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SCN6 alike actuators?

Discussion in 'DIY Motion Simulator Building Q&A / FAQ' started by Michael Hensen, Dec 4, 2017.

  1. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    Looking at the DIY actuators on the forum I was wondering if anybody has looked and build small actuators like the scn6..

    Otherwise for any experienced diy'er.. would it be possible to make these things ourselves??
    Would it be stepper driven?
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  2. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    Any idea on how to calculate the torque needed for a ball screw setup with a pitch of 5mm to lift between 50 and 75kg?
  3. adgun

    adgun Active Member

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    1NM gives 100kg force with a 1605 ballscrew
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  4. Michael Hensen

    Michael Hensen Active Member

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    Thanks .. Now I have an idea of the value
  5. gSeat

    gSeat Member

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    Sorry I don't have more specific info, but:
    yes it's possible
    there are alternatives out there, but the scn5/scn6 are ready to go with simtools, other linear actuators or "cylinders" may meet base specs but you'd need to make them interface with simtools...guess that's where the crazy cool DIY actuator threads come into play though :)
  6. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
    3DOF, AC motor, Arduino, Motion platform
    I have had a 6dof simulator with gearboxes and 0.75kw VFD, all sold and looking for a new challenge..
    So that is why I am interested in the linear actuator trend that is going on..

    Looking at the scn5/6 they are nice and compact but not up to the task I am planning and it is not real diy..
    As I have experienced, in my previous 6dof machine, that going VR in a 6dof is not really giving you the feel of all the motions. Like the heave is only there if it is really fast.. otherwise sometimes you would not notice, as you have no visual reference.
    2nd is that the motion needed to be sharp and hard to give you the sense of being inside the car..

    This is why I am opting to loose some dof's and go for a 3/4 legged device.. so roll, pitch and heave..
    4 legged in the meaning of 4 smaller actuators (own build)
    3 legged in 3 long actuators where you hang in between.. (no picture at hand :))

    Looking at the current builds of the actuators am I correct that I am safe with 75kg of force per arm for a 95kg person and 45kg frame? ( I think I am with 4 motors but not sure about the 3 arm plan)

    This should be a sim for racing only in VR.. So I need sharp movement but that doesn't need to be more that 150mm I think.. but to move sharp it needs to be fast.
    Parvalux PM90 have come around multiple times an I think they are the ones I need..

    Will open a thread as soon as I will start the process..
    Also here.. Cheap China parts as much as possible and 3D printing parts where needed.. Later on perhaps CNC'ed aluminum if I build me a cnc first ( or get one for my birthday)

    The threads on the linear actuator builds are all quite long and I hope I've read enough to see that it can be done, even with a minimum of tools (which is my situation)..
    So any suggestions, pitfall warnings are welcome..


    Oh.. one last thing.. looking at the 4 corner linear actuators .. they seem to have a pretty small motor on it.. can anybody tell me what type of motors they use and how 'heavy (watts) they are.. Could it be that I only need nema32 servo motor to drive it?? But then how many Nm I need on the shaft, the servo motors can go up pretty high!?
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    Last edited: Dec 11, 2017
  7. adgun

    adgun Active Member

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    one of Those Parvalux pm90 motor cost 240,00 euro +vat from parvalux Germany
    rapid online sells ampflow motors in europe
    there e30-150/e30-400 work @24 volt, the sabertooth 2x32 will do the job
    groeten Ad
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  8. Bernd Manger

    Bernd Manger Active Member

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    Hello @Michael Hensen ,
    sounds interesting !

    If you want fast and sharp movements the best way is to use steppermotors for your planned actuators. They have very high torque and an unbeatable precise movement.

    Here is a link to the builders threat of Bordiin with a video of his Sim:
    https://www.xsimulator.net/community/threads/test-simtools-stepmotor.8849/page-2#post-112210

    Here i have posted some torque curves of the common stepper motors:
    https://www.xsimulator.net/community/threads/test-simtools-stepmotor.8849/page-3#post-112349

    The only disadvantage of steppers in my opinion is the terrible noise.
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  9. Michael Hensen

