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gear motors vs scn5

Discussion in 'New users start here - FAQ' started by Donerb, Mar 5, 2018.

  1. Donerb

    Donerb Old Racer

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    Ok new Guy here. Been studying all the different builds on this awesome site. I am working on building a Sim rig with 2 actuators and a 3rd for traction loss.

    I have seen that most people use various gear motors (wiper etc.) vs. the scn5 or linear units. I understand that there is a fairly big cost difference for sure and could be one reason, especially if that is all that is in the budget. That said if your list of what you wanted had BEST performance at the top of your list what would that choice be?

    If you go with the best HD motors, like the ones I have seen on a few builds and compare them to the scn5's for instance what will perform better or can perform better? A couple of the commercial ones I have seen, like the CXC and have been able to try, use linear actuators. The only Neg I can see with the Gear motors with arms, or connecting rods as some call them, is that they accelerate and decelerate through its stroke because of the arc it travels converting to linear motion. That seems like another issue for tuning, but I might be out in left field on that one since you have feedback pots on the shaft.

    Attached Files:

  2. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    If cost and performance are the only criteria then a DIY actuator will win out on both counts: https://www.xsimulator.net/community/faq/diy-linear-actuators.248/

    Suitably powerful DC motors can eclipse an SCN in terms of performance and cost, but are not as mechanically efficient and do have some backlash, though are much quieter than SCNs, which sound like a cage of demented budgies.

    In the end it really comes down to project aims and preference.
  3. Nick Moxley

    Nick Moxley Well-Known Member

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    Gear motor's are near silent compared to Actuators, and coming in @ less than half the price, You would be insane to build a rig with actuator over gear motors.

    A loaded SN5 is lucky to pull a couple hundred mm/s Gear motor's Muchos More.
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  4. principiamacb

    principiamacb Member

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    I wish mine were. The backlash in mine cause a huge amount of banging/clicking.
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  5. Nick Moxley

    Nick Moxley Well-Known Member

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    Then the question remains, Why are your so Perfectly balanced as to allow that, Bias your weight 1-2% and load the motor's with a slight amount of weight, That will always ensure there's some weight on the lever's as to not expose the backlash as much.
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  6. principiamacb

    principiamacb Member

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    I already have it slightly weighted to the back. Ill try some more though.
  7. Donerb

    Donerb Old Racer

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    Ok sounds like motors it is. With some rear weight bias. I was setting up for neutral. Glad I asked!!!!
  8. PiaMan

    PiaMan Active Member

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    I have both. No comparison for simulation scn win hands down. Fine detail is captured that just doesn't exist with dc motors. If you want throw your friends out of the seat go dc motors. Mire power hands down. Ive addressed noise before. Id take squeaking over the dc motor backlash clacking anyday. Price dc motors.

    Dc motors = 65-70% performance for %35 of cost. Great deal performance/$
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  9. Nick Moxley

    Nick Moxley Well-Known Member

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    If your lacking fine detail on your gear motor's....Its Not the gear motor's fault.

    Baby birds nest behind your head VS a little click clack here or there. Im pretty sure i know which 99% of people would choose if they had the option to hear both side by side.
    • Disagree Disagree x 2
  10. PiaMan

    PiaMan Active Member

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    Nick, i know you have your very firm opinion in this matter and i respect that.

    I also dont believe that 99% of people have day to day access with both systems.

    So what i provided was MY opinion to be taken into consideration as an owner and user of both systems regularly i believe its a value added opinion. If it is of no value to you please disregard it yourself but i can tell you 100% or people who have tried my systems agree with me.

    Now to add my technical side to your comments about backlash, maybe your motors are better quality. I cant say having never been on your system. I can tell you ive thoroughly investigated and made changes and i just cannot get the detail i can from my worm gears that i do from scn. With the backlash it is physically impossible. Weighting in favor to the rear may reduce back lash in braking situations but doubles it in acceleration. Thats just physics. Neutrally weighted you split the back lash. Backlash has been discussed before. Its is inherent in worm gear design. Again because you dont notice the detail your system doesnt give you doesnt mean youre not missing anything.

    Im glad youre happy with your system. I understand you prefer clacking to squeaking. To me clacking sounds like things falling off my car. Squeaking sounds like a stiff race suspension and it blends fantastically into the game sound. Even my girlfriend who does not use the machines laughed at the thought that someone would find one more obnoxious than the other.

