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  1. #1
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    Bridgeport Series 1 Retrofit

    I've learned a lot from many people here at CNCZone. First off I want to say, "Thanks" to the many that take the time to share their experiences.

    Over the last few years I've read much regarding the decision to, or not to CNC an old Bridgeport. Some say the old Series 1 machines are junk, too much resonance, too much flexing, cost too much to retrofit, just wait for a better machine like an old BOSS to come along. I waited a long time for an old BOSS to come along reasonably priced, it never showed up.

    You can make a decent little CNC machine from an old Bridgeport. There is no right or wrong answer here. Will you be able to make Orbiter parts for NASA? Perhaps not. But you can make many precision parts with one. You can make many precision parts, repeatable and quickly with one. Think of the arcs, and circles that you can do on a CNC that would require a lot of setup time on a manual mill. Anyone want to discuss how to cut an ellipse with a manual mill. This can easily be done with the CNC. What about script? I believe the value is much more than, just perhaps what it would cost to retro it. For me, the value is, 'What I can get out of it', and 'How much time can it save me over other methods'. In the end we all have to make our own call; we have to decide, 'How much is this old machine worth?

    My conversion cost a little more than $6K, and I believe it would be difficult to do one for less than 5K. Just too much stuff to buy, motor plates to build, cabling, boxes for the electronics, servos, a controller, and so on...

    A partial list of my expenses:
    3 Axis Precision ground ball screw set, Winters Engineering, CA $1,200
    3 Teknic Clearpath servo motors with integrated controllers, 1 power supply, cabling, $2,700
    1 Hicon Integra Breakout board/Controller combo, $600
    Bearings and miscellaneous repair parts, H&W machine, $600
    plate aluminum, belts, pulleys, misc hardware, $500
    Dedicated stand alone computer, used with Windows 7, Mach3, $300

    The listed expenses total $5,900. But, you can easily use a Rockford Rolled Ball Screw Kit for about half that amount I paid for my ground ball screws. And you can find a less expensive and durable controller instead of the Hicon. You might be able to do it under 5K.

    One final note. I used three Teknic Clearpath servo motors, model CPM-SDSK-3441D-ELN. They are awesome servos. When I looked at other servo systems the ClearPath servos saved me a minimum of $1,500. I know the amount does not sound like much, proportionally however, the savings is a little less than 25%.

    So this is the start of my build thread. Since I have X,Y, and Z under CNC control, I am happy. I will share with you next what I've learned along the way.

  2. #2
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    Re: Bridgeport Series 1 Retrofit

    WilliamT4450

    Not sure why anyone would say the series 1 was not a good machine to CNC, the Bridgeport EZ-Trak was really just a modified series 1 machine

    What is the Encoder resolution on the clearparth motors

    The Ground Ballscrews is always the best choice for something like this, Rolled are not suitable unless they equal a C5 grade

    Enjoy your machine
    Mactec54

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    Re: Bridgeport Series 1 Retrofit

    It's easy to get all wrapped up in the theory of counts per revolution. I certainly was guilty of that when I ordered the servos for my router. I purchased the standard model thinking, 800 counts is certainly enough. After receiving them I wondered if I made the right decision to purchase the standard over the enhanced encoder 6400 count model. Soon after getting the router servos in, I purchased the enhanced models for the Bridgeport.

    Today, the 800 count servos are installed on the router, and 6400 count servos are installed on the Bridgeport. Both machines are crazy accurate. I'm happy the way both machines perform.



    The servos I purchased are model # CPM-SDSK-3441D-ELN. They havePositioning Resolution of 6400 counts per revolution (denoted by the bold "E").

    Had I purchased the standard model # CPM-SDSK-3441D-RLN, it's Positioning Resolution would be 800 counts per rev (denoted by the bold "R").


    From the manual:

    Enhanced Options
    R = Positioning Resolution of 800 counts per revolution; Standard selection of RAS settings.
    E = Positioning Resolution of 6400 counts per revolution; Extended selection of RAS settings.
    Note: MCVC available in R only. SDHP available in E only.
    Note: All ClearPath models feature an internal encoder resolution of 12,800 counts per revolution.

