Announcement

Collapse
No announcement yet.

FC130/FK130 Sidewinder Pod

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • FC130/FK130 Sidewinder Pod

    I've recently been working on my sidewinder pod, it's now screwed at the back with a pair of M2 screws rather than the built in flexy system and will accept both types of 130 short motor with 0.25mm motor movement fore/aft to utilise different gear diameters. I may increase this movement.

    I've beefed it up somewhat and will test in the coming days.

    After testing my flexy pods it was obvious they were too flexible on a 3 lane wooden track where more rigid setups rule.

    This is for NSR bearings with glued inserts that fit over the top of the bearing to secure it in the pod.

    SW FCK130 Pod Screwed not flexy v3.png

  • #2
    Kevan, I'll see your motor pod and raise you a monocoque rear sub-chassis.

    Right Isometric.pngRight Rear Isometric.pngIMG_2749-1.jpgIMG_2748-1.jpg IMG_2751-1.jpg

    To date I have been printing these in PLA, which has just enough strength to withstand the distortion needed to insert the motor. I'll be trying PETG next. Also OBC.

    What I have shown is version 6 of 8. Yes, this has gone through a number of design iterations. Some to make the parts lighter, some to make the assembly stronger, or improve the print quality, or to change the mounting method.

    But this has not just been a design exercise. Real parts have been printed, assembled, installed in a car and raced. The race results have been encouraging.

    One goal of this design has been to make the sub-chassis very light but rigid. Another has been to make the centerline distance from the motor to the rear axle highly adjustable.

    The rear axle carrier is designed for flanged ball bearings. It mounts to the motor carrier with four 0-80 machine screws. Sandwiched between the two halves are a set of spacer shims. They show up in the photos as blue-colored parts. The assembly is shimmed to obtain the proper gear mesh.

    The whole assembly is designed for 20 to 22mm rear wheels/tires. The ground clearance is not adjustable except by printing and installing a revised rear axle carrier.

    The particular variation shown is designed to mount to a body shell using ball-end posts. The ball-ends fit into socket feet which are glued to the body shell. The ball-and-socket setup is to help conform to whatever geometry exists inside the body, which is rarely flat and horizontal. But the ball-and-socket joint is not left free to move. It gets glued into position as part of the mounting post assembly.

    The clamps on the sub-chassis allow a small amount of vertical adjustment along their mounting posts. Each clamp is tightened with an 0-80 machine screw and nut.

    So that is the drive end of the chassis. There is a separate sub-chassis at the front that integrates the front wheels, axle and guide. That sub-chassis is designed to pivot a few degrees in the "roll" direction. The intent here is to keep all four wheels in contact with the track, and the guide perpendicular to the slot.

    The reason the rear sub-chassis is not designed to "roll" is to keep the wheel/wheel-well clearance as small as possible, to keep the center of gravity as low as possible.

    Is this going to turn into a world-beater design? Eh, probably not. But I am having a whole ton of fun bushwacking through design space. That's how I get my jollies.

    Ed Bianchi
    Last edited by HO RacePro; 06-22-2020, 12:21 PM.

    Comment


    • #3
      Kevan - I have all the questions - I was hoping others might ask some of them, so I didn't sound like such a nosey beggar .....
      - How is the flexibility fore/aft movement achieved - tolerance in the M2 screw holes and motor mount as a slot rather than round hole, or some other way?
      - What method will it use to mount to a chassis?
      - I am guessing the slide then glue clip is to enable a variable amount of "offset" between motor shaft and axle shaft?
      - Do you plan to do a can-end drive version as well as this bell-end drive one?
      - What have you printed it in so far? which plastics were more rigid and more flexible?
      - Are the NSR bushes the some flanged style and same O.D. as after market ones for "scalex" type applications - like say the Slot.it PA68 and ScaleAuto ones [4.75mm from memory)
      (ScaleAuto have eccentric bushes, which themselves can be useful as you ca rotate them to change either/both the offset height and the distance from centre of motor shaft to centre of axle shaft)

      - Funny when I came in here though. It said that there was one reply to the thread by HO RacePro, but it isn't showing...... weird. I blame Paul, he's to blame for most things....

      Comment


      • #4
        Originally posted by SlotsNZ View Post
        - Funny when I came in here though. It said that there was one reply to the thread by HO RacePro, but it isn't showing...... weird. I blame Paul, he's to blame for most things....
        That figures.

        Even though it's me that flagged the post so that the Administrators could 'Approve' Ed's input so that all of you peasants could see it, too.

        Meanwhile, I do have observations and questions from this thread, regarding Kevan's design. One obvious one is that a dab of CA glue on the end of the can will achieve the same as ensure it's solid location using M2 screws - even with a brass chassis. Another is why the design is for NSR bearings, rather than the spherical ones that Slot.it would normally use. Pros and cons, please? Same thing applies to your question about can-end drive, in a sidewinder setup? To my mind, that 'reverse' mounting is of greatest value in an inline pod design.

        I also wish to give a generous nod to those on the Isle of Man who were able to decide to open the pubs again. Some things make up the fabric of civilized society, even there, eh?

        Comment


        • #5
          It is the flex and wear factor for bell-end mounting I don't like in a sidewinder. That's why most makers use can-end drive for sidewinders, as the solid brass bush or ball race is a more robust setup when seated in the steel can-end, rather than the somewhat flexible plastic bell-end of an FC class motor.
          - You may recall Slot.it switching from bell-end drive sidewinder pods to can-end drive about 6 ?? or so years back. That was the reason given at the time.

          I think a couple of M2 screws would be my preference over CA glue - I have used the CA with older NSR motors in their pods, but very glad they have stated putting matching holes in the new series motors and pods. Quicker and easier to swap motors, and less subject to the something coming loose after a deslot. ( Of course I never deslot, I just get nerfed by the car 2 lanes away, 3 corners in front ) So I am definitely Kevan's acolyte on this one.

