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Heavy Metal Slotcar

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  • Heavy Metal Slotcar

    Heavy Metal Slotcar

    Yes, that´s right. I hav built a really heavy model.

    All that began with an idea. I found three different aluminum U – profiles that fit telescopic. And when I took my caliper to measure them before buying I noticed that my preferred N-20 motors as well as the somewhat bigger GO! Motors ( FF030 ) fit perfectly in.
    The N-20 can be used snug – fit inline in the middle sized one and even as a sidewinder in the biggest one of the three profiles.
    The GO! motor can at least be used inline in the biggest profile. Well, it is difficult to build a sidewinder with this motor anyway.

    Click image for larger version  Name:	01 telescopic aluminum U - profiles.jpg Views:	21 Size:	106.8 KB ID:	150532 Click image for larger version  Name:	02 N 20 fit.jpg Views:	23 Size:	230.3 KB ID:	150533 ​ ​​
    ​​​ Click image for larger version

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    So I bought the three profiles. As usual they stood around for quite a long time. But then the day of heavy metal slotracing dawned.
    Pfutze, the well – known host of the equally known PRO NO MAG proxy suggested a proxy with diecast bodies. A very fascinating idea. And to me the right stimulus to try my profiles at least.
    It took some time to find a car that conformed to my perceptions. Diecasts are heavy. So the higher they are, the worse their performace in the curves would be. And I was by no means interested in making a lightening / milling orgy with a Dremel.
    Finally I found a car that is really flat and that I have known from my times in 32nd scale :
    The Audi R8C.
    As often I put the cart before the horse then ...
    I made a drawing and started cutting, drilling and sawing. I should have better checked the inner space of the Audi...
    First I drilled the holes for the axles. To avoid bending the sides inward when pressing on them with the bench drill I cut a piece of wood that fit into the profile as a support, so the drill could not skid away – what might have happened when the sides had been bent inward a bit when drilling.
    I cut out the basic shape trying my scroll saw. And it worked really well. Not much pessure, a bit patience – voila. Both sides correct.
    Remember the „cart before the horse...“ What did I do next logically ? Put the center part under the body. Shock ! I simply had forgotten to take into account that the R8C is one of the lowest LM cars. So next I put the motor under the body and – what luck – it fitted exatly. The motor is far enough in the front. But it is a matter of a millimeter or so.

    Click image for larger version  Name:	image_37900.jpg Views:	167 Size:	61.3 KB ID:	150345

    Then I made the motor bracket. I used two screws to fix it, so I had the chance to raise it a bit yet if necessary.

    Click image for larger version  Name:	05b motor bracket.jpg Views:	0 Size:	73.5 KB ID:	150358

    Having seen that the axle pillows are too high I cut down the whole rear section until it fit under the body. A side effect was that the bearings were too high now, too, and had to be filed down almost to the axle bore.
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    Fortunately there is an old trick with copper wire to fix even such mistreated bearings really safe. But in my case – the protruding wire makes eveything too high again.
    Last but not least I remembered an old mechanical engineers´ trick which I had introduced in slotracing long ago ( to fasten gears on the axle ) : the tongue – and – groove connection.
    Instead of making a groove in the axle and put the tiny tongue in there and press the gear on then, here I drilled two holes – half in the pillow, half in the bearing. In this hole there is being put and glued a snug – fitting piece of copper or piano wire. It works perfectly.

    Click image for larger version  Name:	12 tongue-and-groove joint.jpg Views:	0 Size:	242.6 KB ID:	150352 Click image for larger version  Name:	13 bearings safe.jpg Views:	0 Size:	148.5 KB ID:	150347

    The sidepans were next. They are made from 0.3 mm spring bronze plate, bent upward 3 mm and screwed and superglued on the sides of the center part. Why not brass – spring bronze is still hard and stiff even if it is so thin. You can work on it much better, w/o bending it somehow.
    Why so thin ? So you could – if necessary – put lead on it without rising the c.o.g. remarkably. Since brass is softer you would have to use a thicker sheet, i.e. a higher cog from the beginning.

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    The last jobs were the guide holder and the small aluminum sheet that is being glued under the motor as a heat sink. ( No space ON the motor...)

    Click image for larger version  Name:	19 rtr.jpg Views:	0 Size:	288.7 KB ID:	150350 Click image for larger version  Name:	20 heatsink under the motor.jpg Views:	0 Size:	324.9 KB ID:	150354 Click image for larger version  Name:	21 rtr.jpg Views:	0 Size:	418.9 KB ID:	150359


    The body holders are tiny parts designed by Pfutze and to be bought at Shapeways. They are excellent !

    Well, the car runs very well. The low body does its part. It did not have the highest acceleration and top speed because the crown diameter is restricted of course, but the composition is almost perfect. I think I will make a vacformed body of the Audi, it is quite easy to vacform with a few modifications which are necessary for an easy release.

    Click image for larger version  Name:	22 the winner of the heat.jpg Views:	0 Size:	254.1 KB ID:	150349


    I hope I did not bore you too much.

    Regards to all,

    Roland



    What is the use of these "attached files ? How can I get rid of them ?
    Attached Files
    Last edited by walker; February 19, 2022, 08:56 AM.

  • #2
    very nice article, Roland!
    and thanks for the flowers!

    Comment


    • #3
      Great write up indeed. The mechanical details and workmanship of your builds are really great to see. From what I can see on the diecast proxy thread this car is blisteringly fast!

      Comment


      • #4
        Very nice work Roland!

        Comment


        • #5
          🏁

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          • #6
            Thanky you very much for your kind comments.
            The Audi is not the fastest. But its performance was by far the best. One reason is that I try to design my chassis for the dedicated purpose, and the focus is especially on really round wheels.
            I knew that it would be difficult to optimize the power and rpm transfer to the wheeels because there is only tiny space under the body where the crown gear sits. So, although I´m using metric mod. m04, the biggest usable crown is 24t. The smallest pinions I had when I built the model were 8t. A 1:3 ratio provided a balanced and smooth running, acceptable acceleration and excellent braking. But the top speed could be a bit higher, especially since I have learned that the last heat will be run on a club track with much longer straights and wider curves. My model is designed for "normal" hometracks, no matter if wood or plastic.
            In a few days but too late I will get 7t pinions. The ratio of 1:4.3 will allow yet a bit better performance then.

            It was fun to run ten heavy metel cars. It is fun to run them at all.
            And being the host of a heat gave me thge opportunity to analyze what could be done even better next time. The fact is, that it is absolutely unnecessary to celebrate a cutting / weight reducing orgy.

            Roland

            Comment


            • #7
              already the Dire Straits had that line in one of their songs:
              its the host who wins the most
              ;-)

              i really like hosting these proxies and i think we can have a 2nd round of a diecast proxy series :-)

              Comment


              • #8
                All the time I have fooled around with aluminum channel, It never occurred to me to use bronze, screwed to it for outrigger weight. You solved the riddle. This is on my list to have fun with when I finally get past this damned stroke. I've been coming back a little at a time, and I'm waaay better, walking, driving, etc.

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                • #9
                  I wish you a speedy recovery !

                  Roland

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