Hot Wire CNC Foam Cutter Frequently Asked Questions – FAQ

posted in: CNC, Hot Wire | 4

I get quite a few questions from users all over the world most asking very similar questions so I thought I’d post the  most common questions and my answers here

Connect/Disconnect and ReScan buttons missing

Some users have reported the “Connect/Disconnect and the ReScan” buttons are missing when they run the software. It seems to be caused by a screen resolution of 1366×768.  If you can change your screen resolution to 1920×1080.  If not, run the program in “Windows 8 Compatibility Mode”.  To do this open the properties of “Grbl HotWire Controller.exe” and on the “Compatibility Tab” select Windows 8.   You may also need to set the Taskbar to auto-hide. On my old Compaq Presario, I could just see the edge of the button until I did that. Afterwards, the two buttons were visible.

Can I use NEMA 17 steppers motors for the machine?

Yes Check my new build using 3d printer electronics here

Can I use 8mm lead screws

Instead of threaded rod. Yes, you can but the steps/mm will need recalibrating. There is a great resource here https://blog.prusaprinters.org/calculator/ . Where it has a calculator that you can enter your lead screw and motor specifications and it will give you the steps per mm. You still need to do a calibration to confirm the motor moves the correct distance. Check my video at this time code to see how it’s done https://youtu.be/CHbdUzbDYh8?t=692

Can I use the demo version of Mach3?

Yes, you can but it’s limited to 500 lines of g-code.  So for a very simple design, you may get all the coordinates in 500 lines.  What happens then is after 500 lines, it just stops. 

Can I use LinuxCNC (EMC2)

Yes, you can. Here’s how to install it and configure it.
For foam cutting, this is the link http://www.rckeith.co.uk/foam-wing-free-cnc-software.
For routing, this is link http://www.rckeith.co.uk/free-linuxcnc-openbuilds-ox-router/

The TB6560 controller board is it OK?

The TB6560 gets some bad press on some of the CNC forums but I’ve had no issues with mine.  I purchased it as a kit with the NEMA 23 stepper motors.  As you probably are aware these come from China and quality control can be an issue when things are built to a price.  I don’t use my CNC machine all the time, in fact, it’s built to be easily dismantled due to space restrictions.  I have used it on several occasions for most of the day and its performed perfectly.  One thing I would ensure is that your machine axis moves very easily.  The way I test this is without any power to try and turn each threaded rod by hand and it should not bind or feel tight.  I spent some time making sure the alignment of the steppers and threaded rods were very straight and true which makes sure the steppers are not stressed.

This kit is good value on Amazon and has everything you need for a parallel port build.

4-Axis-1-2N-Stepper-Motor-3-5A-Driver-TB6560-Nema23-USB-Interface-Board-CNC-Kit
TB6560 separate drivers

How much will it cost

My latest USB CNC Foam Cutter should cost around $200/£160/€180 check the details here https://www.rckeith.co.uk/how-to-build-a-usb-cnc-hot-wire-foam-cutter/

The biggest costs for me has been the software Mach3, DevWing Foam and Dev-Fus Foam. I’ve spent more on this than the build. There are free options that work well for simple designs but I highly recommend the software from DevCad. I would advise starting with the free options and as your needs and knowledge grows to invest in DevWing Foam and DevFus Foam

Here’s my post on the free options https://www.rckeith.co.uk/foam-wing-free-cnc-software/

My post on DevWing Foam is here with links to videos I’ve made as well

Here is a free g-code generator that will generate the g-code for you http://swarfer.co.za/rc/wire/index.php  Here’s my video showing how.  

What type of foam do I use

I use mainly XPS foam which is a pink colour and similar to blue foam.  I’ve also made wings with white polystyrene which is very easy to come by at most DIY stores.  I get my foam from Wicks in the UK their XPS is a bit thicker than other places I’ve found.

What type of hot wire do I use

I’ve tried several different types including MIG welding wire and guitar string but the best results I get are with very thin Ni-Chrome wire about 0.4mm.  It needs less power and the amount melted is very small which helps in calculating the kerf value.  This is used in the software to allow for the amount of foam melted away.  With the wire being very thin and you haven’t got the kerf value right it doesn’t make too much of an impact on your design

What speed and current do I use on the hotwire/ powering the wire

I set the speed at 2mm/s or 120mm/min and adjust the current for a 750mm length on white foam I set the current to around 2.2-2.3 Amps.

Can I use a laptop with Mach3

You can but it’s not supported by Mach3 and you probably not have a parallel port on yours, unless it’s an old one.   I believe its to do with power saving and it can interfere with step pluses.  My advice is to get an old desktop, I use Dell’s compact GX620 which has a small footprint and a parallel port.  You can buy an add-on card to go in a more modern desktop and that works.

Check my link here because if you use a special USB adapter or board then a laptop can be used http://www.rckeith.co.uk/mach3-parallel-port/

What other controller boards can I use

Check this page and it covers several options including USB http://www.rckeith.co.uk/mach3-parallel-port/

What software can I use to generate  g-code from my design

Check this page for the latest I update it as I become aware of any new software https://www.rckeith.co.uk/foam-wing-free-cnc-software/

4 Responses

  1. Jake giubbini

    Hey Keith,
    Can I use the lulzebot NEMA 17s for the usb Hotwire design?

    Specifications
    Step angle: 1.8°
    Holding torque: 55 N.cm
    Rated voltage: 2.8V
    2 phase
    Resistance per phase: 2.8,±10%
    Inductance per phase: 4.8,±20%
    Operation temp range: -20°C ~ +50°C
    Weight: 0.365Kg
    4 AWG22 lead wires (ends are bare and need connectors)
    5mm D-shaped motor shaft

    Thanks, Jake

    • Keith

      Hi Jake
      Yes, they should be OK. It’s mainly the current that needs to be considered for the RAMPS board and the drivers. It looks like you have 1.68A motors which I would use the DRV8255 as they can handle a bit more current. If you can see the actual model number on the motors and google them for the current rating.

      Keith

  2. Juan Cifre

    Hi Jake
    Thank you very much for such good software. I have used it on my Windows 10 computer without any problem.
    I have a Windows 7 laptop and when I run the program the com select menu disappeared as well as the connect button. Do you know why?
    Thank you very much for such an excellent job. A cordial greeting.

    • Keith

      Hi Juan
      Yes, it’s a common problem. Check you have the latest eBook which I update quite often and on Page 38 of Version 3.4 of the ebook it explains the fix. I’ve copied it here as well
      “Some users have reported the “Connect/Disconnect and the ReScan” buttons are missing when they run the software. It seems to be caused by a screen resolution of 1366×768. If you can change your screen resolution to 1920×1080. If not, run the program in “Windows 8 Compatibility Mode”. To do this open the properties of “Grbl HotWire Controller.exe” and on the Compatibility Tab select Windows 8. That usually works.”

      Hope that fixes for you
      Keith

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