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4-axis cnc hot-wire foam cutter (arduino+ramps1.4)

by:Luteng CNC Parts     2020-09-18
A CNC Hot-
The wire cutter is a great tool when you make an airplane with foam.
It allows accurate cutting of any wing shape from CAD design.
A machine with the right configuration can save you a lot of energy and complete the work smoothly.
The machine laid a Nish Roman wire between the two towers.
The wire is heated by the current through it and moves relatively between the towers to determine the shape of the cut.
The 2D CAD design to be cropped becomes G-
The machine moves on four separate axes to produce complex profiles like a tapered wing.
The movement of each shaft can be achieved in any way, such as a linear bearing on a light slide bar or a drawer slider using various sizes.
Each shaft is driven by a stepping motor through a screw, and GT2 belts and pulleys can also be used according to the size of the machine.
The cutting force involved is very small, and the structure only needs to be rigid enough to withstand the tension of the wires stretched between the towers.
This is a real 4-
Being able to cut shaft machines of different shapes on both sides at the same time, then the problem becomes, how to control 4 independent axes at the same time.
Many tutorials focus on 3-
Axis machines like 3D printers, but building 4-
Shaft machines using easily accessible parts and open source software.
We found some people who did similar projects using Arduino and Grbl and decided to do a CNC hot wire knife on their own.
Depending on the design you choose, build logs and documents can be found on Github and you can replace parts with locally found ones.
For example, you can switch the steel pipe/light slide bar with the drawer slider, which can act as a straight-line shaft.
The core component is the Arduino MIGA, oblique month.
4. step Driver and Motor.
The rest of the machine can be made with any design and hardware.
Difficult part of making 4-
Axis CNC is looking for software to generate G-
Code and drive machines.
There are a lot of people using DevFoam and profilli to generate G-
Control their machines.
But unfortunately, the software is not free and most run on outdated hardware with parallel ports.
Our search results are based on Arduino 4-axis G-
Code interpreter developed by Marginally clever, using Arduino Mega 2560 and ramp 1. 4 CNC shield.
His page has code to move 4 independent axes and Javabased G-
Code sender that can send G-
Send code to Arduino using a serial port.
After some fiddling around, we let it work, which is not the easiest way to do it, with almost no documentation on how to use it.
RcKeith has some good documentation on the machines he makes and what he uses to control them.
Some of them use expensive software and outdated hardware.
We stumbled upon a post at rcgroups.
Com, it is for CNC foam cutting machine using Arduino and GRBL, from there we start making machine.
The design is made of 12mm plywood and the linear assembly is made of 1/2 steel pipes and plywood sliders.
The design of the sliding block can be improved by introducing linear bearings or sleeves to prevent direct contact.
Since we are using screws, it has enough torque to overcome the friction and still provides good resolution.
The two steel pipes provide support and constrain the guide block to one shaft.
The vertical tower is placed at the top of the horizontal guide block, which has four tubes to properly constrain the movement.
At least three are required to prevent the vertical tower from bending.
Connect the screws to the stepping motor using a flexible coupling.
This helps with any minor mistakes.
Alignment between the shaft and the screw.
The vertical tower has a stepping motor with integrated lead screw that can be purchased or replaced with a normal stepping motor and coupling.
The two towers are mirrors of each other, and space is provided in the base to clamp the machine onto the work table. Note-
When using a sliding surface, depending on the material, a phenomenon called \"sticking and sliding\" may occur.
This will cause the movement to become jagged and cause vibration.
When using a stepping motor, it can also cause the surface to lock, causing the load to be too large and missing the step.
The next step is to connect the electronics, move the motor and configure the machine.
We have 4 stepping motors that need to be connected to the ramp.
The wires need to be extended in order to provide sufficient shaft travel.
All the lines are connected to our ramp board, which is a CNC shield for the Arduino Lumia 2560.
The ramp can support up to 5 stepper motor drives such as a4988.
We use a 200-step micro-motor running at 1/16.
Give us a smooth rotation.
The A4988 step drive can be connected to the top of the ramp, one for each axis.
Make sure the A4988 chip is in the right direction before connecting to the ramp board.
Each step drive can pull up to 2 amps and the step drive has a radiator to dissipate heat.
There is also an 11 a MOSFET on the board to control the temperature of the wire connected to the D8 pin.
All parts on the board will heat up to ensure proper cooling is provided.
It is important that the stepping motor continues to drain current to maintain position when the system is powered on.
Components such as step drivers and mosfet will become very hot during operation.
Do not operate the ramp without active cooling.
We cut a base for Arduino and ramp laser and connected a 12 v DC fan to provide active cooling for the board.
Each CNC needs to be properly configured before operation.
Since we use stepping motors in open-loop systems (
No feedback)
We need to know how far the carriage will move with every spin of the stepping motor.
It depends on the number of steps per turn of the motor, the spacing of the screw and the level of microstep you are using. Steps _ per_mm = (
Motor_steps_per_rev * driver_microstep)
/Thread _ pitch we are using a step motor of 200 steps/turn, driving with A4988 driver on a 1/16-stage microstep with a drive spacing of 2mm. Steps _ per_mm = (200*16)
/2 = 1600 I use two-
Start one, so the value will be half of the ie above
If it\'s four-
Start one, then the value will be a quarter of the above value.