          Some people don't like the spherical gimbal bushes . . . that's my guess and I'm sticking to it - or it could just be easier to mount these than gimbals. which need expanding claws, or a plastic more flexible than Kevan is probably aiming for.

          Worse news for you Paul, our ale dispensaries have been back open for weeks.
          Last edited by SlotsNZ; 06-22-2020, 08:32 PM.

          Comment


          • #6
            I think the main issue with end-bell vs can drive is where the center of gravity (CG) ends up versus the wheel track. Ideally it would be centered, unless you are racing on an oval.

            The placement of the armature stack tends to move the CG towards the can end. That may be counterbalanced by locating the gears at the bell end. In this case metal gears might be better than plastic or composite gears, since they might be better counterweights.

            Of course the whole motor/gearset centerline can be shifted towards one side or the other, assuming adequate body clearance.

            I really don't see any other advantage locating the gears near the endbell or the can. One way or the other plastic ends up taking the load. Design things strong enough and I doubt there'll be any difference.

            As for self-centering bushings vs conventional flanged bushings, I think properly setup flanged bushings should be better. By properly set up I mean you can drop an axle straight through without any binding, but otherwise a close running fit. Line it up, lock it down and forget about it. One less variable to worry about.

            Ed Bianchi



            Comment


            • #7
              I'll have to answer in more than one post but I love most of that design Ed. 3D printing isn't anywhere near as strong as injection molding and your design is ahead of my current thinking. The 3 pods I've printed have had weaknesses in different places as I try to design one problem out it creates another so separating the axle mounting from the motor mounting is probably the best option for SW...I don't think I'll utilise the pivots.

              I'm going to borrow your thinking and try a couple of things in Fusion but I'm using NSR bearings rather than ballraces (because they're much cheaper). This introduces a weakness straight away whereas a flanged ballrace only needs a hole in a solid wall. Any links to cheap flanged ballraces gladly accepted.

              There is very little fore-aft flex as the channel is for a 3/32 axle to stiffen the centre but be free in roll.

              Sideways flexy was with a pair of 'S' springs fixed in the centre behind the pod.

              This currently mounts into a chassis with a pair of M2 countersink screws behind the pod with free centreline rotation in front of the pod and tape damping underneath.

              PLA is all I have at the moment, I really need to progress to at least PETG for better mechanical strength.

              ...I'll read more of these posts after tea and digest what's been said here but there's some great questions needing answering so far that has created new design ideas

              Comment


              • #8
                Originally posted by SlotsNZ View Post
                • ...tolerance in the M2 screw holes and motor mount as a slot rather than round hole, or some other way?
                • - What method will it use to mount to a chassis?
                • - I am guessing the slide then glue clip is to enable a variable amount of "offset" between motor shaft and axle shaft?
                • - Do you plan to do a can-end drive version as well as this bell-end drive one?
                • - What have you printed it in so far? which plastics were more rigid and more flexible?
                • - Are the NSR bushes the some flanged style and same O.D. as after market ones for "scalex" type applications - like say the Slot.it PA68 and ScaleAuto ones [4.75mm from memory). (ScaleAuto have eccentric bushes, which themselves can be useful as you ca rotate them to change either/both the offset height and the distance from centre of motor shaft to centre of axle shaft)
                Well in order:
                • Hole in the chassis 2.2mm hole in the pod 1.9mm
                • Old 3/32 axle in front of the pod and two M2 screws behind just like a SlotIt pod
                • SW gears are always perfect, just like AW...it's only IL that needs to be careful setting mesh height
                • PLA only so far...PETG and other with similar temps
                • Yes, double flanged NSR bearings

                Comment


                • #9
                  Originally posted by Wet Coast Racer View Post
                  Meanwhile, I do have observations and questions from this thread, regarding Kevan's design. One obvious one is that a dab of CA glue on the end of the can will achieve the same as ensure it's solid location using M2 screws - even with a brass chassis. Another is why the design is for NSR bearings, rather than the spherical ones that Slot.it would normally use. Pros and cons, please? Same thing applies to your question about can-end drive, in a sidewinder setup? To my mind, that 'reverse' mounting is of greatest value in an inline pod design.

                  I also wish to give a generous nod to those on the Isle of Man who were able to decide to open the pubs again. Some things make up the fabric of civilized society, even there, eh?
                  • UHU superglue is my best friend
                  • NSR bearings because I have about 5 pairs but I'd prefer ballraces if they were as cheap
                  • SlotIt bearings are great and a much smaller/stronger mount
                  • We've been Covid-free for 34 days now, I didn't know hugging a friend was such a nice thing to do

                  Comment


                  • #10
                    Originally posted by SlotsNZ View Post
                    • It is the flex and wear factor for bell-end mounting I don't like in a sidewinder.
                    • I think a couple of M2 screws would be my preference over CA glue - I have used the CA with older NSR motors in their pods, but very glad they have stated putting matching holes in the new series motors and pods. Quicker and easier to swap motors, and less subject to the something coming loose after a deslot. ( Of course I never deslot, I just get nerfed by the car 2 lanes away, 3 corners in front ) So I am definitely Kevan's acolyte on this one.
                    • Some people don't like the spherical gimbal bushes . . . that's my guess and I'm sticking to it - or it could just be easier to mount these than gimbals. which need expanding claws, or a plastic more flexible than Kevan is probably aiming for.
                    .
                    • I prefer can drive to endbell drive all day long, as you said the bearing is in metal so can't flap about
                    • M2 screws FTW ​​​​​​​
                    • The spherical bearings can spin in their housings and you can't see that and difficult to prevent

                    Comment

                    Working...
                    X