Pleasant (tentative) surprise with Bridgeport Customer Service

I called Bridgeport (division of Hardinge now) and spoke to customer support. I asked a lady if they have schematic for the electrical
cabinet and repair manual. To my great surprise, she said that they likely have the manual and that she will email it to me today. I hope that it works and I get something.
i
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Hardinge has always had extra great customer service. My only problem is the parts must be gold plated. That's the only way they could cost that much. I've purchased a few items. It turned out cheaper to buy an entire donor machine. So far, I've been lucky, everything I've robbed from the donor was in good shape.
I'm sure you don't want to buy control parts.
Karl
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Karl, I want the schematic to figure out what to do with the control. If I retrofit the mill, I will need to know how to control the spindle contactors, etc. There is also a big row of relays of unknown purpose. One person said they may be limiting relays.
i
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Don't waste your time. Go nuclear. Then just trace the few wires to find out where they go. I make a small exception if you have a lot of outputs. In this case, close the coil with a hot wire and find out what clicks where. Then ID it. The outputs are normally all together and you can leave these relays in place if you aren't using Opto 22 outs. In my case, I wire all the I/Os to Opto 22 boards - a real good idea to have opto isolation. Your spindle is almost certainly a three phase motor - put a VFD in to run it and get rid of all the reversing contactor baloney.
Karl
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It is three phase. If I can get a manual, I cuold decide intelligently on what to keep and what not to keep. In any case, ilmit switches seem like an essential safety feature.
i
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Your chances of getting a useful manual are slim. At least for me, a pile of complex circuit drawings takes more time to deduce than its worth, you're tossing 90 percent of it anyway. Unless you've got a tool changer, there's not much to figure out.
Once your control box is empty and you've pulled the resolvers off the servos (check you may get lucky and have encoders) you'll only have about 30 wires to figure out. Ten of them will be home and limit switches and the common to them. nearly all machines use a special wire color for common just tracing conduit runs will ID these inputs. You'll have three wires to the spindle. Probably a spindle brake, often 120 VAC - note these work backward, power holds them off. Maybe a power oiler and a couple other devices. Your final group will be from your operator panel (which you probably won't use but I do). Again, common is almost always one wire color. I put the rest of the wires on an opto board and start pushing buttons and watching which input lights on the opto board. You'll have to trace the wires from your MPG (manual pulse generator) If you do have encoders, try to find the supplier name and look up the wiring, otherwise white is often five volts common and red or black +5volt. Get a logic probe and start watching which ones flick on when. Encoders have been my most troublesome unit to figure out. You should also have an Estop and Reset button, normally separate.
You will put some of the stuff you took out back in. Your servo power supply should be fine. You can reuse the 5 volt and 24 volt power supplies, but I normally don't. Re use one relay to make into your Estop reset or MCR (master control relay)
I'm sure I missed a couple items, but you get the idea.
Karl
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So far I got nothing at all

No tool changer. QC30 tooling with collar.

Why do I need to pull resolvers off?

Definitely a brake. We already ran the spindle. It stops instantly.

My guess is that I will try to replace it with a PC monitor and a keyboard.

Karl, I bought those AMC servo controls that you pointed me to, on ebay. Thanks a lot. I would think I should junk their servo control boards too? How about linear encoders? Those, IIRC, send some kind of a sinewave signal, not square wave. Thanks a lot. My thoughts are somewhat solidifying.
i
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obsolete, encoders used today. ...

Linear encoders can be a good thing, but you'll need quadrature output. I've not worked with them and AFAIK, this is an advanced subject. Personally, I'd install USdigital.com differential encoders on the servo motors. Very cost effective.
The servo control boards may have eBay value. People are still trying to run your old control. Junk to you. IIRC, you bought 80 VDC servo drives. You can build a power supply for next to nothing, or maybe re-use this from your old control.
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KO, how do I get those encoders, are they a standard item?

OK, maybe I was unclear, I was talking about the linear scales to readout position. Same kind of thing as a DRO.
Do you have a URL handy for those encoders?

I think that I can reuse the transformer from my old control.
i
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Encoder 101:
You have a Heidenhain control. They used a great feedback idea - linear scales. Some had quadrature feedback but most older ones had some sort of sinewave system kind of like a resolver. That's all I know about them. But I have read of folks converting these to quadrature. Linear scales with quadrature feedback would be top-of-the-line. If you go this route, any backlash will kill you (servo oscillation) but its more accurate. Heidenhain scales bring good money on eBay. My control has a system to use two feedback devices, I'm almost certain EMC can only use one. So you use this or a shaft encoder, not both.
Encoders on the servo motors give feedback position also. No backlash, they are on the motor shaft. USdigital.com makes an inexpensive kit that bolts on the shaft extension on the back of your servos. I've not worked with Heidenhain, make sure you have a spot and motor shaft to work with.
It helps to choose encoder counts carefully. My control counts "edges" with four counts per encoder pulse - I think EMC does the same. I won't explain this unless you need, Anyway, the best way to eliminate rounding errors is to have 100,000 or 50,000 or some very even counts per inch. For example, if your servo turns five revolutions to go one inch get 2500 pulse encoders.
Also double check that EMC can use differential encoders. These are MUCH more noise immune. I pulled all my hair out (I'm totally bald now) over what turned out to be encoder noise during tool change.
Karl
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Karl Townsend wrote: My control has a system to use two feedback

