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    #46
    Where any of the materials land in the UL94 flame retardation performance test is going to be hugely impacted by the flame retardants added to the resin. ABS is all over the place with the minimum wall thickness needed to meet V0 (0.8 - 3mm generally), but it is pretty common stuff and presumably some of the filament vendors will actually provide some sort of traceability for their material (although I am a bit skeptical of this unless it's coming straight from Sabic, LG, etc).

    ASA looks like it generally has lower flame test performance, at least based on the few materials I pulled up on Matweb, but again I'd assume it depends on the flame retardants added. There were a couple on there rated V0 at 1.6mm walls.

    Based on experience injection molding with high performance PC/ABS blends with high flame retardant content to meet V0 at thin wall sections on some consumer devices, it's sort of a mess. The retardants have been, in a number of cases, known to plate-out into the tooling and make a hell of a mess. The trouble that stuff would create in a 3D printer seems to be to be significant, so I'd wonder how common those materials would be in printing filaments. Then again, I have never looked into those filaments, so maybe the options are good.

    In all cases, I am not sure how much any of it applies to 3D printed parts since they generally will have very thin & porous walls, at least on the top & bottom faces where you (assuming) have 3-5 0.2mm layers, plus all the infill and air pockets which all sort of seem like the perfect setup for fire lol. The wall porosity probably does a number on V0 wall thickness requirements just on its own. Besides that, how flame retardant is anything else in the E30? The good thing about the 3D printed cluster housing is that, while it is a fairly large volume, it is low mass, so there's not that much to burn.

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      #47
      Originally posted by bmwman91 View Post
      Where any of the materials land in the UL94 flame retardation performance test is going to be hugely impacted by the flame retardants added to the resin. ABS is all over the place with the minimum wall thickness needed to meet V0 (0.8 - 3mm generally), but it is pretty common stuff and presumably some of the filament vendors will actually provide some sort of traceability for their material (although I am a bit skeptical of this unless it's coming straight from Sabic, LG, etc).

      ASA looks like it generally has lower flame test performance, at least based on the few materials I pulled up on Matweb, but again I'd assume it depends on the flame retardants added. There were a couple on there rated V0 at 1.6mm walls.

      Based on experience injection molding with high performance PC/ABS blends with high flame retardant content to meet V0 at thin wall sections on some consumer devices, it's sort of a mess. The retardants have been, in a number of cases, known to plate-out into the tooling and make a hell of a mess. The trouble that stuff would create in a 3D printer seems to be to be significant, so I'd wonder how common those materials would be in printing filaments. Then again, I have never looked into those filaments, so maybe the options are good.

      In all cases, I am not sure how much any of it applies to 3D printed parts since they generally will have very thin & porous walls, at least on the top & bottom faces where you (assuming) have 3-5 0.2mm layers, plus all the infill and air pockets which all sort of seem like the perfect setup for fire lol. The wall porosity probably does a number on V0 wall thickness requirements just on its own. Besides that, how flame retardant is anything else in the E30? The good thing about the 3D printed cluster housing is that, while it is a fairly large volume, it is low mass, so there's not that much to burn.
      Thank you, this is great info. I haven't worked much with plastics before getting this printer, and it did not occur to me that the wall thicknesses would be a factor in terms of flammability.

      For overall mass of the enclosure I think we will be ending up in the ~400g range, depending on the window material, and yes, relatively speaking it is likely the least of your concerns if there is a fire, especially in a stock E30.

      Maybe for now I will shelve the fire retardent plans. I do have a kg of some ABS rated for it here though, so maybe once the design is finalized I can do some crude experimention... definitely not just looking for an excuse to light shit on fire.

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        #48
        Figured I would put together a brief update today. Nothing really too exciting - firmware is moving along, updated stepper board/small gauge is in hand and parts should arrive shortly so I can get that all dialed in. New drive strategy should give me really fine grained control over the motor, and basically zero noise (I found a few whitepapers on the exact motors I am using, basically someone did a bunch of math to get things perfect and I just need to implement it in software). Almost ready to test the back plane in the actual car - but naturally I ran into (what I think is) a fuel pump issue over the weekend so I have been kinda tied up with that. Realistically it isn't stopping me from doing some basic testing but I do need to get it sorted.

        In terms of mechanicals, things have moved along a bit. Final 'draft' of the enclosure and pretty much all the pieces is together (and printed). These are just quick and dirty 'fast' prints to check things like mounting hole location and whatnot, but you can start to see the overall design taking shape. Size wise it is just a touch smaller than the factory cluster, so a little easier to jam in behind the steering wheel :). The smaller size will be made up for by a updated ring piece that essentially matches factory dimensions, but this will be designed last as I need to figure out a window/cover setup.

        With the mechanical layout I am quite happy. Currently I think I need a very slight angle adjustment (the upper arms need to be a touch shorter) but otherwise it is basically where I want it. I will likely leave the slightly different curve shape as it is, but I am also toying with the idea of basically copying the factory shape almost exactly. Either way, any gaps/differences will be made up with the ring piece, which will replace the factory item and also cover the window component. The biggest difference to the stock cluster (IMO) in terms of looks at the moment is that the gauges are not angled 'inwards', i.e. tilted slightly around the vertical center axis of the cluster, so they are a little more flat. I don't know if this is going to be an issue or a feature - I have yet to make my mind up. I can certainly tilt the gauges but this will require adding cost because the daughter boards will need to be connected via cables, which is another set of 2 connectors for every dial. For now I will likely leave it as is, and maybe at some point in the future (if there is enough interest) offer a slightly different front enclosure and cable set so that the tilt can be emulated.

        In terms of electrical work, I need to make a mildly modified version of the small stepper board to allow for an econometer. This really isn't a big deal; in terms of electrical/schematic design it will be identical to the small 52mm board (which already supports dual motors), and just have a slightly different layout, but I may also leave this out of the picture for the prototypes as it is another item to bring in, assemble and test. Additionally, it is easy enough to add it to a prototype cluster - simply replace the translucent dial backing piece (and faceplate) with one designed to match the new board dimensions. One other goody is that the new 52mm board has provisions for a back lighted pointer (full RGB, like everything else).

        At some point in the near future I will also experiment with acetone smoothing on the cluster pieces - this should remove the 3d printed layer effect and also improve strength slightly (not that strength is an issue - even these draft pieces are solid enough that the only thing I am worried about is if somebody drops it on concrete while installing it, or decides to use it as a blunt weapon). Although the plan is still evolving, I am leaning towards offering a smoothed, lightly sanded and ready to paint (or not, up to the end user) set of cluster pieces in the kit option. I really don't want to do a ton of manual labour on the kits though, so this will depend on how easy the smoothing and a quick sanding process actually is.

        Currently the cluster is setup to accept a cut piece of flat whatever for the window/transparent cover. I will likely end up using acrylic cut on a CNC, but may also end up going with a different material or simply leaving this as on option on the kits.

        I plan to spend at least another two solid weeks hammering out firmware, and maybe a month total getting everything ready for a final set of prototypes that I can actually distribute to a few people for testing. After that there will likely be a bit of a lull, however, as I need to sort out some more work so I can fund a low volume production run of the project. This is actually a good thing though - I can work through the issues that will inevitably crop up in the test cases so that there are no major bugs in the final build. And even if there are, I do have a firmware update provision - so I can add functionality as needed and obviously fix issues that arise (this same interface is what will be used to customize the cluster, if so desired. Initially this will be a pretty full featured text interface (i.e. complicated), but I can likely throw together a python program with a UI that exposes most of the interesting bits to make customization more accessible).

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          #49
          Oh man this is really cool!
          AWD > RWD

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