EggFinder Mini (AND Fullsized) 3D Printed Sled - Full Sized EF sleds available

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Cl(VII)

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UPDATE: Go to Post 49 for the Final EFmini Version

UPDATE: Go to Post 55 for Prototype of Full Sized EF Version

UPDATE: Go to Post 67 for the Final Full Sized EF Version

I am a big fan of the Eggfinder products, but I want to be able to quickly swap an EggFinder Mini between projects. I set out to make a shock cord attachable case to make it as easy as possible. After multiple cycles refining it I think I have a good design. The case itself is about 5.5" long, and has space for a LiPo upto about 45 mm x 24 mm. It was designed around the battery I (and apparently Cris) uses for his EggFinders (available here), but will accept slightly larger batteries too. It is the diameter of a 38 mm coupler, and could be used as such if you used set screws instead of button head to keep it closed.





Anyhow, I'm trying to get the design just right as I may offer them for limited sale if there is some interest. As such I'm looking for 1-2 beta testers who currently have an EggFinder mini and battery that would fit, and are willing (and have opportunity) to fly it in the next 2-3 weeks and provide feedback. I'll say I'm on the fence about ever offering these for sale as I am not looking to turn this into a job...I already have one of those and a side gig, so constructive feedback about the design and part quality will be helpful in making that decision.

These are printed in PETG which is fairly thermal resistant (Tg somewhere around 80 deg C), so don't throw it on your dashboard in summer and leave it for the day.

I also made a small adapter that will make these nosecone bulkhead mountable, but I'm not planning to include that in the beta test sets.

If you are interested in being one of these testers contact me by PM (I'll ask that those interested be willing to kick in the material cost and shipping).
 
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Crazyrocket

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+1 for the wildman recon protector. I would try out your sled, but I won't be flying for a month or so. I started making one from a 24mm motor mount but never finished it. My plan was to tape it to the shock cord. Your sled is definitely more elegant!
 

Banzai88

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You can always put this on shapways of one of those other 3D print sites. That way people can pay the service, and they'll mail you your cut of the profit!
 

Cl(VII)

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You can always put this on shapways of one of those other 3D print sites. That way people can pay the service, and they'll mail you your cut of the profit!
Shapeways would definitely be the easy way, but I looked into how much one sled would be from Shapeways. The Shapeways cut alone is well more than I would charge for a complete sled AND the hardware. If you throw in a cut for me the price gets prohibitive for what it is. Besides, I have the printer, and won't be running it every minute for my own uses anyway.

Also, I have one tester, and am looking for one more.
 

Banzai88

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Shapeways would definitely be the easy way, but I looked into how much one sled would be from Shapeways. The Shapeways cut alone is well more than I would charge for a complete sled AND the hardware. If you throw in a cut for me the price gets prohibitive for what it is. Besides, I have the printer, and won't be running it every minute for my own uses anyway.

Also, I have one tester, and am looking for one more.
Understood. Another thought....it would be AWESOME if you had a version that would fit into the couplers/nose cones such as a 38mm min diameter Go Devil. THAT I would buy, without question!
 

Cl(VII)

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Understood. Another thought....it would be AWESOME if you had a version that would fit into the couplers/nose cones such as a 38mm min diameter Go Devil. THAT I would buy, without question!
I just ordered a 38 special that I plan to modify to minimum diameter, so you can be sure smaller NC versions are coming. 38 coupler size was easy, so I started there to get the general design worked out. Looking to pick up a 29mm Go Devil soon too.

EDIT: Just added a Go Devil 29 to my Madcow order. Man, I don't need much enabling.
 
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ksaves2

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Was able to get a full length, higher gain Linx antenna to fit in the Madcow 38 Special: https://linxtechnologies.com/wp/wp-content/uploads/ant-418-cw-hw.pdf
using a regular (shorter EF not the mini). A mini will have no trouble fitting in. I used something like a 1/2" bulkhead plug and used four screws to secure it
to the NC shoulder after turning on the EF and screwing the bulkhead on. JLCR is used for trackable "pseudo" dual deploy fun. Really nice setup as this
rocket will disappear easily on modest loads. Kurt
 

Banzai88

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I just ordered a 38 special that I plan to modify to minimum diameter, so you can be sure smaller NC versions are coming. 38 coupler size was easy, so I started there to get the general design worked out. Looking to pick up a 29mm Go Devil soon too.

EDIT: Just added a Go Devil 29 to my Madcow order. Man, I don't need much enabling.
You're welcome!
 

