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IndustryArena Forum > OpenSource CNC Design Center > Open Source Controller Boards > Open source low cost servomotor controller
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  1. #41
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by RCaffin View Post
    Not wrong planet - wrong galaxy.
    Cheers
    Roger
    Right?

    Heaven forbid that someone should use a professional EDA package instead of the industry's equivalent of Duplo.

    In a more bridge-building, happy light, though, here's a suggestion:

    mcdowswe, if you have the time would you mind adding some files to the github project? In particular, if you can do a generate & export of gerber files for the PCBs, anyone can get them made pretty much anywhere. A PDF export of the schematics would mean those without Altium would also be able to trace things down. If all anyone wants to do is make boards per your design a little bit cheaper this'd be all they needed.

    And it would mean that anyone who wanted to modify the design for themselves would be able to create (and, obviously, publish in the spirit of open source) an Eagle format mirror of the design files.

  2. #42
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    Totally Awesome

    Macdowswe,

    Your work is totally awesome, even better than a triple chocolate custard filled bismark!

    I would also like to thank Websrvr for all his generous contributions and personally wish him happy holidays.
    Santa will visit soon and all the children will be happy too.
    Live from downtown Burbank home of the world famous Christmas Kringle.
    JoeyB



    Quote Originally Posted by macdowswe View Post


    The time has finally come for the manufacturing run of ODrive v3.1. They are now on the way, and should arrive early to mid January.

    At this stage, around 20 board kits are going out the people who signed up to the "Inital development" phase. They have not been all allocated yet, you can signup here.

    Since the boars are going out to just a small group of early developers, I will have the time to personally get you up to speed with the codebase and help to get going with the hardware. Then, together, we can prepare some stuff that is a bit more stable and a bit more documented for when the alpha testing begins.

    The cost for me to get this small batch of boards manufactured was $96 per board, so that is the amount I need to ask for a kit, plus shipping.

    The kit involves basically everything seen in the above picture, and consists of:

    • ODrive v3.1
    • USB Programmer
    • A set of the optional large gauge wire screw terminals
    • A set of pin headers
    • Some nylon standoffs


    I hope that ODrive will be able to help you make an awesome robotics project, thank you so much for your contribution to helping people have access to open robotics hardware and software.
    A doughnut a day keeps the doctor away.

  3. #43
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    Re: Open source low cost servomotor controller

    Hi websrvr

    To explain: this is a hobby project one person is running, and he is running it HIS WAY, as is his right.
    It might fly, or it might not. It might be too expensive, or it might not. But it is HIS project.
    Since it is HIS project, he is at liberty to publish how he wants and as much or as little data as he wants. That is HIS choice.
    For anyone else to come along and try to take the project over and dictate how data should be made available is not only wrong, it is impolite and futile.

    My 2c
    Cheers
    Roger

  4. #44
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by aarggh View Post
    I couldn't see it anywhere but are you planning on producing 3 axis boards?

    Very cool looking project, major props getting it out there!

    cheers, Ian
    Hey, thanks!
    So yeah many people have requested a 3 axis version, and the plan is to do that for v4. I have already identified a microcontroller that has the peripherals required for that.

    Cheers,
    Oskar

  5. #45
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    Re: Open source low cost servomotor controller

    So on the topic of websrvr's offer and the resulting discussion:
    I am intending to make the price point lower than $96, as I already stated previously in the thread, the target price is around $50.
    I have many different options to chose from, including one guy over at the OpenPnP mailing list who offered to manufacture 50 boards for free to get the project started.
    I chose to go with CircuitHub to get some prototype boards done quickly.

    Can we please keep the topic of the thread about not this now?
    How about: What kind of forces are required to do CNCing on your machine? Do you use leadscrews or belts?

    Cheers,
    Oskar

  6. #46
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by dharmic View Post
    Right?

    Heaven forbid that someone should use a professional EDA package instead of the industry's equivalent of Duplo.

    In a more bridge-building, happy light, though, here's a suggestion:

    mcdowswe, if you have the time would you mind adding some files to the github project? In particular, if you can do a generate & export of gerber files for the PCBs, anyone can get them made pretty much anywhere. A PDF export of the schematics would mean those without Altium would also be able to trace things down. If all anyone wants to do is make boards per your design a little bit cheaper this'd be all they needed.

    And it would mean that anyone who wanted to modify the design for themselves would be able to create (and, obviously, publish in the spirit of open source) an Eagle format mirror of the design files.
    So the schematic pdf is already available on GitHub: Link.
    Yeah other people have already asked for gerbers. The reason I haven't provided them yet is because there are still some bugs in the hardware design, that I hope will be fixed with version 3.1 (the one currently being manufactured). Only when I have verified that the bugs are solved will I be comfortable in recommending others to manufacture boards of their own.

