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IndustryArena Forum > WoodWorking Machines > DIY CNC Router Table Machines > Can two clearpath servos be used to power one axis?
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  1. #1
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    Can two clearpath servos be used to power one axis?

    I am planning a build of a 6x4 router build, and am considering the use of clearpath servos. Has anyone else used these where TWO are required to drive both sides of the gantry to move X?

    I really like them, and am pretty set on using them, but the design I want to use needs two motors, and I understand this can be a problem for the clearpath servos, both in set up and perhaps in running as they dont stall out due to having high torque, so if things got of square could it lead to more serious problems?

  2. #2
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    Re: Can two clearpath servos be used to power one axis?

    I doubt it is a problem for the motors or the drives. Dual drives on large rigs are common enough.
    It might be a problem for the gantry if it gets out of square - but that is a separate issue.

    Cheers
    Roger

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    Quote Originally Posted by Dangle_kt View Post
    I am planning a build of a 6x4 router build, and am considering the use of clearpath servos. Has anyone else used these where TWO are required to drive both sides of the gantry to move X?

    I really like them, and am pretty set on using them, but the design I want to use needs two motors, and I understand this can be a problem for the clearpath servos, both in set up and perhaps in running as they dont stall out due to having high torque, so if things got of square could it lead to more serious problems?
    If you read the FAQ on Teknic's site they briefly explain the procedure, but it does look like a bit of "work" as you'll need 2 computers to tune both motors simultaneously.

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    Re: Can two clearpath servos be used to power one axis?

    These are good questions. Dual motor axes are very common and are not a problem for servo motors when the integration is done correctly.

    Out-Of-Square

    It is true that closed loop servos will not lose steps or stall so mispositioning based on these events is prevented. However, if one motor shuts down and the other motor does not also shut down in a timely fashion, it could cause some tension on the gantry (not excessive because one motor is disabled and free to move, but some). The goal here is to have both motors following the same command in real time and to also to be enabled and disabled at the same time. The way to do this is to wire the HLFB output signal ("Servo On" option) from each motor in series with each other. Wiring them in series makes them act like a gate at each motor so if any motor gets a shutdown, it will interrupt the continuity of the circuit the resulting voltage back to your controller will be 0VDC. The controller will see this low state and will disable all the motors.

    "HLFB+" from your controller into motor 1, "HLFB-" out of motor 1 and into "HLFB+" for motor 2, "HLFB-" from motor 2 back to your controller

    This technique means that both motors will be disabled if one motor gets a shutdown. When you resume machine operation, you will need to re-home (square-up) the machine before cutting.

    Tuning Dual Motor Axes

    Yes, there is advice on tuning a dual motor axis on Teknic's website but this process was used more in the past for OEM customers with two trained engineers using manual tuning techniques. Now with the ClearPath auto-tuner, there is actually an easier process that can be used. The basic steps are listed below.

    1) X and Y axes almost always have the exact same mechanical design (same dia pinion, same rack pitch, etc.) to make the machine easier to build and to make the command generation easier

    2) The vertical Z axis is almost always a different mechanical design than the X and Y so generally speaking, it should not be used to create a dual axis motor file

    3) The optimal way to create a dual X file using the auto-tuner is to load 1/2 the total X gantry weight onto the single Y axis and then run the auto-tuner. You usually would not use the Z axis because it is biased downwards based on gravity (which dual X axis is not) and because of the mechanical differences.

    4) After auto-tuning the Y axis with the additional weight, load the Y file into both X motors.

    5) Click the "Reverse Direction" checkbox for one of the X motors and save the two X motor files with different names (e.g. XA_SDSK-3421S_rev1 and XB_SDSK-3421S_rev1)

    6) Run the machine. If the X axis does not seem to have optimal tuning, trying moving the "Fine Tuning" slider to the left to see if your results are better. You will need to do this with both X motor files before evaluating the effectiveness of this step. If you make any changes, re-save the new files (overwrite the old files or create new names) and save the files in a safe location for the future.

    7) If you are still having problems with your dual motor axis after following this technique, you can contact Teknic directly for technical support.

  5. #5
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    Re: Can two clearpath servos be used to power one axis?

    Quote Originally Posted by TeknicTom View Post
    These are good questions. Dual motor axes are very common and are not a problem for servo motors when the integration is done correctly.

