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IndustryArena Forum > CNC Electronics > Servo Motors / Drives > Some advice and opinion on Clearpath servos
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  1. #1
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    Some advice and opinion on Clearpath servos

    Hi,

    I intend to purchase these integrated servo motors: https://www.teknic.com/products/clea...-servo-motors/ and use them with such machine: http://www.c-n-c.cz/download/file.php?id=5384&mode=view

    I am sure some of you are familiar with them, as also I know some of you have already made your own opinion regarding them.

    What I would like to know is, can someone explain it to me what does the "800 counts per revolution. This equates to 0.45° of rotation per count" mean? This is motor internal encoder with 800 pulses per rev. Now I know this is not much but I would like to know what does this mean in actual machine/motion/practical sense?

    This info can be found @ page 106 of user manual: https://www.teknic.com/files/downloa...ser_manual.pdf

    Can someone explain to me how is this any different than using stepper motor with 800 steps per revolution with difference that in this case PID would handle any lost steps etc..?

    This gives me a resolution of 0.45 degrees (if using 5mm pitch screw lead -> 0,00625mm resolution) in theory...

    I apologise if question is weirdly raised or I made any brain fart statement, beginner here

    Thank you for your advice.

  2. #2
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    Re: Some advice and opinion on Clearpath servos

    360/800=.45 So each pulse from the encoder accounts for .45 degrees of the motor's revolution.
    Andrew Werby
    Website

  3. #3
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    Re: Some advice and opinion on Clearpath servos

    Thank you for your answer, however this is clear to me, what I meant to ask was ,what is the difference between such servo with encoder with 800PPR and servo with encoder having up to 100000PPR? Where does such difference show on the machine?

    Does that mean that when machine is "off track" for 0,00625(@800PPR) only then PID makes correction?
    Does that mean that when machine is "off track" for 0,00005(@100000PPR) only then PID makes correction?

    How this works on machine in reality since already 0,001 accuracy on machine is very hard to achieve.

    Again apologise if I ask nonsense.

  4. #4
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    Re: Some advice and opinion on Clearpath servos

    The encoder with 100,000 lines would have a lot more counting to do, that's for sure. I imagine it would have to be pretty large too, to fit all those lines. With quadrature, you get 4 times as many positions to keep track of for each line, so your effective count with the 800 ppr encoders would be 3200, which is enough to hold .001" on all but the fastest screws. (If you're trying to hold a thousandth of a mm, good luck with that...)
    Andrew Werby
    Website

  5. #5
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    Re: Some advice and opinion on Clearpath servos

    Kenny- Sorry to come so late to your thread.

    The problem with the Clearpath servos documentation is, Teknic does a poor job relating their encoders to others on the market. The equipment is good stuff; more people are using it and the Clearpath servos are gaining popularity.

    I bought 7 of these motors three years ago, 4-nema 23s' and 3-nema 34s'. They all perform flawlessly. But when I purchased mine, there were not many people using them, and I could find no videos on youtube about them, except from the vendor videos.

    Most CNC'rs believe, the more lines the better. A 800CPR even with quadrature is quite low for smooth movement. So the answer is to simply purchase a more expensive encoder, with more Counts Per Revolution to make smoother movement. And on and on it goes. This encoder is linear.

    As you read the information from Teknic for Clearpath models below you see their encoders are at least, 12,800 counts per revolution, but then they state settability, of 800 to 6,400 positions depending on the model you buy. What they describe are two completely different physical properties. The 12,800 counts relate to electronic signal. The 800 to 6,400 positions relate to mechanical movement.

    "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)."

    To find more information on Clearpath encoders dig into their Hudson servo motors. Both Clearpath and Hudson servos share the same technology.

    https://www.teknic.com/files/downloa...0rev%202.0.pdf

    Read sections:
    ENCODER AND COMMUTATION SIGNALS --Through--
    SINE WAVE COMMUTATION WITH VECTOR TORQUE CONTROL

    Their incremental encoders utilize a proprietary patented algorithm, whereby data such as, torque, rpm, trajectory, etc, are incorporated to provide the motion control. The Teknic encoders are non-linear.

    Below are listed 5 US Patents issued to the Tekinc Corp. The technologies are incorporated in their Clearpath and Hudson product lines.

