New build - AirMail

Discussion in 'High Power Rocketry (HPR)' started by Dustin Lobner, Feb 27, 2020.

Help Support The Rocketry Forum by donating:

  1. Feb 27, 2020 #1

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Hi everyone,

    Working on a new build that some people might find entertaining. I ordered some dowels from McMaster and got one of those thick-walled shipping tubes, decided to turn it into a rocket because why not? (OK, yes, the "why not" is that the tube is 10x's thicker than needed and is thus HEAVY). It's a 3.3" OD, so nothing "stock" will fit, so I'm 3D printing a fin can/motor mount and nosecone.

    The tube still has all of the packing list and UPS stickers on it, so I'm going to add some more ("this end up", lol) and just fly it in its "bare" cardboard state with all of the shipping stickers on it and call it "AirMail".

    Started the fin can/motor mount print last night. Computer says it's an 88 hour print, reality will be closer to 110 hours because my slicer underestimates for some reason. If we have a power outage or something I'm going to cry.

    Bottom.PNG Side View.PNG Top1.PNG Top2.PNG

    Print after about 10 hours:

    Print 1.jpg


    Hoping to fly this at Bong in April.
     
    SeanW78 likes this.
  2. Feb 27, 2020 #2

    kuririn

    kuririn

    kuririn

    BARGeezer TRF Supporter

    Joined:
    Oct 3, 2016
    Messages:
    3,515
    Likes Received:
    1,126
    Gender:
    Male
    Location:
    Hawaii
    How come two of the fins have jaggedy surfaces?
     
  3. Feb 27, 2020 #3

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    That's the support material to support bottom of the fins. For whatever reason, the slicer only orients those in a direct X-Y orientation, so it ends up being a series of squares oriented X-Y but the part is at an angle. ...image paving a walkway with squares that you aren't allowed to cut down, that you have to orient in the north/south direction, but your walkway goes southwest. The outside will be jaggedy.

    If you look closer to the body, you can see some of the fin coming in looking "smooth".


    Edit: clarity
     
  4. Feb 27, 2020 #4

    kuririn

    kuririn

    kuririn

    BARGeezer TRF Supporter

    Joined:
    Oct 3, 2016
    Messages:
    3,515
    Likes Received:
    1,126
    Gender:
    Male
    Location:
    Hawaii
    Thanks, got it. Wishing you an outage free 5 days and plenty of filament on your spool.;)
    Laters.
     
  5. Feb 27, 2020 #5

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    That's a nice looking design. What is the MMT dia and what impulse class are you planning to fly the rocket at? What material are you using for the print? Are you printing this with solid infill?

    (I'm interested in printing my own fincans as well and just want to learn from others so I can cut the number of iterations I'll need to get a usable part.)
     
  6. Feb 27, 2020 #6

    David Schwantz

    David Schwantz

    David Schwantz

    Well-Known Member

    Joined:
    Jul 23, 2018
    Messages:
    972
    Likes Received:
    262
    Gender:
    Male
    Location:
    MN
    My Ender 5 will resume printing after a power loss. Yours will not?
     
  7. Feb 27, 2020 #7

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    It's the bog standard CR-10...it claims it can, but everyone online who tried it had it not work, so I'm not planning on it working that way.
     
  8. Feb 27, 2020 #8

    David Schwantz

    David Schwantz

    David Schwantz

    Well-Known Member

    Joined:
    Jul 23, 2018
    Messages:
    972
    Likes Received:
    262
    Gender:
    Male
    Location:
    MN
    Guess I would not test either!
     
  9. Feb 27, 2020 #9

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Missed this reply, apologies.

    38mm motor, plan to fly on either quick burning Hs or most Is, biggest concern is having enough punch to get it stable before clearing the rail. I ran a few sims and they were coming out about 1-3k feet.

    Material is Matterhacker's Tough PLA. I use it all the time at work for test fixtures and it's startlingly resilient...it isn't remotely brittle, it bends without breaking. Good stuff, just that it's $52 for a spool, so if the print goes wrong it's $52 down the drain. Calling it a PLA does it a disservice, it's more like ABS in terms of properties.

    The bottom inch or so of the can is 100% infill (which in reality is maybe 50% plastic?). The goal was to make the interface with the motor as strong as possible. Everything above that is 25% infill or thereabouts so I can print the whole thing on 1 spool.

    This is the 3rd fincan I've done. it's very doable, the main issue is designing the can to be easily printed. As far as iterations go, I print a couple smaller pieces beforehand where there's a critical interface. For example, if I have a 38mm motor, I know I have to print the motor mount bore at 38.6mm dia to get the right clearance. For where it meets up with the tube, I printed a 1" long ring with the ID drawn to "match" the OD of the tube...I had to hammer the ring on and off, so I opened it up 1mm on the diameter and that seemed about right. Short version, to get fitment right, you don't have to print an entire fincan, just print bit and pieces of it. Saves time and filament.