    Out-Of-Square

    It is true that closed loop servos will not lose steps or stall so mispositioning based on these events is prevented. However, if one motor shuts down and the other motor does not also shut down in a timely fashion, it could cause some tension on the gantry (not excessive because one motor is disabled and free to move, but some). The goal here is to have both motors following the same command in real time and to also to be enabled and disabled at the same time. The way to do this is to wire the HLFB output signal ("Servo On" option) from each motor in series with each other. Wiring them in series makes them act like a gate at each motor so if any motor gets a shutdown, it will interrupt the continuity of the circuit the resulting voltage back to your controller will be 0VDC. The controller will see this low state and will disable all the motors.

    "HLFB+" from your controller into motor 1, "HLFB-" out of motor 1 and into "HLFB+" for motor 2, "HLFB-" from motor 2 back to your controller

    This technique means that both motors will be disabled if one motor gets a shutdown. When you resume machine operation, you will need to re-home (square-up) the machine before cutting.

    Tuning Dual Motor Axes

    Yes, there is advice on tuning a dual motor axis on Teknic's website but this process was used more in the past for OEM customers with two trained engineers using manual tuning techniques. Now with the ClearPath auto-tuner, there is actually an easier process that can be used. The basic steps are listed below.

    1) X and Y axes almost always have the exact same mechanical design (same dia pinion, same rack pitch, etc.) to make the machine easier to build and to make the command generation easier

    2) The vertical Z axis is almost always a different mechanical design than the X and Y so generally speaking, it should not be used to create a dual axis motor file

    3) The optimal way to create a dual X file using the auto-tuner is to load 1/2 the total X gantry weight onto the single Y axis and then run the auto-tuner. You usually would not use the Z axis because it is biased downwards based on gravity (which dual X axis is not) and because of the mechanical differences.

    4) After auto-tuning the Y axis with the additional weight, load the Y file into both X motors.

    5) Click the "Reverse Direction" checkbox for one of the X motors and save the two X motor files with different names (e.g. XA_SDSK-3421S_rev1 and XB_SDSK-3421S_rev1)

    6) Run the machine. If the X axis does not seem to have optimal tuning, trying moving the "Fine Tuning" slider to the left to see if your results are better. You will need to do this with both X motor files before evaluating the effectiveness of this step. If you make any changes, re-save the new files (overwrite the old files or create new names) and save the files in a safe location for the future.

    7) If you are still having problems with your dual motor axis after following this technique, you can contact Teknic directly for technical support.
    Tom, thank you for taking the time to visit here and reply. As someone who is also looking into, and excited about, the ClearPath products, this is some valuable information.

  6. #6
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    Re: Can two clearpath servos be used to power one axis?

    Thanks Tom, really useful info - I read a similar description on a youtube video review.

    Can you possibly advise which of your servos I am best picking?

    I have heard the motor spec I am after must be equal or better than this

    Item # PK296A2A-SG7.2, Stepper Motor On Oriental Motor U.S.A. Corp.

    Also, can I really run all 4 servos off one of your power supplies?

    Cheers

  7. #7
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    Re: Can two clearpath servos be used to power one axis?

    can I really run all 4 servos off one of your power supplies?
    I have ammeters on all my servo drives. Even when milling steel the ammeters do not show much current.
    The spindle will show a load when it is drilling.

    Cheers
    Roger

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    Re: Can two clearpath servos be used to power one axis?

    Hi Dangle_kt,

    You will need a step and direction servo motor so you are looking at the SD family of ClearPath.

    You will probably get very good results with the CPM-SDSK-3411S-RLN. You can get 70% more peak torque and 80% more continuous with the CPM-SDSK-3421S-RLN for $21. If you want high resolution (6,400 cnts/rev instead of 800 cnts/rev), get the -ELN instead of the -RLN.

    Whether you can run 4 servos off of one power supply depends on a lot of things like motor size, static friction, dynamic friction, # of axes accelerating all at once at what acceleration rate, are any axes decelerating (regenerative power being put back into the system) versus how axes are accelerating, etc. If you are concerned with cost, you could buy one power supply and then test your machine. If you run into problems under certain scenarios, you can either lower accelerations and/or duty cycles or simply add another power supply.

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    Re: Can two clearpath servos be used to power one axis?

    Hi RCaffin,

    Most multi-meters are good for many things, like checking for continuity, but they collect and display data too slowly for things like measuring peak current draw. Fast accelerations may require peak torque (peak current draw) for a period of time measured in milliseconds. These peaks are often too fast for the meter to display. Using an oscilloscope is the only way to be sure that you are measuring true peak requirements.

    Running (4) NEMA23 motors with (1) IPC-5 should be no problem.

    Running (4) 1 stack NEMA34 motors (e.g. 3411) with (1) IPC-5 "should" be no problem (but needs to be tested to be sure)

    Running (4) 4 stack NEMA34 motors (e.g. 3441) will probably require two power supplies (but it depends on your accelerations, friction, duty cycle, etc.)