    Method and apparatus to convert a minimally controlled pulse stream into a proper mechatronic trajectory
    United States Patent 8928271

    Method and system for vibration avoidance for automated machinery
    United States Patent 7957832

    Method and apparatus to remove energy from DC loads
    United States Patent 8004866

    Method and system for vibration avoidance for automated machinery
    United States Patent 7613540

    Method and apparatus for protection of AC-DC power converters
    United States Patent 7911352


    Hope this helps...
    BillT

  6. #6
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    Re: Some advice and opinion on Clearpath servos

    Quote Originally Posted by KennyPowers View Post
    Hi,

    I intend to purchase these integrated servo motors: https://www.teknic.com/products/clea...-servo-motors/ and use them with such machine: http://www.c-n-c.cz/download/file.php?id=5384&mode=view

    I am sure some of you are familiar with them, as also I know some of you have already made your own opinion regarding them.

    What I would like to know is, can someone explain it to me what does the "800 counts per revolution. This equates to 0.45° of rotation per count" mean? This is motor internal encoder with 800 pulses per rev. Now I know this is not much but I would like to know what does this mean in actual machine/motion/practical sense?

    This info can be found @ page 106 of user manual: https://www.teknic.com/files/downloa...ser_manual.pdf

    Can someone explain to me how is this any different than using stepper motor with 800 steps per revolution with difference that in this case PID would handle any lost steps etc..?

    This gives me a resolution of 0.45 degrees (if using 5mm pitch screw lead -> 0,00625mm resolution) in theory...

    I apologise if question is weirdly raised or I made any brain fart statement, beginner here

    Thank you for your advice.
    If you are just running a Router these will work well, if you want to cut more than just wood then you want a higher resolution Encoder, to get smoother running, Dmm is much better with encoders at 16 Bit (65,536 PPR ) at a similar price, and you get much more for your money

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

  7. #7
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    Re: Some advice and opinion on Clearpath servos

    From the clearpath documentation:

    All ClearPath motors are equipped with an incremental rotary encoder with an Internal Resolution of 12,800 counts per revolution. This resolution is used only by the ClearPath motor's internal processes.

    Positioning Resolution is the ClearPath motor's working encoder resolution. There are two available options for

    Positioning Resolution:
    800 counts per revolution (option R). This equates to 0.45° of rotation per count.
    6400 counts per revolution (option E). This equates to 0.05625° of rotation per count.
    It doesn't matter what the encoder resolution is in the case of the clearpath motors, you have either 800 or 6400 counts per revolution positioning options. The literature doesn't state if the system uses reads the CPR of the encoder giving PPR, so as far as we know the encoder is 12,800 counts per revolution and that's it (it's probably post quadrature though). It's a black box function to achieve the either 800/6400 counts per revolution positioning resolution which is Teknik's intellectual property on the motors-driver system. It makes sense that the two positioning resolution options are an integer multiplier of the encoder too.

    I didn't see a specification for positioning capabilities (accuracy and repeatability), though teknik claims it's much better than steppers - and I'm inclined to believe them as a servo positions to an encoder and not to poles.

    Buy the model number with the 6400 counts per positioning revolution option. If you want more system resolution, go with a finer pitch ball ground screw and select a servo with higher rpm (calculate the numbers of course).

  8. #8
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    Re: Some advice and opinion on Clearpath servos

    Quote Originally Posted by mactec54 View Post
    If you are just running a Router these will work well, if you want to cut more than just wood then you want a higher resolution Encoder, to get smoother running, Dmm is much better with encoders at 16 Bit (65,536 PPR ) at a similar price, and you get much more for your money

    DMM | AC SERVO DRIVE | AC SERVO MOTOR | ROTARY ENCODER
    That's an impressive servo motor you listed, even with an absolute encoder.

    I'm not sure he'll need more resolution to cut aluminum though - greater than the 6400 positioning counts per revolution. There will be other factors in a home built system that dominate positioning errors over the available resolution of the servo selected.

  9. #9
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    Re: Some advice and opinion on Clearpath servos

    Quote Originally Posted by UA_Iron View Post
    That's an impressive servo motor you listed, even with an absolute encoder.

    I'm not sure he'll need more resolution to cut aluminum though - greater than the 6400 positioning counts per revolution. There will be other factors in a home built system that dominate positioning errors over the available resolution of the servo selected.
    This is where everyone makes the mistake of thinking that a low resolution Encoder is good enough, the higher the Encoder count the smoother the servo motors will run ( positioning is only a small part of what a good encoder will do for you ) with low count you get the jerk factor, 12 Bit is about as low as you can go below this are a waste of money

    If you look at the clearparth Encoder it is incremental, so there max Encoder of 12,800, is only a 3,200 CPR Encoder

    The main thing to remember is the higher the Encoder Count the smoother the cut will be,14 Bit (16,384 CPR ) to 20Bit ( 1,048,576 CPR ) is the standard being used for Routers and Machining Centers

    Here is a snip as to what is available for machining Centers and they go higher than this
    Mactec54

  10. #10
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    Re: Some advice and opinion on Clearpath servos

    WilliamT4450 Kenny- Sorry to come so late to your thread.

