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OpenBuilds Actuator Test Rig

Actuator Testing for real world results

  1. Mark Carew

    Mark Carew OpenBuilds Team
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    Mark Carew submitted a new resource:

    OpenBuilds Actuator Test Rig - Actuator Testing for real world results

    Read more about this resource...
     
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  2. TerryOx

    TerryOx Veteran
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    Very good. Actual measurements of accuracy, repeatability, max force, and max speed for different actuators. How difficult would it be to include some Rack and Pinion measurements?
    On a somewhat related note, has anyone published the flex of various linear rails of common lengths?
     
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  3. TerryOx

    TerryOx Veteran
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    For the more visually oriented among us (and you know who you are):

    [​IMG]
    [​IMG]
    [​IMG]
     
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  4. Evan F

    Evan F Journeyman
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    Nice graphs. I have to ask about the Nema 23 screws, are they ACME or ballscrew? If ballscrew, what diameter/pitch?
     
  5. Serge E.

    Serge E. Master
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    Interesting. It would be interesting to see the test done with a double belt setup (one into the other). In theory, it should improve at least the repeatability of a single belt setup ...
     
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  6. Jestah

    Jestah Veteran
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    I would love to see that tested too as double belts made a huge difference in cut performance but hard data like yours would blow my mind!
     
  7. Serge E.

    Serge E. Master
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    I'm not (currently) using the double belt setup having good results with the standard single belt. But as I progress with use of myOX, I'm thinking of extending the Y from 750mm (Vslot length) to at least 1000mm AND going to double belt. I have to stop making free signs ("practice" runs) first.
     
  8. Jestah

    Jestah Veteran
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    If I can recommend only one upgrade to ANY ox/belt pulley user it would be to double belt it. It makes SUCH a HUGE difference that IMHO should be done on any length axis. The hardest part is finding a good quality double sided tape that can stick to both rubber and the rail. Too thick and you wont get the two belts under the wheels.
     
  9. FabLab42

    FabLab42 Well-Known
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    Dear Rob,

    First, thanks for your job and thanks to share it !

    It read with interest and attention your two following links :

    https://openbuilds.com/uploadfiles/Part Specs/OpenBuilds® Actuator Tests_V2.pdf
    OpenBuilds Actuator Test Rig

    If there is another document your wrote, I did not find it, and I would be glad if you can transfert it to me (or its link).

    It is clear that you know engineering and mathematics, and I do not doubt that you made your tests properly.

    Have you done your tests on the ACRO systems currently for sale on openbuilds.com ?

    I am concerned by the results you have got : about 0.3 mm for Nema 17 and 0.6 mm for Nema 23 (both for belt driven systems).

    I am using a very cheap chinese laser cutter (a "K40", you probably know). I have not done such tests, but for sure the accuracy is much lower (I mean less than 0.3 mm) as I already produced many objects and had no problem to assemble them with very small clearances. It is also highly repeatable : I can assemble pieces with quite not clearance (less than 0.1 mm).

    I can't believe neither that my K40 is better than ACRO systems. I would like to buy one ACRO systems but now I feel confused.

    Do you have any idea ?

    Thanks in advance to answer me,

    Best regards,

    Fabrice, from France
     
  10. Ariel Yahni

    Ariel Yahni OpenBuilds Team
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    @FabLab42 Im interested in knowing how have you measured your k40 clearance to be less than 0.1mm?
     
  11. FabLab42

    FabLab42 Well-Known
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    @Ariel Yahni

    I have not done evoluated tests like Rob Stehlik, but I produce many identical pieces that I assemble for a very tiny clearance (less than 0.05 mm, measured with a caliper), and all the pieces can be assembled with no problem.
     
  12. Ariel Yahni

    Ariel Yahni OpenBuilds Team
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    Sorry @FabLab42 i have my doubts about that. Are you accounting for the at least 0.1mm beam width?
     
  13. FabLab42

    FabLab42 Well-Known
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    I assume the beam width is constant. The beam width has no consequence on the accuracy of the cut.
     
  14. Ariel Yahni

    Ariel Yahni OpenBuilds Team
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    Yes it does as it does the material being cut and the focal length, mirror aligment. All those factures will influence the type of testing you are doing to calculate the accuracy.
     
  15. FabLab42

    FabLab42 Well-Known
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    How does it ?
     
  16. FabLab42

    FabLab42 Well-Known
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    How the material can affect the positioning accuracy of the laser head ?
     
  17. Ariel Yahni

    Ariel Yahni OpenBuilds Team
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    It does not, but it reacts to the heat from the laser, specially if its a natural derived one. Let me clear thing a bit as i don't want us to go forever with this: Im not against you assessment that K40 is more accurate than openbuilds actuators, but rather in the way you have described you have measure said accuracy
     
  18. FabLab42

    FabLab42 Well-Known
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    Ok, I understand better.

    Do you own a K40 ? An OpenBuilds system ?

    I am disappointed when you write "K40 is more accurate than openbuilds actuators".

    I am searching for a system with the same accuracy than my K40.
     
  19. Ariel Yahni

    Ariel Yahni OpenBuilds Team
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    I do have a K40.

    When did i say " K40 is more accurate than openbuilds actuators". ?

    You need to understand the parts that compose the K40 tu actually find something "better" specially the stepper motors, belt and idler
     
  20. FabLab42

    FabLab42 Well-Known
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    Sorry, my english is not perfect.

    It is a misunderstanding. I though you meant that K40 is more accurate than openbuilds actuators.

    According to you, is it clear that an OpenBuilds ACRO System (belt driven) is more accurate than a K40 ?
     
  21. FabLab42

    FabLab42 Well-Known
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    I am sorry, I am not sure I understand your sentence "You need to understand the parts that compose the K40 tu actually find something "better" specially the stepper motors, belt and idler".

    Your opinion interests me a lot. Can you explain me what you mean in this sentence ?
     
  22. Ariel Yahni

    Ariel Yahni OpenBuilds Team
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    It means exactly that. Look what pieces compose the K40 gantry. Once you understand it then it will be easier to compare when finding something better. Just for your information i made this almost immediately after getting my K40 UK40OB because of how bad it was . Also i will say the ACRO has a great resolution .
     
    #22 Ariel Yahni, Feb 26, 2019
    Last edited: Feb 27, 2019
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  23. FabLab42

    FabLab42 Well-Known
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    Ok, thank you, I am confident ;) ;)
     
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