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    • #18333
      racer68
      Moderator

      I thought I would let everyone know about my progress in designing, building and testing a 3D printed chassis for our Indy Roadster class. For nostalgia’s sake I’ve been working on an Eldon Indy Roadster which  roughly represents the Watson Roadster of the time.

       

      As my printer has a very small bed the chassis had to be made in two pieces and aligned with piano wire pins, this does give the advantage of a wheelbase that will adjust to most roadster bodies.

      .

      The whole process has helped me use up any spare time that I thought I had as I had to diagnose and partially rebuild my printer ( each new part took a month to arrive and I didn’t get it all figured out the first or even the second time) and then had to start learning Fusion 360 in order to make the kinds of designs I was interested in. I can’t tell you how many iterations I printed that didn’t fit the way I was expecting before I realized that my thumb had been hitting the reset button on my digital calipers. I am getting close. Here’s the latest test fitting.

      One of the greatest design challenges was getting the ff050 completely ahead of  the edge of the cowling in order to comply with the spirit of a front motored build. The problem is that those tiny slim line motors are proportionately bigger than a V16 and its tough to get them into the space that originally had a 4 cylinder. Now I’m going to order axles, gears, bearings and a guide to make sure of my final measurements. In the meantime I’m going to start working on the body again.

      I hope that by this fall we can have an in person debut of the Indy roadster class. I look forward to seeing all your designs.

      Cheers

      Steve

    • #18336
      Porsche911
      Moderator

      Very very COOL Steve, and the ‘variable length’ would I guess make the chassis more viable for other cars/classes as well, multi functional!! :good:

      Question though, and I’m sure others waaay more knowledgeable than I can opine… Do you think that your initials, the ‘open/cut out’ part of the chassis may compromise the structural integrity? Perhaps ‘etching’ them, or a raised low profile may work better? Regardless, I’m sure those here may be lining up soon, if you intend to produce/sell?

      Stay well!

    • #18337
      racer68
      Moderator

      Hi Drew

      Thanks for the compliment. I am still developing this chassis and hope to do basic debugging  on my Plastic track. The chassis as it stands is fairly stiff but the space just over my initials is designed to hold some weight, either a piece of brass or some lead in order to move the center of gravity further towards the rear axle.  with  brass glued in it should be extremely stiff, my initials are just a little bit of vanity and are not likely to stay as is. The needs for flexibility in certain planes of a  slot car chassis is very complex in such a small narrow chassis with a front motor but I am experimenting with some webbing reinforcements in  order to keep the flex only where it’s wanted.  3D printing allows me to vary the thickness of the chassis strategically and Fusion 360  even has tools to show where the stresses are, although these are still beyond me. I am trying to modify my design so that I can do a precise wheelbase for those that  already have bodies that they would like to fit. The material I am using is PLA which is very stiff but somewhat brittle and I’m going to experiment with an enhanced PLA, PETG and ABS to see which is the best combination of printability and durability. If I can get my design refined enough to be useful to others I’d certainly consider producing at least a small run. I think the Indy Roadster class is a natural for this type of chassis as between this chassis and Art’s body anyone could build a car to qualify for this class.

      Cheers

      Steve

    • #18347
      f1nutz
      Moderator

      <p style=”text-align: left;”>Well done Steve! It takes great commitment on your part to learn the software and troubleshoot an refine your design. It looks great so far and I look forward to seeing it on the track.</p>

    • #18446
      racer68
      Moderator

      Good Morning Racers!

      I thought I’d share an update on how the 3D printed chassis project was going.  Unfortunately the adjustable chassis idea was just not workable as in order to have enough strength it meant that it would be too wide for some of the roadster bodies eligible for this class. Luckily, as my fusion 360 design skills slowly improved I found that parametric modelling allowed me to easily change the wheelbase in software for each individual car. My wife, who has been very supportive of my various hobby obsessions even bought me a full size 3D printer ( a Tronxy XY-3 Pro ) so that I could print a chassis in one piece.

      I found a free file on Thingiverse for printing a Dremel chop saw attachment and with only minor modifications I had a way of making precise cuts for the motor shaft, the tubing adapter, the spring connector and the 2mm gear shaft.

