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  1. #1
    Join Date
    26th August 2012
    Location
    Somewhere in the Bay Area
    Posts
    127

    Another Eggfinder Tx Mini Sled

    Gentledudes,

    Here's another example of a 3D printed sled for the TX mini. This was designed around a 350mAh battery, and will fit into a 24mm motor tube. My goal was to have a tracker that could move between rockets easily.

    The first prototype shows the basic design clearly:

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    The modifications between that and our final design included changes to the posts for mounting the board, a larger channel for routing the battery wires, and a pocket to hold the battery balancing connector out of the way. The details don't show up well with the black plastic, but hopefully you'll see what we've done:

    Click image for larger version. 

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    I made a simple carrier for this using a 24mm motor tube, with an Estes retainer for the closure on one end. The other end of the tube is sealed up with a 1/8" plywood bulkhead that has a kevlar harness for attaching it to the recovery gear.

    After making the motor tube carrier, we decided to try an even simpler approach -- heat shrink and and tape. We used some heat shrink to cover the center area of the sled where the board is exposed, then covered the whole sled with some good electrical tape (very wide and not too sticky), leaving the JST connectors exposed. In use, we will tape down the JST connectors, and attach the sled to the recovery harness with duct tape.

    We'll try it out at Black Rock this weekend. Backup for the primary tracker on a L3 rocket and the only tracker on several smaller ones.

    Many thanks to Cris for making tracking equipment accessible and affordable, and for the fantastic support he always provides. Sharp eyes will pick up a repair on the Tx Mini board, see if you can spot it.

    Dad is sad.
    Very, very sad.
    He had a bad day.
    What a day Dad had!

    _______________________________________________
    NAR 92379 L3
    LUNAR 1762

  2. #2
    Join Date
    22nd February 2013
    Location
    Garland, TX
    Posts
    3,433
    Nice. That is approaching the minimum space you could ever get an EFmini. Well done.

    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  3. #3
    Join Date
    30th January 2016
    Location
    US > OK > NE
    Posts
    2,984
    THERE we go. Plan to publish the shapes? I'm cramming one onto a g65 sometime soonish.

  4. #4
    Join Date
    26th August 2012
    Location
    Somewhere in the Bay Area
    Posts
    127
    Quote Originally Posted by dhbarr View Post
    THERE we go. Plan to publish the shapes? I'm cramming one onto a g65 sometime soonish.
    Solidworks file attached. I had to do a little bit of clean-up on the black sled with sandpaper and a file to get things to fit. Nothing major and it wasn't worth tweaking the file and reprinting.

    Eggfinder Tx mini sled V.3.STL
    Dad is sad.
    Very, very sad.
    He had a bad day.
    What a day Dad had!

    _______________________________________________
    NAR 92379 L3
    LUNAR 1762

  5. #5
    Join Date
    3rd February 2012
    Location
    So Cal (ROC, TRASD, SCRA)
    Posts
    2,406
    Very nice! While you're at it, run a bead of epoxy between the brown antenna and the metal can on the GPS module. It prevents the antenna from dislodging in the event of a hard landing.

    I'd love to see something like a Go Devil 24, for the CTI 6G 24mm motors... this would be perfect for it.

  6. #6
    Join Date
    30th January 2016
    Location
    US > OK > NE
    Posts
    2,984
    Quote Originally Posted by cerving View Post
    Very nice! While you're at it, run a bead of epoxy between the brown antenna and the metal can on the GPS module. It prevents the antenna from dislodging in the event of a hard landing.

    I'd love to see something like a Go Devil 24, for the CTI 6G 24mm motors... this would be perfect for it.
    Talk to Charlie at Carolina Composites :-)

  7. #7
    Join Date
    26th August 2012
    Location
    Somewhere in the Bay Area
    Posts
    127
    Quote Originally Posted by cerving View Post
    Very nice! While you're at it, run a bead of epoxy between the brown antenna and the metal can on the GPS module. It prevents the antenna from dislodging in the event of a hard landing.

    I'd love to see something like a Go Devil 24, for the CTI 6G 24mm motors... this would be perfect for it.
    Cris, you remind me about that every time we correspond! It's bonded down on all four sides, but it's a thin fillet and doesn't show up in the pic. I didn't use as much finesse when I potted the repair we made for the RUN pad that I burned off with my son's soldering iron though. I guess he's into speed-soldering...runs the iron way to hot for my ham-fisted technique.

    I don't have anything in 24mm that would need a tracker...closest I get is a Wildman Darkstar Mini--38mm body with a 29mm motor tube. The 6-grain CTI motors will push the rocket up over 6000 feet, making it hard to track and prone to drifting a long way. We're doing this at Black Rock so I'm not worried about getting it back, provided I know where to look. The sled and the motor tube both fit with just enough room for an appropriate recovery package. Problem solved.
    Dad is sad.
    Very, very sad.
    He had a bad day.
    What a day Dad had!

    _______________________________________________
    NAR 92379 L3
    LUNAR 1762

  8. #8
    Join Date
    18th October 2016
    Posts
    276
    Quote Originally Posted by dhbarr View Post
    Talk to Charlie at Carolina Composites :-)
    I'm way ahead of you.
    TRA L2. I-class record: "Vanish 29" with an I224, 14,596ft, Mach 1.92. Video here.

  9. #9
    Join Date
    26th August 2012
    Location
    Somewhere in the Bay Area
    Posts
    127
    The pic shows a carrier I made for the Tx Mini sled. It's basically a 24mm motor tube and an Estes retainer. Looks cool, but I ended up not using it this weekend because the retainer added length and bulk that I didn't have room for in two of the three rockets I used it in.

    Duct taping the sled to the shock cord (and covering everything to keep it clean and protected) worked fine.

    Click image for larger version. 

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    Dad is sad.
    Very, very sad.
    He had a bad day.
    What a day Dad had!

    _______________________________________________
    NAR 92379 L3
    LUNAR 1762

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