Nope, not true. EMC2 out of the box doesn't do dual-loop feedback by default, but a number of people have certainly done it. It does require additional encoder counter inputs and a little bit of special HAL code to link it all up. From the www.linuxcnc.org case studies page http://jmkasunich.com/cgi-bin/blosxom/shoptask/wichita-trip-02-20-08.html There's a lot of unrelated stuff about Stuart Stevenson's awesome shop in Wichita, but there is also a couple paragraphs about his dual-loop servo setup on the G&L HBM under "the Project". (By the way, he is using my PPMC analog servo interface for this.) The hal and ini files are on line, but I don't want to post the URL here. I could send you these files.

Well, as long as the resolution is high enough, there really is no "roundoff" problem, at least with EMC. All calculations are done in floating point format. Now, a low-res (.01mm) scale is just low, and non-inch, resolution. That isn't really "roundoff" it just has position points that don't fall on even .001" boundaries. You get .0000. .0004, .0008, .0012, etc. readings, and nothing in between. That is why it is good practice to spec a higher res encoder. Much easier to get there with shaft encoders and ballscrews than linear encoders.

This is entirely a function of the encoder counter board used. If it doesn't natively support differential inputs, you can always use a US Digital diff. receiver board, they are $12, I think.
Jon
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Ignoramus16651 wrote:

If the motors have Harowe Controls resolvers in the NEMA size 11 package, it may be hard to fit encoders in place, as they are 1.1" (28mm) diameter. I have a resolver converter that makes them look just like encoders to the CNC control.
Resolvers are not obsolete. They were the top choice when cost was no object and optical encoders had light BULBS in them, as you got a servo runaway when the bulb burned out! Now they are just more expensive, but will run underwater, fully filled with oil and coolant, and at 150 C. They are nearly indestructible.
If you mean linear encoders from DROs, the problem with them is the general DRO-class encoders have low resolution, typically .01mm ~.0004" This is really not good enough for CNC motion control. You generally want 10X the encoder resolution compared to displayed resolution. I have 50 uInch resolution on my X and Y, and 25 uInch on Z on my Bridgeport mill retrofit. You can get higher resolution linear encoders, and now 1 micron resolution is becoming pretty affordable, but they will still cost several hundred $ each. If your machine has resolvers and good ballscrews, just keeping that system and using the resolver-quadrature converter may be the easiest way to go.
Jon
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    [ ... ]

    You *don't* want to use the contactors for the motor if you are building a VFD into it to give three phase.
    Instead -- send TTL commands to the forward and reverse inputs (assuming the voltage will work -- otherwise try CMOS which will go as high as 15 V), and set aside a spare axis D/A converter in the controller to send speed voltage commands to the VFD. Just set up the old contactor to drop power from the VFD's *input* when the computer is turned off.
    Good Luck,         DoN.
--
Email: < snipped-for-privacy@d-and-d.com> | Voice (all times): (703) 938-4564
(too) near Washington D.C. | http://www.d-and-d.com/dnichols/DoN.html
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DoN. Nichols wrote:

Yes, except DC SSRs work really well, and safely, for controlling the VFD command inputs. Otherwise, I completely agree. The command inputs are set up for contact closure type controls.
Jon
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On Apr 8, 1:21pm, Ignoramus16651 <ignoramus16...@NOSPAM. 16651.invalid> wrote:

That IS a pleasant surprise. Please be sure to let us know wheter you actually receive it.
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Not so far. I fI do not get it today, I will call them tomorrow.
i
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There was an article or series of articles in the Home Shop Machinist some years ago where the author detailed methods of converting some of the those semi automatic Bridgeports to manual machines. If that's what you have and if you are interested, email me off list and I will try to dig up the articles if you don't already have them.
Pete Stanaitis ---------------------------
Ignoramus16651 wrote:

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Ideally, I would like to run it as a CNC machine with a Linux based control.
Less ideally, I would like to fix the monitor, which is what is supposed to be bad in this machine.
It has handles and dials that would let me use it manually.
i
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what kind of monitor? why is it hard to just fix it?
wrote:

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It is some kind of old EGA monitor, like those found on "IBM PC XT".
i

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