First run video here: https://www.youtube.com/watch?v=Oe-pj3NSOOw
After hundreds of iterations, it's done! This is a 4-axis CNC machine that is designed to cut dynamic shapes in foam. Complex curves, letters, any shape you want. Each tower moves independently and the entire machine is adjustable to create steep angles if need be. It is built around v-slot rail, but all other parts are printable. For the most part the construction is pretty straightforward. The dimensions are totally flexible, although I've found v-slot in any length over a meter will start to twist. It requires 4 lengths of 2040; 2 the length you want horizontal travel, 2 the length you want the towers to be spaced from one another. My build supports about 44" of hotwire and is adjustable down to about 18" (for extreme angled parts). In all the pictures the machine is set to 35". For the Y & A towers, 2 lengths of 2020 are used. I'm using 1 meter lengths for these. My machine is all PETG.
The build uses NEMA17 motors and GT2 timing belt. That may seem fairly weak for the sheer size of the machine, but if your wire temp and speeds are correct there will be little to no resistance. Cutting foam is more of an art than a science, so experiment with speeds and temperatures as you go.
All the axis bolts are 5mm. 55mm and 45mm lengths are required for the carriages, 12 & 16mm bolts for miscellaneous mounts and 5x30mm bolts for the belt turnarounds.You'll need a bunch of 5mm T-nuts for the v-slot mounts. I used #8 nuts and bolts for motor mounts and the carriage and belt tensioners, however, 4mm bolts are nearly identical. The motors use 3x12mm but your motors may vary. I source all my bolts from https://www.boltdepot.com/. For all hardware I used stainless steel socket cap bolts.
Belts & Drive:
• GT2 belts, youll need about 10 meters.
• Belt Turnarounds: https://www.amazon.com/gp/product/B01H3F8LUU/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
• Timing pulley: I'm using 11-tooth but 16 will work as well depending on your microstepping: https://www.amazon.com/gp/product/B01IMPM44O/ref=oh_aui_search_detailpage?ie=UTF8&psc=1
• Belt tensioners (I use 2 per axis): https://www.amazon.com/Mercurry-Timing-Torsion-3D-Printer/dp/B01E913IJK/ref=sr_1_cc_1?s=aps&ie=UTF8&qid=1523833455&sr=1-1-catcorr&keywords=3d+printer+timing+spring
• V-slot wheels, rails can be sourced from a number of places, all 1/4" spacers I used from here: http://openbuildspartstore.com/nylon-spacers-10-pack/
• Each carriage is tensioned to the rail via adjustment_wheel.stl. Pass bolts through carriage with these on the outside; they can be turned and locked to press the wheels against the rail. Don't over-tighten.
Because the machine creates variable angles, it needs a way to keep tension on the wire with variable lengths. One side of the hot wire is anchored to the tower, the other is attached to a torsion spring. I used the entire assembly from this https://www.amazon.com/gp/product/B01H4E9Z6O/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1. Take it apart and use the center pulley. When you ruin the hotwire, make sure you have at least 15-20 turns around this pulley then anchor it. The hotwire passes through a welding tip screwed into Hot_Wire_Guide_Pass.stl. Welding tips available here: https://www.harborfreight.com/0025-in-mig-welding-contact-tips-10-pk-63796.html. Your hotwire supply attaches to this and passes power to the wire via contact. I have not used this extensively, so i have no idea how hot this area will get. If it overheads I'm going to build a heat-sink.
I'm using a HobbyCNC board, hence the need to use an old PC with a parallel port and Mach3. I already had the hardware but if I didn't I'd have used RAMPS. The software I'm using comes from here: http://www.profili2.com/eng/default.asp. The switch panel is designed to fit these switches: https://www.amazon.com/gp/product/B00ZWWZ0GK/ref=oh_aui_search_detailpage?ie=UTF8&psc=1.
The led strips are mounted to the towers via this: https://www.thingiverse.com/thing:2834133.
The table can be made out of any 3/4" material, or v-slot. I opted to build a lighter table. Each table mount (remember to mirror 2 of them) runs a 5mm bolt through a t-nut to make the bed adjustable. Be sure to square the towers from another as well as the table.
Warning: Cutting foam releases some pretty nasty stuff, make sure if you are cutting any you are in a very well ventilated area. I built a vent especially for this machine. You'll have to source your hot wire power supply. I'm not going to provide details on mine as I don't want to be liable for a fire. Be careful and have fun!