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Jul 09, 2018, 04:16 PM
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Thread OP
Slow but steady progress on the Gripen, the last sections of the body printed and glued. Now on to the wings, after a few test pieces I think I have found a tolerance that will work on the wing attachment, so now I just have to buy more plastic!

I also made a Meteor BVRAAM to hang underneath, I really love how easy it is to make scale details using a 3d printer. The Meteor was maybe 4 hours of CAD work, and after that I can make as many as I want just pressing a button (well, more or less at least ) This way it's no big deal if i strip them off in a rough landing, it may even be a good thing as they might take some damage off the A/C.

The model has 6 points for payload (yes, I forgot the center points, they will be included in next version), so I have to figure out some more fun stuff to hang under there. It isn't really realistic for the typical Gripen user to have 6 Meteors considering a unit price of about 2.5 million usd...
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Jul 09, 2018, 09:43 PM
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Dirty Dee's Avatar
Coincidentally, I have been making several 1/10 scale ordinance for my freewing A-10. looking at this info-graphic, looks like the Gripen can use GBUs, MK80s, and AGM-65s like I have already modeled (and soon JDAMs):




If you want to save yourself some time:

https://www.thingiverse.com/DirtyDee/designs
Jul 10, 2018, 04:45 PM
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What a coincidence, I actually downloaded your AIM-9 for this purpose earlier this year. But back then you didn't have all those other fancy loads published, thanks for the heads up

You don't happen to have the dimensions of the mounts for these, aka the freewing mounts?
Last edited by evolve; Jul 10, 2018 at 05:04 PM.
Jul 10, 2018, 10:10 PM
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Dirty Dee's Avatar
Quote:
Originally Posted by evolve
You don't happen to have the dimensions of the mounts for these, aka the freewing mounts?
check here for a replica, though not the same shape as the stock freewing:
https://www.thingiverse.com/thing:2858226
Jul 11, 2018, 12:04 PM
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Thread OP
Quote:
Originally Posted by Dirty Dee
check here for a replica, though not the same shape as the stock freewing:
https://www.thingiverse.com/thing:2858226
Thank you!
The shape doesn't matter, as long as it is dimensional correct on the critical parts. The "female" part will be integrated in the hardpoints (not sure if that's the correct english word) under the wings.
Jul 12, 2018, 01:29 PM
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Quote:
Originally Posted by Lynxman
Nice Gripen model. Are you printing single extrusion walls?
By the way, how did you solve the single extrusion wall challenge?

My 0.25mm method produces great results, but it takes nearly twice the time to print...
Jul 12, 2018, 04:16 PM
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Lynxman's Avatar
I tried it and it worked well for me too. I got slightly reduced print quality (visible waves in the photo) when I tried two thin walls instead of a single 0,4 wall, but weight was reduced slightly as well. The photo below shows 0,4 single perimeter on the left, and then two 0,2 mm perimeters in the middle and two 0,25 perimeters on the right. The one with two 0,25 mm perimeters weighs the same as the one with single 0,4. the one with two 0,2 weighs a bout 10% less. I haven't tried printing a complete airframe with your technique yet because of the extra time it takes with my big plane.
Jul 13, 2018, 02:57 PM
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Quote:
Originally Posted by Lynxman
I tried it and it worked well for me too. I got slightly reduced print quality (visible waves in the photo) when I tried two thin walls instead of a single 0,4 wall, but weight was reduced slightly as well. The photo below shows 0,4 single perimeter on the left, and then two 0,2 mm perimeters in the middle and two 0,25 perimeters on the right. The one with two 0,25 mm perimeters weighs the same as the one with single 0,4. the one with two 0,2 weighs a bout 10% less. I haven't tried printing a complete airframe with your technique yet because of the extra time it takes with my big plane.
When I print with 0.4mm and check "allow single extrusion walls" in S3D, it goes bananas and comes up with a totally unusable result. Where the skin meets the inner structure, S3D breaks the skin and makes part of the structure to outer surface, see the attached image.

Any tips on how to avoid this?
Jul 13, 2018, 04:08 PM
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Lynxman's Avatar
When I made structure for 0,4 mm singel wall I make it 0,7 mm inside the outer walls. Maybe that helps.
Sep 17, 2018, 10:55 AM
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I'm watching this thread intensely! Same with the L-39 which I have already started! Would love to try and print this one up! Any way the files will be available? I'll start up my second CR-10S and get right to printing it.
Sep 17, 2018, 12:17 PM
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Quote:
Originally Posted by evolve
When I print with 0.4mm and check "allow single extrusion walls" in S3D, it goes bananas and comes up with a totally unusable result. Where the skin meets the inner structure, S3D breaks the skin and makes part of the structure to outer surface, see the attached image.

Any tips on how to avoid this?
You internals need to be offset more so it will not interfere with the skin. When I am modeling my single outer skin pieces that have internal structures from a solid I have to offset the internals by .7 mm with a .42 extrusion width. This allows the internal to print close enough that it actual is touching the skin but not protruding it.
Sep 17, 2018, 05:51 PM
Registered User
To form the internals, make a second 'shell' of the aircraft outer parts which is 0.4mm to 0.8mm smaller than the real outer skin. You can then use this inner shell to 'boolean'/cut the internal structures to be that amount smaller.
When it is printed the extrusion width will bridge that difference and thus the internals will bond against the INSIDE surface of the real outer skin.

In these pics, the wing shaped skin is a 'shell' of the real surface. The ribs are made just by making flat rectangle planes of 0.1mm, into a grid pattern, then placing the wing shell into that and 'boolean' cutting those planes. It will produce ribs, and those will be that 0.4mm smaller than the inside surface of the real wing piece. Then 'join' those ribs into the real wing surface 3D model part(s).

....
Apr 05, 2019, 07:00 AM
Vertical Unlimited
Straight Up's Avatar
How is this going? Terrific thread, but now quiet.
Apr 08, 2019, 11:15 AM
Registered User
Sorry to bother you. How did you do this ribs in wings? Do you use some certain software?
Apr 08, 2019, 11:38 AM
Registered User
Quote:
Originally Posted by PeterVRC
To form the internals, make a second 'shell' of the aircraft outer parts which is 0.4mm to 0.8mm smaller than the real outer skin. You can then use this inner shell to 'boolean'/cut the internal structures to be that amount smaller.
When it is printed the extrusion width will bridge that difference and thus the internals will bond against the INSIDE surface of the real outer skin.

In these pics, the wing shaped skin is a 'shell' of the real surface. The ribs are made just by making flat rectangle planes of 0.1mm, into a grid pattern, then placing the wing shell into that and 'boolean' cutting those planes. It will produce ribs, and those will be that 0.4mm smaller than the inside surface of the real wing piece. Then 'join' those ribs into the real wing surface 3D model part(s).

....
Sorry to bother you, but I dont understand how you build those ribs with your computer. Do you use perculiar software?


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