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  1. #61
    Join Date
    22nd February 2013
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    Quote Originally Posted by Oberon View Post
    If you need someone to play with the "just the sled" full size eggfinder version, I'd be happy to volunteer.

    I have a 4" Madcow Patriot with a nose bay built using the John Coker method (4" x 54mm centering ring epoxied into the cone, 4" coupler bulkhead attached to that using t-nuts and machine screws). I've got a couple of different antenna sizes I could play with (no stick antenna unfortunately).
    I will keep you in mind.

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

  2. #62
    Join Date
    22nd February 2013
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    EggFinder (Full Sized) Sled

    Ok, I think I have this one about at the done stage. The suggestion of a sandable antenna support was a good one, and easily implemented. I wanted it to be removable, in case you mess up you don't wreck the entire sled. You just try again on another dodad. It will come separately and attach via a single screw from behind. I will include 3 nubs in every kit in case you have different antenna or just bugger one beyond use. Anyhow, with the spacer in place you simply wrap a zip tie around the antenna and through the tie down holes.



    I also greatly increased the area for a battery to attach. You can even wedge a 9V in there now, but it would be too big to fit in a 38 mm Nose Cone. This is something I love about PETG as a material, it is strong, but has some flex to it. I would still recommend a small LiPo though.



    Anyhow, with everything attached as with the previous versions it slides right into the 38 mm RW/Madcow nose cone. As mentioned before, this version is never fitting the CTI/Wildman 38mm cones, sorry.



    Please note it isn't really warped. I was lazy and used my crappy camera this evening.

    This needs one more cycle of very minimal tweaks, and then it should be ready to produce. Would there be interest in these? These would not be available with an outer sleeve for shock cord mounting...just too many antenna variations to account for. You could make your own sleeve out of a 38 mm coupler and a bulkhead though.

    Last edited by Cl(VII); 12th July 2017 at 04:48 AM.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  3. #63
    Join Date
    10th July 2007
    Location
    Melbourne, Australia
    Posts
    1,148
    Received your sled down under today. I guess that makes you an international businessman now

    Great design, great service. Keep up the good work!

    I guess I had better start building that Go Devil 38 I purchased last November...
    TRA 13430, Level 3

    "Everybody's simulation model is guilty until proven innocent" (Thomas H. Lawrence 1994)

  4. #64
    Join Date
    22nd February 2013
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    Garland, TX
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    Great. Glad you are happy with it, and thanks.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  5. #65
    Join Date
    15th July 2015
    Location
    Tidewater area of Virginia
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    1,392
    Again, Eggcellent work! I like how you implemented the nub.
    ATCS(AW) Tom Keith, USN, ret. _____NAR 99781 L1_____MDRA 212
    SEVRA, NAR 621http://www.sevra.org/ Tripoli East North Carolina (Bayboro), TRA #65, http://ncrockets.org/, MDRA http://www.mdrocketry.org/
    LVL 1 24 October 2015, Leviathan, CTI H133, 2469 ft, Bayboro
    LVL 2 Soon, Super DX3, AT J420 Redline, est 3500 ft, Bayboro or MDRA

  6. #66
    Join Date
    22nd February 2013
    Location
    Garland, TX
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    Quote Originally Posted by Banzai88 View Post
    Again, Eggcellent work! I like how you implemented the nub.
    Thanks. I printed the latest test with three different nub thicknesses...8 mm (wire antenna), 6mm and 4mm. That way you can start from the one closest to your antenna size. The 6 was close to right for the nub antenna, the 4 was perfect for a middle sized antenna I have, and none at all fits the big antenna I have. This is probably the way I will kit them.

    The latest version had one weak point that could be an issue on a hard (failed main) kinda landing if it hit just right, so I'm going to take some time to strengthen that area before offering these up.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  7. #67
    Join Date
    22nd February 2013
    Location
    Garland, TX
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    3,604

    EggFinder (Full Sized) Sled - 38mm kit

    38mm RW/Madcow Nosecone mount kit.



    Includes: Sled, Drill Guide, Bulkhead, Antenna spacers (4, 6 and 8 mm), (5) M4 set screws and (2) 4-40 set screws.

    You will need to add: Nosecone (plus coupler and bulkhead), EggFinder (with antenna), LiPo (4) zip ties (only 3 pictured), Eyebolt and hardware (1/4-20 or M6 recommended), 4-40 screws for mounting Eggfinder to sled (not pictured).