  4. #4
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    Re: Bridgeport Series 1 Retrofit

    Quote Originally Posted by WilliamT4450 View Post
    It's easy to get all wrapped up in the theory of counts per revolution. I certainly was guilty of that when I ordered the servos for my router. I purchased the standard model thinking, 800 counts is certainly enough. After receiving them I wondered if I made the right decision to purchase the standard over the enhanced encoder 6400 count model. Soon after getting the router servos in, I purchased the enhanced models for the Bridgeport.

    Today, the 800 count servos are installed on the router, and 6400 count servos are installed on the Bridgeport. Both machines are crazy accurate. I'm happy the way both machines perform.


    The servos I purchased are model # CPM-SDSK-3441D-ELN. They havePositioning Resolution of 6400 counts per revolution (denoted by the bold "E").

    Had I purchased the standard model # CPM-SDSK-3441D-RLN, it's Positioning Resolution would be 800 counts per rev (denoted by the bold "R").

    From the manual:

    Enhanced Options
    R = Positioning Resolution of 800 counts per revolution; Standard selection of RAS settings.
    E = Positioning Resolution of 6400 counts per revolution; Extended selection of RAS settings.
    Note: MCVC available in R only. SDHP available in E only.
    Note: All ClearPath models feature an internal encoder resolution of 12,800 counts per revolution.

    You payed way too much for them with such a low Resolution Encoder, it has not much to do with accuracies, it's the smoothness that your machine can run at, with a low count like this the jerk factor is very high, the minimum count is 14 Bit (16,384 CPR ) and anything above, the higher the better the smoother your machine will cut/run

    Are they Incremental or absolute Encoders
    Mactec54

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    Re: Bridgeport Series 1 Retrofit

    Mactec54
    I do not understand your claim that I "payed way too much for them (my servos) with such a low Resolution Encoder". Perhaps, the Teknic literature was not clear with their description of the encoder. So I found a description from Teknic that better defines it.

    Their description reads:

    "ClearPath encoders are at least 12,800 counts per revolution. Because ClearPath is a servo, this means that the positional repeatability of the motor shaft will be one part in 12,800. The positional “settability” of ClearPath motors varies from 800 to 6,400 positions per revolution, depending on the model (the lower cost models generally have a lower amount of positional settability). So, even if you buy a model with 800 positions (or “steps”) per revolution, each position will be repeatable to 0.028 degrees (1/12,800 of a revolution)."

    From their description, I believe this makes it a 13bit encoder. Teknic places the value of their encoder at $30. As said before, I own both encoder models, the 800 and the 6400; the 800's on the router and the 6400's on the Bridgeport. For all tasks, these servos operate and respond flawlessly. They run very cool, even in the heat of an August day in a shop without air conditioning. They are very quiet and they are very smooth.

  6. #6
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    Re: Bridgeport Series 1 Retrofit

    Quote Originally Posted by WilliamT4450 View Post
    Mactec54
    I do not understand your claim that I "payed way too much for them (my servos) with such a low Resolution Encoder". Perhaps, the Teknic literature was not clear with their description of the encoder. So I found a description from Teknic that better defines it.

    Their description reads:

    "ClearPath encoders are at least 12,800 counts per revolution. Because ClearPath is a servo, this means that the positional repeatability of the motor shaft will be one part in 12,800. The positional “settability” of ClearPath motors varies from 800 to 6,400 positions per revolution, depending on the model (the lower cost models generally have a lower amount of positional settability). So, even if you buy a model with 800 positions (or “steps”) per revolution, each position will be repeatable to 0.028 degrees (1/12,800 of a revolution)."

    From their description, I believe this makes it a 13bit encoder. Teknic places the value of their encoder at $30. As said before, I own both encoder models, the 800 and the 6400; the 800's on the router and the 6400's on the Bridgeport. For all tasks, these servos operate and respond flawlessly. They run very cool, even in the heat of an August day in a shop without air conditioning. They are very quiet and they are very smooth.

