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Fabrication ADHD Continues

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  • Fabrication ADHD Continues

    The Micro-Cuc III (inline iso-fulcrum chassis with Slide Guide (tm)) and the Micro-Cuc IV (inline iso-fulcrum chassis with a conventional guide pin and wiper pickups) have proven to be reliable, fast, good handling chassis. But looking forward, I had plans (thoughts?) for a Micro-Cuc V that would feature an inline iso-fulcrum chassis with a center hinged central section that would feature a conventional guide pin and wiper pickups.

    Before I get too deep into this discussion and present photos, I'd like to give a shout-out for Al Thurman and his Landshark series of components. These components present all sorts of opportunities to experiment with different configurations and construction methods.

    My design/construction method can best be described as Ready, Fire, Aim; repeat as needed. One of the great things about soldered brass construction is that if you don't like your results, you can easily disassemble and reconfigure/refrabricate your components. This scenario was what I went through with the Micro-Cuc V. However, what I ended up with yesterday after all the brass cooled down definitely was not a Micro-Cuc V! I think I will call it the GCLS I, as I have a feeling I will me making additional variations of this chassis.

    Somehow, everything assembled itself on my jig as a center hinged inline chassis that not only features controlled movement in the roll axis, but also controlled flex in the pitch axis. Following are some photos of this resulting chassis. There is one interesting detail in its construction that I will not call out. I'm interested if anyone can catch it and identify it. Besides the center hinge feature which is new to me, I have my built in pocket at the base of the motor box. This makes a handy-dandy location for the weight that I like to add under the rear axle.

    The following photos were taken just after I finished construction. Since the photos where taken, I've cleaned up some of the solder joints and have run the chassis through my vibratory tumbler with crushed walnut shell media. Last evening I was able to appropriate insulate the front of the chassis and install the pickup wiper holders. By the way, I use Zap Goo for that and it works very well in retaining the holders. Later today I will make my lead ballast weights as well as install the running gear. I hope to be able run some test laps if not by this afternoon, certainly by tomorrow afternoon.

    Without further ado, here are the photos:

    IMG_8320 by gcullan, on Flickr
    IMG_8319 by gcullan, on Flickr
    IMG_8318 by gcullan, on Flickr
    IMG_8317 by gcullan, on Flickr
    IMG_8314 by gcullan, on Flickr
    Last edited by gmcullan; 01-24-2018, 09:45 AM.

  • #2
    Looks familiar. I built an inline center hinge car to compare to the sidewinders and anglewinders out there. Still need some tweeking. It's fast, but the handling is not to the same level as the anglewinders and sidewinders. The pan is from Motown HO.


    • #3
      Gerry, Keep them coming. I love watching what you come up with. Reminds me of the East Coast - West Coast 1/24th chassis wars of the early 70's, as the bar keeps getting set higher and higher. And we go faster and faster.



      • #4
        Another jewel-like chassis Gerry!

        I find your use of four piano-wire flex members interesting. It gives you a slight fore-aft flex in the chassis, plus your roll-axis flex. But it also provides some spring-to-center action in the roll direction. That will create some differential loading of the wheels whenever there is any roll-flex in the chassis.

        (Sorry for the bafflegab guys. But I think Gerry understands me.)

        One thing I don't see is shock absorption. You know I consider that critical in chassis design.

        My own current chassis fantasies don't include a roll-pivot in the chassis per se, but instead making the front axle mount flexible in the roll direction. Of course that does not allow the guide to pivot. A problem? Maybe.

        If I ever get time to do some fabrication, we'll get to test that out on the track!

        Ed Bianchi


        • #5
          SSR, I think my chassis might have more flex in the pitch axis. That might help with forward bite. Still, yours is also a nice build

          A thought on the gears. Try a combination of a Landshark 8-tooth brass pinion and a Quicker Engineering 15 tooth T-Jet crown gear. They mate well, help tame the snap on acceleration, and help make the chassis very driveable. Oh, and it's also much faster. That might not be a need on a road course, but it sure helps in the banked ovals we use in HOCOC.

          I have a sidewinder/anglewinder in the planning stages. It will be an iso-fulcrum chassis with the center section hinged and making use of a conventional guide pin and wiper pickups.

          By the way, I've had the opportunity to see a couple of your center hinged anglewinders first hand. They are absolute jewels of craftsmanship. Nicely done, top shelf for sure.


