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Looking for motors with large hollow shaft.
  • Hi all.

    Starting a cool project and I need some motors.
    These motors won't be taking the weight of the camera as I am using bearings to do the heavy lifting. They are only driving motors.

    I am going to be running small to medium size cinema rigs so think 2-8KG cameras.
    I need high precision so looking for compatible encoders ideally built in to reduce BOM items and engineering work.

    For my roll axis, I need a single motor with a 22mm hollow bore for a split rig to fit through.
    For my tilt axis, I can use either one or two motors, no hollow bore required. Can use the extra motor channel for the 2nd motor.

    Looking to use the SimpleBGC 32bit Extended.
    Powered via 11-16v batteries.

    Rather use regular gimbal motors over smaller motors with gear/belt configuration as I need the least amount of parts and engineering work as possible.


    Thank you!
    Jack
  • iFlight has quite a few pre-made kits. https://shop.iflight-rc.com/index.php?route=product/category&path=34_48&page=2

    Are they legit resellers/manufacturers of Basecam boards?

    Their website is a tad... You know.
    https://i.postimg.cc/RVGymwkT/Capture.jpg
  • Hi jackstar,

    i have already ordered at iflight and the products are also delivered - i don't know if they have a license for the boards.

    but i recommend to buy the board and motors separately for your project and use the mcu version directly, then you save the external drivers and buy motors allinone or use the stronger mcu drivers you need for such a weight.

    why you need 22mm hollow shaft, is 12 mm standard not enogh?

    regards tom

  • Hi @Moti0nGFX

    I contacted Basecam and they said they sell modified ones. So ill order the electronics from Basecam.

    My issue is that I don't have a lot of space and the off the shelf slip rings with an HD-SDI coax cable are all 22mm diameter.
    So I am trying to fit as much of the slip ring in the motor shaft as I can.

    This is the slip ring I am using. https://www.moflon.com/images/msdi216b.jpg
    I am waiting on them to get back to me about a custom housing, basically swapping the outer large 22mm shell around so that this can be done.
    Hoping that it will be a perfect press fit.
  • Looks like my best bet is to go with an Orbis™ true absolute rotary encoder
    https://www.rls.si/media/catalog/product/cache/1/image/655x300/9df78eab33525d08d6e5fb8d27136e95/n/e/new_orbis_2019.jpg

    I have seen on a few videos that this style of motor has a black bit in the shaft held in with 2 screws. This holds the magnet they include I presume. Other videos show it being hollow with encoder but I don't think this is correct?
    https://ae01.alicdn.com/kf/He7a81fe8aa7e40f6936a030dbf9d352at.jpg

    The plan is to make my own one of these that then has a wider flange that will allow me to press-fit the included magnet in place. I then also have to make a new cover to enclose the back of this part of the motor as well as hold the PCB.
    Yea it is 2 more items on the manufacturing BOM which I am not happy about but looks to be my only solution to have slipping and encoding. Of which looks to be a better encoder than the stock ones anyway. Though in this application, I probably won't see the benefits.

    The only issue is with this setup, the PCB is 45mm wide and the screws are 48mm. Not cool.
    But might work to my advantage as I can make the mounting better for the rest of the setup.
    Won't know for sure until I have one of these motors in my hands or if I get an accurate 3D model of them.

    Hopefully, the slip ring manufacture is able to route around the housing so the large flange is on the other side. This will allow me to place most of the slip ring inside the motor shaft resulting in taking up less space.
  • @Jackstar

    Moin,

    yes, the black cover is for holding a magnet, Orbis is a good choice and can also be installed as "hollowshaft", for this a magnet ring is fixed to a shaft.

    Now, I know why you need a 22mm shaft, but is it impractical to run the SDICable through 3Axixs and then use a gimbal wired?

    I assume you will be working with rechargeable batteries? Then it might be worth considering using the SDI-W transmitter and mounting it directly on the camera plate,

    A larger shaft is a long list of disadvantages. Big shaft>bigger motor>bigger mounting plates>more weight>better berrings>need more, Stability due to mass > more power to hold...

    regards tom

  • Your "XING 8108 87KV Multi-rotor Brushless Motor" looks same like GBM8108-90". Iuse the second one witch clossed housing and 12mm shaft, i use slipring and self constucetd 3d print and aluminiumcnc parts combined with rls aksim2 for endless rotation.

    My First try wars to use all 12 wires from slipring for all things that i need(remote control, focus etc) - now i use only for power and data, i split the Driver, so i have each axis a "brain" and the slipring is not so highlowed and if one wire is destroyed another one takes over and I do not have a fatal outcome.

    Video Link is via w or direct downlink from camera.
  • @Moti0nGFX

    I got confirmation that this is the rear of the motor I am planning and have bought the other day to visually inspect.
    https://i.postimg.cc/J7gMr3Cm/1.png
    I should be able to pull that small assembly off the back and replace it with my own that will allow one to house the magnet on the rotating part of the motor while also being able to pass through the power, data, and coax cable with ease.
    I'll get some CAD work done tomorrow to visually show what I am probably poorly explaining.

    I am creating a 2 axis gimbal (3rd axis optional) that requires one of the axis to have unlimited degrees of ration. Using wireless and batteries is just not an option.
    I already need a powerful motor as the cameras we are working with are quite large with decent metal housing lenses.

    Where did you get your slip ring from?
  • ya, that's right "I should be able to pull that small assembly off" - but you have to make sure that the new holder protects the bearing and keeps it in position.

    I have a simple noname slipring from example from iflight.

    Do you already have an idea how to draw your shaft? A tip from me, don't run the cable through the shaft but through a groove from the outside. otherwise assembling and configuring it is a source of problems.

    Where are you from?
  • The cable is going to be rotating in the shaft.
    Going to have to assemble the cables so that connectors are small enough to fit through.

    UK
  • https://i.postimg.cc/9FcWFRgW/IMG-20200608-113158.jpg
    https://i.postimg.cc/HWwYg42Z/IMG-20200608-113216.jpg

    It should be easy to add a magnet to this motor and make the bore big enough so the cables have more clearance to pass through.

    https://i.postimg.cc/x8FqBhB4/GM8112-a.png
    https://i.postimg.cc/Wp9DDqtw/GM8112-b.png

    Instead of creating the whole assembly, I could just create a push-fit part that goes where the normal magnet goes. There is around 3mm of meat there to push into. The width of the wall will be around 1.5mm. It would cost less than having to CNC mill the larger part and drill screw holes.

    It is not holding much. 10-20g worth of magnet that won't be reacting to much other than what is behind it, potentially pulling it into the motor anyway. We will have to experiment.
  • https://i.postimg.cc/43N1XvRN/IMG-20200624-222058.jpg
    https://i.postimg.cc/DzjP0W7Q/IMG-20200624-222017.jpg

    Working well!
    Yes, the aluminium is a bit rough. The slip ring I got (at a great price) has large BNC connectors on it so had to enlarge the OD of the magnet mount bore. Only 0.2mm of metal there xD
    Need to learn how to terminate coax now. Need these to go to SMA connectors so they will pass through the hole.
  • So I am slightly concerned that these motors are too loud and also cog too much.

    https://i.postimg.cc/7hnbTVjs/Capture.jpg

    I noticed motors in most gimbals on the market have pretty much 0 cogging. I have the DJI Ronin here and it has none.
    As for noise, I can hear the motors quite a bit.

    Note I have not fully loaded the motor yet.