    To install:

    Decide which antenna spacer is best, and modify by sanding if necessary. 8mm Spacer is designed for the stock wire antenna. The spacer mounts by fitting into the slot on the top of the sled and with a single 4-40 screw from behind.

    The EggFinder directions call for the stock wire antenna to extend 80mm above the board. In my RW cone there is 83 mm of space above the board with the sled installed in the recommended way, so the stock wire should be accommodated. However, I can't speak to variability between RW/Madcow cones. The maximum antenna base size that can be accommodated is 16mm diameter.



    Attach LiPo with zip ties (vertical zip tie first), and snip excess.



    Attach the Eggfinder with your chosen hardware, feed the power connector through the pass through at the bottom of the sled, and secure the antenna with a zip tie.



    Attach the sled to the bulkhead with your chosen hardware, and the nut capture in the base of the sled as shown. It is optional, but strongly recommended, to include the fiberglass bulkhead supplied with the nosecone in the stack. Lastly, slide the sled into the pre-drilled nosecone and secure with (3) M4 set screws being careful to recess them sufficiently that they do not interfere with deployment.

    Last edited by Cl(VII); 14th July 2017 at 10:43 PM.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  8. #68
    Join Date
    22nd February 2013
    Location
    Garland, TX
    Posts
    3,604

    EggFinder (Full Sized) Sled - General Bulkhead Kit

    General Bulkhead Kit:

    Another way to mount these would be on an existing removable bulkhead. To do this you can use any threaded (1/4-20 or smaller) anchor point that passes through the bulkhead.



    Includes: Sled, Antenna spacers (4, 6 and 8 mm), Bulkhead Spacer and (2) 4-40 set screws.

    You will need to add: Bulkhead with associated hardware (14-20 or M6 recommended), EggFinder (with antenna), LiPo, (4) zip ties, 4-40 screws for mounting Eggfinder to sled.

    To install:

    Decide which antenna spacer is best, and modify by sanding if necessary. 8mm Spacer is designed for the stock wire antenna. The spacer mounts by fitting into the slot on the top of the sled and with a single 4-40 screw from behind.

    The EggFinder directions call for the stock wire antenna to extend 80mm above the board. In my RW cone there is 83 mm of space above the board with the sled installed in the recommended way, so the stock wire should be accommodated. However, I can't speak to variability between RW/Madcow cones. The maximum antenna base size that can be accommodated is 16mm diameter.



    Attach LiPo with zip ties (vertical zip tie first), and snip excess.



    Attach the Eggfinder with your chosen hardware, feed the power connector through the pass through at the bottom of the sled, and secure the antenna with a zip tie.



    Need an existing (removable) bulkhead containing an installed anchor (M6-eyebolt shown). Without removing the hardware that attaches the anchor point slide the spacer over the existing nut (recess in spacer is 15 mm wide and 10mm deep), and screw slide onto threaded part using the nut capture in the base of the sled. This secures the sled without it becoming a load bearing part of the anchor attachment. This will fit almost any 54mm or larger nosecone.

    Last edited by Cl(VII); 14th July 2017 at 10:44 PM.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  9. #69
    Join Date
    22nd February 2013
    Location
    Garland, TX
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    3,604
    As you can see above, the full sized EggFinder sled is done, and it will be available as soon as I work out batch print times.

    The sled (with antenna spacers and 2 screws) and bulkhead spacer will be available separately also. Some folks already have the bulkhead and drill guide from the EF-mini kits, and the bulkhead spacer would also work with the EF-mini sled as well.
    Last edited by Cl(VII); 14th July 2017 at 11:03 PM.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  10. #70
    Join Date
    15th July 2015
    Location
    Tidewater area of Virginia
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    1,392
    Oooooooo, put me down for one of the full size sleds, too!
    ATCS(AW) Tom Keith, USN, ret. _____NAR 99781 L1_____MDRA 212
    SEVRA, NAR 621http://www.sevra.org/ Tripoli East North Carolina (Bayboro), TRA #65, http://ncrockets.org/, MDRA http://www.mdrocketry.org/
    LVL 1 24 October 2015, Leviathan, CTI H133, 2469 ft, Bayboro
    LVL 2 Soon, Super DX3, AT J420 Redline, est 3500 ft, Bayboro or MDRA

  11. #71
    Join Date
    22nd February 2013
    Location
    Garland, TX
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    Available in the Yard Sale section for anyone interested: http://www.rocketryforum.com/showthr...D-printed-sled
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  12. #72
    Join Date
    22nd February 2013
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    Garland, TX
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    FYI: The illusive LiPo of choice for these sleds is in stock at the HobbyKing International Warehouse: https://hobbyking.com/en_us/turnigy-...lipo-pack.html

