How to draw this trapezoide isosceles with rounded edges?

spawn · October 5, 2017, 4:04pm

Hi everybody.

About the following picture I’d like to know:

How to draw this isosceles trapezoid with these rounder edges on sides and top.
How to measure the dimensions of the top with the intention to draw it same size.

I wish to know how to draw it using native tools instead of using Fredo6 RoundCorner extension or FredoScale, of course I did several tries with follow me, push/pull and intersecting options with no success before writing this post.
There are a couple of reasons why I want to do it with native tools.

Even if an extension can do it, I want to know how the manual way to do it.
I’m working in something I’d like to show with native tools.

This is the .skp file if it was required: myquestion.skp (65.0 KB)

Thanks in advance

TheOnlyAaron · October 5, 2017, 4:46pm

SImply put, this is not something that I would generally do without RoundCorner. While it CAN be done, the whole point of extensions is that what will take many steps manually can be done in a single step.

Having said all of that, I would draw the initial shape, then, whole still in 2d, add the arcs to the top two corners. Then P/P into 3d and use follow me to pull arcs around the sides. After that you will likely need to do a little clean up.

(20+ steps vs 5 or so)

spawn · October 5, 2017, 4:50pm

Thank you so much @TheOnlyAaron I have to check the hidden geometry but it looks like what I was looking for.

john_drivenupthewall · October 5, 2017, 4:54pm

spawn · October 5, 2017, 4:54pm

Thank you @john_drivenupthewall
I agree with the use of the extensions, I use RoundCorner from time to time, but I also like to understand what it’s doing for me.

Anssi · October 5, 2017, 5:37pm

Your example is an easy one. Follow Me would fail if you wanted the same radius fillets in all the directions while RoundCorner manages that OK.

spawn · October 5, 2017, 5:43pm

@Ansii, this is the result with the way Aaron told me.
I think it’s 5mm radius in all directions but I’m not sure.
Does it look ok to you?

spawn · October 5, 2017, 5:56pm

I’m considering the possibility of making a tutorial about how to draw a model I found in the 3D Warehouse (it’s a LEGO man toy) and I’m not sure what it would be bettter for people looking for some exercises or tutorials, to show this way or the way using RoundCorner.

It’s true that RoundCorner makes it fast, easy and perfect but the intention of the tutorial would be that people like me can learn something so I’m not sure about what method would be the best choice.

Anssi · October 5, 2017, 6:02pm

I would guess that when you zoom in close enough you will see this

Follow Me doesn’t want to turn a corner with a zero radius. Some other modellers fail this test too (Revit, for instance)

spawn · October 5, 2017, 6:06pm

I don’t have the file now but I will keep making some tries and taking in consideration what you told me.