    The problem with the Clearpath servos documentation is, Teknic does a poor job relating their encoders to others on the market.
    You can say that again! that is the most obtuse and confusing description of a systems encoder I think I have ever read.
    They do state they are INCREMENTAL encoder but I still don't know what the basic count is?
    The terminology is all wrong also, the smallest degree of commanded motion it is usually referred to as 'The Least Input Increment'.
    Al.
    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.

  11. #11
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    Re: Some advice and opinion on Clearpath servos

    As Mactec said ...
    More res is better, until high res.

  12. #12
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    Re: Some advice and opinion on Clearpath servos

    Im building a router with Clearpath servos right now. Almost ready to power them up but not ready to yet.

    My Z axis has a 5mm pitch ball screw and i put a standard model servo on it that uses 800 cpr. Per inch of travel the motor shaft will rotate 5.08 times. That will give me potential positioning accuracy of 4064 counts per inch of movement.

    Lots of very informative responses but one thing that wasn't mentioned was you can set the resolution of the motor in its software. According to Teknic engineer i spoke with, the standard (800 cpr) and the enhanced (6400cpr) use the exact same encoder. They just unlock the higher resolution in the software on the enhanced models. And he also said that the motors see all pulses regardless of version. The difference is the enhanced version can position to 6400 points per rotation while the standard version can only stop at 800 points.
    For my Z axis 5mm pitch ball screw, i think im going to set the resolution down on the encoder to 400 pulses per revolution. This still gets me over 2000 pulses per inch and unloads the processing requirements a little.

    Also, i think the manual is informative and easy to follow. And ive received good tech support from Teknic so far.

    Sent from my VS980 4G using Tapatalk

  13. #13
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    Re: Some advice and opinion on Clearpath servos

    Quote Originally Posted by 1Jumper10 View Post
    Im building a router with Clearpath servos right now. Almost ready to power them up but not ready to yet.

    My Z axis has a 5mm pitch ball screw and i put a standard model servo on it that uses 800 cpr. Per inch of travel the motor shaft will rotate 5.08 times. That will give me potential positioning accuracy of 4064 counts per inch of movement.

    Lots of very informative responses but one thing that wasn't mentioned was you can set the resolution of the motor in its software. According to Teknic engineer i spoke with, the standard (800 cpr) and the enhanced (6400cpr) use the exact same encoder. They just unlock the higher resolution in the software on the enhanced models. And he also said that the motors see all pulses regardless of version. The difference is the enhanced version can position to 6400 points per rotation while the standard version can only stop at 800 points.
    For my Z axis 5mm pitch ball screw, i think im going to set the resolution down on the encoder to 400 pulses per revolution. This still gets me over 2000 pulses per inch and unloads the processing requirements a little.

    Also, i think the manual is informative and easy to follow. And ive received good tech support from Teknic so far.

    Sent from my VS980 4G using Tapatalk
    Do they not have Electronic Gearing that you can set to take care of the processing requirements, you don't want to go lower your encoder CPR, if they have Electronic Gearing, that will allow you to have max Encoder Resolution and control the Step/Per to what ever number you think is ok for your system, you should not have a Steps/Per problem anyway no matter what the needed number is
    Mactec54

  14. #14
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    Re: Some advice and opinion on Clearpath servos

    If i understand the Teknic engineer the internal encoder resolution doesnt change no matter what version you have or what set the counts per revolution to. It still uses the 6400 counts per revolution to move between points. The difference in resoultion beween versions and software settings only affects how many points it can stop at. So i guess the benefit is smooth movement all the time. The " electronic gearing" can be set in the motion control program which in my case is UCCNC.

    Sent from my VS980 4G using Tapatalk

  15. #15
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    Re: Some advice and opinion on Clearpath servos

    Quote Originally Posted by 1Jumper10 View Post
    If i understand the Teknic engineer the internal encoder resolution doesnt change no matter what version you have or what set the counts per revolution to. It still uses the 6400 counts per revolution to move between points. The difference in resoultion beween versions and software settings only affects how many points it can stop at. So i guess the benefit is smooth movement all the time. The " electronic gearing" can be set in the motion control program which in my case is UCCNC.

    Sent from my VS980 4G using Tapatalk
    No the Electronic Gearing is setup in the Servo Drive, all good servo drives have electronic Gearing, as standard, this is not done in your control software
    Mactec54

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