    My favorite things about 3D printed fincans...1) you can do fin root to tip taper, makes the fins really stiff and sexy and 2) because they're as "perfect" as can be easily done, they don't rotate on flight...just a wonderfully straight boost. Rotating is something I didn't realize my "standard" rockets did until I flew a printed fincan. It was startling the first time.
     
  10. Feb 27, 2020 #10

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    That is the exact same approach I use as well. Whenever I design a part to 3D print I focus on the critical interfaces first and print some test articles to get the design perfected. Then the rest is all about printability.

    What infill pattern are you using?

    That filament is very pricey. Have you ever tried using PLA+? I just finished my first spool of PLA+. I was quite impressed with it and it's under $20 per 1kg spool. I am 100% confident I could design and print a fincan to withstand flight on H-I motors using that material. The only unknown for me is how it would handle environmental exposure. I suspect it would be fine other than being left inside a car on a sunny, hot summer day.
     
  11. Feb 27, 2020 #11

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Infill...honestly not sure, lol. Either rectilinear or a honeycomb thing.

    And yeah, it really is $$. My "normal" filament is eSun PLA Plus, which might be what you're talking about? I love that stuff. I made a fincan I flew twice on a G with no issue, it landed on a chicken coop at my friend's and snapped a fin off. Where I fly (Bong), one of the landing surface options is gravel, so I wanted to try this as it'd be more robust. If this doesn't work (power outage, warping, or whatever) I'll probably end up reprinting in PLA Pro just for financial reasons if nothing else.
     
  12. Feb 27, 2020 #12

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    Yep, the eSUN PLA+ is exactly what I was talking about. I think I got 2 x 1kg spools for ~$35. I looked at the matterhackers stuff and it is all expensive IMO, even the PLA PRO. Not sure what makes it so expensive. I am happy with the results I am getting with the eSUN PLA+ material - easy to work with and relatively strong when used appropriately. I've considered getting a spool of ZYLtech carbon fiber PLA to experiment with as well. I've never used their material but I have heard nothing but good things about their stuff.
     
  13. Feb 27, 2020 #13

    Joekeyo

    Joekeyo

    Joekeyo

    Forum Supporter TRF Supporter

    Joined:
    Sep 12, 2019
    Messages:
    89
    Likes Received:
    35
    Gender:
    Male
    Location:
    Sun City Center, FL
    I was eyeing some big cardboard tubes in the last isle of Home Depot. The tubes looked to be about 4' long and 6" inches in diameter. I suspect that they are used for forming concrete. My wife comes by and says, without hesitation, "Thinking about an upgrade?" She never missed the beat.
     
  14. Feb 27, 2020 #14

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Hah! Yeah, good times. Only issue I'm aware of with printing is that anything M or above needs glass or carbon reinforced parts for fins? Something like that, I know there's a thing, the concern is flutter and fin departure from the rocket.
     
  15. Feb 27, 2020 #15

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    I've never flown anything near that big but I'm positive I could print a fincan from PLA (assuming I had a large enough printer) and it would survive on a P motor flight. Likewise, I'm certain I could print one and it fail on an A motor flight. It's all about designing to the loads and environment that will be seen in use. I think as long as you are staying under M0.6 (maybe as high as M0.8) PLA+ is going to be ok. It's not the motor size that's important, it's the flight profile.
     
    Last edited: Feb 27, 2020
  16. Feb 27, 2020 #16

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Concur completely, also has a lot to do with the design. A nicely filleted and tapered fin is gonna be crazy stiff and won't flutter as much.

    If I had to guess, the "threshold" of M or larger has more to do with the amount of damage that can be done from a departure from controlled flight with an M vrs with a G.
     
  17. Feb 27, 2020 #17

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Got home tonight to happiness (see below)...and my 100% infill is dang near solid plastic, lol. When I started the print last night at 8pm it was saying an 88 hour print. 22 hours later it's saying 56 hours remaining, so apparently my printer doesn't know math. Not arguing though, lol.

    Got some stringing and whatnot, not too worried though. The important parts all look good presently.

    IMG_20200227_172656685.jpg IMG_20200227_172617439.jpg
     
  18. Feb 27, 2020 #18

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    Looking solid (pun intended)

    What layer height are you printing with?

    I normally print at 0.2 mm and if I want a really good finish I step down to 0.12 mm.
     
  19. Feb 28, 2020 #19

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    0.2mm... I'll go all the way down to 0.1mm in similar situations, this would've taken a month though, lol. This is thru a 0.4mm nozzle.

    I tried a 0.6mm nozzle once, never got it sorted out...think I need to give it a try again, lol.
     
  20. Feb 28, 2020 #20

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    LoL, at 0.6mm the extruder stepper would be smoking after that build.
     
  21. Feb 28, 2020 #21

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Lol, yeah. Especially since I put a Bondtech on it which is geared 3:1. It screams now with "normal" prints.

