JS3

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wibblywobbly
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Re: JS3

Post by wibblywobbly »

Lol, I don't do much with it. Just load it into Netfabb and tell it to fix any mesh problems. I then save that file and load it into Blender, and run a command that smooths the surface. I then save that and load it into Cura.

Cura shows up the printed surface in yellow, and the support material in red. The red support material is visible through the yellow around the hatches, which means that the surface is too thin. If I print it, the top of the turret would be wafer thin, or it wouldn't print at all.

An interesting discovery is that the underside of the hatches has an enclosure, this would only be of any use on a plastic model. I am wondering whether WOT get there tanks from model kits, simply by 3D scanning the sprue parts, and then assembling the parts in a CAD system. This would explain how you are then able to extract the parts separately. The moulding would prevent a 3D scanner from seeing the underside of the hatches, so it would guess at the thickness of the material behind it, so the underside of the hatches is wafer thin.

The 2mm wall approach will fail if the original 3D scanned part is less than 2mm, which to my untrained eye is what has happened.

I will see if I can master the basics of Blender, and add material in the transparent parts. :thumbup:
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reds turret.png
turret under.png
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wibblywobbly
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Re: JS3

Post by wibblywobbly »

This is what is happening and why.

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Re: JS3

Post by biertje »

I think they made it like that because the destroyed model has open hatches and the hatches are separate parts so I could remove them if you want to print the turret without.

Greetings tim
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Re: JS3

Post by wibblywobbly »

There is a way of solving this in Blender, but unfortunately I am not a Blender guru. Need to find a way of selecting the inner surface, then something called solidify, and then thickening the inner surface not the outer one.

Blender is full of hotkeys, and terminology that is alien to me, so trying to figure out how it works is like climbing a mountain.
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Re: JS3

Post by wibblywobbly »

After much faffing about with Blender, Meshlab, Netfabb, Cura and Openscad... 8O ....I reverted to Tim's STL file. I will do a test print of just the top of the turret to see what Cura does with the hatch area. I suspect it will either be very thin or non-existent, but I can cut that out and recreate the hatch area in Openscad. I did try sculpting the entire turret, but as I suspected it is a nightmare shape to replicate, so Tim's will have to be made to work one way or the other. I scaled it down 'very' slightly to get it to match the upper hull. The scanned turret is probably the correct size, but I had to make some very minor adjustments to my upper hull to clear the HL gearboxes, so there is a knock on effect with the turret size, and proportions.

It will need a coat of filler, but Russian castings are pretty rough anyway so that won't be a problem.

I have now done all of the angles on the front of the hull, but plenty more to do yet.... :/
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Re: JS3

Post by biertje »

If it gift you to much problems I can send you the fully striped down turret. So then I'll remove the hatches on top and everything
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Re: JS3

Post by wibblywobbly »

Just doing a test print, if it doesn't produce the desired result I will take you up on your offer. If WOT had not simply scanned a model turret that base for the crew would not have been inside, and the scan would have calculated a uniform thickness. I always assumed that WOT did their own CAD drawings to create the tanks, but this adventure shows how they really do it...they copy scale plastic models and cheat. 8O
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Re: JS3

Post by wibblywobbly »

Success!

I configured Cura to fix the mesh, and to my amazement it did exactly that. The test came out absolutely solid.
cura.png
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DSCN0020.JPG
DSCN0022.JPG
The printed surfaces aren't perfect but that can be fixed with a bit of filler and sanding. So, a big thank you to Tim, you have saved me a whole ton of work.
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Re: JS3

Post by wibblywobbly »

Around 11 hours for the front half of the hull, plus around 1.5 hours for the turret ring, said a prayer, and inserted the ring into the hole in the hull. Ye Gods! a perfect fit, rests on the shoulder on the ring, and rotates nice and smoothly without any sanding.

If anyone wants a turret ring it is on Thingiverse, it is Tiger size, and meshes with the gear on a turret motor perfectly.

https://www.thingiverse.com/thing:2272121
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IMG_20180413_222038.jpg
IMG_20180413_222027.jpg
IMG_20180413_222018.jpg
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Re: JS3

Post by B_Man »

wibblywobbly wrote:I always assumed that WOT did their own CAD drawings to create the tanks, but this adventure shows how they really do it...they copy scale plastic models and cheat. 8O
Apparently the bloke who does the Chieftain's Hatch videos on YouTube spends most of his days reading things in archives and travelling around the world taking photos and measuring and tanks for the game modelling team. He talked about it in a recent video and said they are continually redesigning and making improvements to the models and their characteristics as they go. It would make sense to use something they could scan like a model kit to quickly get things done at the start though and as no one usually sees the inside it wouldn't normally be noticed.
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