2 GANTRY CNC HOTWIRE MACHINE

Only 1 of the 2 gantry's are pictured above.

Designed with affordability in mind, This is my second hotwire cnc machine. The first was designed for a commercial application and completed almost a year ago. It has been happily fulfilling the desired goal since.
Then I stumbled across a controller called the theremino master dil, that is very affordable and has it own cnc software. That gave me the idea to make an inexpensive machine with the knowledge that I had gained from my commercial build and some other commercial machines that I have seen.

My personal build has:

750 mm x 550 mm (29.5” x 21”) X&Y axis cut area.

Two individual gantry's can be attached or left unattached allowing for a wire length only limited by the power supply used to heat the wire. Both gantry's areindividually controlled allowing for tapered parts.

The X and Y movements are on c-beam rails. My machine uses custom plates, acme screws and acme nuts that I make. For simplicity reason I suggest that anyone building this stick to standard size c-beam bundle packs and chose your sizes, but recommend that the y beam not exceed 500mm.

Due to the nature of the hotwire machine melting the foam and not actually touching it, the only resistance the machine see's is its own inertia. Hence I'm using nema17 motors due to the low cost and availability of low cost drivers (specifically drv8825's).

The frontend cnc software is free. The controller is only $10 and and the board with the 8825's can be had for less >$15.

I will not be providing any hotwire power supply details. There are plenty of websites for this information, but personally I think there may be a liability issue here which is why I choose not to provide any details. Sorry.


Expectations and Limitations

The machine should be able to cut all sorts of airfoils and fuselages as well as many things only limited by your imagination. One limitation of hotwire cutting is that the wire is always in the foam, which means that unlike a router you can't traverse an already cut path or you'll slice your part in the process. I use Devfoam from Devcad.com for the tool pathing. It handles this limitation beautifully. He also has his own software that will drive the machine itself. For the frontend of the machine software I am using Theremino cad which is available free. I have been able to cut foam at 900mm per minute. That limitation is basically because any faster and the wire tends to drag. I could tweek the heat and feed rates to go faster, but have found this to be sufficient. I tried devfoam CNC from devcad.com and for a hot wire machine it works much nicer than theremino CAD. Expect a video of the machine actually cutting soon.

This video shows the machine moving being driven by a tablet. Towards the end you'll see me put my hand against the y c-beam and the whole machine slides as the nema 17s have plenty of power.



I completed the other gantry. The build is essentially done and it could be used at this point. The things I have left to do are, the limit switches, power for heating the wire, wire routing for the previous 2 things and an enclosure. The video below shows the machine cutting a 4 axis gcode path on an insignia tablet. I taped an orange string between the gantry's to simulate the hot wire.



The picture below is all the electronics to run the movement of the machine. They are very simple and inexpensive.