Bridgeport CNC conversion to manual?

hey gang, i have an opportunity to buy a 1977 bridgeport series 1 that
came from the factory as a CNC machine. this is an urgent request, as if
i don't drop the money by tomorrow morning, off it goes to a wholesaler.
needless to say, the price is phenomenal regardless. ($1500) here's
what it comes with:
the mill itself(9x42 table, varispeed)
sargon 2 axis DRO
rotary phase converter
whole buncha tooling
the original papertape contoller for the mill!
a mazak mazatrol cam m-2 controller seperate.
the machine has been sitting idle for 15 years, but doesn't have a spot
of rust on it. it is not under power, so i don't know what works or
doesn't. the hour meter only reads 140 hours, and from the condition of
this thing, i believe it really is that low.
so, since i'm not a CNC guy, and frankly an amateur hobby machinist,
what would it take/how easy would it be to convert it back to manual
control, OR to hook up the mazatrol and use the dials on it to manually
control the servos and make it work that way? effort and cost opinions
are welcome. if needed, i can send a zip file with pictures of the
TIA for quick responses!
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Hmm ... at that period, it is probably a BOSS-3 (the first one to escape the factory), and uses steppers, instead of servo motors.
Should be 12" Y-axis travel, if it is what I think.
A nice add -on.
Hmmm ... this I don't know -- but it well may be an improvement over the original BOSS-3 controls.
It should also be chrome-plated ways on the machine, and you can check for the flaking in the Y-axis ways.
Hmmm .... If it is what I think, it will be difficult to convert to manaual controls for the following reasons:
1) he leadscrews are ball-screws, which don't co-exist with manual operation very well.
2) The X-axis ballscrew does not rotate -- it is rigidly mounted to the right-hand end of the table, and the ball nut is mounted in bearings on the knee, and *it* rotates. (This minimizes whipping when the machine is moving fast.
3) The Z-axis ballscrew is concentric with the quill, and the nut spins around it. No provisions for hand feeding the quill.
Hmm ... I don't know the Maztrol package, so I don't know how easy that would be, but I have used a Series-I BOSS-3 with just the jog controls to move the table and quill. Awkward, but doable. Probably the simplest thing, since these are probably steppers, is to make up drivers which take step and direction information from encoders on handwheels. The machine should have Veeder-root encoders on both axes to tell the position in both X and Y -- but nothing in Z. Your DRO may be a lifesaver in this.
Other than that -- one of the PC packages to drive the steppers might be a good choice.
If it is a machine of the sort which I think the serial number should be on the knee (perhaps hidden by the sliding chip guards), and it should be a low number, starting with CNC, then several spaces, then the number. Mine is "CNC 108", and I've been told that Bridgeport started with "CNC 100". :-) If it is this low, it will probably be controlled by an LSI-11, and a set of custom logic boards (which were wire-wrapped, in mine. :-)
Why not put it in the dropbox (check out:
formatting link
And then post here what the images are named. A bit of advice -- avoid spaces in the filename and it will be more friendly to other systems than Windows boxen. Also -- include a file with the same name as the photo, but with a ".txt" extension, (with lines preferably not longer than 72 characters each) which explains what the image is, and why it is there.
Good Luck, DoN.
Reply to
DoN. Nichols
okay, i posted the photos the guy sent me to the dropbox under the name 'cncbridge'. check em out and let me know what you know!
Reply to
OK, it is a BOSS machine. It will be VERY expensive and difficult to convert this to a manual machine. The X axis leadscrew doesn't turn, the nut, buried deep inside the knee turns! The quill has a ballscrew track ground into it, and the ballnut rotates around the quill. It will be relatively easy to junk the control and replace it with a PC and modern stepper drives, and have a very nice CNC machine. But, I would forget any plans to convert back to manual on this particular design of machine. It is NOT a manual machine that was converted to CNC, as some other machines are.
The Mazak control doesn't really have anything to do with this machine. it most likely is for servo motor control. If anything is missing (motors, encoders, software) it will be thousands of $ to get it running.
Reply to
Jon Elson
thats exactly the type of analysis i wanted to hear. unfortunately, it's not the answer i wanted to hear. oh well. i'll find one some day that i can afford. just gotta keep using my little benchtop guy nutil i do.
thanks for the help! --joel
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Well, I guess it is too late for this one, but CNC is actually quite neat. A PC and about $300 worth of stuff will make such a machine run. You might even be able to sell off parts of the old Bridgeport control. And, with CNC, you immediately have a built-in DRO of sorts, if you choose to just move it around manually with the jog keys. But, you can mill circular paths and odd angles just as easily as cutting along the X axis on a manual machine. All I can tell you is, I'll never go back to manual!
Reply to
Jon Elson
Joel, where is this machine? Is it still available?
Jim Tucson, AZ
Reply to
Jim Wilson
O.K. In numerical order:
1) It does not appear to have the pneumatic motor on the spindle speed control which appeared in later machines, suggesting the BOSS-3.
2) (Sideways image) It looks like it *is* the stepper motor on the side of the spindle housing for Z-axis motion, which means that it is BOSS-3 through BOSS-6 I think. (BOSS-8 went to servo motors.)
It does not have the Pneumatic actuator for the brake lever (again neither does mine).
The motor direction switch, and the panic switch are mounted differently than mine, FWIW.
3) O.K. The control pod says that it is BOSS-3 (or maybe BOSS-4?). BOSS-5 and BOSS-6 have a different panel, with more displays.
4) I think BOSS-3 (though it might be BOSS-4). A bit later than mine, because the serial ports have been relocated for easier access. (You can see them under the telescoping protector for the leadscrew under the table and to the right of the X-axis stepper motor (big finned object)). The vertical orientation of the belt guard for the Y-axis says that it certainly is not the servo motors, but rather the stepper motors.
5-8) Images not present.
9) O.K. I don't know this one, so I suspect that is the alternate set of control electronics, and it looks as though you could use it with the cranks to emulate a manual machine -- once you know how to set it up properly.
10) Another view of the alternate control electronics, with what looks like the stepper driver electronics below the control pod.
11) A rather out-of-focus view of the whole machine.
So -- stepper motors not servos, LSI-11 CPU in the box on the side (with punched tape reader in the top, usually).
The instruction set of the BOSS-3 is rather limited, and the jog controls will move in steps of 0.001", 0.010", 0.100" or 1.000", and nothing in between, so controlling it with the jog is a real pain -- though it can be done.
You'll be better off with the other set of electronics, if you can find enough information to connect them to the steppers.
Note, also, that you can reduce the weight significantly by removing the electronics box on the right and the transformers and saturable reactors in the box of electrical stuff on the back of the machine. You'll probably still want to keep the relay which handles reversing the spindle motor. In mine, it is in a box bolted to the side of the large box with the transformers and saturable reactors, but the manual shows it inside the larger box.
There is one transformer in the CPU box which you will probably want to keep -- to converts the 240V input to 120V for things like the one-shot oiler lamps, and the punched tape reader. (Though I doubt that you'll be using the punched tape reader for anything -- lacking an 8-level punch. :-)
I hope that this helps.
Good Luck, DoN.
Reply to
DoN. Nichols
san francisco bay area. it has to be picked up and GONE by thursday noon, or the wholesaler takes it away.
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