How to build your own Hot Wire CNC foam cutter. Firstly if you’re not sure what a hot wire cnc foam cutter is, then let me explain. Most types of foam can be cut with a hot wire and if you can control the wire accurately then you can make wings and fuselages for RC airplanes and many other things e.g. signs. Its possible to do without a CNC (Computer Numerical Control) machine just by guiding a hot wire over templates. This method is less expensive and is a good place to start on the hot wire cnc foam cutter journey. You’ll get good experience of working with a hot wire. My Super VC10 wings were made this way before I had my machine.

Is it difficult to build ?

No. If you are reasonably practical and maybe RC modeller then you have all the skills you need. Don’t be put off by the electronics. It can look quite daunting but if you follow my articles on the website or download the eBook you have all the information you need. If you do need help reach out to me via the contact page and I’ll get back to you with some suggestions. I get quite a lot of questions from all over the world asking for advice and recommendations on parts to buy. I’ve provided links to all the parts I’ve used and some other that I’ve researched.

Why build one?

  • When I built my Vickers Super VC10 airliner I’ve had to make many templates for wings and tail plane.  The first couple aren’t so bad  but after a while it gets a bit tedious. A CNC cutter would eliminate this.
  • I  visited Mike Black of Green Air Designs  to see his VC10 and had a very pleasant time. Mike showed me his laser cutter working and showed me his other machines.  That inspired me to build a hot wire CNC
  • It’s really quite easy to do and a quick search on the internet shows up many DIY CNC machines, most tend to be routers and 3D printers (I’ve got them as well, the CNC bug bit me)
  • I’m always been fascinated by CNC but never thought it would be possible on a small budget but thanks to the Chinese and the affordable CNC kits its quite easy.

After a lot of research and some real good advice from CNC forums ( http://www.mycncuk.com/ and http://www.cnczone.com/) I decided on building this version. Full details on this page http://www.rckeith.co.uk/cnc-detailed-build-and-plans/

hot wire cnc assembled

 

How much does it cost to build a Hot Wire CNC Foam Cutter

Probably not as much as you think. My 4 axis CNC kit came from a company called Sunwin in China which included the stepper motors and the controller board and a few cables. These range from about £170-200. The power supply I made from two old computer PSU and the rest came from Local DIY stores. See the build page for a full list with links. I’ve spent more money on software than the rest of the build, but there are some free alternatives, again on the build page

Parts required to build a Hot Wire CNC Foam Cutter

  • Stepper Motors – these drive the towers where the hot wire is attached
  • Control Board  4 axis – sends signals to the stepper motors to move a certain amount and in which direction.  Receives inputs from limit switches and pendants
  • Computer – drives the control board.  It receives g-code and turns that into signals for the control board.
  • Lead Screw – connected to the stepper motors and then the towers to move them in the desired direction,
  • Software – I use Mach3 which turns the g-code into signal that the controll board and stepper motors can use.  I use Profili2 Pro and DevFus Foam to generate the g-code from the design.
  • Drawer Slides – used to provide vertical and horizontal movements for the two towers
  • Power Supply 24V – this powers the control board and the stepper motors

 

I’ve decided to use threaded rod for the lead screws, because the accuracy required for hot wire foam cutting is not as much say for a CNC router with wooden or metal parts.

I used 2 PC ATX Power supply in series to give 24 Volts. This can be a little dangerous if you not careful to isolate the second PSU, so I’d recommend  purchasing one specially designed to give 24 Volts. These are now quite cheap and take up up less space

The X-axis use a captive T-nut the one with spikes on that bites into the wood. The Y-axis uses a small aluminium block which I drilled and tapped the threads into. I’ve turned the ends of the threaded rod to match the size of the stepper motor spindles and used rubber hose with two hose clips. Seems surprising solid and give a little bit of flex. Update – worked OK for a while but dropped of so I replaced them with couplers. See the details page

 

cnc_axis

 

Build was finished see pictures and video below. Tested and it works. I used RJ45 cables and sockets to connect motors to controller. This allows easy dismantle when not in use, my space is limited . It’s been wired so each motor wire uses 1 pair of the RG45 cable to allow for higher current.