    That's what all normal servo's do, I'm not saying there is anything wrong with what you have, Just you payed to much for them with having such a low resolution non standard Encoder

    Your Encoders are not normal, meaning they do not follow normal standards. 1024 is 1 Bit there numbers don't relate to this you would also need to know if you are using Incremental or Absolute Encoders, Your 12,800 does not fit as a standard as 12Bit=12,288 and 13 Bit=13,314 Encoder ,they can have any number of PPR, what ever the manufacture wants to make, But the norm it using Bit format

    It has noting to do with accuracy with your 800 PPR, this is not very smooth running compared to 65,536, the more PPR you have the smoother the servo motor will run

    I don't think you understand what Encoder's, are all about, as I said 14 Bit is the minimum any one wants for a Mill, Routers does not matter quite so much, but they too will do as good as a Mill with the right hardware, 14 Bit=16,384 PPR 16 Bit is the new norm which has 65,536 PPR, lot's are using this, and some are using 20Bit which has 1,048,576 PPR for there Routers
    Mactec54

  7. #7
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    Re: Bridgeport Series 1 Retrofit

    Mactec54--The subject of this thread is, Build Thread, Bridgeport Series 1 Retrofit.

    This thread is about the retrofit of a Series 1 Bridgeport. Because this retrofit is technically complete, there is no reason to discuss in great detail the subject of encoders. The subject of encoders are discussed Ad nauseam all over CNCZone and other places. If you want to discuss encoders, I encourage you to go elsewhere.

    Moving forward, feel free to comment on the subject matter professionally, with unambiguous clarity.

    THE DISCUSSION OF ENCODERS IS CLOSED!

  8. #8
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    Re: Bridgeport Series 1 Retrofit

    Posted are three photos of the Bridgeport Z-Axis as it sits today.

    I machined all the fixtures you see here using my CNC router. The gantry type router I built is quite large, the bed envelope is 72"x144"x10". With a 10"-Z you can imagine; there is no expectation of good surface finish. So, what you see today was built to provide a working prototype. The final parts kit will be cut from this machine. After the bugs are worked out and the prototype design is acceptable, I will complete the machine with newly scraped ways, fresh paint, and of course new axis fixtures. But for now, this is a test mule!!

    When pooling the documentation to build this machine I considered a number of Z axis kits; MicroKinetics, Elrod kit, and a couple of others. Truth is, they were all beyond my budget.

    Searching for information for a Z-axis retrofit, I found RayL, a very knowledgeable CNCZone contributor, with his thread, http://www.cnczone.com/forums/bridge...ve-design.html. In this thread you will find discussions regarding the technical information to build his Z-axis. Later, Ray was kind enough to leave his CAD and his tool path documents at the CNCZone, for those seeking to build an assembly. http://www.cnczone.com/forums/bridge...ing-forum.html. Ray used the CAD drawings, primarily to generate his tool paths needed for the project.

    OK, so the stage is set. I used his drawings as inspiration to build my Z-axis assembly. While my parts are not identical to his, the most important part of Ray's design that carries forward to mine is the addition of a plate, directly under the transmission housing. This plate provide tremendous rigidity; it is the backbone for the Z-axis assembly, and it is superior to any other fixture method.

    All the drawings are self explanatory. If you have comments or questions please feel free to post them.

    Further plans:

    The DRO display is temporarily held in place by a piece of aluminum extrusion. It will receive a proper fixture when done.

    The BP 1hp three phase motor will be replaced with a servo motor. The Lenz frequency drive goes away.

