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| This goal is still a while away for now, but as always, we are full of Ideas and this is a convenient place to put them. | | This goal is still a while away for now, but as always, we are full of Ideas and this is a convenient place to put them. |
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| == CNC plasma cutter based on VSL X-Z table ==
| | <gallery> |
| [[File:X-Z_traverseerunit_front.jpg|thumb|left|250px|X-Z traversing unit before any modifications]]
| | File:X-Z_traverseerunit_front.jpg|X-Z traversing unit before any modifications |
| | File:X-Z_traverseerunit_stuurelektronika.jpg|Current control electronics with DC-motor controllers and Mitsubishi PLC |
| | </gallery> |
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| |
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| === The working mechanics === | | == System set-up == |
| | We're basing this project on an old X-Z traversing unit originally made for measuring air velocity distributions in wind tunnels at a metrology institute. The current motor controllers, however, seem to be made for a fixed speed and it's probably easiest to replace the electronics altogether. |
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| Once upon a time, three consecutive interns at VSL made a X-Z traversing unit to automatically measure wind speed velocity distribution of one of VSL's primary standars. This traversing unit was put out of use over half a decade ago, and was finally put on the scrap metal list. If it wasn't for a hackers intervention, it would have been there by now. Luckily it can now have a second life in the spark shack.
| | A Z-axis seems required to control the torch height. It won't need to move very far, quickly or precisely, though. |
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| The X-Z traversing units has a DC motor for each direction of travel. These motors are coupled to a gearbox and a rotary encoder. A toothed belt then transfers the rotational motion into a linear motion.
| | == To-do list == |
| | | # Decide how to control the machine. There seem to be two basic options: GRBL and LinuxCNC |
| === Hardware that works === | | # Design and build interface/driver hardware for motors and encoders |
| [[File:X-Z_traverseerunit_stuurelektronika.jpg|thumb|right|250px|Control electronics with DC-motor controllers and Mitsubishi PLC]]
| | # Set up a PC that can withstand the general environment of the SparkShack (EMI, humidity, temperature) |
| | | # Get basic motion control working so that the machine moves |
| *The motors move the X and Z axis when operated by the joystick controller.
| | # Design and build interface hardware for the plasma torch, so it can be turned on and off. Will probably want voltage sensing for torch height control. |
| *The X and Z directions have smooth movement over an approximate 1 x 1 m range
| | # Add a third axis to the machine for torch height control |
| *Speed is adjustable by means of knobs inside the contol cabinet.
| | # Put everything together -- implement the software side of things for torch height control and reading e.g. SVG files |
| *The two motorcontollers work [[http://www.alpatek.com/file.html?id=419]]
| |
| | |
| === Hardware that needs to be sorted ===
| |
| *The onboard RS-232 PLC (Mitsubishi something or other) may or may not work. If it still works, we need a way to program it. Possibly it's easiest to take out the PLC and put an Arduino or Rpi in there instead
| |
| *Interface with the plasma cutter (relay, some cable and a plug to match the plug that's already on there)
| |
| *mounting for the plasma cutter head
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| *some rig to reliably hold the sheets of steel vertical (very important for thin sheets that may bulge or buckle otherwise)
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| *a PC that will survive the Spark Shack
| |
| | |
| | |
| === Software that needs to be sorted ===
| |
| *Program for the hardware controller
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| **Motion control
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| **Speed control
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| **Plasma cutter on/off
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| **position feedback
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| **...
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| *CNC software to draw/cut
| |
| **Perhaps use the software from the laser cutter?
| |
| | |
| == Original Ideas (before 2013) ==
| |
| | |
| | |
| === Specs ===
| |
| * 3x3 m working area
| |
| * movement speed of 1000mm/s
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| * Calibrated accuracy and precision of +/- 0.1mm
| |
| | |
| === Axis motors ===
| |
| [[User:Smeding|smeding]] is going to design and build a proof of concept linear (synchronous) motor for use in the X- and Y-axes. This test rig will be used to determine whether a DIY LSM is at all useful for our application and to finalize the design if we choose to go with the concept. Specifically, this involves figuring out:
| |
| * How the attainable accuracy compares to the wanted specifications
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| * How the attainable movement speed compares to the wanted specifications
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| * A final design for the drive electronics
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| * Coil and armature geometries
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| * Rail geometries (magnet size, spacing and orientation pattern and any backing)
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| * Optimal control schemes
| |
| | |
| After this, we'll be ready to construct the three rails (2x X and 1x Y) that make up the bulk of the CNC machine.
