New build - AirMail

wsume99 said:

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.

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No other mods. Running Simplify3D as slicer, that helps a lot. I have an E3D V6 hotend that I bought, but haven't installed yet because my controller doesn't have a bootloader, so I have to hack that in with an Arduino...it's a bit to-do, which I haven't done yet, lol.

Made it "around the horn" on the end of the fins. In the last 24 hours only 17 hours have elapsed on the print clock, so again my computer doesn't understand time. Hoping I don't run out of filament.

Close!!! Here's the can:



And here's how much filament I have left:



I THINK I'm OK because the bottom inch of this thing was pretty much solid plastic so I smoked a LOT of the roll then. We'll know in about 10 hours, lol.

Did you start with a new spool on this project?

wsume99 said:

Did you start with a new spool on this project?

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Yeah, minus 30 grams for a test print. Slicer said this was gonna be 830 grams. Looks like "more than 830, but not by enough that it will matter". Based on where it's at and where it has to go yet, I'm feeling good. Could stop the print now if I had to and just epoxy the tube in instead of bolting. 6 hours remaining.

Nice, it looks like you're gonna make it! And you'll have a beefy fin can too. [emoji1787][emoji1787]

Print is done successfully. Fit on the tube is about as perfect as I was hoping for. Snug, but not so snug that the parts can't be separated. Fins are <solid>, I'll set this against any fin can I've made from "traditional" techniques.



Picked up some motors from my dealer last night and when I told him of the plans, he threw in a couple DOT "Explosives" orange diamonds, so those are going on. Also printing a "This end up" sticker.

BTW - a 1kg fin can is HEAVY. Holy smokes, lol. That's OK though, this build isn't about performance, it's about entertainment.

Looks amazing. Glad it finished without any hiccups. You're making me want to accelerate my own experimentation with a printed fincan. I planned to assemble a few rockets on my build pile before attempting one but I just might pull the project ahead in line now.


I forgot to ask, how many perimeter walls did you use, three?

Thanks!

Yeah, 3. Frequently, I'll print 4 or 5 layers if I feel it needs it.

So, tragedy/idiocy has struck this project. Recall how I made a big deal out of printing test pieces to check for fit? Yeah...that happened. When I drew up the fincan/motor mount, I didn't have a 38mm motor laying around to print a test piece with. I have said motor now. The AT I140W that I had slated for this rocket calipers at 1.503" outer dia. The inside of the motor mount, which I drew at 38.8mm dia, printed at 1.502" ID. Motor doesn't fit.

Going to try sanding it out. If that doesn't work, I'm sitting on an I205 (29mm dia) and I'll just print an adaptor for it. Still...Ug.

Printing this up tonight, goes on the end of the rod that get chucked up in a drill. sandpaper in the slot, will use it as a sandpaper hone. Need to take off 0.001", not a ton. Hopefully this works.





Edit: and printing it out of $18/kg cheap PLA, lol!

Oh man [emoji2357][emoji2357][emoji2357]

I'd be tempted to design a 2 piece sanding drum that I could mount on a drill driver and clamp a piece of sandpaper on.

Edit - lol, hit send and I see you posted exactly what I was thinking

Success!


Implement of destruction:


5 Minutes with that:




Noticed that I didn't drill the pilot hole large enough when I put in the rail buttons yesterday, some slight delamination around the screw. That's in the area that is still 100% infill, so I'm not worried about it.



Weather looks good for Saturday, should get to fly. Need to print a nose cone and motor retainer yet. ...need to design them too, lol.

Had a minor issue with printing the nose cone...it fell off the printer. There was a pretty big "impact" looking point that looks like it was knocked over by a goober on the print head. Either way, printed a new tip for the nosecone and epoxied it on. Looks good minus a little seam. This is what I came up to, pretty much 12 hours of filament sitting there on the bed.



Also finished the motor retainer/boattail, which looks really awesome (only one retaining bolt in the end-on picture, will have 4):




The completed rocket:




Rocket weighs a bit over 5 pounds all up. Flies tomorrow on an I140W, sims to about 2100 feet. 12" drogue on motor eject, 45" with a Jolly Logic Chute Release on it. First time for the Chute release, aughta be entertaining at minimum. Forecast for Burlington WI tomorrow - 51, sunny, and 14mph winds. Don't know that it gets better this time of year for Wisconsin.

AirMail flew today! Windy day, lots of rockets getting blown WAAAY down range.

Heavy rocket on a pretty slow motor (I140, good for about 5.5:1 TWR) and a 2.5 caliber stability margin meant a pretty strong weathercock. RockSIM said 12 seconds to apogee, I left the Aerotech delay at 14 seconds so it'd come down some before opening the chute. Lots of people started doing the "ooooooooOOOOOOOHHHH!!!!" thing until it popped. Then had it on a 12" drogue with a 45" main "opened" with a Jolly Logic chute release. Had that set at 300 feet because I didn't want to walk to Guam to get it. Same deal, "oooooooOOOOOOOHHHH!!" and then "poof" opened up perfectly.

