Z-axis motor

Discussion in 'CNC Machines and Conversions' started by Rudy, Jun 5, 2019.

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  1. Dec 14, 2019 #21

    ahughes3214

    ahughes3214

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    Rudy,
    If you are still working on motorizing your z-axis; or anyone else who may be interested in ideas for motorizing the z-axis on a manual mill, I have finally finished the z-axis controller that I use for my manual PM30 mill.
    As I do with all my complex projects, I drafted a document that provides details on what I put together so I can maintain, fix, or improve years later. It's amazing how much one forgets after not working on a project for some time.
    I'm happy to share the document with anyone interested and the link is below. ** Implement any of the ideas at your own risk **
    https://www.dropbox.com/s/8rmyyv8vcq2l8vr/Mill Head Controller User Manual 2019Nov19 Ver37.docx?dl=0
    I know there is certainly room for improvement, so I welcome input from anyone willing to offer feedback.
    Apologies for not taking videos as I mentioned previously, I just have not got to that yet.
    Thanks,
    Drew
     
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  2. Dec 14, 2019 #22

    Rudy

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    Drew,
    Thank you so much for sharing this document. Not just any note, it's propper documentation! I have not yet got around to do my modification, so when I do, I will for certain study it in detail.
    I'm one year into a two year marathon work project that consumes most of my time, så I haven't been much in the shop lately. Looking forward to get back.
    Rudy
     
  3. Dec 14, 2019 #23

    deeferdog

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    Impressive. I would be far to embarrassed to show my grease stained, coffee blotched notes that even I can't read. Well done. Cheers, Peter
     
  4. Dec 15, 2019 #24

    Qtron

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    Hi ahughes, I just tripped over this thread re your slick z axis controller.. been watching Clough vids.
    Read your very nice manual, a/a.
    Where do I find the info to build the controller? I wish to fit it to my 270kg dovetail mill.
    Thanks,
    Qtron.
     
  5. Dec 16, 2019 #25

    ahughes3214

    ahughes3214

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    Qtron,

    Thank you for the feedback.

    I posted the document and pictures so anyone (who enjoys a project like this) and wishes to make their own controller may take away ideas and maybe avoid some pitfalls I experienced.

    It also gives the opportunity for others to critique what I have done and hopefully offer feedback I can incorporate to improve my design.

    Unfortunately, with regards to info to actually build the controller; I have no instructions or additional construction information beyond what I included in the posted document. I've been working on this project well over a year and it has evolved much over that time, starting with a breadboard and ending up with a custom PCB. I included the final wiring and setup instructions in my own document because the peripherals (power supply, motor controller, motor, limit sensors, etc.) may get damaged or fail. When time comes for me to replace these items, I need to remember how the heck I wired them.

    My apologies for the lack of info to build this controller; though I would be more than happy to (try to) answer any questions you may have that could help you develop your project.


    Thanks,
    Drew
     
  6. Dec 16, 2019 #26

    Qtron

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    Appreciate your prompt reply Drew.
    I can't write s/w, so no chance of creating my own controller.
    Did u use a pic or atmel or arduino?
    I'd love to see a photo of ur PCB, & perhaps the bgeneral interconnecting wiring diagram..
    Surely you must have a schematic of your own PCB? ;-);)
    Very hard to 'to critique what I have done and hopefully offer feedback I can incorporate to improve my design'
    if I cant see what you have done!
    I saw the last photo of the stepper, but cant see what it's connected to.. maybe its all internal to the head, so maybe not possible.
    Anyway your manual is well written, first class.
    Did U use C or C++ to write the code?
    Are you in the USA or?
     
  7. Dec 17, 2019 #27

    ahughes3214

    ahughes3214

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    Qtron,

    After a number of iterations I ended up using a Teensy 3.5 micro controller. Micro controllers like the Arduino MEGA were much too slow. I used the Arduino IDE to write the code (C++).

    The areas where I'm fishing for feedback is how I handled the user interface and also the boring "function" as detailed in the document. I use the word "function" very loosely as it is a simple setting for the mill head movement speed to bore (or drill) between a start and end point. I started thinking about feed rates vs tool size vs rpm, etc. to calculate a rate but that got crazy complicated. As a result, I decided to just put in the simple method to set the mill head feed rate. I also chose a boring/drill speed range of 0.006 to 12 inches per minute.

