purchase)

Additional specifications and features:

• Maximum Cutting Speed: 720 inches per minute (18,288 mm/min)
• Maximum Rapid Speed: 1,800 inches per minute (45,720 mm/min)
• Z-axis Travel: 8” (200mm)
• Positional Resolution: 0.0006” (0.015mm)
• Closed-loop stepper motor system with 7.2:1 gearboxes
• Rack and pinion drive system on all axes
• ER25 collet system (includes 1/4” and 1/2” collets)
• Control software: ShopBot Control Software (proprietary)
• Compatible with various CAD/CAM software including Fusion 360

Safety

1. Personal Protective Equipment (PPE): Always wear safety goggles, safety shoes, and ear protection to protect yourself from flying debris and noise.

2. Clothing and Hair Safety:

Avoid wearing skirts, wide-leg pants, or wide-sleeve shirts and ensure long sleeves are rolled up or wear a lab coat without loose clothing that could get caught in the machine.

Cover your hair or tie it up to prevent it from being pulled into the machine.

1. Machine Inspection: Before operation, check the machine for any visible issues, ensure all parts are secure, and verify that the cutting tool is properly installed.

2. Emergency Stop: Familiarize yourself with the location and operation of the emergency stop button in case of an emergency.

3. Clear Work Area: Keep the work area clean and free of obstructions. Ensure no one is standing too close to the machine while it is in operation.

4. Proper Setup: Make sure the material is properly secured to the machine bed before starting the cutting process.

5. Supervision: Never operate the machine without proper training and, if needed, supervision.

6. Dust and Debris Control: Ensure that dust collection systems are properly set up and functioning to minimize airborne particles.

7. No Distractions: Avoid distractions and always stay focused while the machine is in operation.

8. Power Down After Use: Always turn off the machine and disconnect power when maintenance or adjustments are required.

Materials

At the lab we use the machine to cut different materials such as:
- [Material] up to a thickness of [thickness] mm.
- [Material] up to a thickness of [thickness] mm.
- [Material] up to a thickness of [thickness] mm.
- [Material] up to a thickness of [thickness] mm.

For this assignment and this week we will be using [material] with a thickness of [thickness]mm. All the testing is done on this material.

Fixturing and machine setup

describe the process of fixing the material on the machine. What do you use? nails? special fixing tools? show what you use and explain why and how you use it and where to install it.

After making sure the material is securely in place, we continue the machine setup process.

Describe the process of setting up the machine after fixing the material. Show the process of replacing the bit & zeroing the axis including the Z axis.

Toolpath generation

Describe and showcase the steps needed to generate toolpath for your machine. Generate a cut/engrave toolpath for ~6 squares with different feeds and rates and showcase the steps taken to generate the toolpath. Do NOT go too far above or below your lab’s pre-determined speed and feed as that can be a safety hazard

Speeds, feeds

To find the best speeds and feeds for the material being used, we tested multiple speeds and feeds for cutting and engraving to see which gave us the best results.

write on each piece the speed/feed setting used

By completing this test, we found that for cutting [material], with a thickness of [thickness]mm, using a [diameter]mm bit, the best settings are the following:

Feed rate:
Spindle speed:
Plunge rate: Pass depth:

Runout & Alignment

Runout is the deviation in the tool/spindle from it’s true circular rotation. Where it will no longer rotate on its intended axis. This can be measured with a dial test indicator.

Axis alignment ensuring that the machine’s axes (X, Y, and Z) are properly aligned and in parallel with each other. Misalignment can result in inaccuracies, poor surface finish, and other issues in the machined parts.

cut a ~large square on the machine

To test this, we cut a simple square and measured the square at multiple ends. If the machine has perfect alignment, the square should be the same dimension if measured from any side. We measured the square from multiple areas and found the difference to be [measurement]mm.

reflect on if this is a good result or not.

Sources

Source 1
Source 2
Source 3
Source 4

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Last update: January 27, 2025