Salvage-1

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I love the pure simplicity of this idea. I am starting to fly Min Diam birds on some hefty motors. The problem that I am finding, is the finding. We launch in High Desert with sage brush so thick that you can have a 5" (airframe) rocket landed and all splayed out, and yet unless one part of it is lying over the sagebrush, you can be 10ft from it and still not see that darn thing.

Looking at your product, it would be so easy to drop this into the tube between the drogue chute and the AV bay. Popping out with the drogue and hanging free in the air all the way down!!

If you haven't got enough testers yet, I would love to try this AND pay you for the privilege.
 

Cl(VII)

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I love the pure simplicity of this idea. I am starting to fly Min Diam birds on some hefty motors. The problem that I am finding, is the finding. We launch in High Desert with sage brush so thick that you can have a 5" (airframe) rocket landed and all splayed out, and yet unless one part of it is lying over the sagebrush, you can be 10ft from it and still not see that darn thing.

Looking at your product, it would be so easy to drop this into the tube between the drogue chute and the AV bay. Popping out with the drogue and hanging free in the air all the way down!!

If you haven't got enough testers yet, I would love to try this AND pay you for the privilege.
PM sent, and with that I have enough testers.

Thanks.
 

cerving

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Was able to get a full length, higher gain Linx antenna to fit in the Madcow 38 Special: https://linxtechnologies.com/wp/wp-content/uploads/ant-418-cw-hw.pdf
using a regular (shorter EF not the mini). A mini will have no trouble fitting in. I used something like a 1/2" bulkhead plug and used four screws to secure it
to the NC shoulder after turning on the EF and screwing the bulkhead on. JLCR is used for trackable "pseudo" dual deploy fun. Really nice setup as this
rocket will disappear easily on modest loads. Kurt
Kurt, I think you got the wrong link... that's for a 70 cm antenna. This is the one you want: https://www.linxtechnologies.com/resources/data-guides/ant-916-cw-qw.pdf
 

ksaves2

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Kurt, I think you got the wrong link... that's for a 70 cm antenna. This is the one you want: https://www.linxtechnologies.com/resources/data-guides/ant-916-cw-qw.pdf
You're right. I had APRS on the brain. I've used this one: https://linxtechnologies.com/wp/wp-content/uploads/ant-916-cw-hwr.pdf
and this one: https://linxtechnologies.com/wp/wp-content/uploads/ant-916-cw-hw.pdf
Where there's room to use 'em. I use SMA sockets and not RP as I had a load of them on hand. I do have an adapter in case one would and
to borrow my patch antenna or Yagi (Yagi for ground recovery only) to plug into their receivers.
Tune the EF to the closest frequency for lowest SWR an one will be milking as much as they can out of the 100mW. I apoloqize as this has nothing to
do with the mini. Kurt
 

Salvage-1

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Got my unit... looking forward to testing it out at the next launch. I would post pics, but they would look just like the ones at the start of the post.

This really is a nifty little unit!
 

Cl(VII)

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From the feedback I'm getting already, thanks guys, it looks like I was looking at the demand differently than what actually may be there. There appears to be more interest in NC mount type sleds than in a shockcord mount type sled. Which is good by me. I came back from vacation to a Go Devil 38 kit that I plan to outfit with a NC mounted EF mini, electronics bay Stratologger CF, and an internal MD motor retainer.

I also got in some bright orange PETG which was one of the suggestions received so far.
 

Banzai88

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Yup, nose cone mount would be the holy grail for something like the Go Devil. I've tried several, haven't hit on one that I like yet, but it looks like your design is pretty cool!
 

woferry

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I've had no trouble getting a full-size EF and a larger 2s LiPo (900 mAh) to fit in my GD38's NC. I've posted pictures of it before on this thread, flown it a bunch of times.
 

Banzai88

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I've had no trouble getting a full-size EF and a larger 2s LiPo (900 mAh) to fit in my GD38's NC. I've posted pictures of it before on this thread, flown it a bunch of times.
Unfortunately, that product is no longer offered, and the one that he does have will not fit the coupler.

Care to share your sled on thingverse or another print on demand service?
 
