Haas cnc mills use a kitchen stove top heating element for their spindle braking resistor. The smaller diameter elements are about 45 ohms, and the bigger ones 27 ohms. Wattage is over a kw, as they run at 240vac. The resistance is a bit low for a capacitor discharge resistor, but at the price you could stack a few in series.
Haas mounts them in a metal cage on top of the electrical cabinet. -- Ralph ________________________________________ From: andy pugh [[email protected]] Sent: Monday, December 07, 2015 8:13 AM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] Poor mans soft turnon On 7 December 2015 at 15:53, Jon Elson <[email protected]> wrote: > I would just get some vitreous enamel resistors. They are > not that expensive, even new. Or higher-power lower-resistance for a faster discharge. http://www2.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyTHS50560RJ As the capacitance and voltage rise you get to the point that the bleed-of resistor becomes an electric heater, but I think you may be below that point. My mill has 6600uF at 300V, and I wanted a 10 second discharge That means a 500R resistor, A 500R resistor permanently across a 300V bus dissipates 180W. And that's a pretty big resistor. Which is why, in my case, I decided to only switch-in the resistor at power-off. With less capacitance, and lower voltage, the power requirement falls rapidly. (with the square of V). 120V and 3300uF comes out at a far more reasonable 14W with a 1K resistor -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto ------------------------------------------------------------------------------ Go from Idea to Many App Stores Faster with Intel(R) XDK Give your users amazing mobile app experiences with Intel(R) XDK. Use one codebase in this all-in-one HTML5 development environment. Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs. http://pubads.g.doubleclick.net/gampad/clk?id=254741911&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users ------------------------------------------------------------------------------ Go from Idea to Many App Stores Faster with Intel(R) XDK Give your users amazing mobile app experiences with Intel(R) XDK. Use one codebase in this all-in-one HTML5 development environment. Design, debug & build mobile apps & 2D/3D high-impact games for multiple OSs. http://pubads.g.doubleclick.net/gampad/clk?id=254741911&iu=/4140 _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
