Parametrics curves (again)

I 've just discovered that I started a similar post last year, and though I’m more familiar with inkscape now, I wonder if this is possible.
I’m creating a number of curved top frames, each custom sized, but of a constant width.
They would be made, brick wall fashion, by laminating segments of the curve on top of each other. The two variables are the inner radius (with a fixed width, the outer radius is a function of it), and the angle of the arc. The ends are identical, and joined by a separate piece of fixed size.
I’ve made the arc angle about 50 degrees in this example, but I would want to set that.
The shape of the ends allows me to use a ‘bow-tie’ shaped insert which makes assembly self aligning.
While it might, in the long run, be as quick to layout each frame separately, I thought this might be a neat approach. The idea of using segments is to allow more economic use of the board.



I’ve done this when I’ve exceeded the Y axis capabilities of the :glowforge: , I use Fusion 360 though as the sketch tools just work so much better for me.

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Unfortunately Fusion doesn’t install on my Ubuntu 32 bit system, and I don’t want to start learning yet another vector program !

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Multiple problems with inkscape para curves, but I’ll just ask for guidance on the first two.

  1. Selected a rectangle, and opened the para menu - it doesn’t indicate units ?
  2. Which perhaps might be 1. - I can’t get the rulers to display in inches. I’ve been to the document properties numerous times, and my default template for new files is a 12x20 page, which shows in the menu, but the ‘Display units’ are always px, and even if I change it in the menu, it doesn’t reflect that on the page.
    At the moment it looks as if I’m stuffed, so back to drawing everything once at a time, and forget parametrics.
    What does’ NameError: global name ‘x’ is not defined’ mean, and how do I define it ?

I didn’t even know Inkscape did parametrics.

Perhaps it doesn’t, and is just yanking my chain !


On google, I found a posting by serenblip that didn’t work, but a quick mod did , and I’ve drawn a circle !
So now I have a starting point, at least.
I’l post here, and if anyone wants to join in, please feel free. It may start as my own journey, but might be a useful first lesson, if not so grand as a ‘tutorial’
Watch this space.

If it turns into a tutorial you might be prevailed upon to write it up. :smile:

I’m afraid your post appeared about three seconds after I’d decided that the inkscape help pages were about as useless as (enter your own expletive ridden sense of frustration here) chocolate teapot.
I will see if it becomes possible, but don’t hold your breath !
Happy hedgies,

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You need to change to inches instead of px or mm in two places under the File-Document Properties.

Screen shot of my efforts, but it has no effect.
I’ve been here many times, but it just doesn’t seem to want to change !


Currently experimenting, and have got an arc drawn, but trying to fathom out what it does in response to my instructions !

You must be using a different operating systems than me. Mine looks completely different.

Very likely - I’m using version 0.93 in Ubuntu 14.04
Weird, I know,

Yeah, if I change where it says display units and units the change is instantaneous and permanent for that document. Saving that template makes it permanent.

'Fraid I’ve been here before. For some reason that I can find no explanation for, my rulers don’t respond to my change in units. I’ve tried re-installing, but to no effect.
Frustration assuaged by a quick trip upstairs to check up on an oyster catcher which is nesting in the field opposite, about 100 feet away from me.
Three hares are wandering nearby, but will do well to keep away from that very long, pointy beak that she has.
Yesterday I saw the mate fly down, and take over for a spell of keeping the eggs warm and safe.

Well, I’ve done quite a bit of trial and error, and now have a bit of insight into what Inkscape parametric curves might do.
As far as I have gone, so far only dipping my toe in the water, it will draw a curve as defined, with the parameters you set.
That’s one curve.
So my idea that I could define a shape that was made up of two curves, plus a few straight lines has made no progress.
Unless someone can point me towards some online, or downloadable software that will do that, I’ll just draw a set of primitives that I can modify to suit my needs.