After flashing Mega 2560 with the Grbl8c2MegaRamps file, open the serial monitor and type \"$\" to access the Grbl settings panel.
To change any value type, $ number = value. Eg-
$0 = 100 once the machine is configured, make sure the machine moves the exact amount as shown in the controller.
In order to cut the foam, you need a resistor wire made of the right material, which can withstand heat and will have a uniform temperature in its length.
Nichrome is a suitable material and I have seen some people using steel fishing lines.
For more information, please read select Nichrome wire.
It is best to have the thinnest line possible to reduce the formation of the cut at the time of cutting and to provide a clean cutting line.
Generally speaking, the longer the wire, the greater the tension that must be applied, and the thicker the wire must be.
Experiments were conducted with various wire thicknesses from 32 ad hoc working groups to 28 ad hoc working groups.
The next step is to connect the nichrome wire to the machine because we have 4 separate shafts and we cannot tie both ends of the wire to the tower.
The wire needs to have some extension to the weight of the end by spring or by connecting to it with a pulley. Note-
Constant tension can be applied to the wire by using a flat spring (
Constant force Spring)
Or hang a heavy object at the end.
A cheap way to get a constant force spring is to use id to pull-up reels.
To get a high quality spring, you can even stack the spring in parallel to provide more tension.
We are using the Grbl control panel developed by Garret Visser, adapted by Daniel Rascio for hot wire cutting.
The panel has independent jogging control over all axes including homing.
There is also a Gcode graphics visualization tool that can save its own macros.
You can use the M3/M5 on/off and the S \"xxx\" command to control the hotline temperature, set the voltage output manually or by the scroll bar in the software.
The hotline should be connected to the \"11 A\" output and powered by a power supply connected to the \"11 A\" input on the ramp. Wing G-
Code generator is a program that generates xyuv g-
Code for wing model of wire-cut aircraft.
It runs on python 2.
It is also possible to integrate with the Axis interface of Linux CNC.
There is also an online version.
It allows you to enter parameters of the wing such as root string, pointed string, scan, gantry length, and even support flushing.
It has a database of wings. dat format.
New wings can be imported in the same way.
The software is easy to use and supports layering wings on the same piece of foam to save material.
Output G-
The code can be sent to the machine via the Grbl controller.
Jedicut is a cool software that can do both CAD/CAM and machine controller.
I think the machine controller needs a PC with an old parallel port interface.
It also has a plugin to generate G-code.
This is not the easiest to configure.
Some options and error messages are in French, but you can get it to work if you sit with it for a while.
It has a lot of features, such as the cutting Wizard, which can help you sweep the wing and compensate the seam by increasing the skin thickness.
It can cut more than the wing profile, just like lettering and other shapes. Note-Wing g-
Code generation G-
Code in absolute mode, working on Grbl, no problem but Jedicut generated G-
Code in incremental mode.
When we let it work for the first time, we had difficulties and the machine would move back and forth.
If this happens, please edit G-
Delete the code for unnecessary lines in the header. Both Wing G-
Code and Jedicut generate G-
The header contains some code that Grbl does not support code, and when such an error occurs, the controller will be displayed in the Monitor. Edit the G-
Remove unnecessary lines of code. Working G-
Include the code of two software, use them to test the controller.
Unlike conventional milling, the wire is cut by melting the surrounding plastic, and when the wire stays in one position for a period of time, the surrounding material is continuously melted.
This increases the incision of the cut and causes the size to be inaccurate.
There are two variables that affect the incision of the incision.
The cutting feed speed is the speed at which the wire passes through the material.
Expressed in mm/min.
The faster the speed, the smaller the cut, but the higher the required temperature, the tension in the wire must also be enough to withstand the cutting force.
Good starting speed is about 350/min to 500/min.
The temperature of the wire must be a little higher than the melting point of the foam you cut.
Ideally, when the wire is not actually in contact with the material, but is cut in front of the material, you just want to cut with radiant heat.
The temperature is determined by the electrical flow through the wire, and the electrical flow is determined by the applied voltage.
There is software that allows the PWM control of the wire to be heated at the appropriate time to optimize the cutting feed rate.
The temperature of the wire is determined by the square of the current multiplied by the resistance.
If you are using Nichrome wire, The Nichrome wire app calculator is a cool app that helps you determine the temperature of the wire based on the length and the voltage applied.
For the setting with a line length of 850mm, we applied a voltage of 26 V and cut at a feed rate of 350/min.
This process starts with the design and it is exported as DXF.
Then import the file into CAM software and G-code.
The machine is turned on and calibrated, the material is placed on the workbench and the origin is now set.
Heat on-Wire, run G-
Code file, watch the machine do the work for you.
I hope you like Instructure, you try it yourself, the machine is easy to make and tolerant.
There are many amazing things you can do with it. Happy Flying!
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