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Disappearing lines in drawing


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Greetings everyone;

 

I hope that someone might be able to help me correct something which has started happening,  and I don't know why!

 

I am creating a draught of Royal Caroline,  working with a digital image of an original draught loaded into a CAD drawing as an underlay.

 

Everything has been proceeding well,  until a moment when arcs (and circles) that I am trying to draw no longer appear on top of the underlay during selection of the points (up until this moment part-drawn arcs had shown just fine)  The arc now only appears when I select the third point (using the default 3-point arc method)  This means that I have no idea what the arc will look like until I lock it in place by clicking the third point.

 

I have tried selecting the underlay,  and using draw order to send it to the back,  but still new arcs and circles are invisible until the size is locked.

 

I am using AutoCAD LT 2009,  and the underlay was inserted as a raster image reference.

 

Does any fellow modeller have any suggestions as to how I can get my arcs back? :(

 

Many thanks in advance for any replies.

 

Mark P

Edited by Mark P
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I think you need to change the title of this topic so that folks will know what its about because as of right now.....it looks like spam.

 

Click the edit button and make your topic title say what the topic is actually about.

 

Chuck

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In my experience the image used for sketching needs to be on a layer that is underneath the sketch layer. I think this is true for most cad programs. If you are trying to sketch on the same layer as the image, your lines, arcs and or points are being hidden because the cad program doesn't know what you want displayed. Try using a different layer for your sketching and a separate layer for your image.

Edited by Don9of11
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Hi Don;

 

Thank you for what is an eminently sensible suggestion.  I have changed the layer of the underlay to a completely new,  dedicated layer.  Unfortunately,  nothing else has changed.

 

The biggest puzzle for me here is that it was working fine,  with any arc visible during construction,  and then for some reason they stopped being so.

 

Thanks again,

 

Mark P

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I have opened a new drawing and inserted a fresh background draught.  If I then attempt to draw an arc or circle,  this is fully visible during construction.

 

It would appear that somehow the attributes or properties of the inserted underlay in the first drawing have been altered in some way. 

 

I hope that someone out there can suggest a possible reason,  or I will have to start again;  not a pleasant thought.

 

All the best, 

 

Mark P

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Mark,

Any cad program can have this issue, and it's the connecting nods no matter layer.

One of the nods got connected with another in a hidden layer. To solve it is to go through each layer making sure all nods are closed and connected.

Otherwise as you write, start again.

 

Good luck

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You might try locking the draught layer.  I've run into similar situations where I accidentally started working using the draught layer instead of the active drawing layer.   Comes under the category of "crap happens" I think.  

 

This was years ago working with engineering drawing and AutoCad... so your CAD program may not have a lock.  I'm not sure if the current versions of AutoCAD have that feature either.

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Hi Per;

 

Thank you for the comment.  I will look into this,  and see what I can do.  I think you mean 'nodes' by the way?  Thank you for your help.

 

Mark:  thank you for the thought.  I don't think I have done this,  but I will check.  I think what you are referring to is what is called 'model space' and 'paper space' now.  Thank you again.

 

All the best,

 

Mark P

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Suspect you are not using the proper command. 2 points, if used as end points can define a line, it's direction and the length between them, also 2 points on the line can define direction but not length. Two points will never define position, size or anything on a curved line except that there should be some kind of curve that passes through those points, the relationship between the points can be determined but does not even hint about a curve. If you can't draw a curve using those two points, nether can your computer. Try using straight lines and at the angle points ask for a fillet, need to tell your software what radius you want, it should draw you a nice tangent circular curve, unless your radius length won't work at that corner and it will tell you about the problem.

 

A part from a description I once wrote for a property line alongside a State Highway with a circular curve, 'no transition spirals' involved. Putting it here only to show there is more to circular curves than radius points used in the real world.

 

Thence N 76°42'21" E 300.53 feet along the southerly right of Way line of Oregon State Highway ---------- to a 5/8" X 30" Steel Rebar with a plactic cap stamped LS 8888; Thence 334.22 feet along the Arc of a 3010.15 foot Radius Curve to the Right, the Chord of which Bears N 79°53'15" E 334.05 feet to a 5/8" X 30" ....... " On the Plat I included the Length of the Tangents, '167.28 feet', in and out as well as the Degree of Curve, '1°54'12" ', the Deflection Angle was 6°21' 41" all shown on the Plat".

 

If fillets won't work or you want another simple way to make your curves, using your intersection points from above, determine where you want your curve to begin and end, average the two and make a point on the tangents in and out of the corner at the average distance. From those points draw perpendicular lines to an intersection and use the intersection as the radius point for your curve then draw it. It will fit, it will be tangent and it can be repeated.

jud

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Hi Jud,  and thanks for the explanation. 

 

The thing is,  I am using three points  (as mentioned in the first post)  which is AutoCAD's default to draw arcs.  Normally,  after you define the beginning and the end,  a ghost image of the arc appears,  and changes radius according to where you move the cursor.  The advantage of this is that it is possible to position the arc over those on the original draught and get a close fit,  then click to lock the third point,  after which the arc becomes a firm object. 

 

The problem now is that the 'ghost' arc is no longer visible,  and without seeing it,  I have no idea of where to click for the third point.

 

All the best,

 

Mark

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When I open multiple massive assemblies in Solid works and then open individual components it seems after a fashion SW starts acting weird and strange things happen when working in a sketch or drawing. I've learned with experience the solution is to save my work and reboot. Have you tried rebooting?

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Don,

That sounds like SW has memory leaks...  Rebooting is the best fix.  Might work for the AutoCAD problem also.  Seems like more and more programs...err.. the correct name now is "apps"... have memory leaks.  I guess the developers don't bother checking for such things any more.

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Greetings gentlemen;

 

thank you for the suggestion.  I have tried re-booting,  with no success. 

 

However,  I have now created a new drawing,  copied into it all the lines I have drawn in the original CAD drawing,  and then imported a fresh copy of the original underlay draught to work on top of.

 

This has been successful,  so far,  and the arcs and other shapes appear during construction,  as 'ghost' lines,  as they always did previously.

 

Per:  I have tried to check the nodes,  but they are many.  Additionally,  there is no hidden layer or object that I know of in this drawing.  However,  I will keep your comment in mind,  and try to find out more about this kind of problem.

 

All the best,

 

Mark P

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