  10. #10
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    Re: Can two clearpath servos be used to power one axis?

    Tom,

    In the website it mentions the power can be daisy chained from servo to servo. Does it matter then if say, the X and slave axis motors are daisy chained and hooked up to one output on the IPC, and the Y and Z are hooked up in a star configuration on the second output?

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    Re: Can two clearpath servos be used to power one axis?

    Hi Louie,

    No, it doesn't matter how you configure it. You can do whatever is most convenient. Some power supplies (like the DC power supply for my landscape lights) have a partition between the two output connectors. Balancing the load here is very important.

    All of the circuitry for the IPC-5 power supply outputs are in parallel so really the only consideration is the power cable quality and wire size that you use. Connecting everything in a daisy-chain fashion would require a "heavier" gauge (not necessarily heavy, just "heavier") than if you used a star configuration. The Teknic PWR DC power cables are made with 16 gauge wire with lengths up to 55 feet long.

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    Re: Can two clearpath servos be used to power one axis?

    Thanks Teknic tom, I maxed out all the options on the top model you listed and with 55ft cables for everything, power supply and shipping I'm already at $3100... I may try a more modest quote to see if I can justify the extra.

    Thanks

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    Re: Can two clearpath servos be used to power one axis?

    Dangle_kt,

    That seems really high, though I don't know what you are building.

    I am guessing that you chose the HP model "just to be sure". The HP model is important for "high speed-high power" applications like pumps and fans where the load never gets easier to move. In other words, thanks to Newton, we know that it takes the most torque to get a mass moving from a standstill up to a constant velocity (this is all about peak torque requirements, not power). Once you get to that constant velocity, it gets much easier to maintain that velocity. Deceleration will require more torque than running at constant velocity, but less torque than the acceleration phase because friction helps you slow down.

    if you want the high resolution of the HP (6,400 cnts/rev) but don't need the extra power, you can order the SDSK with the -E option (the default -R option is 800 cnts/rev).

    Running a pump at high speed with a viscous load that never gets easier to move requires higher power than an inertial type load, like a gantry. We just don't want you to spend more money than necessary to achieve your expected results.

  14. #14
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    Just as a heads up guys I've been trying for over two weeks now to get a set of servos from these guys to test out. I live slightly over an hour from their sales office/factory and have gotten zero help from them.

    Apparently they won't let the small guy pick up from them. So as to save a bit of cash. They'd rather screw around and make life difficult for everyone involved.

    Have spoke to Aaron/Erik/another random.

    Erik was the most helpful but difficult to get in touch with.

    So beware if you purchase/try to establish a relationship with these guys






    Quote Originally Posted by TeknicTom View Post
    Dangle_kt,

    That seems really high, though I don't know what you are building.

    I am guessing that you chose the HP model "just to be sure". The HP model is important for "high speed-high power" applications like pumps and fans where the load never gets easier to move. In other words, thanks to Newton, we know that it takes the most torque to get a mass moving from a standstill up to a constant velocity (this is all about peak torque requirements, not power). Once you get to that constant velocity, it gets much easier to maintain that velocity. Deceleration will require more torque than running at constant velocity, but less torque than the acceleration phase because friction helps you slow down.

    if you want the high resolution of the HP (6,400 cnts/rev) but don't need the extra power, you can order the SDSK with the -E option (the default -R option is 800 cnts/rev).

    Running a pump at high speed with a viscous load that never gets easier to move requires higher power than an inertial type load, like a gantry. We just don't want you to spend more money than necessary to achieve your expected results.

  15. #15
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    Re: Can two clearpath servos be used to power one axis?

    Quote Originally Posted by Dangle_kt View Post
    Thanks Teknic tom, I maxed out all the options on the top model you listed and with 55ft cables for everything, power supply and shipping I'm already at $3100... I may try a more modest quote to see if I can justify the extra.

    Thanks
    Look at Dmm for a better price, and much better encoder option

    DMM | AC SERVO DRIVE | AC SERVO MOTOR | ROTARY ENCODER
    Mactec54

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    Quote Originally Posted by ericclinedinst View Post
    Just as a heads up guys I've been trying for over two weeks now to get a set of servos from these guys to test out. I live slightly over an hour from their sales office/factory and have gotten zero help from them.

    Apparently they won't let the small guy pick up from them. So as to save a bit of cash. They'd rather screw around and make life difficult for everyone involved.

    Have spoke to Aaron/Erik/another random.

