3D Printing 3D Printed Doorknob here we come.

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Curlrup

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Once I build it and fly it. I don't like sharing unproven designs. Safety first.
 

Curlrup

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Running my Doorknob SLA from Siraya Tech Fast Green. The goal is to keep it transparent acid green by clear coating, and Black. Essentially the Doorknob paint scheme but transparent acid green and black. Engine mount integrated into the end with slots for Balsa fins.
 

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Curlrup

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Fin can off the machine. Motor fits. Nose cone is re-running. Wavy bottom. I have to adjust my supports. The nose cone is two pieces glued via the material it made from and a uv light. You can also fill and sand the seam with the material and a uv light. So the nose cone is sanded. Two more pieces to run.
 

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Curlrup

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Coming together nicely. The transparent acid green didn't quite work. Too much finish work inside the tube to get the look I wanted. However, I have a plan.

Also, new toy at work. HP 5200 machine. Sintered nylon. Nice.
 

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lowga

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That looks great! Can't wait to see it painted and to hear how it flies.
 

lowga

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Beautiful rocket. Finishing 3D rockets can be a chore. What did you do in terms of sanding? I find that a corse sand with 80 or 100 grit sandpaper (dry), followed by 400 grit (wet) sanding does well.

Cannot wait to hear how it flies. Really nice work. Now, I want one!
 

Curlrup

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Thanks. With SLA there is little to no sanding. Pretty much worked the seams with 150 grit. Primer and paint.
 

lowga

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Nice. I've only assembled 3-D models from Boyce Aerospace, which require a bit of sanding. When finished, though they are beautiful models.

Can't wait to see your Doorknob fly.
 

Curlrup

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Not sure if this is allowed but any interest in an SLA Doorknob kit? After some test flights? It would of be raw SLA 3d printed parts. Fin can with motor mount slotted, 2 body tubes all snap together and secured with CA. A nose cone with a cap that has an eyelet molded in. Also profiles for fins.
Or like an STL file pack with fin profiles, and part files unsupported, parts files supported for SLA and SLA resin profiles?
This was designed with SLA 3d printing in mind. I think FDM results would vary.


Just a thought. If I'm off base here let me know.
 

Curlrup

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Flew great on a standard Estes Super C. About 300 feet which is what wanted (small launch field). There was a breeze, I had a little too much angle. More this weekend.
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IMG_20200703_182841038_HDR.jpg
 

Curlrup

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Well...two very successful flights today. However. The last flight the ejection charge blew a hole through the side, and somehow the nose cone got a burn mark on the side. I'm seeing a trend here. This particular SLA resin can't take repeated impacts and pressures from the ejection charge. So I'm going to remake it from a custom blend of resin that should be tougher. Stay
VID_20200704_091054905_exported_6927_1593870043116.jpg
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tuned.
 

lowga

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Ouch! I know that had to hurt. But that's rocketry, right? A series of failures marred by the occasional success! :)

Beautiful rocket--maybe you can rotate it and use it as a static display.
 

Curlrup

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Had a spare upper tube. A little Dremel, a little filler, it will be back in one piece. The top tube is the one that blew out so sperating the seam was easy to swap it out. I think it's still going to blow out after a few shots though. Different resins on order.
 

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lowga

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That's great. I know less than nothing about 3D printing. It almost seems like a whole other hobby--and I don't have time for that. I do know that most rockets seem to be made out of PLA (whatever that is.)

You seem to have a lot of expertise, so I'm sure you'll lick the problem soon enough. Thanks so much for sharing this with the community.
 

Curlrup

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Graphed a new 3d printed upper body tube into the 3D printed Doorknob. The joint was relatively easy to separate. Pulled the busted one out, put the new one in, finished out the seam, primer, paint, clear. Next silver line work as before. Also some hot ejection charge hit the nose cone leaving a scorch mark. I like it. It's part of it's history, so I cleared over it.
I'm thinking about laminating some paper inside the tube for extra reinforcement. Thoughts on that?
IMG_20200705_142312315.jpg
IMG_20200705_142305399.jpg
 

Curlrup

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Oh, I got the color break higher on the tube where it should be.
 

lowga

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The repair looks very nice.

Meant to ask you how you achieved the silver bits on the model? Tape and paint or decals?

I'm a big fan of rocket patina and battle scars. I've got about a half dozen rockets that are either salvaged from my own childhood (mostly Centuri models that survived my many moves) or flea market discoveries. Nearly all of them were flown dozens of times. Also mine were painted with Testors and a brush as I didn't discover spray paint until my 20's.

No matter...they remind me of a simpler time when the joy of "whoosh" and seeing a successful ejection were thrill enough. Now I obsess over the smallest details and seem to worry a great deal about what others in my club will think about the latest build.

My vote is to leave the battle scar. The bird earned it fair and square.

Never heard of anyone lining the inside with paper. That is a thought. Wonder if aluminum foil might be an even better choice.
 

Curlrup

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The repair looks very nice.

Meant to ask you how you achieved the silver bits on the model? Tape and paint or decals?

I'm a big fan of rocket patina and battle scars. I've got about a half dozen rockets that are either salvaged from my own childhood (mostly Centuri models that survived my many moves) or flea market discoveries. Nearly all of them were flown dozens of times. Also mine were painted with Testors and a brush as I didn't discover spray paint until my 20's.

No matter...they remind me of a simpler time when the joy of "whoosh" and seeing a successful ejection were thrill enough. Now I obsess over the smallest details and seem to worry a great deal about what others in my club will think about the latest build.

My vote is to leave the battle scar. The bird earned it fair and square.

Never heard of anyone lining the inside with paper. That is a thought. Wonder if aluminum foil might be an even better choice.
Laminated the inside with regular old paper, and watered down wood glue. Got a long brush and overlapped 4 strips. That should help once dry. The silver bits are aluminum tape cut, stuck, and burnished smooth with a scrap piece of balsa. Works great. Looks cool too.
 

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Fixed and flying. One more flight and I'll post up the STL files and fin pattern.
VID_20200713_172951953~2_exported_248_1594677922198.jpg
 

Curlrup

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Version 2.0, sintered nylon from an HP machine. One ounce lighter, twice as strong, more impact resistant than SLA resin. More to come.
IMG_20200718_174257950.jpg
 

Curlrup

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If I released the files what motor mount would people want? Right now loaded the rocket comes in at 7 OZ. I have a small flying field so I run it on a Super C C5-3 motor that pushes it about 200 to 300 feet which is perfect for me. So currently it has an 18 mm mount, but could change it easily to 24 or 29...
 

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