MillDroid Pendant

The MillDroid Pendant is a handheld/desktop controller box that provides physical buttons and a jog wheel to my MillDroid CNC sofware. It cuts down on the amount of mouse and keyboard used for positioning and operating my CNC mill and lathe.

I designed and built the pendant to access my KFlop-based MillDroid Controller hardware via a 25 pin cable. I based my job wheel/encoder reading software on some that was included with the KFlop hardware. Once modified for my own use I added the montoring code for the buttons and communications with my main app. Global variables are shared between the KFlop hardware and my VB.NET-based MillDroid application and it is through these variables that the apps communicate with each other by the sending of variables that they both monitor.

The case was built from 1/8″ styrene, ‘welded’ together and reinforced at all the joints for strength. Styrene is easy to mill once you get the feeds and speeds correct to prevent melting. Nice chips that clear with compressed air and no lubricant is required during cutting. I cut at a steady pace of 8 inches per minute, a .04″ depths of cut and spindle speed of 1500 RPM using a 1/8″ end mill on my Sherline Mill.

It took a couple hours of work cutting all the pieces from styrene, sanding then gluing it all together.

The internal wiring took considerably longer. I like to label every wire and document all my work for later review. Too many times, I’ve come back to a project I built, looked inside and thought “what was that idiot thinking when he did that?”. Since I document my hardware, software and every project, there is never any doubt when I open something I had previously built years later: I always know what that idiot was thinking when he did it.

The design it relatively straightforward. A few switches needed pull-down resistors because not all of the KFlop’s IO pins have them by default. Simple enough to add a few where needed. I wanted the pendant as small as possible so I tried to keep all the smarts outside of the pendant. This meant a few more wires externally but they all fit in a 25-pin printer cable with a a few to spare. I even had enough for another shiny red chrome abort button.