Electrical Musings

In a response to Where the heck? What the he11? HUNH? on CNCZone I posted the following. I realized later that it is a good summary of my retrofit so I will repost it here. I am in the process of doing the same thing (a Bridgeport Boss CNC Retrofit). I have the gecko drives working, a Automation Direct GS2 VFD, and a power supply built with T1 (the 240 v to 120v transformer tapped at 40v). I already had Gecko 201s but the 203s would be better because of the auto short circuit protection circuitry. Just remember that "common" on the Gecko 201s is 5 volts to power the opto-isolator LED. Also just wire 2 windings of 4 of the stepper motors because the windings are in bifilar (which means that 2 windings are wound together). There are jumpers on the motors that show which terminals are the ends of the windings and then wire to the other side. I have 1 sigma and 2 superior and the geckos work fine so far. I used a C11G breakout board from CNC4PC which has some extras AC relays f

One of the first things that one needs to retrofit a Bridgeport Boss CNC machine is a power supply for the steppers. That is assuming that one has drives which I do in the form of Geckodrive G201s. The original Bridgeport power supply for the steppers put out 56 volts dc so most people use this voltage although some use 60 or even higher voltages. As far as current goes most people use 6-7 amps, 7 amps being the maximum that G201s will source. While researching stepper power supplies I found a great reference on Gecko's website. http://www.geckodrive.com/upload/Step_motor_basics.pdf This document not only shows how to wire the drives but gives a good example of a power supply with sample component values. Basically a power supply (unregulated) only needs a transformer putting out a desired voltage that is rectified by a full diode bridge and filtered by a big capacitor. To get 56vac you need un-rectified 39vac. (56 v /1.414 = 39.6 v) For a capacitor value C = (80000 u

One of the big questions that I have about the new milling machine is maintenance and cleaning. Cleaning the ways I was almost tempted to get out the Foamy Engine Clean and spray down the machine and let all the sludge drip onto the floor. However I avoided cleaning anything that may contain grease or lube with any degreaser. On the painted surfaces I used a version of "Orange Clean" (which I could not find locally). It is called "Greased Lightning Blast" with orange oil. It made short work of most of the grease on the machine grey paint. The machine after a bit of cleaning. Anyone have a source for cans of enamel spray paint that matches? Way Wipers A quick Google search shows that many people want to sell you exotic and probably expensive way wipers. But on Ebay a couple sellers offer felt way wipers specially for Series 1 Bridgeport. I still haven't decided what to do about the wipers. It is suggested that they are changed out yearly so I am g

I have a new project. Recently a series 1 Bridgeport BOSS CNC milling machine was posted on Craigslist. The machine was in the process of being retrofitted as the control went down and a previous owner threw it away. It came with a couple tool holders, some Gecko stepper drivers, some software packages and all the manuals. I contacted the seller to ask about its availability. It was available so I made arrangements to go inspect the machine. In the meantime I learned a little about Bridgeport BOSS CNC milling machines. Basically they are similar to manual Bridgeport milling machines but have ball screws and big stepper motors that drive the screws on the X, Y, and Z axis. They do not run manually. Also they have pretty obsolete controls that were quite capable for their time. The stock controls have a resolution of 0.001 and have 200 step per revolution motors with 1:1 pulleys. But basically they are VERY capable machines when retrofitted and a similar ball screw CNC mill