Unable to line up drawing origin and sketch origin.

[Jaeger1787]

I have created three arcs, each one on a separate plane. 

The middle arc should be aligned so that its bottom edge is on the XY plane as are the other two arcs.  I am unable to move this arc so that it lines up with the drawing origin.  I need to do this inorder to create the guide rails for a loft before proceeding further.  All sketches appear to be fully defined.

I attach the file.

[TheCADWhisperer]

Drawing?

Why not simply round off these dimensions?

Why are there two arcs here when one would suffice?

What is the purpose of Sketch2 (unless I missed something - it is empty)?

Sketch 3 has some really "strange" dimensions and a white dot (no connection) on the left side?

Same issue on the right side - no Coincident Constraint?

Two different dimensions left to right?

Where do you want this circle?  What is the diameter?  Why is there an extra point?

More "strange" dimensions in Sketch Bow end.  I think I am missing the logic?

[TheCADWhisperer]

@Jaeger1787 

Notice that fewer dimensions are needed to fully define Sketch1.

[Jaeger1787]

Thanks for taking the time and trouble to respond to my queries. I shall comment on the points you have made.
1. Round off the dimensions. The sketches are based upon a canvas prepared by scanning a paper drawing, importing it and calibrating it to scale. Consequently, the dimensions are the result of tracing over the canvas to produce as close a reproduction as I can. There are no real life dimensions on the drawing that could be used to accurately dimension the various entities – lines, arcs etc. The result is that these multi-decimal dimensions as shown.
2. Fewer dimensions to fully define sketch 1. : I found that if I deleted the smaller radii dimension (13.843) the sketch reverted to undefined.

When attempting to fully define a sketch all I can do is to dimension every entity until dragging them ceases to move it, and adding constraints where possible. Sometimes I have found that the requjred action seems to be elsewhere from the sketch entity. Deleting the small radius also made the sketch undefined.
3 I notice that sketches 1 and 2 on your attached file has two horizontal lines in construction linetype. Why are these needed?
4 Length of vertical lines. When I created and dimensioned these, I actually entered a number to one decimal place (1.0 or 1.5) but Fusion changed the dimension to the multi-decimal (and incorrect) dimension without my control. Incidentally, when I open my original file, I notice that the dimensions are now as they ought to be – again without input from me.
5 Sketch 2 is required as part of the loft to be created subsequently using all the sketches, plus guide rails.
6 White Dot in sketch3 (do you mean sketch 2?): I have no idea why or where this was generated. I see if I zoom in/out of the sketch it disappears/re-appears.
7 Circle in sketch 3. I created this circle centred on the origin, then tried to make this and the midpoint of the horizontal line co-incident – without success.

8 Some of the artefacts you highlight in the thumbnails are not in my file eg the apparent gap between the end of an arc and the horizontal line.d

It appears from your file that rounding of the dimensions allowed the sketch to be aligned with the other sketches, but I can not see why this should be so. I still do not know what is causing the middle sketch to be displace by some 10mm above the origin or what to do to correct it.

[TheCADWhisperer]

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@Jaeger1787 wrote:

8 Some of the artifacts you highlight in the thumbnails are not in my file eg the apparent gap between the end of an arc and the horizontal line.

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@Jaeger1787 
I dragged the points to illustrate the issues.

Perhaps the most powerful tip in sketching - drag points to “exercise” the sketch and observe if the behavior is as expected/predictable.

Given that the source is art - what harm does it do to round dimensions?

Are dimensions used in real world manufacturing?

Are dimensions used for interchangeable parts in the real world?

Horizontal construction line keeps vertical lines equal length without having to add 2 dimensions or equal constraints, plus gives a visual indication of Design Intent.  Back in the last century this is what we did on the drawing board in pencil and paper.  

BTW - I don’t think Loft is needed for your design.

[Jaeger1787]

Thanks for clarifying the gap shown in the thumbnail and the use of the horizontal line.

Re dimensions. I am not too fussed about having accurate dimensions (most of the time) being more concerned with appearance, on the principle of 'if it looks right, then it is right', and more to the point of producing a working model. I am not building an exhibition entry. However, in this particular case, because the finished 3D printed item has to fit with another part, I would prefer the dimensions to be the same. Changing the primary part would not suit either as it has to fit yet a larger part.

Dimensions in the real world. It depends. One could have a fascinating discussion on manufacturing techniques. If one reads the history of gun making in Birmingham, England and in the USA during the 19th century, initially guns were made by hand and individual parts made to fit another one. This is fine for a one-off or a special, but when thousands are required machines have to be developed to produce parts that are identical to the next. It can be argued that gun making was the founding stimulus for modern machining techniques. Once parts are made in disparate places, then some dimensions are required that can be applied any and everywhere. However, this forum is probably not the place to continue.....

To return to the original subject, what would you suggest in place of a loft feature?

Jaeger

[TheCADWhisperer]

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@Jaeger1787 wrote:

Re dimensions. I am not too fussed about having accurate dimensions (most of the time) being more concerned with appearance, on the principle of 'if it looks right, then it is right', …

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@Jaeger1787 

Good luck with your Fusion pursuits.

[Jaeger1787]

Thanks, but what is your alternative to using a loft feature?