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Help a 3d tard out!


danny_galaga

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I'm so fucked at CAD. I use these sorts of programs so infrequently I forget what little I learnt last time. So I figure you guys can be my computer. The attached sketch took me about a minute to draw with a pen. You guys can do it in a minute on the puter for sure! Basically the top sketch is a holder for a magnet. Looks a bit like a flying saucer with a hole in the middle. I try and do a rotation in freecad and it be won't be work.

Anyway if you can draw that for me that would be great. One step further is to take half of that flying saucer and stretch it into a tear drop. But not critical.

Then I can print the fucking thing. I could have carved it out of wood in all the time I've fucked around with it 😡

 

 

 

Edit: oops, forgot to draw the height. It's 3mm high. Hole is 5mm radius in case that's not clear. And 15mm total radius for the whole thingy

IMG_20220131_211338_HDR.jpg

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10 hours ago, Zzap said:

Haha, it’s good practice for me too 🙂 

I’ve got an idea how to do your teardrop too, but won’t get to that til tomorrow.

Hey what software are you using? I was determined to force myself to learn autocad stuff and was using freecad. But it hurts my brain. Maybe I should give up on on the pretension and learn something that doesn't hurt my head even if its less versatile. Bit like learning BASIC before Machine Language. I used to use something else, maybe sketchup and then left it a couple of years and when i got back to it, theyd changed it into something that seemed less useful AND it hurt my brain!

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And one teardrop shape!

image.thumb.png.ef1f771de997874b43d5547b0325b100.png

 

I created these in Fusion 360. The first one was done using a sketch in the Z plane. Drew that side profile, then used the 'Revolve' tool to rotate it around the Z axis 360 degrees. The second one required the sketch to be done from the top, basically drew out the circle shapes as below, tangent lines to the circles. This was then extruded up by the 0.4mm to form the base. A new sketch was created at an offset of the 3mm of height and projected the circles from the hole and the 0.5mm radius top flat bit. Then the 'Loft' tool was used to join the top of the base (from 0.4mm) up to the circle at the top. When I did this, it filled in the hole, so I had to extrude (using the cut option this time) to cut it out.

I learnt all of this a couple of years ago watching this guy on Youtube https://www.youtube.com/channel/UCo29kn3d9ziFUZGZ50VKvWA.

I really want to move to FreeCAD too to get away from Fusion 360 (it's still free for non-commercial use - limit to having 10 files that you can edit at a time, but you can still save more, and turn on and off which ones you are currently editing). Autodesk have been stuffing around with their licensing, and I'm concerned that I'll lose access to it altogether one of these days. But I've learnt so many tricks in Fusion 360 that I need to try and relearn in FreeCAD...

One of the great tricks I learnt was when doing sketches, lines will be blue when they aren't fully constrained. That means that there's something about their position that isn't locked in, and you can grab them and move them about freely - which isn't good when you're trying to make something precise!. Once you add in enough constraint (like specify a specific length, or that it is a horizontal line, or the line is tangential to a circle etc), it will go black, and you know it's locked in and good to go. As you can see in the second picture, I deleted a couple of the constraints to show what happens. I removed the tangent constraint from the top of the line between the two circles, and I removed the construction line I had added that constrained the distance between the centre of the circles to 39.5mm. This meant that the right circle and the top line are now free to move, and aren't precisely positioned. Adding those constraints in makes them precisely located and oriented.

 

 

image.png.c800b96b6c9524e68ba6954c21666608.png

image.png.ad31141758d25c3c9f946b4e63ce6380.png

 

Saucer_Teardrop.stl

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Meh, didn't quite work as hoped. But I've ordered larger magnets and I will follow your tutorial and modify the design 🙂

Basically it's for a magnetic door Catch on my ultralight. The door hinges up against the under side of the wing. Ididn't want to put a hole in the wing fabric so the idea is I have one magnet on the outside and one on the inside to hold it in place. An existing Bolt on the door then sticks to the magnet. 

Silly thing is I didn't need the 3d printed part right away to test if the idea works but I was really confident. 

IMG_20220206_080830_HDR.jpg

IMG_20220206_080810_HDR.jpg

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