Simple altimeter sled design... In progress

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ttabbal

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I'm working on a simple design to be 3D printed. I just thought I would share it here to get comments and in case other people find it useful. The hole pattern is a placeholder for now, it should fit an MAWD. The sled is designed to fit in a 3 inch rocket with 1/4 inch all-thread.

I'm planning to add a battery case that screws down, probably with heat-set threaded inserts.

https://cad.onshape.com/documents/1...70d18a3c889603ad0c/e/1d0afb97dcc8ce78af8fd508
 

djkingsley

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I print all my sleds these days using a common design and customized for each rockets needs. Once your design is finished you won't go back to stick built sleds. I have been using these screws with great success.

sleds.jpg

Image on the left is a test print to accommodate the RTx and RRC3 boards, the image in the middle shows the fit of the boards and the image on the right is the final products for my 4" Sensor and Black Brant rockets. I have another design in the works with the RRC3 stacked on top of the RTx board.
 

ttabbal

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Thanks for the pics! I'm curious about the loop at the end, is it to add strength? Centering? A handle? :)

I'll check out the screws, always nice to have options. I like your built in standoffs, I might have to try adding something like that.

And what material are you using? The green looks like PETG.
 

djkingsley

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The green is a translucent PETG, I really liked the material but inland has done away with it and the new stuff is very brittle and breaks in the extruder. The red and yellow are a reformulated 200deg PLA that I found it is not as susceptible to softening in the sun as regular PLA.

The ring in some of my av-bays hold a switch. In these two they support some wire that is zip tied to it and I removed the hole.
 

ttabbal

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Thanks. I have been really happy with PETG in general. Tough, prints easy, handles high temperature well. I get mine from makergeeks.
 

markkoelsch

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I print all my sleds these days using a common design and customized for each rockets needs. Once your design is finished you won't go back to stick built sleds. I have been using these screws with great success.

View attachment 300646

Image on the left is a test print to accommodate the RTx and RRC3 boards, the image in the middle shows the fit of the boards and the image on the right is the final products for my 4" Sensor and Black Brant rockets. I have another design in the works with the RRC3 stacked on top of the RTx board.
They look nice. Let me ask you a question- how do you fit two altimeters and the RTX board? Have you looked at that?
 

djkingsley

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My first reaction is to get a bigger rocket to fit more altimeters, but I think I could stack 2 - RRC3's in the 4 inch design.Would have to add another small battery cage on the back for the third battery.

I am looking at mounting a 808 camera body to the sled this weekend with a ribbon cable to the lens mounted on the switch band. First I have to convince my self that the the camera lens shroud won't impact my baro readings.
 

ttabbal

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You could also add vertical parts to the sled to mount gear to. The flat sled is a kind of inefficient use of the internal space. It's simple and generally sufficient though.
 

djkingsley

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I could add a couple longitudinal walls and mount two altimeters with the wiring coming up between them. The battery box is almost big enough to hold 3 LiPo's if I put them on 90 degrees from where I have them now.

I am also using that last 2 inches where the spacers are for a camera sled. I have a mobius unit and the lens extension cable coming, I will pull the camera out of the case and mount it on a sled. I will design a streamlined appendage for the lens that will attach to the switch band. At least thats the plan.

Once you start printing your own sleds you have a lot of freedom to try new configurations.
 

AlphaHybrids

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Very nice design. Is there any reason to use two 1/4" rods? I've used a single central rod on all my rockets up to 5.5" and ~50 pounds.

Edward
 

ttabbal

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I honestly don't have a good reason for 2 rods. I started that way as I was concerned about it rotating in flight, pulling on the pyro cables. I can see ways to prevent that being a problem, but the only down side I saw was weight. I didn't mind a few ounces. I have been known to overbuild though. :)
 

ttabbal

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I'm considering adding a bulkhead to one end, so it's printed in place, then I could use various methods of mounting it to one of the AV-bay bulkheads. Perhaps replacing one of the plywood bulkheads. Then any all-thread etc could be smaller, single run, or even eliminate it and run kevlar harness through it and pin the bulkheads with temporary rivets, nylon screws, etc.. Lighter, plenty strong, and a bit simpler.
 
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