    Cheers,
    Oskar

  7. #47
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    Re: Open source low cost servomotor controller

    Champion, Oskar. And thank you for your efforts with this design - and for deciding to share it with us. Very generous of you!

  8. #48
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by macdowswe View Post
    So on the topic of websrvr's offer and the resulting discussion:
    I am intending to make the price point lower than $96, as I already stated previously in the thread, the target price is around $50.
    I have many different options to chose from, including one guy over at the OpenPnP mailing list who offered to manufacture 50 boards for free to get the project started.
    I chose to go with CircuitHub to get some prototype boards done quickly.

    Can we please keep the topic of the thread about not this now?
    How about: What kind of forces are required to do CNCing on your machine? Do you use leadscrews or belts?

    Cheers,
    Oskar
    Hi we use 4nm motors on our mills and lathes if that helps


    Gesendet von iPad mit Tapatalk

  9. #49
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by Tkamsker View Post
    Hi we use 4nm motors on our mills and lathes if that helps


    Gesendet von iPad mit Tapatalk
    Cool!
    How difficult would it be for you to install a motor that was 1Nm, but could spin 4 times faster?
    Would this be a dealbreaker?

  10. #50
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    Re: Open source low cost servomotor controller

    Hi
    difficult not but depending on the prices of motors. The issue is normal the power curve we use Nanotec st6018 L3008 now and to get similar curve i need an bigger motor than https://granitedevices.com/store/bl7...th-cables.html or Welcome to Delta Group we would end up in 750W range. We do lathes and mills for steel (similar to torch or Novakon ) but really build in europe no china stuff ! so the advantage of servo is that it can turn around 2k-3k RPM compared to stepper 0,52 - 0,75k And looking at the curves there is a power gap (similar to 2 stroke engines - if we overcome that i would be verry interested. thomas

  11. #51
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by Tkamsker View Post
    Hi
    difficult not but depending on the prices of motors. The issue is normal the power curve we use Nanotec st6018 L3008 now and to get similar curve i need an bigger motor than https://granitedevices.com/store/bl7...th-cables.html or Welcome to Delta Group we would end up in 750W range. We do lathes and mills for steel (similar to torch or Novakon ) but really build in europe no china stuff ! so the advantage of servo is that it can turn around 2k-3k RPM compared to stepper 0,52 - 0,75k And looking at the curves there is a power gap (similar to 2 stroke engines - if we overcome that i would be verry interested. thomas
    So I had a look at the stepper you are using, and it has the following speed/torque profile:
    Attachment 343774

    I calculated the mechanical power capability at the selected point, and it turns out to be 17W. If you check the table of motors I made at the bottom of the motor post on the project page (link), you can see that they can deliver a much higher power, and they are very inexpensive. For instance, the Turnigy Aerodrive SK3 - 4250-350kv will run relatively cool at 0.7Nm, and it will happily run up to 7k RPM.

    So basically, the inexpensive brushless motors are not as high torque, but they make up for it by being much faster, and able to deliver full torque through the whole speed range, and hence being much higher power.

  12. #52
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    Re: Open source low cost servomotor controller

    Hi,
    thank you i see the data funny the Link i use is Nanotec: ST6018 Schrittmotor - NEMA 24 We never run the motors faster than 562.2 RPM because of the power delivered. We also need some force to decelerate our mill. I am sure (or not sure depends ) that the motor your mentioned has much lower braking resistance as we need for our application. But in the hopefully quiet time i will have a look on the data you mentioned ,.. i am not sure they can deliver the flu torque around the full speed range but it may be worth a check ,.. and you have col project on rout hp thumbs up

  13. #53
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by Tkamsker View Post
    Hi,
    thank you i see the data funny the Link i use is Nanotec: ST6018 Schrittmotor - NEMA 24 We never run the motors faster than 562.2 RPM because of the power delivered. We also need some force to decelerate our mill. I am sure (or not sure depends ) that the motor your mentioned has much lower braking resistance as we need for our application. But in the hopefully quiet time i will have a look on the data you mentioned ,.. i am not sure they can deliver the flu torque around the full speed range but it may be worth a check ,.. and you have col project on rout hp thumbs up
    Yeah when it comes to deceleration, the motors are not very high friction, so you will need to actively brake the motors. The resulting energy absorbed can be either dumped into a brake resistor, or if you use a battery, you can charge the battery.