    Below is a picture of the circuit board with the Teensy 3.5 piggy backed onto my PCB. The hardware is straight forward and I'm not looking to solicit feedback or alter that again. I have already been through too many revisions for that piece.

    The controller unit has only a few inputs/outputs that are necessary; two limit inputs (top and bottom), external stop input, power input, and stepper output. The limit inputs can be either contact or inductive; I prefer the inductive. The stepper output drives an off the shelf stepper motor controller and motor.

    I am in the US. Thanks,
    Drew


     
  8. Dec 17, 2019 #28

    Qtron

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    thanks aga
    Thanks again Drew, yes a bit far to visit the scene of the crime!
    Nicely done indeed.. now i can see what your manual is referring to.
    Your Teensy must be doing sums on the fly for the amount of grunt the MCU has.
    I think i recognise the symbol on the chip - Freescale?
    Would an appropriate amount of $ help procure a prog'd MCU & gerbers for the adapter board, wiring info.?;) speeds/feeds charts annoy me cos my mill doesnt tell me how fast i am turning the handle! Bah.
    Can I just say, You, & others too, are in a VERY privileged position to be able to correctly conceive the solution, then write the code- if only the frustrated ones like me (old school analogue tech)
    could do the same.
    A big drawback health wise is sitting time - flat bum society stuff!
    My mill has a worm threaded shaft with handle that drives a spur cog, on the side of the mill head, which drives the rack spur gear to cause the quill to go up or down with a strong spring to counter balance the quill - i assume your stepper drives similar?
    i cant see any pics of how U have done that, except that your stepper appears to be on the top of the head?
    When i am using the quill i almost always set the brass clamping (locking) lever to a position that makes the quill a little stiff to move, to ensure the worn quill bore doesnt cause issues.
     
  9. Dec 22, 2019 #29

    ahughes3214

    ahughes3214

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    Qtron,

    I'm not sure which chip you are looking at with regards to "Freescale".

    What type of mill and model do you have? I have a Precision Matthews PM-30 that had the crank on the side of the column to move the head. It is a ridiculous placement that was much too high and also interfered with the DRO mount.
    Before I even purchased the machine, I knew I would not use the handle and I would be removing the handle completely.
    My stepper motor drives the lead screw directly from the top by means of a lovejoy coupler. I replaced the standard lead screw with a ball screw. This also necessitated the replacement of the top plate to mount the ball screw bearing.

    The mill came with a gas strut that was sufficient, but I did replace it to get a little more travel.

    I will need to think about whether it would be feasible to sell a programmed MCU and PCB. There are many things that need to be considered to make it viable for you and it could turn out to be a waste to you.

    1) My controller is setup specifically for a lead screw with a 5mm pitch. I installed a SFU1605-600 ball screw with bearing. A ball screw is needed so a huge stepper can be avoided. Also, a smooth low friction screw will help avoid missed steps, etc.
    2) The stepper setup also necessitated the fabrication of a custom ball screw to head mount, top plate, and motor mounts.
    3) You lose the manual crank all together (to integrate into the new ball screw would have been extremely complex).
    4) In addition to the controller unit, there are other substantial parts; stepper motor, stepper motor controller, ~75VDC stepper power supply, and External dual voltage power supply for the controller
    5) Soldering up the board is very time consuming and also has some very tight pitches (1.25mm) for the connectors
    6) More than the MCU and PCB would be needed. A specific 2.8" TFT display and driver chip must be used, the rotary encoder needs to be modified for pull up resistors, etc.

    The above is not meant to be discouraging, just trying to think about all the nuances of pulling this together. Many would consider this too complex for a manual machine. They would also consider this far too expensive for a bench top machine.

    What type if analog circuits have you worked on in your career?

