CNC Hotwire 4 axis foam cutter

**mitchejc** · 15-06-2015

Sorry can't help you with any info on the 4 axis hot wire but Silyavski may have a point depending on what you want to do. If you need to cut a lot of wing profiles rapidly the hot wire is obviously the way to go but if time is on your side then simple 3 axis milling is not such a bad idea as it gives you a lot of options that hot wire can't do. A relatively flimsy but fast 3 axis router dedicated to foam cutting should be easy to build.

Had to dig around to find the model but several years back I did cut a few gliders for a friend on my router. He asked me to cut two wing profiles and I suggested we cut the whole aircraft in one go. The entire model including the fuselage was cut from one big piece of foam with a two sided strategy excluding the wing tips which were glued on afterwards. The screenshots below shows the model I drew using his wing profile. I know sh%t about aerodynamics so I just went with a sort of a teardrop shaped thing for the fuselage so he's got somewhere to put the battery and receiver:-) The white round bits you see on the wings are just supports used when I turned it over to cut the bottom profile. The piece of foam was bigger than the model so it was supported at the wingtips as well.

Don't think I have any pics of the actual cut models but apparently they flew very nicely :-)

**Skipsoaring** · 15-06-2015

Nice work on the glider Mitchejc. I agree that a router would be much more versatile and I will be making one to go along with the hotwire. One of the crucial things with supplying wing cores for people to finish is to also supply the beds. A router cuts the beds into little bits that are really hard to put back together ;-)
I'm aiming to produce 3 types of glider from foam as kits and hopefully the funds from them will help me to make my 'aluminium capable' router for making parts and moulds for composite gliders.
Prototypes for the composite gliders will be routed as you suggested above, especially the fuselages.

**Skipsoaring** · 16-06-2015

Originally Posted by jregholdsworth

I've built both if you call and eshapeoko strong enough to cut ali ..so if you do need any advice pleased to give it..and I just live down the road in Chestow.. Ok its the M4 ..I've programmed my own arduino based hotwire controller which is compatible with mach3 and GMFC, which I'd be glad to share and I've tried quite a lot of the software out there such as Mach3, and most of the devcad stuff including profili

Thanks mate, I'd be glad to get some help, especially with the program bits.
Clayt.

**Skipsoaring** · 17-06-2015

Thanks for that. Some rene on its way. Power supply is going to take some thought. It will need to be adjustable as the foam types and sizes will differ regularly.
Design of the machine is coming along slowly (the drawing is the slow bit, the design is evolving in my head)

**Skipsoaring** · 18-06-2015

Arduino sounds pretty useful, but I think it might be one too many things to learn from scratch for this project. I'll see how expensive an appropriate power supply and heat controller are and then decide if I need to take the Arduino learning route.
Thanks again

**njhussey** · 18-06-2015

I'll be following this with interest as I want to build a cnc hot wire cutter to make my own wings...

**Skipsoaring** · 22-06-2015

I've been playing with fusion360 and have come up with a bit of a design.
I've designed it so that when I'm not cutting cores I can utilise a flat surface for other projects so have gone a bit over the top with regards to the structure.

The idea is that the runners are interchangeable on the supported rails to enable some flexibility in the length of the cutting wire and it will be tensioned with a weight over a pulley.
The vertical axis will have a little bit of lateral force applied to them as the bases move independently. To deal with this, I am aiming to use hiwin rails for the vertical block.
There is hardly any force required to pass the wire through the foam, so I am planning on running belts and pulleys to control the axes (as per printer).
My drawing isn't very good and doesn't allow me to change and modify things (still learning CAD on the fly) but I am also aiming to do some epoxy levelling to the frame before mounting the rails and plates.
The way it is drawn at the moment gives a max effective cutting area of 2100mm long x 550 wide x 170mm high.
Just looked at the clock and I am about to be late for work! Gotta go! Sorry if it's a bit disjointed (The post) hopefully you get a little bit of an idea about my project.