    Anyways my 0.02. Take it or leave it but i dont believe you speak for 99% of people on here with your opinion and dislike of scn.
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    Last edited: Mar 6, 2018
  11. Nick Moxley

    Nick Moxley Well-Known Member

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    Opinions aside, well just stick to facts, Actuators are Far louder and have a Very High Pitched whine/Squeal which is far more noticeable in game.

    Fact Gear motor's on the other hand, have a Much less noticeable soft clicking sound of sorts the motor's are making when Switching directions, Upon Violent oscillations, you might get some clacking from the motor's, But overall Nothing compared to what you hear from An SN5 as seen below,

    Fact we both have PGsaw motor's, so no difference there, Fact Backlash when set properly is not really noticeable, and if it is. it is very small, rare situations where the Axis are lining up Just so, and your running into a balance issue where its being centered over the pivot, allowing a little more backlash to present itself.

    Fact, you not getting uber fine details from your Gear motor's does not mean they cant produce said Uber small details. When i can pin point a 7 sided tri in a Physical mesh on one of my Favorite tracks. Im pretty sure my motor's/Tuning are doing their job.

    Fact my motor's are 4+ years old, have 1000+ game hours on them and still provide the ultra small details Kunos and other Legit laser scanned tracks offer.

    nDip.png



    Fact @24 seconds you can hear a good oscillation with No game volume as I was exposing a damper issue that was fixed with a Physics polling rate update







    Fact, we've had users say No WAY to actuators once they hear the volume level they produce, I cant say we've had anyone say the same to Gear motors. And if i had to listen to my Chassis squeak like that all race, i would be asking my Race engineer who the heck welded the cage in this car, Its cracking and squeaking like its going to fall apart. lol
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    Last edited: Mar 6, 2018
  12. PiaMan

    PiaMan Active Member

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    Nick, 2 users in just this one thread have said the clacking is too loud but you ignore them. Also since you push your opinion on the matter like its law (99% of people agree type of stuff comments)

    What you state as facts in the above posts are actually your opinions. You are essentially saying "see i felt this, so there is no way i could be missing anything else and mine must be best"

    because we ordered our motors from pgsaw does not mean anything. manufacturing differences occur. However you stating that as fact cannot be true because youve never been on my rig.

    How much backlash do you have on your motors after the lever (ie that will be present on the arm)? I have 2.159mm. Thats noticeable on 55mm ctc levers. That is something measurable and is a fact.

    I will say however that if you cannot agree that backlash will cause a loss of detail then we are not even discussing anything at this point because you are ignoring physics.

    Great you have 1000+ hours on your rig. How many on an scn rig? Did you run your triangle mesh test on scn? What other tests have you run on both scn and gear motor? Until they are equal with equal amount of time spent tuning the systems you're comparing apples to internet videos.

    Someday i will make a video comparing the noise but usually i have better things to do like race.

    Cheers
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    Last edited: Mar 6, 2018
  13. Donerb

    Donerb Old Racer

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    So I guess my question is is there a a better gear motor that is comperable in price you could use that has an antibacklash gearbox on it. Then the best of both worlds.
    I drove a CXC sim and it was to be honest simply amazing. When I was done I felt like I had just done a real qualifying session when I used to drive. To be honest I never heard the I am guessing scn5,s over the sound and other vibrations. So to me it all boils down to ultimate performance.
    So Piaman what are you using for electronics?
  14. PiaMan

    PiaMan Active Member

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    I have the sim xperience diy kit for my scn system and the pgsaw motors for my dc system. I stopped spending on my dc rig because for me the backlash was never going to be overcome to my satisfaction. I only measured one motor today but over 2mm (at rod end of lever) of backlash for me is significant and i can feel it.

    However had i not owned my scn system i would have been very happy with the dc system. As with lots of things at the higher end of the spectrum you spend lots more for small gains. I even partially regret going scn purely for the cost vs what i have into my dc rig but not for the end result performance.

    I believe the cxc is scn and as you said, once youre driving you dont hear anything from the actuators. I think most people who own the system are happy with it. As are dc people.