CNC Hot Wire Cutter Software

I’ve used a old Dell computer running XP and no other unnecessary software installed. You need a PC with a parallel printer port usually known as LPT1.  There are other options now for USB and Ethernet(LAN) connections check my post here http://www.rckeith.co.uk/mach3-parallel-port/

To control the CNC machine you need some software and after much research I decided to go with Mach3 from ArtSoft http://www.machsupport.com/ its very well supported and there are several videos on YouTube that describe how to install and configure. There is a free version that allows 500 lines of g-code to run.

G-code is the instructions sent to the machine that tells it how far and what direction to move he stepper motors. You don’t need to learn g-code as there is software to convert drawings into the code. I’ve tried a couple FoamWorks and Profili2 Pro and have settled on Profili2 Pro which does a lot more than generate g-code for wing profiles.

Here is a free g-code generator that will generate the code for you http://swarfer.co.za/rc/wire/index.php I’ve not actually used it on my machine but should be enough to get you going for simple wings.

Another free one is JediCut which I haven’t tried yet seem to have good support https://www.jedicut.com/en/

This one cost a few dollars but I haven’t used it. NCGen http://www.foamcasualty.com/products/ncgen-2 Its a plugin for Sketchup http://www.sketchup.com/ . Skeckup is very good and the plans I’ve drawings on the build page were all produced with Sketchup

The Hot Wire

The wire between the 2 towers is tension-ed by a spring so they can move independently for tapered wings. The wire is usually ni-chrome but several other can be used including guitar strings. I’ve powered my wire with the iCharger 206 which has a foam cut program but I have used a car battery charger connected to a house dimmer switch for manual cutting. This allows control of the heat and works very well.

It works

Its quite exciting when you get it all powered up and move the cursors keys and see stepper motors spinning. The video show a small test aerofoil which was about the 5th attempt. The hot wire cuts my radiance so its basically melting the foam in front of it. My first pieces were not very good as the feed was too slow but as you can see it didn’t come out too bad when I got the cut the feed right

Below is the flying wing which was the first model plane I made with the CNC machine. This was just a quick test as a proof of concept and its proved to be the model I fly most now. Its flies really well and is fast. Profili2 Pro http://www.profili2.com/ is very good for generating the code and has a massive database of aerofoils.

Hope you found this of interest and if you need any advice or help then you can contact me through this website.

I’ve included the configuration for Mach3 with the TB6560 controller board on this page Mach3 TB6560 configuration

First airplane made with the Hot Wire CNC foam cutter

This is the flying wing I made first with this CNC machine and its a little gem. I now fly this most weekends. It goes really fast with a 2200 KV motor and a 6×4 prop. Its a blast. If you want to build it then check http://www.rckeith.co.uk/hot-wire-cnc-ymf-38-flying-wing/ I’ve included the gcode for each wing as well.

 

 

Hot Wire CNC flying wing
Hot Wire CNC flying wing

 

 

I’ve now made a Hawker Hurricane with the CNC machine both wing and fuselage, you can see it here http://www.rckeith.co.uk/cnc-hot-wire-hawker-hurricane/

I’ve also made a much bigger wing for FPV(First Person View) with it as well details here http://www.rckeith.co.uk/fpvfw/

The CNC machine is now starting to pay for itself as I don’t buy many ARTF models very much  now, nothing against them but I just enjoy researching and making my own RC Models much more.

Updates I would make to the Hot Wire CNC foam cutter

After making several models and getting through a lot of foam if I were to build this again what would I do now.

The actual machine the only change I’ve made has been the couplers to the stepper motors. The rubber hoses occasionally came off which ruined some foam so I purchased some proper couplers and these have been very reliable. Details on the build page.

I would now probably use a usb controller like the ones I’ve listed  Here as alternatives and a purpose built power supply. This would allow me to use a laptop as well. My machine takes a lot of space when running. The TB6560 has been very reliable and never missed a step.

2 Responses

  1. Rafael Moreno

    Hi keith my name is Rafael Moreno,

    thak you sooo much for sharing your design,i built a cnc foam machine many years ago,unfortunately i never got to use it because i never could figure out the programing on it,years went by and i got divorced loosing all of my assets including that machine,anyway you don’t need to know all this,i just want to say that you seem like a strait up guy and i really like that you took the time to post your design for others to appreciate and build,

    I have a better idea for a cnc foam cutter but no plans,my idea is based in the foamlinx design,in case you have not seen their design you can go to their website
    Foamlinx.com anyway i hope you’re still in the hobby and hope your machine is still working

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