    Erik was the most helpful but difficult to get in touch with.

    So beware if you purchase/try to establish a relationship with these guys
    Well as I am in the UK I won't be collecting anything, and I don't need a relationship, just a good product.

    I guess we all ask for different things from companies and have different expectations.

    Hopefully you get sorted.

    Ref my $3100 order, it's the cables, I'm in nearly $1000 just for them, then $300 for shipping.

    I imagine I will be able to get cables cheaper locally, and cut them to the right length as 55ft is overkill for my needs really.

    Loving the product though, and keen to see the openhouse for nyccnc!

  17. #17
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    Re: Can two clearpath servos be used to power one axis?

    Hi Eric,

    You have caused quite a bit of buzz around the office today with your request to pick up your motor directly from Teknic. I am not sure if you got the correct message because it sounds like you are very upset. First things first...we care very much about our customers and their success, always. It has been that way for 30 years running and will always be true in the future. The fact that you are unhappy means to me that we must be missing something here.

    My understanding is that you are requesting to be able to pick up your ClearPath servo motor directly from the Teknic factory in order to avoid the shipping costs and to avoid paying Canadian customs.

    Teknic is a high volume OEM supplier. To be able to make our lead times as short as possible and consistent, we have a very tooled out and automated manufacturing and order fulfillment system. While the system is somewhat rigid, as you have found out, it does provide the important value of on-time shipments and fully tested components. To the uninitiated, the costs associated with the little special requests is inconceivable. In order to be fair to all customers and to meet our commitment that we make public to everyone, we simply cannot accommodate requests that go outside of our automated systems. We are sorry that this is causing you some problems.

    Aside from Teknic's automated systems, there is an ethics discussion here about cutting the Canadian government out of the fees that they are legally entitled to. I have been a college student in the past, like you are now, so I can appreciate and understand budget constraints (that can cause things like considering Ramen noodles a food group). However, we are not willing to break the law for anyone, whether a high volume OEM or a college student. Again, we are sorry if this causes you some inconvenience.

    For an example of our commitment to our customers, please look below and you will see where I suggested to a prospective customer that he may be able to save money by buying a different motor model than he was considering. Having an OEM suggest to someone that he may be able to spend less money rather than more (the anti "do you want fries with that" approach) should be refreshing.

    I doubt that I will make you feel any better about your situation but I hope you have some appreciation for the reasons why. I work with very talented and committed professionals and completely trust that they are keeping the customer's best interest at heart. Getting stopped at the boarder for a "quick search" could surely ruin an otherwise splendid day.

    if you do get a motor in the end, I am confident that you will be very satisfied with the company and the product.

  18. #18
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    Eh. It's moreso about the shipping fee. Canadian customs is a different story. They generally do not collect customs on stuff that isn't alcohol/tobacco

    I declare EVERYTHING every time I go across the border. It's up to the individual officer as to whether or not they collect a duty on every single item.

    In my experience, unless you have alcohol or tobacco products they don't pull you in. Despite the value of the item.

    Whereas if some thing is shipped in they collect it. So Tom, that's not on me. They simply don't have the manpower or time to pull every single person in for every single purchase. It just wouldn't make sense. Hence why some items are on the collect every time list.

    Lastly. If a canadian citizen or resident spends 48 hours out of the country they are entitled to a $800 duty free exemption. So I wasn't doing anything unethical. Do the research before you start mouthing off and pointing fingers.

    Here's the link on it ace.

    http://www.cbsa-asfc.gc.ca/travel-voyage/ifcrc-rpcrc-eng.html


    Quote Originally Posted by TeknicTom View Post
    Hi Eric,

    You have caused quite a bit of buzz around the office today with your request to pick up your motor directly from Teknic. I am not sure if you got the correct message because it sounds like you are very upset. First things first...we care very much about our customers and their success, always. It has been that way for 30 years running and will always be true in the future. The fact that you are unhappy means to me that we must be missing something here.

    My understanding is that you are requesting to be able to pick up your ClearPath servo motor directly from the Teknic factory in order to avoid the shipping costs and to avoid paying Canadian customs.

    Teknic is a high volume OEM supplier. To be able to make our lead times as short as possible and consistent, we have a very tooled out and automated manufacturing and order fulfillment system. While the system is somewhat rigid, as you have found out, it does provide the important value of on-time shipments and fully tested components. To the uninitiated, the costs associated with the little special requests is inconceivable. In order to be fair to all customers and to meet our commitment that we make public to everyone, we simply cannot accommodate requests that go outside of our automated systems. We are sorry that this is causing you some problems.