| |
| | |
| ==== prototype BOM ====
| |
| * angle extrusion, probably aluminium for the prototype
| |
| * skate bearings (we already have some)
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| * magnets
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| * copper wire (we already have some)
| |
| * electronics:
| |
| ** Microcontroller ([[http://www.dickbest.nl/index.php?_a=viewProd&productId=8128|AT90PWM3B]]?)
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| ** MOSFET drivers (half-bridge or BLDC)
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| ** MOSFETs (N-channel, high current)
| |
| | |
| == Some rough ideas by Yotson ==
| |
| | |
| *1.5 x 3.0 Meter max. material size. Spec of plasma cutter mentions 12mm as max thickness.
| |
| Table should manage to hold the weight of a 1.5m x 3.0m x 20?mm sheet of steel.
| |
| | |
| *weight of plasma nozzle + hoses/wires?
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| | |
| *length of nozzle + hoses/wires?
| |
| | |
| *speed of nozzle over material > 10 cm per second. (non cutting)
| |
| | |
| *nozzle placement accuracy: < 1mm
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| | |
| *transportable. Able to fit through 'standard' door (on its side, obviously)
| |
| | |
| *Maybe:
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| 'upgradeable' by placing rotary cutting tool, pencil, knife, spray can, .... ???
| |
| | |
| ---------------------------------------------------
| |
| | |
| Transport axes:
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| x, y:
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| angle iron and skate wheels + bearings?
| |
| | |
| | |
| linear motors?
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| threaded rod, DC motors, encoders?
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| | |
| z :
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| ? + threaded bolt, manual adjustment between height of 0mm and 50mm.
| |
| | |
| | |
| ---------------------------------------------------
| |
|
| |
| == Threaded rod info ==
| |
| ISO standard. From HTTP://en.wikipedia.org/wiki/ISO_metric_screw_thread
| |
| {| class="wikitable"
| |
| |-
| |
| !scope="col" | Diameter in mm.
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| !scope="col" | Pitch (fine)
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| !scope="col" | Pitch (coarse)
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| !scope="col" | Rotational speed 10 cm/s lin. motion (coarse)
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| !scope="col" | Rotational speed 10 cm/s lin. motion (fine)
| |
| |-
| |
| |20 or 22||2.5||1.5 or||40rps, 2400rpm||50rps, 3000rpm
| |
| |-
| |
| || || ||2 || ||66.7rps, 4000rpm
| |
| |-
| |
| |30 or 33||3.5||2||28.6rps, 1714rpm||66.7rps, 4000rpm
| |
| |}
| |
| Project CNC plasma cutter
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| Status
|
Initializing
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| Contact
|
[[Project Contact::Walter, Smeding, Gori, Yotson, Semafoor]]
|
| Last Update
|
2014-12-21
|
After acquiring a plasma cutter at the space, it seemed only logical to try and fabricate a CNC version eventually.
This goal is still a while away for now, but as always, we are full of Ideas and this is a convenient place to put them.
System set-up
We're basing this project on an old X-Z traversing unit originally made for measuring air velocity distributions in wind tunnels at a metrology institute. The current motor controllers, however, seem to be made for a fixed speed and it's probably easiest to replace the electronics altogether.
A Z-axis seems required to control the torch height. It won't need to move very far, quickly or precisely, though.
To-do list
- Decide how to control the machine. There seem to be two basic options: GRBL and LinuxCNC
- Design and build interface/driver hardware for motors and encoders
- Set up a PC that can withstand the general environment of the SparkShack (EMI, humidity, temperature)
- Get basic motion control working so that the machine moves
- Design and build interface hardware for the plasma torch, so it can be turned on and off. Will probably want voltage sensing for torch height control.
- Add a third axis to the machine for torch height control
- Put everything together -- implement the software side of things for torch height control and reading e.g. SVG files
X-Z traversing unit before any modifications
Current control electronics with DC-motor controllers and Mitsubishi PLC