    The electrical box behind the Lenz goes away

  9. #9
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    Re: Bridgeport Series 1 Retrofit

    X and Y axis photos attached

    all three handles remain

  10. #10
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    Re: Bridgeport Series 1 Retrofit

    Quote Originally Posted by WilliamT4450 View Post
    X and Y axis photos attached

    all three handles remain
    3 Problems with having the original handles, ( 1 ) a safety Hazed, and out of balance, make yourself some balanced round handles with a fold away handle, or buy them if your servo drives can take it

    The main thing apart from Safety, is when you turn the Handles by hand you will be sending Voltage back to the Drive which they don't like at all, unless your servo drive manufacture says this is ok to send Voltage back to the Drives when manual turning the handles, then I would say don't do it

    You have some kind of gearing as well that is not 1:1 so turning the Handles will make the motor turn quite fast, Just not a good idea
    Attached Thumbnails Attached Thumbnails Hand Wheel With Folding Handle.jpg  
    Mactec54

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    Re: Bridgeport Series 1 Retrofit

    WilliamT4450,
    Looks like you are doing a great job on this conversion. Don't believe all the stuff they say about these old Bridgeport's, I had a one with the EZtrack installed and it was exceptionally accurate. I sold it long ago, but now that I only have a router I am sorry I let it go as it could cut metal with no issue. The Eztrack system was really outdated and I probably should have updated it to MACH3 but my wife told me I had too many toys. LOL

    Keep up the good work.

    Russ

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    Re: Bridgeport Series 1 Retrofit

    Nice work William,
    Your Clearpath servos with drive function included, simplify the cabling and electronics on a conversion project and should perform very well. I have my original handles fitted but disengaged to my X and Y ball screws and they spin freely during CNC movement but can be used to move the table manually when power is off. They do not pose a hazard and look good flipping around when videoing a part being machined. I have done my Z axis a bit differently and would welcome your feedback. I have been using Fusion 360 to Model and CAM some basic trial parts with great success and are ramping up my expectations now that my machine is proving its capabilities.
    http://www.cnczone.com/forums/knee-v...-new-post.html
    The whole project has been good fun and is now producing promising results.
    Looking forward to more from your thread and have subscribed.
    Cheers,
    John

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    Re: Bridgeport Series 1 Retrofit

    Mactec54 - I apologize for the brash tone yesterday. A brash tone in verbal conversation between two guys, is sometimes the way we guys get our point across. But, in the forum it is more difficult or impossible to understand the true meaning of someone's written word.

    There were two basic reasons needed to move the thread along, 1) my servos were purchased, they were installed, they were performance tested and I am happy with them. Further discussion of the merits of their integrated encoders was bringing nothing relative to the mission of the thread. 2) The thread had already accumulated 350 views, but no one was willing to join in until the encoder controversy was over. We have people joining now and for that I am happy.

    Mactec, I have read a number of your post, perhaps a hundred or more, certainly not the 5800 you are nearing, but, in all cases you try your dead level best to bring help, or to bring conclusion to whatever challenge the thread poses. I do not want the brash tone of my note to send a message to others, that I do not have confidence in you posts'.

    I believe you to be knowledgeable, I believe you to be professional, and I expect you to bring your experience here.

    BillT

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    Re: Bridgeport Series 1 Retrofit

    Quote Originally Posted by WilliamT4450 View Post
    Mactec54 - I apologize for the brash tone yesterday. A brash tone in verbal conversation between two guys, is sometimes the way we guys get our point across. But, in the forum it is more difficult or impossible to understand the true meaning of someone's written word.

    There were two basic reasons needed to move the thread along, 1) my servos were purchased, they were installed, they were performance tested and I am happy with them. Further discussion of the merits of their integrated encoders was bringing nothing relative to the mission of the thread. 2) The thread had already accumulated 350 views, but no one was willing to join in until the encoder controversy was over. We have people joining now and for that I am happy.

    Mactec, I have read a number of your post, perhaps a hundred or more, certainly not the 5800 you are nearing, but, in all cases you try your dead level best to bring help, or to bring conclusion to whatever challenge the thread poses. I do not want the brash tone of my note to send a message to others, that I do not have confidence in you posts'.

    I believe you to be knowledgeable, I believe you to be professional, and I expect you to bring your experience here.

