Well... Boss3 RetroFit anyway

[HawkJET]

I started a thread in the EMC forum and then switched to Mach3 so the EMC forum is no longer appropriate (many of you may have seen it). So I am here now.
I got some great help in the other thread that allowed me to understand enough about the parallel port that I designed and built my own BreakOut Board. I have this machine to do and three others (an old BP Series II NC, an X3 benchtop, and a customer's machine), so I designed the B.O.B. to be versatile enough to adapt to them all.

This means I have jumpers to select several options... like onboard 5v relays or transistors to drive external relays or solenoid valves (which also requires the option of an external 12v or 24v). All in all, I am VERY happy with its operation. It includes the standard 5 opto-isolated inputs, and WatchDog Circuit (commonly called a charge pump in these forums), and can handle 3v parallel port outputs. I often say I know just enough electronics to be dangerous (since I am a mechanical engineer), so to have this working so well is really gratifying.

After doing the PC Board layout then building and testing, I only found one circuit error and two layout errors. I also made a "daughter board" that sits beneath the B.O.B. to have a place to plug in the cables to the Compumotor ZETA drivers and also a cable to a small display board with status LEDs. Plus there is a row of terminal strips to attach a bunch of I/O.

The first two pics are the B.O.B. and daughter boards.

The circuit error was that I neglected to have the input buffers disabled unless the WatchDog was alive. The third photo shows a jumper to fix that.

I installed WinXP on a brand new computer, followed by Mach3, and in a couple hours I was configuring Mach and learning how to setup all the features (I/O, charge pump, step resolution, etc.). The next day I had Mach3 moving all three axes on the mill.

The forth image is what it looks like "bread-boarded". I have been actually using it this way (I've been making parts for the previously mentioned "customer machine").

The next picture is a closer look at the electronics... such as it is. I will be packaging it all into a pretty metal box, 16" x 20" x 8" (computer and all) that will attach on the back of the machine. I will install the monitor into the console (I think that what you call it) and mount the "arm" to a bracket where it originally was attached.

The vital statistics:

Bridgeport Series I Boss3
Stock Sigma stepper motors
Compumotor ZETA drivers (modified to double current)
Custom designed B.O.B.
AMD dual core computer

I'll update as I package everything in the metal box and mount the monitor (I want to go with a touch screen so I'll probably design a new Mach3 screen too).

[HawkJET]

To get the machine ready for the retrofit, I first read through a three part series from Home Shop Machinist about Boss retrofits:

http://www.mgertech.com/cnc/BPORTPT1.pdf
http://www.mgertech.com/cnc/BPORTPT2.pdf
http://www.mgertech.com/cnc/BPORTPT3.pdf

I found a lot of valuable information there. However I didn't do things the way the articles suggest. I ended up removing ALL of the old electronics and power supplies. The only thing I left on the machine was the stepper motors and limit switches. I didn't even use either of the cabinets since they are so much larger than what is needed (or at least what I needed).

For now, I am using the wiring that was already attached to the stepper motors and limit switches. Although when I package everything in my smaller cabinet, I'll replace it because the stock Bridgeport wiring is not shielded. Though I used the cables, I hooked them up differently. The limit switches are now set up as normally closed and I wired the motor coils to be in parallel (the third article, above, has a diagram that tells how to wire them).

At some point, I will also replace the old Sigma steppers with modern high torque steppers. Back when the original motors were designed, microstepping was not yet invented. As a result, they were optimized for "full step" torque and are not smooth with a sinusoidal wave form - there is almost no advantage in microstepping with these motors since they practically "full step" anyway.

The spindle wiring with the Fwd/Rev switch was cumbersome. I replaced it with a standard drum switch from a manual mill. I will still wire it up with an E-Stop button and use a magnetic switch like this one:

http://www.grizzly.com/products/Magn...nly-3-HP/G4673

The machine looks a lot more like a standard Bridgeport with both of the bulky cabinets removed.

After removing the unneeded parts, I cleaned the entire machine. To get the built-up grime removed, I "painted" on liberal amounts of Goop brand hand cleaner and let it soak for a while. It removed almost all the grime and even some oil stains that I thought were permanent. A word of caution though, the hand cleaner seems to soften the paint a little, so when I was rubbing off the grime, I noticed some gray paint on the rag also. The places that were well abraded by constant abuse from being battered by metal chips would remove paint along with the embedded chips.

[M250cnc]

Well good luck with the project. I would agree that support for EMC2 seems to be lacking in the sense that EMC users seem to be unwilling to help and just offer links to the manuals.

The Mach3 forum is full of people with motors that do not move and questions like how do i work out how many steps per inch i need.

I am fairly experienced in Mach and am going the other way to EMC as there are some things that Mach is never gonna be able to do.

As someone who has just made there own BOB as you have documented above i feel that you should stick at it and keep on with EMC

[HawkJET]

I would agree that support for EMC2 seems to be lacking in the sense that EMC users seem to be unwilling to help and just offer links to the manuals.

you should stick at it and keep on with EMC

There is a lot to the learning curve that is far easier to get through with Mach3. After getting a machine or two running, I may give EMC2 another try. I have a better sense of the big picture and the basics of PC based CNC. The process may not seem so overwhelming. Plus, I have a friend that wants me to help him retrofit a couple of CNCs with servos instead of steppers, and EMC2 is better suited for that application.

[khadeaniruddha]

hi i am from india.i have small work shop (my work like pattern makeing,small job shop ).i have a universal milling and a Bridgeport type knee mill taiwan make.so i am looking for retrofit for this knee mill with mach3 so please give me a addvise its viable or not.
i am waiting for your important add.

thanks.
aniruddha khade
91+ 9890645364
my email- khadeaniruddha@rediffmail.com

[HawkJET]

so please give me a addvise

My machine is already a CNC machine and is equipped with ball screws and motors. I am just replacing the old control with Mach3.

Your machine is apparently a manual machine and you would need to add ball screws and motors that I am not doing. I don't think I would be able to assist in that area as well as others. You might want to start your own topic to get help.

[MSFAB]

Compumotor ZETA drivers (modified to double current)

What do you mean by modified to double current?
Is this required for certain stepper motors?

Does your other Bridgeport use servos? Or were you going to use steppers on that one also? I was just curious if your break out board enabled you to use servos or steppers? I hope my questions are not out of line.

thanks
marcus

[HawkJET]

I hope my questions are not out of line.

Marcus your questions are welcome.

What do you mean by modified to double current?

The stock motors that came with the Boss3 system are 7 or 8 amps as I understand. The Compumotor ZETA drivers are 4 amps. I modified them to put out 8 amps.

Is this required for certain stepper motors?

There is really no need to modify a stepper motor driver. It is a matter of selecting an appropriate driver for the application. In my case, I already have a bunch of ZETA drivers so I modified these instead of getting different drivers.

Does your other Bridgeport use servos? Or were you going to use steppers on that one also?

My other Bridgeport has the same stepper motors as the Boss3 in this thread (it is even older than the Boss3 and it predates the use of G-Code). I'll first get it running with the steppers, but may decide to change to servos at a later date.

I was just curious if your break out board enabled you to use servos or steppers?

My understanding is that the BreakOut Board is more a function of the computer using the parallel port rather than if steppers or servos are used. The B.O.B. should work with both steppers or servos and with either Mach3 or EMC2.