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smartarze
Posts: 14
Hi all I hope someone can help me with the following problem, I've been searching the internet and this forum but got nowhere.

I have a home made throttle which i want to make motorised, I'm using xplane with zibo mod. Hardware wise i'm using mega2560 with 28byj 12v stepper motor with uln2003 driver. I have no problems getting it working with mobiflight, the stepper follows the throttle. My problem is there is no torque in the motor in that i can literally stop the motor by touching it with my finger. I did some research an did the conversion to bi polar as this said it would give more torque but it hardly made any difference, also it meant that the motor no longer worked with the uln2003. I then purchased an easy driver, again the motor works with mobiflight but still no torque. The driver board in both cases is powered by external 12v supply. I previously was using a 5v stepper but it had no torque, i thought the upgrade to a 12v version would fix it but it hasn't. probably some simple setting i'm missing. I have it wired to pin 44 and 45 on the mega and in the mobiflight module settings i have repeated the pin so pin1:44 pin2:44 pin3:45 pin4:45. Any guidence would be much appreciated.

Ian
2019-12-05 17:00
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VR-FlightSim
From: United Kingdom
Posts: 93
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Hi Ian
Acording to the datasheet, the stepper you're talking about only provides 34.3mN.m (milinewton meters) which equals roughly to 0.35kg/cm (0.35kg of force applied on 1cm long arm attached to the output shaft).
Such low torque won't be sufficient enough without further transmision.

I would suggest to use decent steppers for throttle quadrant (like in a 3D printer or desktop CNC milling machine).

Not sure about the drivers though.

Jay
2019-12-05 21:04
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VR-FlightSim
From: United Kingdom
Posts: 93
Supporter
Just read an article about the bipolar mod but it seems to have more issues that benefits.
As this is something I'm going to be batlleing in my cockpit build too, I've had this idea that I wanted to tinker with in the future.
How about modifying decent sized servo and fitting it to the throttle levers via "slip clutch" ?
You would have to take the potenciometer out of the servo and instal it onto the lever axis.
That way, when you engage A/T, your servo will sense where to move the lever but you can still operate them manually with or without A/T active.

Just an idea though;)
Jay
2019-12-05 23:01
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smartarze
Posts: 14
Hi Jay


Thank you for your input, will start to look into other ideas, The reason I used the 28byj steppers is because the throttle i have is 3d printed and it was designed around those motors. I will instead experiement with servos and clutches and see how that goes, with the throttle design i'm using, the bottom of the throttle lever has a gear on it, one side has a potentiometre with a gear, the other side has a motor with a gear, so all 3 are linked with gears, i can simply change the motor for a servo.



Ian
[Last edited by smartarze, 2019-12-06 01:57]
2019-12-05 23:21
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IFLY3
Posts: 14
Supporter
You would be better off running belts or sprockets down to the steppers,theres physically no room for that size of motor in the quadrant.
2019-12-10 00:50
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IFLY3
Posts: 14
Supporter
https://www.google.com/aclk?sa=l&ai=DChcSEwiM0pWb4anmAhUi54YKHfRJCk4YABAFGgJ2dQ&sig=AOD64_3Gu1VStynQxN7bARrfZhl3ewe3Qg&ctype=5&q=&ved=2ahUKEwiew4mb4anmAhXnpVkKHQh1A28Q9aACegQIDRA-&adurl=
2019-12-10 00:52
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