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Cl(VII)

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I've had no trouble getting a full-size EF and a larger 2s LiPo (900 mAh) to fit in my GD38's NC. I've posted pictures of it before on this thread, flown it a bunch of times.
Oh yeah. You can definitely fit a good deal in there. Have been kicking around the best way to make the attachment point...i.e. if the PETG will be the load bearing attachment for the screw eye. I think it would be fine, but I have a 110 lb spring scale on order. I will print the sled, and find out what the breaking point is. If it holds 100 lbs that would be a shock of well more than 100Gs as there is no way the NC comes in over 1 lb with everything in), and I would be comfortable using an eyebolt attached to the plastic as the attachment point for the shock cord.
 

woferry

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Unfortunately, that product is no longer offered, and the one that he does have will not fit the coupler.
He still makes the 38mm NC bulkhead, it's this part. The only difference is he's added a charge well to allow for it to be an altimeter bay. I don't know if he'd make out without the well, or I'd think he'd still have the files for the older design. But I can't speak for him obviously, I would believe that he doesn't have any of the older ones in stock. Looks like the newer version still has the same two holes that mine does for locking to the NC shoulder and attaching the sled, though strangely the one shot on that page doesn't show the holes on the flat side of the lip, but the other ones clearly show the sled screwing into this area so there has to be a hole there. :)

Care to share your sled on thingverse or another print on demand service?
I can definitely post the .stl, at least to the STL thread on this forum. I built it using OpenSCAD, but my sources are a bit of a jumble as I tried to make libraries out of everything, so the battery, EF TX and magnetic switch data all comes from separate files, as well as support libraries, etc. Works great for my source control system, but not so much for sharing to others without basically sharing every file. It's also one of my older designs and I've improved a lot of my common routines since then, so I'm not sure that the current state of the sources would even reconstruct the shape properly.
 

woferry

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Oh yeah. You can definitely fit a good deal in there. Have been kicking around the best way to make the attachment point...i.e. if the PETG will be the load bearing attachment for the screw eye. I think it would be fine, but I have a 110 lb spring scale on order. I will print the sled, and find out what the breaking point is. If it holds 100 lbs that would be a shock of well more than 100Gs as there is no way the NC comes in over 1 lb with everything in), and I would be comfortable using an eyebolt attached to the plastic as the attachment point for the shock cord.
I've never tried transferring the shock load through anything I've printed (the idea just scares me too much to try that), I've always preferred my printed things to ride within something that will handle the actual stresses to ensure my rocket stays in one piece. After having some initial bad luck with wood bulkheads splitting, even for AV bays I try to do a direct transfer from lower eye-bolt to upper eye-bolt (i.e. using a coupler nut and using the eye-bolt's threads to run the entire length of the bay, rather than separate threaded rods through the bay and U-bolts or eye-bolts at each end with the bulkheads transferring the load). I have designed some NC tracking sleds where the sled captures a nut, and that nut screws into an eye-bolt which is the shock cord attach point, it wasn't to hold the rest of the nose on (the nose itself screws onto the eye-bolt also) but how the sled attached inside a plastic NC where I'd cut away part of the shoulder to insert the sled (probably makes no sense as words, I can attach a picture of it when I get home).
 

OverTheTop

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I've never tried transferring the shock load through anything I've printed
Keep the 3D printed stuff in compression and you will have almost no troubles. Just make sure the print is thick enough to prevent a failure along the 45deg shear plane, or have some other method of keeping things compressed.

Tension is bad, especially in the Z-axis, for most current printers.
 

Banzai88

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He still makes the 38mm NC bulkhead, it's this part. The only difference is he's added a charge well to allow for it to be an altimeter bay. I don't know if he'd make out without the well, or I'd think he'd still have the files for the older design. But I can't speak for him obviously, I would believe that he doesn't have any of the older ones in stock. Looks like the newer version still has the same two holes that mine does for locking to the NC shoulder and attaching the sled, though strangely the one shot on that page doesn't show the holes on the flat side of the lip, but the other ones clearly show the sled screwing into this area so there has to be a hole there. :)



I can definitely post the .stl, at least to the STL thread on this forum. I built it using OpenSCAD, but my sources are a bit of a jumble as I tried to make libraries out of everything, so the battery, EF TX and magnetic switch data all comes from separate files, as well as support libraries, etc. Works great for my source control system, but not so much for sharing to others without basically sharing every file. It's also one of my older designs and I've improved a lot of my common routines since then, so I'm not sure that the current state of the sources would even reconstruct the shape properly.

I spoke with APE today, the part you have is no longer made and the part that you linked to he was clear does not fit the madcow coupler (such as in the current generation of Go Devil/Rapton/Hurricane) or anything other than the injection molded nose cones. Did you do something different when you constructed your nose cone shoulder?