    Thanks, I hope it can be useful!

    Cheers,
    Oskar

  14. #54
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    Re: Open source low cost servomotor controller

    I think $96 is rather reasonable for a two driver board. Anyone who has priced a commercial brushless servo driver from companies like Parker, Applied Motion, Copley, AMC will pay a couple hundred more for a single driver solution. $48 per driver is rather cheap. I'm actually interested since I have a couple of larger CMC brushless motors that have peak current well over 35amps. My Applied Motion brushless drivers are max 14amps. The 24 volt supply voltage is the limiting factor. I have to look up the Kv parameter to see what rpm the motor can achieve with only a 24volt supply.

  15. #55
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    Re: Open source low cost servomotor controller

    Ho Oskar,

    I was thinking about this project and I really think to get some critical mass you should target the 6040 purchasers. The 6040's all come with a non-functioning crappy blue box TB6560 based controller, and usually the only good option is a G540, which puts it seriously over budget for a lot of people. A 3 axis (or 2 x 2) controller with a "cheat sheet" on hooking it up for these machines will be an instant target market for you I believe.

    If your solution is coming in around half the cost of the G540, it seems your ideally positioned for taking this quite large segment on head on which no other vendor is doing now!

    cheers, Ian
    It's rumoured that everytime someone buys a TB6560 based board, an engineer cries!

  16. #56
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    Re: Open source low cost servomotor controller

    A 2 axis board at that prices would be good for useing it as a coil winder motor controller, or a small lathe
    http://danielscnc.webs.com/

    being disabled is not a hindrance it gives you attitude
    [SIGPIC][/SIGPIC]

  17. #57
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by aarggh View Post
    Ho Oskar,

    I was thinking about this project and I really think to get some critical mass you should target the 6040 purchasers. The 6040's all come with a non-functioning crappy blue box TB6560 based controller, and usually the only good option is a G540, which puts it seriously over budget for a lot of people. A 3 axis (or 2 x 2) controller with a "cheat sheet" on hooking it up for these machines will be an instant target market for you I believe.

    If your solution is coming in around half the cost of the G540, it seems your ideally positioned for taking this quite large segment on head on which no other vendor is doing now!

    cheers, Ian
    However these 6040 type cnc's come with steppers. Converting to servo motors isn't a hard task but the cost of drivers, servo motors, encoders, motor mounts etc. will be atleast the cost of a gecko540 I would think.

  18. #58
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by macdowswe View Post
    So on the topic of websrvr's offer and the resulting discussion:
    I am intending to make the price point lower than $96, as I already stated previously in the thread, the target price is around $50.
    I have many different options to chose from, including one guy over at the OpenPnP mailing list who offered to manufacture 50 boards for free to get the project started.
    I chose to go with CircuitHub to get some prototype boards done quickly.

    Can we please keep the topic of the thread about not this now?
    How about: What kind of forces are required to do CNCing on your machine? Do you use leadscrews or belts?

    Cheers,
    Oskar
    I think you have a good idea for a much needed product and I'm hoping you are successful in meeting your goals and hopefully provide a final product that is a transition away from stepper motors.

    Leadscrews, ballscrews, belts along with machine size, drag and mass all have different motion/drag coefficiencies and the HP to weight ratio is more important when offsetting cutting forces when selecting a drive to make it move so you can't get results from a CNC machine and use them as a blanket statement/value representing all machines.

    Now, I believe this project is targeting the home/hobby/DIY users who really need a solid solution but the off-chance that you could grab a large portion of the 6040 market is unrealistic considering that not only would they need to purchase the board, they would need to purchase motors with encoders, fabricate mounts for their specific machine and power supplies as well and the only person I know who produces inexpensive BLDC servo motors isn't a business and doesn't stock or sell them to the general public so waiting to hear about an up-coming production run is on my monthly to-do list so I don't miss out as I stash a small collection of suitable BLDC servo motors and if I had an extra $13K I could spare for a year I'd just make my own production run (200pcs) and sell the BLDC servo motors on ebay.

    Of course I've seen the DIY 2500KV and 3500KV outrunners motors reworked to add an encoder or hal sensors which seem suitable for router type machines but even this is an expensive solution unless you have the motors and encoders laying around.

    I purchased 5pcs of a single axis 10A (25A peak) 60V STM32F1 based servo driver including heatsink for cheap and have the eagle files for them, so I am able to produce the board for cheaper than I paid but the issue is I have no firmware because the guy who created it isn't sharing it or giving it out and I'm not a programmer so I've set the files aside for a later time since I was also able to get my hands on 3pcs of the assembled board for free which don't have any firmware and the ones with firmware are set up so you can't dump the firmware from them to write to the empty boards.