    Thanks,
    Andrew
     
  10. Dec 23, 2019 #30

    Qtron

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    I looked up teensy and saw what I thought was Freescale logo on a chip.
    But dunno what chip u actually used.
    Not familiar w teensy.
    ...
    Mill is old, uncommon. Floor standing.
    120 mm quill stroke,
    350 mm knee travel, on dovetail pillar.
    Motor 1.1 kW, 4 speeds.
    Boring work usually done with quill locked and knee travel used.
    Quite heavy to raise, no counter weights, needs gas strut I guess.
    Probably cant justify big $ to do what u have so nicely done.
    Not enough customers ATM.
    ...
    Audio filters, mainly, application specific. Some filters designed, had to done with a minimum active devices, tricky!
     
  11. Jan 6, 2020 #31

    ahughes3214

    ahughes3214

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    Qtron,

    Apologies for the delay in response; with the holiday, getting back to work, etc. it has been quite busy. I wanted to follow-up on our conversation (e.g. #4) and let you know what is into my unit with regards to cost. This may allow you to make a more informed decision on whether you would like to pursue a solution like this one. I get all my stuff off the retail market, so the costs are from ebay, Amazon, Digi-Key, etc. Below is the rough estimates for the parts and materials that went into the controller setup. As this is my hobby, I did not list any values for time spent machining, machine disassembly, reassembly, electronics assembly, cable making, testing, etc..

    Ball screw and bearing: $ 100
    Steel (new head support for ball screw): $ 25
    Gas strut for mill head: $ 30
    Lovejoy connector: $ 30
    Stepper motor and controller: $ 170
    Stepper power supply: $ 70
    Aluminum for stepper mounts and top plate: $ 50
    Various cabling: $ 10
    Mill Controller, limits, and power supply: $ 450
    External stop button: $ 10

    Rough material costs (no time or labor): $ 945

    If it is something you decide to move forward on, and if my electronics can help, we can probably work something out. I would want to include some important parts of the controller so you have a better chance of success.

    I think the more important part to get started with is your plans for how you would motorize your Z-axis. That I think is the most challenging part for an old machine as much of the information out there for adding motors to axis deals with the dovetail bench machines.

    Many years ago, I started as an instrumentation tech within a manufacturing company for the process and power industries. It was a really good starting point for the hardware and software and solidified the hobby for me. Machining came much later.

    Thanks,
    Andrew
     
  12. Jan 6, 2020 #32

    Qtron

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    wow big $,
    hope its paid for itself! thanks for the detailed response- much appreciated Andrew.
    One thing I don't get, & of course i havent seen the schematics of the mother board that the teensy sits on,
    but it seems complex. I see you chose a Lovejoy coupling.. not Oldham?
    Yes mechanical issues re where, what, how. Am wrestling with all this right now as am in the midst of employing an ELS on my lathe (Clough42, Youtube).
    One point i am trying to stick to is to retain full original manual operation should something fail.
    Can you do this with Z Mill control?
    looking at sites like banggood.com, stepperonline-OMC, etc, it seems prices could be trimmed.
    labour is expensive tho, wife is a shed widdow, THATS expensive.
     
  13. Jan 14, 2020 at 3:32 AM #33

    ahughes3214

    ahughes3214

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    Qtron,
    Nothing much I do ever pays for itself. Though I'm really am happy with this controller; I would never go back to manual cranking again.
    The majority of the components are related to de-bounce, noise rejection, and input selection.
    Lovejoy connector was just convenient to use.
    To retain manual control of the hand wheel for the z-axis I would need to special order, or machine the ball screw to accept the ring gear that meshes with the crank handle. I did not want to bother because the crank is in a terrible location anyway. An unusable position in my opinion.
    Most certainly could trim costs by doing more creative sourcing. Though it is much easier to go to places like Digi-Key and get exactly what you need.
    Thanks,
    Andrew
     
  14. Jan 14, 2020 at 3:58 AM #34

    Qtron

    Qtron

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    Thanks for your reply Andrew, my machines have paid for themselves but not the associated tooling. Years ago.
    Manual cranking esp smaller motions with the DRO is handy for fine tuning a setup. But i havent used yours!
    The normal usage, the most accurate way is to raise & lower the knee when boring.
    It has a larger Z travel, & the quill would be locked.
    But winding the Knee up as is, without a gas strut fitted, requires lots of mechanical force input.
    so the stepper motor would have to be huge - Will have to investigate how to mount struts, travel span, forces etc.

    How much, do you estimate was spent on the actual electronics? so not limit sensors, power supply, just the pcb's..
     

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