    I just picked up 10 of them for $60 with shipping...I'm unwilling to wait for them to become in stock at the US warehouse to save a few $ on shipping.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  13. #73
    Join Date
    22nd February 2013
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    Garland, TX
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    OK, there are quite a few of these in the wild, particularly the mini. Any construction or flight feedback? I tried to dish out maximum abuse in my GoDevil38 K627 flight, but I would imagine folks have done "worse" by now.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  14. #74
    Join Date
    12th April 2015
    Location
    Arizona
    Posts
    280
    I've got the bulkhead mount for a full-sized Eggfinder. First, the part itself is clearly well made and designed, and Chris delivered it promptly. It should work great.

    Unfortunately I've yet to fly it because (my fault) I underestimated the overall length and it doesn't fit in the cone I'd designed for it. I was trying to fit it in a 4" Madcow Patriot kit with a removable "John Coker style" bulkhead. Between the relatively short ogive and the lead nose weight, there wasn't enough length for the Eggfinder on this mount (I rigged up a much less pretty plywood sled that does fit the Eggfinder (barely)).

    A few suggestions for refinement:

    1) There's a lot of wasted height on the bulkhead mount, could be a problem for shorter/smaller cones. I'm assuming this was designed for maximum commonality with the NC sled design, so it makes sense, but it still precludes some applications.
    2) I'm not a big fan of the nut capture design - it's a bit fiddly and requires you to have a nut just the right size. There's not really room to get a finger or tool in there to tighten/loosen a smaller nut, and a bigger nut (for e.g. a heavier duty eyebolt) won't fit at all. For the bulkead mount, some sort of open flange design that would allow you to secure the sled with any size nut and washer, and tighten (gently) with a wrench would be preferred.

    But overall this is a cool design, thank you Chris for making it!
    I aim at the stars. But sometimes I hit London.

    NAR #99868
    L1: MDRM on CTI H175, 7/26/2015 @ NARAM 57
    L2: "Flugel der Freiheit", AT J420R, 11/4/2017 @ GHS Memorial

  15. #75
    Join Date
    22nd February 2013
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    Garland, TX
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    Quote Originally Posted by Oberon View Post
    I've got the bulkhead mount for a full-sized Eggfinder. First, the part itself is clearly well made and designed, and Chris delivered it promptly. It should work great.

    Unfortunately I've yet to fly it because (my fault) I underestimated the overall length and it doesn't fit in the cone I'd designed for it. I was trying to fit it in a 4" Madcow Patriot kit with a removable "John Coker style" bulkhead. Between the relatively short ogive and the lead nose weight, there wasn't enough length for the Eggfinder on this mount (I rigged up a much less pretty plywood sled that does fit the Eggfinder (barely)).

    A few suggestions for refinement:

    1) There's a lot of wasted height on the bulkhead mount, could be a problem for shorter/smaller cones. I'm assuming this was designed for maximum commonality with the NC sled design, so it makes sense, but it still precludes some applications.
    2) I'm not a big fan of the nut capture design - it's a bit fiddly and requires you to have a nut just the right size. There's not really room to get a finger or tool in there to tighten/loosen a smaller nut, and a bigger nut (for e.g. a heavier duty eyebolt) won't fit at all. For the bulkead mount, some sort of open flange design that would allow you to secure the sled with any size nut and washer, and tighten (gently) with a wrench would be preferred.

    But overall this is a cool design, thank you Chris for making it!
    Thanks for the feedback. The bulkhead is long, but I wanted to make sure that the holes you drill in the shoulder were not too close to the aft end. I assume that if you have too little space there, particularly in the filament wound couplers that tear out could be an issue...this is probably me worrying too much. The nut capture is 11 mm, which is spot on for the typical 1/4-20 nylon lock nut (I got from several sources), but is a loose fit for others. As an alternative, I've had luck with the M6. In that case you can slip a small screw driver along side the nut, and turn the bolt in. I'll timnker around with the design, and see if I can make something a bit more universal without compromising strength.

    Thanks again for the feedback.