    Adding additional axis would cost roughly $10.00 per axis or less in a small quantity run so your driver in 3, 4 or 5-axis is very possible if the hardware is reworked as needed.

    According to my friend, one of the major design issue is related to FET current/peak current and requires alterations, use different FET's, copper thickness should be 3oz minimum and to allow for higher peak current based on trace surface area and thickness, stopping the trace would allow you to use up to a 6A noload current motor which will typically have up to 30A peak current requirement depending on it's design and intended use, bigger inertia motors have lower RPM and are more suited to axis driving but low inertia motors will have faster acceleration and provide significantly higher rapids due to the higher achievable RPM so there is some flexibility/trade-off depending on the machines mechanical limitations but also consider, the cost of a decent (such as Tamagawa) 10KRPM encoder is about $100.00, a decent (such as Tamagawa) 16KRPM encoder is about $160.00 and a decent (such as Tamagawa) 20KRPM encoder is around $200.00, luckily I have a source for 16KRPM A/B/Z encoders for $31.00ea so high speed incremental encoders isn't an issue I have to deal with.

    Your PDF schematic reference schematics not in PDF format so it couldn't be properly examined however, from the available PDF schematic he says it doesn't look like the motor encoder signals utilizes complimentary or balanced input signals (+/-) thus advising, adding something like a MAX3097ECSE encoder receiver which supports A+/A-/B+/B-/Z+/Z- input signals with single ended A/B/Z outputs and includes outputs for individual encoder signal errors and a combined encoder error output line so you can drive LED's for individual (A/B/Z) error lines and use the combined error line to notify the MCU that the encoder has an error requiring you to look at the board to see which encoder signal is at fault which could be open, shorted, missing pulses etc...

    Because they can't wait for you to finish the design to obtain something for their own lathe project, someone else following this project has decided to create Eagle v7.7.0 files and he's paying my friend to fix the major electrical issues and sadly he has no desire to share the files he creates at his expense so no one else can benefit and this sucks because I think it's selfish but I do understand his logic since he's paying to get it for his own use and not interested in sharing at his expense.

  19. #59
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    Re: Open source low cost servomotor controller

    Quote Originally Posted by aarggh View Post
    Ho Oskar,

    I was thinking about this project and I really think to get some critical mass you should target the 6040 purchasers. The 6040's all come with a non-functioning crappy blue box TB6560 based controller, and usually the only good option is a G540, which puts it seriously over budget for a lot of people. A 3 axis (or 2 x 2) controller with a "cheat sheet" on hooking it up for these machines will be an instant target market for you I believe.

    If your solution is coming in around half the cost of the G540, it seems your ideally positioned for taking this quite large segment on head on which no other vendor is doing now!

    cheers, Ian
    Quote Originally Posted by jfong View Post
    However these 6040 type cnc's come with steppers. Converting to servo motors isn't a hard task but the cost of drivers, servo motors, encoders, motor mounts etc. will be atleast the cost of a gecko540 I would think.
    I checked ebay very briefly, and I found that there are kits available without any motors or controllers for $800, Link, and that kits with motors, driver, spindle and spindle driver are about $1300, Link. Supposing someone currently has to spend $300 on a G540 on top of the full kit (totaling $1600) to get a usable system, that leaves a $800 space to compete in.

    One approach is to just buy a VFD and a spindle motor, and subtract that off the $800 margin, and start from there. For the motion, I know there exist appropriate motors, appropriate dirt cheap encoders, and the missing piece would be some mechanical bits to put it all together.

    However, in a more interesting scenario, we go one step further: We could use two ODrives: three channels for motion and the 4th channel to drive the spindle. For the spindle, you could do something like this: Link.

    In both cases, I think we have a chance to do something interesting here ;D

    Cheers,
    Oskar

  20. #60
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    Re: Open source low cost servomotor controller

    websrvr makes a very good point about the ability of the copper foil on a PCB to support the peak currents. Take note of his concerns.
    I have met problems here myself. It's not just the current carrying ability, its also about how you connect TO the copper. Abrupt transitions between heavy connectors and light foil can be problematic, as shown here (commercial unit):
    Attachment 343960
    I did wonder why the driver had stopped working!
    But there were other faults on the PCB as well. Eventually I replaced the 3 units with 3 Gecko drivers.

    Anyhow, there are design guides on the web for the current carrying capacity of copper tracks.

    Cheers
    Roger

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