       

      I went through several iterations of the chassis design to make sure all the components would fit and align properly and that the chassis would be strong enough to take the abuse that a roll over expert like myself could inflict. Here is the final result in black and another earlier version in orange, for greater visibility, sitting on the 3D printer bed.

       

      There’s some more work to do fitting and testing the components and then trying the whole thing out on my plastic test track. I’ll try to do another update in a couple of weeks. In the meantime you all stay healthy and we will be racing again by the end of the year.

      Cheers

      Steve

       

      • #18481
        MiA
        Moderator

        Steve. Great to see what can be done with a little ingenuity!! I have been looking for something similar to your chop saw attachment ever since I discovered that square cuts were much easier to work with than my freestyle ones!! :wacko:

        Would you consider making one for me?? If so let me know how much and we can work out the details.

         

    • #18482
      f1nutz
      Moderator

      Stellar work on the chassis Steve!

      That mini chop saw is also awesome!

    • #18484
      Luis Meza
      Moderator

      Wow, Great job.

      That chassis can easily go viral on the Scratch32

    • #18485
      racer68
      Moderator

      Thanks guys

      At some point I think I’ll try to get a list of the wheelbases and overall chassis lengths of the bodies that people would like to use so that I can modify and  archive the appropriate print files for each body.  I’ll need to finish my testing of the final chassis first. There are also some hard limitations on what can be designed. The chassis at this point is exactly 20 mm wide at its widest point and can not be made any narrower without rotating the motor 90 degrees. The position of the motor in the chassis can not readily be set back without running afoul of it’s front engined intent, as it is already at the base of the windshield on my Eldon Watson Roadster, though other cars may have a little more leeway. The wheelbase which is currently 66.9 mm can be lengthened readily but using a spring coupler for the shaft means there are some real packaging constraints and the current space of about 18 mm between the motor and the support for the rear axle and gears is the only place to shorten the wheelbase. With careful fabrication the most the wheelbase could be shortened would be about 10 mm. If you wanted to use body posts for mounting the body the front post would have to be ahead of the guide and the rear post behind the crown gear. These limitations are not unique to this 3D printed chassis but are based on the provisional rules, scale and packaging constraints. There are many alternate ways to mount a body but they would have to be accounted for in the chassis design. I still have a lot to learn about 3D printing and design but I think it is another tool that can make our Hobby more rewarding.

      Cheers

      Steve

    • #18486
      Art
      Moderator

      Great work Steve! :good:

    • #18500
      Felix
      Moderator

      Amazing work Racer68!  Opens up a new dimension for the hobby.  You’re a techno wizard!

    • #18507
      racer68
      Moderator

      Bracket for shaft bearing

      Cheers

      Steve

    • #18508
      racer68
      Moderator

      I added the bracket as the shaft bearing was popping out at speed, the snap fit I had designed was enable to restrain the torque of such a mighty motor!

      All better now, things are starting to slowly pull together.

      Cheers

      Steve

      • #19896
        Art
        Moderator

        Hi Racer68,

        I’ve got one of your chassis left for anyone contemplating this class – I can include it with any shipping DArt online order too – Racer68’s ask is just $20 – a great deal if you ask me…

    • #18499
      racer68
      Moderator

      Hi guys

      I thought I’d give a quick update on my Roadster chassis. I scavenged some parts from existing cars so that I could start some testing. Very quickly I found that the shaft bearing would need some additional support as snapping it in had allowed  it to  occasionally pop out at speed and I didn’t want to glue it in until the entire car was finished and ready to race. So I designed a little screw in brace. The 3D printer really has trouble printing tiny parts and holes but after a couple of iterations I came up with this :

      It’s strong enough to accept the small Professor Motor body screws I had on hand and keep the bearing in place, while still being removable for any drive train changes.

      Cheers

      Steve

       

    • #18520
      MiA
      Moderator

      Looks like your R&D work is proceeding well!! :yahoo:  Very slick!! Can’t wait to see it on track, hopefully soon.

    • #19897
      f1nutz
      Moderator

      Nice work Steve! Digging out my chassis and parts for assembly as we speak.

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