Servo II CNC system replacement / questions
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  1. #1
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    Default Servo II CNC system replacement / questions

    Recently purchased a Bridgeport vertical mill at an estate sale. It's in great shape and has a 3 axis Servo II CNC system, 2 axis Acu-rite DRO along with an Acer EVS head and Kurt air powered draw bar. Even got the original Bridgeport Series I head in the deal (on a pallet, supposed to have bearing noise).

    Cabinet for the CNC system has a slot for the 4th axis board but it was never installed.

    First problem: computer for the CNC system will not boot up so the operating program is probably gone. It was installed in the mid 90s and the computer has a 5.25 floppy drive so parts for it will be impossible to find. The hand held controller (called a 'pendant') will operate all three axis. They run smooth and everything is tight. The Z axis seems a little too tight but it moves without excessive noise from the servo.

    Found a source for the original Servo II program and parts, which leads to the second problem:
    Windows 7 compatible operating system, one board and rebuilt servo for a rotary table will cost more that I paid for the machine. So if one of the other servos goes down or it smokes a board? There's going to be major expense involved in the repairs.

    Started looking into CNC retrofit systems and found some on e-bay. Can get 4 stepper motors with controllers for less than 1000$. Now the third problem and some questions:
    The X and Y axis bolt to the table like a standard servo, but the Z axis servo attaches directly to the knee.
    What's involved with removing the Z axis servo?

    Also, any advice on a which CNC system and controllers to get?

    Thanks in advance, will try to post some pictures below.

    20190616_093604-2-.jpg

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    Close-up of the Z axis servo
    z-axis-servo-resized.jpg

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    FWIW, old 286 and 386 PCs depended on a battery to maintain data they needed to recognize the disk drives and etc. When that battery died after 5 years or so, you had to hand enter some parameters to get the BIOS to recognize the hard drive so it could load the DOS system, etc. This is more likely than that the hard drive is dead. It's been long enough that I've forgotten all that but Googling will turn up lots of info if you can figure out exactly what PC or motherboard you have there.Try terms like starting up MSDOS PC

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    Do you still have the hardware key? If you do, then I can send you the software, legally. It was the key that they charged for. The original, pre-windows software was free. You might even be able to download it from their website: servosource.com

    Once you have software sorted out, the computer is just a standard, off the shelf PC. Most configurations needed an open ISA slot, so it would have to be a pretty old computer. In theory, it needs to be running on DOS, but I never had any problems running in windows 95/98. (windows SE or newer won't work with the old software)

    I've run Servos off and on for 20+ years, so I can help with most questions you might have. It's a pretty good control, especially for the mid 90's.

    As to changing the motors, I wouldn't recommend it until you have actual problems. Those motors are a strange hybrid servo/stepper, and I doubt they, or the control, are compatible with anything else on the market. They put out an insane amount of torque, which you need for the table Z. I can't imagine those cheap steppers you're thinking of would move that much weight reliably. Plus, you'd probably lose the ability to move the axes by hand. That was the best part about the Servo kit, with the table Z. You could run it as a full CNC, a full manual, or anything in between.

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    Thanks for the replies, here's where I'm at so far:
    Friends in the local 4X4 club have connections and resources they've met at rock crawling events and swap meets. One is an old school computer geek in the Dallas area who loves a challenge and is willing to look at the computer. Tower also has a 3.5 floppy drive so he's pretty sure parts are available if it's fixable.

    Lady I got the mill from thinks there's some hard back binders with programming info and floppy discs in the shop office. She's in the process of cleaning out her Dad's business and dealing with a lot of grief so I told her there was no rush.

    Evenglischatiest,
    I'm guessing the hardware key is going to be an in-line connector for one of the cables?
    Run into that on automotive and diesel diagnostic equipment with proprietary software. Some of those require a alpha-numeric start key as well. Hoping that will be in one of the manuals or there's going to be a floppy to boot the system.

    Building I'm working out of only has 220V single phase. Already ordered a 5hp rotary phase converter which should be in the first part of next week. Plan to take some vacation time from my real job the end of this month or the first part of July to get the mill set up and wire everything in.

    Will post updates and progress reports asap.
    Thanks again.

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    The hardware key will look like this:
    https://sentineldiscussion.safenet-i...61000000003001

    It should be plugged in to the parallel port. If the computer is still in the original housing, (black box, with a CRT monitor, and a slanted keyboard shelf) then the parallel port should be labeled, on the back. If it's not there, check inside the box to see if it's anywhere in there. If you don't have the key, the control is a paper weight. I'm not aware of a hack for it, and I don't think Servo stocks them anymore. They want to sell you the absurdly expensive Windows version, and a new computer.

    I tried running off a rotary phase converter once. If you're on a residential line, without any power factor correction, you'll end up with huge electric bills. Residential meters read the amps flowing in to the converter, without reading what's coming back out. Even though it's just spinning, with zero load, the meter sees it as drawing the full amperage of a 5 HP motor, and you'll be charged accordingly. I don't know much about this, but that's how it was explained to me when I complained about my first bill.

    Since then, I've had good luck running the spindle off of a cheap Chinese frequency drive. (the control runs on single phase 220) You put pretty much any power you have in to it, and it rebuilds the output to 3 phase. It also lets you change the frequency, giving you electronic control over the RPM. You might even have a card in the computer to control a frequency drive with an S code.
    I've been running this one for years, with no problems:
    4KW 5HP 220V Variable Frequency Drive Inverter CNC VFD VSD Single To 3 Phase 860962744646 | eBay

    Good luck with it.
    Last edited by Evenglischatiest; 06-19-2019 at 08:51 PM. Reason: fixed the link... hopefully


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