Foam XL hot wire cutter

[Boyan Silyavski]

Hi, after adding some hot wire attachment to my main machine wich showed excellent results cutting 1200x600x50 foam sheets, i decided to build something bigger. And better.

At the moment i use DEVFoam LE to generate the paths and i believe this is the best program at the moment. Yep, tried them all before i purchased this one. Its worth every cent.

Basically i would like to be able to cut 1200x2300 foam blocks 10-1000mm thick. After considering this and that, i decided to purchase another application DevCNC Foam and drive the contraption using Arduino Mega and Ramps 1.4 which connects via USB to PC. Then from DEV CNC Foam on the PC i could visualize what's happening and most of all hit a button and all axis home and square. Aint that great. The big deal is that Dev Foam CNC has and upload feature to the Arduino, so hopefully i will not mess with firmware.

As you can imagine after calculating this and that price, for sake of sanity and simplicity i will have Hiwin 20 on all axis. Not Hiwin, but the copy they sell from Germany on ebay. Hopefully it will slide ok.


The challenge is what to use for linear movement. I wanted ball screws but price wise decided on lead screws as speed will not be big. So choice still is between 10mm and 8mm lead screw which will spin a whopping 2500mm length. I need 200mm per minute cutting speed which i find is the best quality wise, when cutting with 0.16mm constantan wire. So with 2mm 2 start lead screw / 4mm per turn/ i will need to spin the screw mere 50 times per minute. Anyway i decided to upgrade to 24V the Ramps board and use DRV8825 drives that will be coupled with the most powerfull Nema17 Step Motor 42BYGHW811 4800g.cm 2.5A 2Ph. may be even at 1:3 for the sake of resolution. thought at 50 steps per mm resolution will be 0.02 and if i use some micro stepping even better
I believe the motors have to be good enough to move the "gantry" at that low speed and low acceleration. I am somewhat more worried of the natural sag of the long lead screw. i will design and print the nut, so backslash is not a worry.

here is the initial design. It could be wide as much as i like in future by just changing a couple of aluminum pieces . i am still contemplating to fully separate the sides and connect only the " gantry bar" which is a must for everyday use as i will be cutting mainly letters not wings. Profile for the sides and gantry legs will be 30x60 Bosch. It must not vibrate and be strong even if i am radiation cutting, as if it vibrates in any way, then i have to sand. And that's a tedious process ... better to be perfect quality result from start


I have contemplated another linear solutions, offline controllers, bigger motors but at the end i believe this is the proper way to do it. FYI end result will be better than 6k foam cutter which dont even use supported rails

Hopefully i will even avoid separate PSu for the wire and heat it from Ramps