          • #6
            Ed, notice how the outer torsion wires connect to the motor box. There is some foo-foo behind that reasoning.


            • #7
              This is extremely cool!! I love watching this type of stuff.



              • #8
                I'll have to try the different 8/15 gear ratio. Right now I'm at 7/21.


                • #9
                  Very nice guys. Having done a considerable amount of work with torsion bars in my time; I can really appreciate what ya all are up to.

                  I presume the sizing and double ladder arrangement has already been established, or are y'all still goofing around with it?

                  Isnt one of the micro cucs a tri-bar?


                  • #10
                    I tried 7/21, 7/20, 8/21, and 8/20. With anyone of them it was way too easy to get wheel spin if you were a little aggressive with the throttle on corner exit. The 8/15 really tames them down. You also get some nice roll into the corners. Now, if you are a driver that favors heavy brake usage, then the 8/15 might not be for you.

                    The Quicker Engineering 15 tooth T-Jet crown gear is intended for use on a 0.063" axle. I've found that they hold well with the Viper splined axle that is a nominal of 0.060"


                    • #11
                      MM, the rods that might look like torsion bars on the Micro-Cuc III are actually brass rods soldered together. If you note at the front of the side pans that the rods are bent up 90 degrees, thus providing the mounting location for the front axle. That construction technique is an old 1/24th scale thing that goes back to about the mid 60s. The four torsion-bar design is a first for me. But I'm sure that someone, somewhere, has already done it.

                      Nothing that I am doing is new and ground breaking. It's just adapting techniques that go back something like 50+ years. Now applying these techniques to HO might be different, but the originators are probably people like Philip DeLespany, John Curkas, and a host of others whose names have been misplaced in my slightly jumbled memories.
                      Last edited by gmcullan; 01-24-2018, 05:10 PM.


                      • #12
                        O.k. Gerry I'll take a shot !
                        I see two things of note that pop right out . The first is the way the longitudinal rails attach to the motor box . The way they turn upward 90 degrees to the attachment point will allow the long axis of the piano wire rails to flex the vertical section and it's bend ever so slightly giving the chassis a little more longitudinal flex (in warp) then you would get with a conventional straight rail . It could be considered to be a development of Thurman's "paper clip" rail concept except rotated 90 degrees to stand it on edge . The "softer" springing of the extended , leveraged rail should be beneficial on shorter tighter turns .
                        The second thing is a bit more discrete and yet more forward thinking . Throughout this thread the principle of compliance has repeatedly come to the fore . Both in chassis design and tire selection more compliance has led to more speed . Mechanical grip , the grip that comes from tires and chassis, independent of downforce either aero or magnetic is greatly related to compliance and it's "application and timing" of the weight of the car . This chassis appears to have a fixed spring rate on one side of the chassis and a progressive rate on the other side . Whereas this chassis is primarily intended for use on an oval this may prove to be a benefit .
                        Sharp thinking going on here !


                        • #13
                          Winner winner chicken dinner!

                          Durf, you still have to post photos of your iso-fulcrum chassis. It is an absolutely gorgeous piece of fabrication!


                          • #14
                            One other thought that occurred to me after pondering your picture some . You may find the chassis as you have built it works fine . However , if you find the handling isn't what you expected on corners as tight as those on your oval the chassis may have too high a spring rate in roll . (when twisted longitudinally) Although it seems most everyone has referred to the thin piano wire spring rails as torsion springs they really aren't . Despite being made of a round material they are functionally a leaf spring . it is the nature of a leaf spring that when they are flexed their "length" changes some . In this case it won't be a lot but it will be enough that having both ends of the spring in fixed mountings is going to drive the rate of the springing through the roof .
                            As the chassis twists one of the springs gets bent up a given amount . The piano wire becomes curved which effectively shortens it . For this to work effectively the end of the spring needs to slide back slightly . If there is any preload on the other spring it's tip will want to move forward slightly. Without this motion the piano wire on one side will want to be compressed , on the other side stretched . The design of your chassis will allow for some of this to happen in the vertical leg of the spring but that is a very short very stiff spring .
                            If the handling isn't what you hoped for you might try detaching the joints in the springs at the front of the chassis so they can slide forwards and backwards . Look closely at Paul's chassis and/or the Reimles chassis and see how they floated one end of the spring .


                            • #15
                              This is the bare chassis on the jig . Completed pictures to follow