    BillT
    I take no notice of how people respond to my posts, I used to fire back, but that solves nothing, I don't think there was any controversy, I just made a statement, that other should look at all options before buying

    Until you posted the Photos of your Build most, can't relate to what you were Posting, so Photos are good, if you want reply's, You will always have lots of lookers, I used to rebuild build Bridgeport machines, by the dozen, and CNC retro fit them, I only have one now that I just experiment with, like trying different servo Drives Motors Breakout Boards and different controls, here is a photo of the one I have left, this has may modifications, 6,000 RPM Spindle with Rigid Tapping, this mill now is getting a full Z axes with linear Rails, so will have a Head like a Machining Center has, this is just a spare time project
    Mactec54

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    Re: Bridgeport Series 1 Retrofit

    mactec- did you servo the spindle motor, or leave it an induction, single phase, three phase. and did you move from the R8 spindle?
    reason is, i am moving from the 1hp-3phase to possibly a servo, still looking at the posibilities

  16. #16
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    Re: Bridgeport Series 1 Retrofit

    Quote Originally Posted by WilliamT4450 View Post
    mactec- did you servo the spindle motor, or leave it an induction, single phase, three phase. and did you move from the R8 spindle?
    reason is, i am moving from the 1hp-3phase to possibly a servo, still looking at the posibilities
    The motor is a 3 hp 3 ph Bridgeport motor 3450 RPM some had these motors as standard, it is driven by a Yaskawa VFD Drive at 120 Hz giving it double the rated RPM, the spindle has a Erickson 30 Taper, which was also a standard on some machines, this spindle can run to 12,000 RPM as I have modified most of it, nothing in the Head is standard Bridgeport, the Head in the photo, is 5" shorter than the standard Head

    A Servo can work quite well for a spindle drive, and you have the benefit of being able to set it up just like an axes and have very tight positioning control, you would need different type of pulleys if you want accurate positioning of the spindle, servo motor size also would want to be no less than 1.5Kw if you were just replacing the 1Hp you have, the problem is as the servo motors get higher Hp the RPM also drop
    Mactec54

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    Re: Bridgeport Series 1 Retrofit

    Thanks Mactec for the info. Yep, I see the same thing you say about the servos. One has to decide the direction one wants to travel. I've got my eye on a 463 oz-in @6,000 rpm, 2kw servo. We'll see where this goes.

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    Re: Bridgeport Series 1 Retrofit

    Just a short post this morning.

    Description of photos are:

    1) Before disassembling the machine, the drive assembly sounded overall quiet and generally smooth. The bearings were a little rough and the belts had taken shape as all belts do in time without running. Overall, it was something to work with. As I tore the machine apart I found the spline drive shafts worn, as shown in the photos. The top shaft, attached to the belt hub shows slight wear with rounding on the edges. The bottom driven shaft shows more wear, with much more rounding on the edges. I reassembled the head anyway, knowing the head would come back apart soon with a redesign on the horizon.

    2) A blank piece of 6061 was thrown into the vice for a 'First Cut' test of the machine with varying result. I used a feed and speed calculator to determine the initial cut. Unfortunately, the SFM numbers vary quite a lot for 6061, so for a first test of the machine, this material is probably not the best. Regardless, the overall surface finish needs improvement.

    3) New spline drive shafts. Notice the sharper corners of the teeth. Sit firmly in the chair as you price these parts out!

    4) This is a handy book to have if you plan to disassemble the machine. There are detailed disassembly and reassembly procedures here with great photographs. My copy has an H&W sticker on the front. I'm not hawking their products, but their pricing is competitive and they ship quickly.

  19. #19
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    Re: Bridgeport Series 1 Retrofit

    Quote Originally Posted by WilliamT4450 View Post
    Thanks Mactec for the info. Yep, I see the same thing you say about the servos. One has to decide the direction one wants to travel. I've got my eye on a 463 oz-in @6,000 rpm, 2kw servo. We'll see where this goes.
    In most cases you need the Servo Drive that goes with that Servo Motor, and for your system you would want to make sure that Servo Drive will take Step/Dir signals
    Mactec54

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    Re: Bridgeport Series 1 Retrofit

    Yes, thanks, all the servo drivers I'm looking at come complete with matching servos drives. Don't want to mislead here, the torque mentioned earlier was Peak Torque @ 6,000. Continuous torque is lower.

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