There must be an easy way to create a bowl

I am trying to create a round bowl with a flat bottom. Easy huh?
not so much because I want the horizontal thickness to be a consistent 1.2mm.
I am doing this at x1000 so 1200mm. Right now I am brute forcing it by measuring each step up.
The bottom thickness is 1.2mm and the sides from the first layer to the top (50mm) must be 1.2mm thick.
the outside (or inside) arc is trivial.
So how do I construct this with arcs/circles or something else and get it a consistent side thickness?

Upload your SKP file as you’ve got it.

If you want the walls to be 1.2m thick horizontally and the base 1.2m thick measured vertically:

Draw your external profile. Move with copy vertically with the base up 1.2m and move with copy horizontally with the curved wall by 1.2m. Join them up.

If you want the walls 1.2 thick measured at their thinnest point, like radially if your curve is an arc, do this:

Draw your outside profile. Make it a closed shape then use the inset tool with 1.2. Delete the outside part at the top or extend the inside, depending on what shape you want the lip.

@McGordon
what that yields is a curve spaced 1.2mm from the original curve.
Now draw some horiz lines and measure them.


see the problem?

So here are two curves drawn such that there’s 1.2mm horizontally as you asked for.

As you can see, as the curves flatten out toward horizontal themselves, they get closer together. Is that what you want?

Here are the two methods I mentioned.



Having the 1.2m horizontally and vertically will mean an uneven thickness over the curve, but I think that’s what you wanted?
The horizontal and vertical parts were moved separately, then joined up, not moved at the same time as in your drawing.

otherwise known as…

you can only measure consistency from a constant datum, in this case a line from the shared centre point …

arbitrary measurements taken from anywhere else will be different…

john

1 Like

I don’t think you have it. I took the wall lines from my brute forced bowl and tried to merge them. Not going to happen. The error was not big and probably would be OK in the print, but if you are taking exact, that won’t do it. The 2 walls must have a different radius or be rotated slightly and I am sure some math student can come up with a formula to determine what they are, but I can’t. Searchng google didn’t turn up anything either. I think this is a question for Quora.

What I am trying to do is to get the print to print the same # of lines per layer. When it prints 5 at the bottom, then 4, then 3, the surface at the transition point gets messed up. When it gets to 3 or 1.2mm it is a lot smoother the rest of the way up.
It is like it is extruding too much when trying to fill 5 & 4 perimeters.

You are asking for two different shapes:
1)

You can do that by copy/moving the outer wall horizontally by 1.2mm.

Like concentric circles? You could get that with the inset method above. That would give an even thickness measured radially to the centre of the arc. That doesn’t sound like what you want for your 3D printer. If you want the same number of lines on each layer, you want method 1).
Every slice would be 1.2 measured horizontally.

Try this:
Draw the curve for the outside of the bowl, using the 2-point arc tool.
Get the protractor tool. Hover it at the endpoint of the arc, draw a guideline at 90 degrees to the first line segment of the arc. Draw a line 1.2mm long over the guideline. Repeat for each vertex on the curve. Connect the ends of the 1.2mm lines. See the attached image.![21 PM|597x500]
You’ll get a uniform wall thickness this way; horizontal lines won’t do that, as other responders have shown.
21 PM

withdrawn

thanks David. The issue isn’t a uniform RADIAL thickness. That’s easy. I’m after a uniform horiz thickness so that the printer prints the same # of traces for each layer.

@McGordon
take 2 concentric circles and measure the horiz distance at different levels. They will all be different. So if you start out with different #s and add a constant to them, what will you get?

you will even get to a point where you can’t connect both circles and the distance to the same circle will be larger than any other distance.

Just use the move tool to copy the curve 1.2 inwards then add the top and bottom edges.

@Box
I’m sorry, I need to try this again
where are the constant horiz dimension lines going to be placed?
constant

This is what I mean.
Bill

you do that so well.
I have no idea why it didn’t work when I did that.
Probably because I didn’t do it exactly like that.
I’ll try it again when I am awake.
thanks

Of course they will be different horizontal sizes. This is one of the TWO methods I’ve been talking about all along. You can’t have uniform radial thickness AND uniform horizontal slice size. You need to pick one. Both methods have been mentioned multiple times in this thread.

@DaveR’s pic has 1.2 horizontal size like the move/copy method.
@Box’s video is the same as my move/copy horizontal method.
@davidheim1’s picture uses a different method but will give uniform radial thickness similar to my insets method.

I had to do it to believe it - it was an optical delusion. Sometimes I just don’t get it.
Thanks to all.

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