    Michael Hensen Active Member

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    Tx.. still a good 400+ euro for just motor and driver.. perhaps The Stepper route is something to investigate..
    Last edited: Dec 12, 2017
  10. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    Will read up on the topic.. had Steppers in mind but was looping at a size bigger toen nema23.. but will probably try that route.. can always reuse NEMA23 in a CNC build.. Thanks for the links!!!!
    Last edited: Dec 12, 2017
  11. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    Looking at the stepper driven actuators I think I will be going for a Nema32 solution with 1610 leadscrew. The ones I've found should still have at 1800rpm a torque of around 1NM
    I guess I should be ok with 4 off them.. .. looking at 150 to 200mm range .. Will design (probably copy and adjust the currect actuator designs) and share
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  12. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    Closed loop Servo motors are also a possible option. Something to think of when i start the ordering next year.
  13. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    I think it is getting near the point I should start a build thread, but as I am still in the planning phase I will keep my questions in this thread and have the Q/A transferred to the build thread as soon as I have ordered something relevant..
    So my idea is settling around the Nema32 and 4 (small) actuators with a max travel of 250mm.. (although I think I would need the full range but ball bearings of 300mm are what I'll be using, should be enough travel..)

    With this kind of setup, speed of the Stepper is essential.. So having it move fast in either direction.. and all moves are mostly short bursts..
    So my question is: As most of the torque in a steppermotor is in the lower region of the RPM (mine are around 1600oz-in, is 11Nm) would it be possible to use that biggest force by having a Belt running from motor to the ball bearing with a 1:2 setup..
    So 1 rotation of the motor is 2 rotations on the 1610.. that way I am less relying on the speed in rpm.. (I assume 1000 rpm is max on steppers under load and reasonable torque.. )
    according to this I would have instead of 1000rpm/60s *10mm =166.6 mm/s would go to 333,3 or go 1:1.5 that would be around 250 mm/s

    All ideas but nothing build yet.. although this will be my 3th sim.. But this time I want to keep it simple and small
    So I will be using a playseat F1 type of maybe even the actual playseat F1..
    I saw that the motion set for the playseat was set at 1300 Euro per 2 actuators so I am well within that range.. (around 200E a piece is my rough estimate)

    But back to the question.. would a gear increase work in this situation of will the torque required go sky high?
  14. Bernd Manger

    Bernd Manger Active Member

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    My Motion Simulator:
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    If you use a nema with 2Nm at 1000rpm and a 1610 spindle you get round about 128kgf. With a 1:2 belt setup you half the force, but this should be more than enough. If you watch the speed-thrust-curves of the common SCN6 actuators, you'll see that they have low force at high speed:

    SCN6_Speed-Thrust-Curve.png

    Placing the motor beside the spindle with a belt drive would also hold the length of the actuator short, so that it can be mounted under the seat.

    These are just theoretical considerations from my side, maybe i'm wrong.
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  15. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    Indeed mount side by side was the idea.. making it a whole lot shorter.. I'll try and find the characteristic of the stepper I am after.. I hope I have the 2Nm left at 1000rpm..
  16. Bernd Manger

    Bernd Manger Active Member

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    My Motion Simulator:
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    The formula is:
    Force (in Newton) = 2 * PI * Torque (in Nm) / Spindle Pitch (in m)

    Example: 2 Nm spindle 1610:
    2 * 3,14 * 2 / 0,01 = 1256 N = 128 Kgf
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  17. OZHEAT

    OZHEAT Active Member

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    My Motion Simulator:
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    I believe the SCN6 uses a 2 start 5mm pitch trapezoid lead screw.
    There is a thread somewhere on forum about rebuilding a SCN6.
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  18. adgun

    adgun Active Member

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    Closed loop stepper drivers works as a stepper and bldc motor, they have more torque at high rpm.
    I looked fore it in the past and if you search with closedloop stepper on ebay you can find a speed torque curve from the 4,5 NM set if you look at the 12NM set, i regret it will take some time
    I am not shure but i believe it was 1.2NM at 1800rpm
    sorry fore the bad englixh
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  19. Michael Hensen

    Michael Hensen Active Member

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    My Motion Simulator:
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    I am looking at either stepper Nema34 or Closed loop Nema34.. but I have some things to check and try.. like coding the Arduino or go for a networked raspberry. with the raspberry I can write C#.. That is what I am used to.. :)
    But indeed it is in the nature of the closed loop steppers to have more torque left at higher rmp.. I have both of them in my aliexpres wishlist but the closed loop variants are almost double the price..
    And reusing Nema34 in a small CNC machine is a bit too much.. Nema 23 would be ok'ish.. So I need to be sure of what I can.. Perhaps buy a small version of both and do some programming ..
  20. adgun

    adgun Active Member

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    A Thing with steppers is the bigger they get the faster the torque drops.
    above 1500 rpm a nema 34 gives allmost the same torque as a nema 23.
    I dont know how much you want to pay, but for about 150 euro you have a leadshine 2nm closedloop stepper set
    Leadshine is a brand and you can adjust them to get more torque at high rpm, in there software
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