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equipment:cnc_mill [2020/04/25 22:17]
alexrowe
equipment:cnc_mill [2020/05/31 20:25] (current)
alexrowe coolant section
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 <callout title="​Induction Required"​ type="​warning"​ icon="​true">​ This equipment requires an induction prior to use. For your own safety and to avoid damage to the equipment do not attempt to use it until you have been inducted. </​callout>​ <callout title="​Induction Required"​ type="​warning"​ icon="​true">​ This equipment requires an induction prior to use. For your own safety and to avoid damage to the equipment do not attempt to use it until you have been inducted. </​callout>​
  
 +<callout title="​Loud Equipment"​ type="​warning"​ icon="​true">​ This equipment is extremely loud. Ensure that you and those in the room are wearing ear defenders. Hearing damage is permanent and debilitating. </​callout>​
 ====How do CNC machines work?==== ====How do CNC machines work?====
-The following videos give a much better explanation than this author can+  * The following videos give a much better explanation than this author can
   * Where Mach3 is mentioned, we use bCNC   * Where Mach3 is mentioned, we use bCNC
-  * [[https://​youtu.be/​YBGqknN3gGs|CNC Basics 1]] + 
-  * [[https://​youtu.be/​J4bMAIEFCYU|CNC Basics 2]]+{{youtube>​YBGqknN3gGs?​medium}}{{youtube>​J4bMAIEFCYU?medium}}
  
 ====What is it?==== ====What is it?====
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   * It can cut many things:   * It can cut many things:
     * Tested:     * Tested:
-      * Aluminium, carefully+      * Aluminium 
 +        * lubrication is critical 
 +      * Titanium 
 +        * the hackspace logo on the door was machined from titanium 
 +        * lubrication is critical 
 +        * slow cuts can cause work hardening
       * Steel - a small experiment has been carried out, more attempts needed       * Steel - a small experiment has been carried out, more attempts needed
       * Wood, quite easily       * Wood, quite easily
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       * Plastics       * Plastics
       * Carbon composites       * Carbon composites
-      * Titanium?! - approach with extreme trepidation 
       * Human Fingers       * Human Fingers
  
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     * Hold the button to unlock the door     * Hold the button to unlock the door
     * This only works when the machine has power     * This only works when the machine has power
-    * There is an intention to interlock this to the spindle motor, but this hasn't happened yet+    * The spindle motor is interlocked ​to the cover - it will not turn when the cover is open. The cover 
   * Other buttons   * Other buttons
     * They do nothing     * They do nothing
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   * Metal chips can scratch your eyes   * Metal chips can scratch your eyes
     * They will likely get stuck to the door and then fall on you when you open it. Watch out for this!     * They will likely get stuck to the door and then fall on you when you open it. Watch out for this!
 +  * If you tell the machine to move, it will move, regardless of whether your fingers are in the way
 +  * The compressor is extremely loud, and will probably start as soon as you power the machine on
 +    * warn others in the room, so they can use hearing protection
 ====How do I make something with it?==== ====How do I make something with it?====
   * Have you watched the videos linked further up the page?   * Have you watched the videos linked further up the page?
     * watch them     * watch them
-  * design your part in CAD software +  * design your part in Fusion 360 - or CAD software ​of your choice 
-  * use CAM (computer-aided manufacture) software to create the g code (.nc file)+  * use CAM (computer-aided manufacture) software to create the g code (.nc file) - ideally use Fusion 360 for this as well
   * transfer this to the CNC mill computer   * transfer this to the CNC mill computer
   * on the desktop, press "run bCNC"   * on the desktop, press "run bCNC"
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     * grumble to yourself and others     * grumble to yourself and others
     * try again     * try again
 +====Feeds & Speeds====
 +{{:​equipment:​20191129_173024.jpg?​400|}}
 +
 +The result of poor Feed/Speed selection!
 +
 +  * Feerate: How fast the spindle is moved accross the workpiece (mm/min)
 +  * Speed: How fast the spindle turns (RPM)
 +  * The combination of these factors, along with the cut depth determines the forces on the tool
 +  * The free mobile app FSWizard is very useful for selecting the right speed/feeds in an intuitive manner. https://​app.fswizard.com/ ​
 +  * Because of the cheap spindle motor driver, the mill has very low power below 10'000 RPM. Therefore, it is better to use smaller tools, which use higher spindle speeds.
 +  * Maximum spindle speed: 24'000 RPM
 +
 +====What is a collet?====
 +{{:​equipment:​single-er-11-collet-6-00-5-50mm-swiss-quality-116523-en-g.jpg?​400|What a lovely collet}} {{:​equipment:​20200530_121457.jpg?​400|Drawer full of collets, nicely lined up}}
 +
 +  * A collet holds the tool nicely in the spindle
 +  * Select the correct one for the diameter of the tool shaft
 +  * Ensure it clicks fully into the holder on the spindle
 +  * Insert the tool
 +  * Tighten the holder onto the spindle using the big spanners
 +
 +{{:​equipment:​20200530_121543.jpg?​400|Oh dear, not properly inserted}} {{:​equipment:​20200530_121555.jpg?​400|Nicely seated}} {{:​equipment:​20200530_121510.jpg?​400|The collet goes in the black part}} {{:​equipment:​20200530_121618.jpg?​400|Big Ol' Spanners}}
 +
 +====Lubrication/​Coolant====
 +{{:​equipment:​20200530_105004.jpg?​400|Spindle and Mist cooler}}
 +  * Compressed air is used to spray a fine mist of cutting oil on to the material to be cut. 
 +    * This is known as Mist coolant
 +    * For some reason, the control board thinks it is controlling a flood coolant system (where lots of liquid is dumped onto the part, like on our lathe)
 +    * Therefore, we must go along with this fiction, by telling Fusion 360/bCNC to turn on/off flood coolant, when we need the mist to operate
 +  * Some materials (Aluminium, Titanium) absolutely require lubrication,​ as they try to stick to the cutting tool
 +  * Other materials, e.g. wood, do not require it. However, the air blast will help to avoid chip recutting
 +
 +{{:​equipment:​20200530_104947.jpg?​400|Coolant Controls}}
 +  * These two screws control Air and Oil flow
 +  * If lubrication is required, it is desirable to use as little as possible
 +    * Using more than necessary probably won't improve the cut, but it will make a mess, and increase the risk of inhalation ​
 +  * There is also an adjustment knob on the air compressor
 +    * LEAVE THIS AT OR BELOW 1
 +    * Experiments showed that turning this any higher resulted in the compressor overheating and seizing ​
 +
 +Interesting and nerdy article on coolant strategies https://​www.cnccookbook.com/​cnc-coolant-system-mist-high-pressure-through-spindle/ ​
  
 ====What is the build volume?==== ====What is the build volume?====
  • equipment/cnc_mill.1587849439
  • Last modified: 6 weeks ago
  • by alexrowe