MPCNC 2826/2822 Brushless RC Motor Foam Cutter by dkj4linux

Last crawled date: 3 years, 1 month ago

This is a 2826/2822 brushless RC motor version of the MPCNC foam cutter attachment (http://www.thingiverse.com/thing:1138627). In addition, an improved flywheel has been developed to better balance and handle the higher RPM's of a brushless motor. A symmetric and balanced clamp screw system is used that allows the bearing and mounting screw to be more simply counter-balanced by a weight that is easily calculated and placed directly opposite it on the flywheel. The flywheel needs to be balanced well enough to run at 6000-9000 rpm to allow feedrates of 600-900 mm/min, giving 10-15 strokes/mm which will result in clean cuts in DTFB with the paper on.
UPDATE 04/11/17: I've updated the needle cutter body to the latest version I use/recommend, which in addition to increased height, motor shaft to needle guide, adds sideboards to effectively reduce the number/intensity of any resonances. It also stabilizes and straightens the needle's motion before it enters the guide, and dramatically reduces the friction, and resultant heat, which had become an issue with some previous versions of the needle cutter. The red-bodied cutter in the photos is effectively obsolete and left only for reference. The V2 version operates exactly the same as previous versions but with smoother operation and longer needle life.
The development of this version of the needle cutter may be followed in my FliteTest forum thread
http://forum.flitetest.com/showthread.php?24251-Cutting-foam-sheets-with-a-needle!&p=326963&viewfull=1#post326963
The prototype version was made of wood and shows that there are many ways to build a successful needle cutter. Other users' cutters are also featured in the above thread.
The sideboards are slightly slotted and adjusted to the angle of the needle in the 3 o'clock and 9 o'clock positions, close but not touching. These sideboards prevent the needle shaft from flying further outward with increased cutter RPM. I intend to eventually print the sideboards with NYLON filament but wooden or printed plastic sideboards will work quite well, especially if lightly lubed with a suitable grease.
UPDATE 11/18/16: The most current information about the development of this needle cutter (and variations, including a "no-flywheel" version) may be found at
http://forum.flitetest.com/showthread.php?24251-Cutting-foam-sheets-with-a-needle!
Original development thread and earliest (mostly obsolete) version information is at
http://rcpowers.com/community/threads/mostly-printed-cnc-and-cutting-foam.18808/
Check out also jhitesma's parametric (and improved!) version of this cutter platform at
http://www.thingiverse.com/thing:1723915
Other related threads may be found at
http://openbuilds.com/threads/brushless-motor-foam-cutter-and-cutting-sheet-foam.5862/https://www.rcgroups.com/forums/showthread.php?t=2566143
UPDATE 5/13/16: An easier and better approach to the guide tip holder... get a thin piece of plywood (a small wooden mousetrap "plank" is great) and match-drill the holes for mounting it to the printed foam cutter body. Then thread either an inflation needle or welding tip (your choice) into the wooden guide holder. The wooden holder will most certainly be far more heat tolerant than the plastic one and less parts/complexity to assemble (https://www.youtube.com/watch?v=7yA7XSl-wnU).
UPDATE 1/25/16: The MPCNC foam cutter is now outfitted with a "floating" guide tip holder with 0.035" copper welding-tip. The "floating" tip holder uses a short section of carbon arrow shaft for a spacer/insulator and a 3-point set-screw arrangement to effectively isolate the hot (in use) copper tip from the PLA plastic.
UPDATE: added a 2822 version... different mounting hole pattern.
UPDATE 12/23/15: More info/pics about the design and construction of this foam cutter -- and more specifically balancing the flywheel can be found athttp://www.rcpowers.com/community/threads/mostly-printed-cnc-and-cutting-foam.18808/page-8#post-252173
MPCNC Brushless Foam Cutter V2 in action:https://youtu.be/HvBNPGIN62chttps://youtu.be/QO3jcprPHCUhttps://youtu.be/BlYrvLNocB0