Heck, I'd be willing to pay for a definitive version, much like we're all addicted to the MW/Additive Aerospace/Landru sleds.

Watching the development of this thread and sled :)
 
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Cl(VII)

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Keep the 3D printed stuff in compression and you will have almost no troubles.

Got it! Keep it all in compression. I think I have it figured out now. Will not be a big deviation from the sled pictured above with one extra component to make it NC ready. I'm test printing the "extra piece" now to make sure I'm not delusional.
 

woferry

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I spoke with APE today, the part you have is no longer made and the part that you linked to he was clear does not fit the madcow coupler (such as in the current generation of Go Devil/Rapton/Hurricane) or anything other than the injection molded nose cones. Did you do something different when you constructed your nose cone shoulder?
The NC shoulder is simply a coupler, it's the exact same type of coupler as the AvBay, just shorter. I don't have any pictures of my RW kit as I received it, but it just came with two different lengths of 38mm couplers in the red FG, one for the NC and one for the AvBay. Uploading pictures showing the perfect fit in both couplers (my AvBay coupler is epoxied into the upper airframe section along with the vent band) as well as caliper measurements of the ID of my coupler and the OD of my APE piece (the inner stepped portion, of course, not the outer lip). No modifications of any kind were necessary.

I'm picking up two 54mm NC AvBay sets from APE at lunch today (for two more Madcow/RW kits, a Go Devil 54 and a Double Shot), I'll bring along my Go Devil 38's NC and show Chris what I have. I don't know how Madcow has changed RW's kit or what APE has changed on their end, mine works exactly as I'd hoped it would when I ordered it. I guess I didn't see how the NC shoulder he had pictured on his site would be much different than the FG coupler used in RW's kits, the OD obviously still has to fit in the airframe tube, I guess the ID could have been a bit different based on material thickness, but in this case it wasn't an issue, and I'd have thought that a plastic part if anything would have a thicker wall than a FG part would, so I didn't even ask any questions I just ordered APE's part at the time. Now if the kit is no longer using a coupler for the NC shoulder or the ID has gotten smaller than the ~34.9mm mine is then that obviously could be an issue, or if the OD of APE's machined part dimensions have changed for some reason but that seems unlikely to me.

P6150001.jpgP6150002.jpgP6150003.jpgP6160004.jpgP6160006.jpg
 

Banzai88

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...... I'll bring along my Go Devil 38's NC and show Chris what I have.
Excellent, thanks. As far as I know, nothing was changed by MadCow as your measurements are close to what I have.
 
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ChrisAttebery

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Hmmm, interesting. I could have sworn that the injection molded NC had a thicker shoulder. I'll take a look at Will's NC today at lunch. I think I have one of those older style bulkheads in stock. If so, it's yours Tom.

I don't want to make up a bunch and have them sit on this shelf, but if I can get a few committed buyers I can make another batch next week. Sent me a PM if you're interested.
 

woferry

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I'm in.....take my money!

Cl(VII), I'm in for one of your 3D printed toys, too. I have several birds ready to test!
Hi Tom, do you happen to have calipers? If you can accurately measure the ID of your coupler that's probably best. I just sent a similar email to Chris before remembering he'd posted here also, the two 54mm kits I picked up from him today were for formerly-RW-now-Madcow kits as I'd mentioned above, turns out they have the size issue of concern here, the part that goes inside the nose shoulder has an OD slightly bigger than the coupler's ID (I measure 51mm for APE's part OD and 50.8mm for Madcow's coupler ID). In this case the part I need to reduce in size is FG instead of aluminum so I can make my parts fit, but it does point out that it's best to measure your application to ensure it should fit, if your coupler is also ~34.9mm you should be fine, if it's less than 34.7mm it probably won't work (and in-between may be risky, I'm not sure how much gap the two parts really need to be a "fit"). I did suggest that Chris should probably state the OD of his parts on his product pages (though perhaps the ID it's intended for would be better), which might help someone to take the measurement of their application and judge whether it should work or not.

Trying to bring things back to the intent of this thread (sorry for the derail), similarly here I'd suggest making it clear the ID of the tube you're trying to make your part work with, CI(VII), as there can probably be quite a bit of variance from vendor-to-vendor, perhaps kit-to-kit and maybe even age of the kit (at least in the RW->Madcow change, but I'd imagine parts could change for other reasons also like just manufacturing tolerances, switching source vendors, parts standardization across a line of kits, etc).
 
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