    Aside from Teknic's automated systems, there is an ethics discussion here about cutting the Canadian government out of the fees that they are legally entitled to. I have been a college student in the past, like you are now, so I can appreciate and understand budget constraints (that can cause things like considering Ramen noodles a food group). However, we are not willing to break the law for anyone, whether a high volume OEM or a college student. Again, we are sorry if this causes you some inconvenience.

    For an example of our commitment to our customers, please look below and you will see where I suggested to a prospective customer that he may be able to save money by buying a different motor model than he was considering. Having an OEM suggest to someone that he may be able to spend less money rather than more (the anti "do you want fries with that" approach) should be refreshing.

    I doubt that I will make you feel any better about your situation but I hope you have some appreciation for the reasons why. I work with very talented and committed professionals and completely trust that they are keeping the customer's best interest at heart. Getting stopped at the boarder for a "quick search" could surely ruin an otherwise splendid day.

    if you do get a motor in the end, I am confident that you will be very satisfied with the company and the product.

  19. #19
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    Re: Can two clearpath servos be used to power one axis?

    Quote Originally Posted by ericclinedinst View Post
    Eh. It's moreso about the shipping fee. Canadian customs is a different story. They generally do not collect customs on stuff that isn't alcohol/tobacco

    I declare EVERYTHING every time I go across the border. It's up to the individual officer as to whether or not they collect a duty on every single item.

    In my experience, unless you have alcohol or tobacco products they don't pull you in. Despite the value of the item.

    Whereas if some thing is shipped in the collect it. So Tom, that's not on me. They simply don't have the manpower or time to pull every single person in for every single purchase. It just wouldn't make sense. Hence why some items are on the collect every time list.

    Lastly. If a canadian citizen or resident spends 48 hours out of the country they are entitled to a $800 duty free exemption. So I wasn't doing anything unethical. Do the research before you start mouthing off and pointing fingers.

    Here's the link on it ace.

    Travellers - Residents Returning to Canada
    The issue is you're dealing with a company who is predominantly an OEM supplier, not a wholesale distributor. I think Teknic seems to be more accommodating to the DIY crowd here than maybe some of the other automation/motion control manufacturers. Their policy doesn't include local pick-up. Frankly, if you bought something from me online, I wouldn't want you picking it up at my house either; we'd meet at a neutral location. Basically, they told you, in a cordial way, "No, you CANNOT come to our facility to pick up an order. Period." Doesn't seem like a red flag to me either way, but maybe if they were a bit more blunt about it you wouldn't be so persistent.

    One issue I could see would be proving that the industrial components you are importing into the country is for personal use. Which could potentially open up a whole can of worms depending on whether you end up dealing with someone at the border who may have had a bad day.

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    Re: Can two clearpath servos be used to power one axis?

    Quote Originally Posted by louieatienza View Post
    The issue is you're dealing with a company who is predominantly an OEM supplier, not a wholesale distributor. I think Teknic seems to be more accommodating to the DIY crowd here than maybe some of the other automation/motion control manufacturers. Their policy doesn't include local pick-up. Frankly, if you bought something from me online, I wouldn't want you picking it up at my house either; we'd meet at a neutral location. Basically, they told you, in a cordial way, "No, you CANNOT come to our facility to pick up an order. Period." Doesn't seem like a red flag to me either way, but maybe if they were a bit more blunt about it you wouldn't be so persistent.

    One issue I could see would be proving that the industrial components you are importing into the country is for personal use. Which could potentially open up a whole can of worms depending on whether you end up dealing with someone at the border who may have had a bad day.
    Hey guys - I'm new here and have been following some of these threads as I am getting into motion control.

    Anyway I saw these comments and am intrigued. Everyone is entitled to their own opinions of course but I do find it quite interesting when people are bothered by a situation like this. If you get misled by a company about the goods/services they offer that is one thing but to get frustrated with a company for not offering goods or services that they don't normally offer is something I don't understand. It is like going to a restaurant that doesn't offer pick-up and getting mad at them for not bending their rules. Might be stupid, it might make no sense to us but if the rules are clearly stated and you are not misled by them, then why not just go somewhere else? I once tried to order pizza from a local shop and they said they could not deliver because we were just outside of their "zone" - looked online and we were 100ft from where they would deliver, I mean literally just down the road...talk about frustrating. I almost thought about ordering it to the house down the street and being there to pick it up haha. That said I did not hold it against them...it is their rules and it is what it is.

    Again, I am new to this thread so maybe I missed something but I am definitely going to check out these motor guys that everyone is talking about (for better or for worse). If I get anything from them I will be sure to let everyone know how it went!

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