    I can actually buy a 1mm nozzle for it. The filament is only 1.75mm, so it's cutting the diameter by less than half at that point....seems like it wouldn't work too well, lol, nevermind the extruder stepper glowing red at the same time.
     
  22. Feb 28, 2020 #22

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Switched over to the low infill percentage, should start growing quicker now.
    IMG_20200227_192245424.jpg
     
  23. Feb 28, 2020 #23

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Here's some pics of the second fin can I printed. Flew well on a G80. The fins are really thin compared to what I'm doing with the one that's printing now, didn't have an issue though.

    IMG_20200227_192128441.jpg IMG_20200227_192114058.jpg IMG_20200227_192118511.jpg
     
  24. Feb 28, 2020 #24

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    Nice! I assume the tube runs down to the bottom of the fin can and is secured in place by the two phillips screws between the fins near the bottom? Do you happen to know the thickness of the fin at the tip? Doesn't look like it could be more than a couple lines.
     
  25. Feb 28, 2020 #25

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Correct, that's how the old one was laid out. It worked, but I feel like I'm "losing" length. Because of this, the one currently printing only supports the bottom 3" or thereabouts, there's a ring of 6 screws to capture the tube.

    Couple of other screenshots of previous (successful) attempts.

    Gen 1: separate motor mount and fincan over the outside. This is the motor mount, which was epoxied in. The tube slid over it (from the right in this picture). It was held together with epoxy - the almost gear looking things are cavities for the epoxy to sit in and get some good surface area on the inside of the tube. The fincan was just a cylinder with fins, slid on from the outside and rested against the flat surface on the left. Motor would insert from the left. Worked well except it still relied on epoxy, so when one of the fins was broken off the whole rocket went in the bonfire that was keeping us warm that night. Flew twice on F42's, great until it landed on the chicken coop and the "normal PLA" fin shattered.
    Motor mount screnshot.PNG





    Gen 2: the fincan from a different post above with the thin fins. Motor mount and fincan all in one, bolted in instead of epoxy. The tip width measures at 0.92mm, so...yeah, about 2 layers. Here's a CAD view of the internals:
    Fin Can Screenshot.PNG


    Current one printing is Gen 3 as mentioned. I like how it's coming together. Only thing to work on in the future is to re-separate the fin can from the motor mount. Idea being you can swap out the motor mount if you want to change the motor size, and you can replace the fins if one breaks.



    ...Reminds me of another thing I tried in the past, having a sleeve that would allow replacing individual fins. Printed the sleeve and a couple of fins, it's just too fiddly to really make sense. Can't find the CAD file...I feel like there's a good idea buried here somewhere, but my $400 printer can't execute it:
    IMG_20200227_200924074.jpg
    IMG_20200227_200929777.jpg
     
  26. Feb 28, 2020 #26

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    Thanks for posting these. Helps give me lots of ideas. I like the thought of removable fins. I'm pretty sure with enough experimentation that a good solution could be designed.
     
  27. Feb 28, 2020 #27

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    One of the neat and also mentally taxing things about 3D printing is you get to see things "grow"...but too slowly! Drives one slightly crazy.

    Status as of this morning below. Should start going faster because after passing the tip of the fins there's no more support material, and things are getting smaller/layer.

    IMG_20200228_062755133.jpg IMG_20200228_062757866.jpg
     
  28. Feb 28, 2020 #28

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    Just occurred to me, with a 3 fin design I would have only put three stringers between the OD and ID. I would have oriented them to be inline with the fins. This allows the load to more directly transfer thru to the MMT and also reduces the weight, material used and print time. Obviously it's your design but that's what I would do.
     
  29. Feb 28, 2020 #29

    Dustin Lobner

    Dustin Lobner

    Dustin Lobner

    Well-Known Member

    Joined:
    Sep 3, 2019
    Messages:
    115
    Likes Received:
    43
    Gender:
    Male
    Agreed. I originally had this as a 4 fin but couldn't print it in 1 spool so cut one off. There's a lot of "meat" to the design so I'm not worried about it, but in the future that's the plan.

    EDIT - also, this way the rail button is sunk in solid.
     
  30. Feb 28, 2020 #30

    wsume99

    wsume99

    wsume99

    Well-Known Member

    Joined:
    Feb 28, 2014
    Messages:
    198
    Likes Received:
    51
    For sure strength is not going to be an issue with your design. I was just pointing out I thought three would be just as strong and a little cheaper and faster to print in case you hadn't already thought of it. I'm excited to see the finished product.

    Looks like you are using Capricon tubing and you mentioned a bondtech extruder drive. Any other mods to your printer?

    I have an ender 5 plus. Only mods I have done that affect printing are Capricorn and the creality all metal extruder. I did install a raspberry pi running octoprint, a webcam for remote monitoring, LEDs so I could actually see what was happening on the webcam, and two relays to turn the printer and LEDs on/off.
     

Share This Page

Group Builder