    Hope that helps.
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  15. Donerb

    Donerb Old Racer

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    Yeah it does. Much thanks! That is why I’m going to do this in stages. Once I get the main base done I can at least have something to play with while I work on this project.
  16. SeatTime

    SeatTime Well-Known Member

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    At half the price of a SCN-5 (well to OZ anyway) and way more powerful - DIY DC Ballscrew Actuator..and from experience, a badly setup/implemented PID can also effect the performance of a DC motor. Eg. If your controllers PID does not allow your motor to correctly track the telemetry data - there will be a loss of detail.
    • Agree Agree x 2
  17. SeatTime

    SeatTime Well-Known Member

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    Just a stupid question - are you two guys using the same controller/software - it can matter with DC motors. I have used JRK, Arduino and 1280 (new and old) and they all feel slightly different.
  18. PiaMan

    PiaMan Active Member

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    No we are not and I didn't bother mentioning it because I know it makes a difference to end feel but i didn't want to convolute the main issue and agree that mine could be improved, however I don't agree that the backlash and loss of fidelity would be overcome. And that is what i alluded to by I stopped spending haha.

    I took a few more measurements today on mine. Yesterday I had only quickly measured the one side with dial calliper. I measured the other side today as well as the number of degrees of backlash using a digital angle finder.

    Both have 55mm CTC levers and measurements were done at the rod connecting points.

    Motor 1:
    2.159mm backlash
    2.3deg missing before motor engagement

    Motor 2:
    1.821mm backlash
    1.6 deg missing before motor engagement

    Now one can easily argue that this amount is insignificant and i wouldn't wholeheartedly disagree. However since much of the heave is in 5% of the total travel starting in the mid point I can feel this as can anyone who rides my sims.

    I do have it slightly rear weighted so I agree with everyone this is the best compromise to have more immediate reaction on +heave and braking rather than try to split the difference.

    Since most motion is concentrated within about 20-25deg each direction I would calculate the loss of efficiency at ~5%

    Again potentially not a big number but for heave it is potentially a very large percentage of travel. Again, able to be overcome by increasing the amount of movement to ensure the motor engages. However (for me) this does not provide as natural a feeling road sensation as I get from the SCN.

    Now for noise level i don't have a decibel meter but i do have a decent recording device with a manually controllable gain. Unlike the video posted of SCN in silent room. The two devices have similar sound levels. SCN being louder on long movements, DC louder on things like grass and crashes where the motor hits both sides of the backlash

    The difference I feel is that squeal can cut through more especially when recording. Thats why people don't need to fill their trunks with mids and tweets but with subs. For some people that may bother them. Im not trying to say they don't make noise. Also when recording them unless you setup some really high end mics the SCN sound picks up better. Especially on low end recording devices like phones and point and shoot cameras and even more when the room starts silent. The auto gain cranks up in case it needs to record a whisper. There is a reason the bass player in most bands uses a direct box and doesn't mic the amp

    Anyways, I digress.

    In conclusion:

    Above are the measurements on my PGsaw motors. I'm in no way am saying this is what you will get from PGsaw or any other motor supplier.

    The measurable data is there and one can decide if that amount is negligible or important to them.

    On the issue of sound, it is indeed a subjective personal opinion. Anyone claiming a fact one way or another is just pushing their opinion as fact. All I've done is provide my opinion as an owner of both. It may not jive with someone else opinion or someones housemates opinions of what is loud.

    Hopefully these measurements help people in their own choice. I don't believe you can really go wrong with either system.

    cheers
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  19. Donerb

    Donerb Old Racer

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    You points are well taken! I know there are ways around backlash but that is a whole other issue to deal with and will definitely change the cost scenario. I have done several projects with ball screws and you can get plenty of speed w/o backlash the only issue there is the total amount of force needed. The more you need the more the cost. 500mm per sec is not to difficult. I have one router that I run at 300mm sec all day.
    Maybe Seattime from above can give a bit more input on his construction?

    Most of the once I use are AC stepper so not sure what you would have to do for an interface.

    What do you do for your balance point with the scn's and are you using 150's. It seems like if you have zero backlash you would want basically zero or neutral?
  20. noorbeast

    noorbeast VR Tassie Devil Staff Member Moderator Race Director

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    In my earlier comment in this thread I included a link to the DIY actuator FAQ, and a lot more can be found using the Google Custom Search near the top right of Xsimulator pages.

    A DC rig is capable of fine motion detail, with the degree to which DC backlash is a factor being a function of design and implementation, keeping in mind there are are range of designs using various DOF.

    There is also human physiology and perception/processing to consider, as past certain points people are incapable of detecting differences, and motion simulation in fact relies on exploiting those weaknesses: https://en.wikipedia.org/wiki/Motion_simulator
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