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Thread: Team Expat - Beetleweight Adventures

  1. #11
    First few bits and bobs have arrived! Am going to stick pics on photobucket, here -

    So, 4x 1000rpm 12v gearmotors. They are surprisingly heavy, which gives a positive feeling of maybe being not-entirely-unreliable. The shaft spins very smoothly, and the build quality seems reasonable. The shaft has a bit of play in-and-out, but is solid laterally, which is promising. I have yet to hook them up to a supply but so far they look the part.

    The weapon bearings also arrived. 5x (will either use 4 or 2 in the weapon, not sure) 12mm ID, 21mm OD, 5mm wide ball bearings. Not much to say, other than I think they'll serve.

    Desperately waiting for more goodies now!

  2. #12
    Disc has been cut and is at Mario's currently. That's a 151mm literal diameter, 162mm diameter "bitten", 5mm thick Creusabro 4800 (similar to Hardox 450/500) single tooth, weighing around 360g.

    Just did a rough energy calculation, and that looks like this:

    The resulting joules figure seems quite high... if anyone can spot a glaring flaw in that mess of imperial figures, let me know. I don't think there's a screw up but ~1750J of energy seems a bit crazy?

    edit: for the record, thinking about this I'm fairly sure it's wrong, one day I'll muster the energy to recalculate...
    Last edited by Ellis; 9th August 2013 at 20:17.

  3. #13
    Good job the arena has 10mm polycarbonate.

  4. #14
    Coming my way, courtesy of Mario.

    That's the disc, a 12mm silver steel shaft (thank you Mario's lathe), and a sheet of ti.

  5. #15
    How's the disk made?

  6. #16
    Watercut. The CAD design was sent to a watercutting company, and they cut it out of material they stock. The design has slots between the bore and the gaps between the spokes, to make for fewer individual "windows", as I believe the number of blow-throughs the waterjet has to make has an effect on price. Mario has welded the slots up for me, which is what's visible on the pic.

  7. #17
    Quote Originally Posted by Ellis View Post
    The design has slots between the bore and the gaps between the spokes, to make for fewer individual "windows", as I believe the number of blow-throughs the waterjet has to make has an effect on price.
    Why would they charge extra for that?! You mean there's a fee for every time the machine starts and ends a cut?
    If so, I consider myself lucky to have found a reasonable shop where they just charge by the length of cut only as I had in the range of 100 separate cuts performed on my waterjet job I had!

    Looking good tho, going to be one hell of a beetle weight!

  8. #18
    The blowtrough takes more time than plain cutting, so it isn't abnormal that they charge for every started hole. Also , especialy for waterjet cutting, evey startup has a marked wear and tear on the nozzle. Again logical it costs a bit extra.
    Of course, some firms will use a flat fee and add the avarage hole-cost to that making intrate designs a tad cheaper, but simple ones a tad more expensive.
    So in my case the firm I work with atm uses the blowtrough cost, and that can be avoided by clever design.
    And yes, there are firms a tad cheaper. But this one is only 15 minutes drive away, and they don't complain about small jobs. Even better, they have cut offs at hand in most consievable materials. Send the dxf, specify material, get the pricetag. Confirm order and 4-5working days later the stuff is ready.

  9. #19
    Granted mario, its all wear and tear on their machinery, the shop I use machine most spares they need inhouse, so that could contribute to the way they charge.

  10. #20
    New stuff has turned up!

    Parts are:
    1x pack of assorted heatshrink.
    1x 1300mah 35c 3s LiPo.
    2x 20mm diameter neodymium magnets, 2.2kg pull.
    3x m4 taps, slightly different shapes for different tasks.
    3m of red and 3m of black 20 gauge silicon wire.
    1x set of different cobalt drill bits.
    1x 3.3mm drill bit (for tapping).

    Well this morning was rather Christmassy!

    Also, I'm organising a website. Once I've got some content on it I'll link it, and I may decide to post detailed updates on there rather than here. It'd also contain write-ups on anything we do, for example we're currently building a new workshop space ahead of T3.

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