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New DIY 3DOF dynamic workstation project

Discussion in 'DIY Motion Simulator Projects' started by Milani Fabio, Feb 27, 2019.

  1. Milani Fabio

    Milani Fabio Member Gold Contributor

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    First test of mechanical movement.
    This is the ugly prototype, the beautiful one will come later and it will also be aesthetically beautiful.
    Not having done a project with mechanic woftwere, but only with pencil and ruler, I didn't know if the size of the movement could work.
    This test helps to understand if the moving mechanical parts work without problems.
    Everything works as I had foreseen in my head ...…


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  2. Milani Fabio

    Milani Fabio Member Gold Contributor

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    But now I'm stopped because I have difficulty finding that I create 3D gears for potentiometers.
    I keep searching on the internet ....
  3. Joeri

    Joeri Member Gold Contributor

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    nicely built. maybe a stupid question but why are resistors needed? electricity is not my strong side :)
  4. noorbeast

    noorbeast VR - The Next Generation Staff Member Moderator

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  5. Milani Fabio

    Milani Fabio Member Gold Contributor

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    Power Supply

    Sabertooth 2x32 connected to a power supply and voltage clamp resistors.

    Sabertooth 2x32 can be used with a suitably sized power supply. Power supplies used with a Sabertooth 2x32 should have output voltages between 7V and 30V. It is important to make sure the power supply being used can produce enough current for the load. Power Supply mode is selected by setting DIP switch 3 to the ON position. One major improvement in the third generation Sabertooth motor drivers is the addition of the Power outputs P1 and P2. These can be used with an appropriate resistor to dissipate the regenerative current generated when the device slows down or stops. This allows the use of power supplies without batteries or capacitors to absorb the regenerated energy. A calculator on the Dimension Engineering website will assist with choosing appropriate resistor packs. At least one of the power outputs should be configured as a voltage clamp when using a power supply.
    resistor.png
  6. Milani Fabio

    Milani Fabio Member Gold Contributor

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  7. yellofella

    yellofella Member

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    I also use gears. my gears are roughly 4:1 on my pgsaw motors (63:16 tooth) so +/- 40 degrees from centre point gives me roughly 300 degrees of pot travel. I do this so the smc3 receives the full 1024 points of resolution from the pot. I may be wrong but surely if I directly mounted those pots on my motors wouldn't the smc3 only see 256 points of resolution from the pot as im only using +/- 40 degrees of motor travel. When the smc3 outputs the 8bit pwm signal to the motor drivers wouldn't that pwm only have 63 points of resolution instead of the 256 that I get with the gears. maybe noorbeast could explain this better but if I can ditch the gears on my motors it would make for a more compact motor setup for me anyway
  8. Milani Fabio

    Milani Fabio Member Gold Contributor

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    I had a remnant of a 3mm carbon plate and I thought I'd create the potentiometer mounts.
    Here is the result.
    I already have a prototype of the gears that will arrive in a few days.
    The prototype of the gears helped me to size the support, which was not easy to create.
    20190429_172244.jpg
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  9. Milani Fabio

    Milani Fabio Member Gold Contributor

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    Hello Yellofella,
    my gears will have a 2: 1 ratio.
    76 tooth engine gear, potentiometer gear 38 teeth.
    I would like to use an angle on the engine of about +/- 75 degrees, tot 150 degrees.
    With a 2: 1 ratio I will have a potentiometer that covers me 300 degrees.
    150 degrees are many, they usually use 120 degrees (I like movement a lot), why do you use only +/- 40 degrees?
  10. yellofella

    yellofella Member

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    Hi Milani Fabio. I only use +/- 40 degrees because any rotational movement above 40 degrees is inefficient. if you draw a 90 degree radius you will notice that the bottom 45 degrees of the radius has a lot more vertical movement than the top 45 degrees. By only using +/- 40 degrees I get a lot closer to true linear movement then use longer lever arms (mine are 100mm centre to centre) to increase the amount of tie rod travel to nearly 100mm. This works the motors harder so I use the moto monster in half bridge (duel motor driver to 1 pgsaw motor) for double the power and a separate power supply for each motor. My old wiper motor setup used a 2:1 gearing and worked well. I just clipped the input in the smc3 software to use less motor rotation but struggled to get the lever length I required without the wipers getting really hot so i upgraded to stronger motors.
    hope this helps fella
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  11. Milani Fabio

    Milani Fabio Member Gold Contributor

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    I also use 100mm levers with the possibility of even 80mm.
    Actually I had thought about what you say, and you're right.
    Over 45 degrees it is less efficient but still useful.
    I have potentiometers of 360 degrees of reading, if my dimensions are not going well, I have the same potentiometers but with 180 degrees of reading.
    Possibly with the same gears, I have the possibility to make the 4: 1 ratio like yours.
    [​IMG]
  12. Milani Fabio

    Milani Fabio Member Gold Contributor

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    The gears have arrived.
    20190430_153103.jpg
    Potentiometer support gear assembly
    20190430_173712.jpg
    20190430_173819.jpg
    Motor gear assembly plus potentiometer gear
    20190430_174303.jpg
    Alignment.
    20190430_174317.jpg
    20190430_175022.jpg 20190430_175034.jpg 20190430_175044.jpg
    I think it was a great job.
  13. yellofella

    yellofella Member

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    Looking good mate. I really like the milled aluminium leavers and the carbon fibre pot mounts are a nice touch as well. Looks like a good sturdy motor setup with very little backlash on the pot gears so should work great with a well written motor profile. Are you considering mounting the motors on a aluminium profile or welded steal base at some point?
    Keep up the great work
  14. Sean Thompson

    Sean Thompson New Member

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    Hey man, Been following this one closely and finally looks like I'll be getting my own sim underway,

    Wanted to ask what was the size of the wooden floorboard you're using (Knowings it Temporary) just want to get a feel for how large the base of this design will take up
  15. Milani Fabio

    Milani Fabio Member Gold Contributor

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    Thanks Yellofella,
    It seems simple, but for me it was challenging to size the supports of the potentiometers in relation to the size of the gears .... I remember that I am not an engineer and I do not use softwere for drawing ..... only paper and pencil ... .
    The base will not be in wood, but in aluminum profiles with a 3-point star design .... 3 motors ...
    Consequently the engines will be mounted on aluminum and in the center a small base where the power supplies and electronics will be installed.
  16. Milani Fabio

    Milani Fabio Member Gold Contributor

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    Hi Sean,
    the base measures 90 cm x 90 cm.
    The distance of the motors on the center axis forms an equilateral triangle of 60cmx60cmx60cm
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  17. Milani Fabio

    Milani Fabio Member Gold Contributor

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    Sorry!
    The distance of the motors on the center axis forms an equilateral triangle of 74cm x 74cm x 74cm....:blush
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  18. Milani Fabio

    Milani Fabio Member Gold Contributor

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    Ready some parts for definitive basis.
    20190507_184726.jpg

    20190504_153203.jpg

    20190507_184426.jpg
  19. early_m

    early_m Active Member

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    Great looking sim - in the distant future I'd like to build something similar. What gearboxes are you using? What is the output torque and RPM?
  20. Milani Fabio

    Milani Fabio Member Gold Contributor

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    My motor:
    20190315_130343.jpg
    20190315_130437.jpg
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