Quite a few firsts for me one this one - first I-class motor on a monolithic 3D printed fincan/motor mount, first 3D printed boat tail (which got a little toasty as you can see, definitely flyable yet), and first time on a Jolly Logic CR. Great day all around, thanks to the crew at Bong who did a great job coordinating tons of people wanting to fly.

Next thing to do - email McMaster Carr and let them know that their stickers and packing list sticky bag thing is good to Mach 0.4 and 2000 feet!!!



Thanks everyone who followed along on this short journey, hope you enjoyed.

Dustin

Nice flight! Question... how far was the motor recessed into the tailcone?

The motor sat flush against the bottom of the fin can and the tailcone is 2" tall. So, 2" minus the thickness of the thrust ring was the very bottom of the motor.

Dustin Lobner said:

The motor sat flush against the bottom of the fin can and the tailcone is 2" tall. So, 2" minus the thickness of the thrust ring was the very bottom of the motor.

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Thanks.

Will get a better picture of the tailcone up at some point, short version is I washed it and what I thought was dirt/mud is actually charred PLA, lol. So, it held together fine, but one could and probably should consider the tailcone a disposable item.

Dustin Lobner said:

Will get a better picture of the tailcone up at some point, short version is I washed it and what I thought was dirt/mud is actually charred PLA, lol. So, it held together fine, but one could and probably should consider the tailcone a disposable item.

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Yeah, was just wondering because Mike at MAC Performance made a custom tailcone for an Arcas build I have scheduled. I have some leeway on how the retainer is placed in the assembly, but just did some measurements and I don't have any recess at all (well besides what is normal for the 75mm Slimline when the motor is inserted).

Closer looks at the charring on the tailcone. Not bad, usable again if needed...but not good either, lol.

Thanks for posting all this feedback. Honestly, I'd say what you are doing here is dispelling a lot of myths about 3D printing and PLA. The damage to the tail cone looks cosmetic to me. I would definitely feel comfortable flying that again. I bet the charred surface would not get much worse with more flights. It's almost like a protective layer at this point. Only real reason to replace it is if you want something that looks better. And even if you had to print a new tail cone for every flight it's probably under $1 in material. Nothing to worry about whatsoever.

I’d be interested what happens if you were to paint the inside of a second tailcone with jbweld and fly it again and see what happens

Dustin[/QUOTE]

Dustin Lobner said:

Closer looks at the charring on the tailcone. Not bad, usable again if needed...but not good either, lol.

View attachment 408506 View attachment 408507 View attachment 408508

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That's a sexy, hot ass end of a rocket!

Jay Dub 4009 said:

I’d be interested what happens if you were to paint the inside of a second tailcone with jbweld and fly it again and see what happens

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I was thinking the same, but I worry about using something thermally conductive? Seems like it might serve to get more heat into the PLA. Don't know how big of an effect that would have, but it's not something I want to find out on an I motor with motor ejection.

Maybe I'll try just standard epoxy but filled with microballoons or something like that to lower the thermal conductivity. Also - I'm working on the design to my first dual deploy (which obviously won't have motor ejection), that'll have a 3D printed motor mount / fincan, I'll try JB on that one. ...didn't really say it, but AirMail was just a cheap way to do some "pathfinder" testing for that DD rocket, mostly in the motor mount/fincan area.

Dustin Lobner said:

Closer looks at the charring on the tailcone. Not bad, usable again if needed...but not good either, lol.

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Thanks for sharing, Dustin! I'm always amazed at how well some of the 3D printed parts stand up. I print everything near heat in PETG, but have had success with PLA nose cones, transitions, fins, centering rings, etc. Mostly just on MPR, though I've done HPR parts in PETG (NC, centering rings for motor adapters, motor retainers).

Joe Bruce said:

Thanks for sharing, Dustin! I'm always amazed at how well some of the 3D printed parts stand up. I print everything near heat in PETG, but have had success with PLA nose cones, transitions, fins, centering rings, etc. Mostly just on MPR, though I've done HPR parts in PETG (NC, centering rings for motor adapters, motor retainers).

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Right - to be clear, this thing was made with Matterhacker Tough PLA...I print PETG at 235°C, the Tough PLA I print at 245°C. So, yes, this is technically PLA, but it's a "hot" PLA.

Have you considered painting the tail cone with a high temp engine or grill ceramic spray paint?

FlyBy01 said:

Have you considered painting the tail cone with a high temp engine or grill ceramic spray paint?

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I have not, but will try it in the future. I'll see if I can track down another I140 and will print a new end and try painting that, do an A/B type test on it. Will report back if I do.