    Also, I am neck deep in a bathroom remodel, but when I am out of the woods there (in a week or so), I will probably offer up a holiday discount. Everyone with new Egg Things and small rockets to fly them in can try these out too.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

  16. #76
    Join Date
    21st September 2017
    Location
    NY/NJ
    Posts
    169
    Quote Originally Posted by Cl(VII) View Post
    OK, there are quite a few of these in the wild, particularly the mini. Any construction or flight feedback? I tried to dish out maximum abuse in my GoDevil38 K627 flight, but I would imagine folks have done "worse" by now.
    I've flown mine on F-though-I engines, with all good / BAU results.

    The engine size doesn't really matter here, as much as the ejection force that puts stress on the cord attachment point. That, plus an occasional hard landing.

    For me, the only question is long term durability, especially of the three threaded attachment points to the nose shoulder. Time will tell how long those will last, as I seem to be getting plastic crumbs falling out of something each time I take the sled out of the nose cone.

    a
    __
    Radrocketeers.org NAR L2

  17. #77
    Join Date
    21st September 2017
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    NY/NJ
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    169
    Quote Originally Posted by Cl(VII) View Post
    Available in the Yard Sale section for anyone interested: http://www.rocketryforum.com/showthr...D-printed-sled
    PM sent.
    __
    Radrocketeers.org NAR L2

  18. #78
    Join Date
    12th April 2015
    Location
    Arizona
    Posts
    280
    The bulkhead is long, but I wanted to make sure that the holes you drill in the shoulder were not too close to the aft end. I assume that if you have too little space there, particularly in the filament wound couplers that tear out could be an issue...this is probably me worrying too much. The nut capture is 11 mm, which is spot on for the typical 1/4-20 nylon lock nut (I got from several sources), but is a loose fit for others. As an alternative, I've had luck with the M6. In that case you can slip a small screw driver along side the nut, and turn the bolt in. I'll timnker around with the design, and see if I can make something a bit more universal without compromising strength.
    Yeah I think that makes a ton of sense for the original application as a coupler/nose cone mount. Th ability to use it on existing bulkheads is something of a bonus, and I imagine it would look a bit different if that was the primary goal. Either way, cool product!
    I aim at the stars. But sometimes I hit London.

    NAR #99868
    L1: MDRM on CTI H175, 7/26/2015 @ NARAM 57
    L2: "Flugel der Freiheit", AT J420R, 11/4/2017 @ GHS Memorial

  19. #79
    Join Date
    22nd February 2013
    Location
    Garland, TX
    Posts
    3,604
    All new EFmini sleds will be getting an upgrade. Specifically, a collar that can be fitted to the sled that will stiffen the sled at its weakest point. The collar still allows for the sled to be mounted in the Wildman/CTI or Madcow/RW nosecones. It is similar in design to the shock cord mount sleeve, where an internal ridge braces against the sled to reinforce it. The difference is here the screws are partially recessed into the collar to maintain the clearance needed for nose cone mounting, and it is shorter of course. This collar shouldn't be considered required for flight (lots of flights have gone off successfully without it), but as extra insurance against hard landings.



    This upgrade came about as a result of the first report I've gotten of a production sled breaking in use. The flyer also provided a wealth of data. The circumstances of the flight: Temp estimated in high 30s/low 40s, impacted ground at 52 fps, horizontal landing of the payload bay/nosecone section. I suspect this constitutes a worse case recovery...relatively high speed, impact perpendicular to mounting axis and relatively cold. The sled broke at the base (along the bottom zip tie hole for the battery), but the EFmini kept transmitting (tough bugger). I believe if this collar would have been in place this fracture would not have occurred as there would have not been opportunity for bending at that point. I designed these with an assumption that the greatest forces experienced on boost, ejection and landing would be along the Z-axis...which on a completely nominal flight they would be, but as we know, rockets do not always fly and recover that way. I think this collar is the answer for X/Y force insurance. There will always be a speed of plastic, but I want to get as close to that theoretical limit as is possible.

    Actions:
    - I have sent the user a new sled and collar.
    - All new sleds will come with a collar and 2 additional 4-40 screws (price will not change).
    - I will supply reinforcing collars to existing sled owners (one for each EFmini sled they own) either by including them in a future order, or if they would like to pay $3 shipping I will mail them within a week.

    Also, I would like to note that the EF full sized sleds are a fundamentally different design that has more X/Y strength inherent in the design...at the expense of size of course.

    Thanks to the flyer for the detailed report of the sled failure. Their data rich report allowed for this solution to become available within a few days of their report.

    Last edited by Cl(VII); 20th November 2017 at 05:43 PM.
    So much of my rocket building time has been diverted toward my "other hobby": Race Timing

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