New User help

Hi,

I am a newb with lots of computer experience, but little CAD time.

I am hoping to create a 2D drawing based on a template I made out of cardboard.  I imported a photo of my template and successfully traced it into a polygon, so success on that front.

Now I want to make sure the dimensions of the object are correct before sending it off for laser cutting of metal.

This seems like it shouldn't be hard,  but the measuring and scaling functions seem CRAZY.  If I use the point to point measuring, I seem to get weird values displayed at the bottom of the window?

I have set the Application preferences to display in inches, but don't see any inches" displayed when measuring.

THANKS FOR ALL OF THE HARD WORK!  I appreciate the software and hope I can figure this out.

Welcome!

Drawing a 2D image with LibreCAD should not be hard at all, that's where it is at it's best.

I think you have done things in reverse order. A card board template is a good idea, but trying to get the dimensions from imported photo is not.
 
Accuracy is why CAD is used anyway.

Better measure the dimensions from the cardboard model, start a new empty drawing, and then insert those measured dimensions, save. If you want to fine tune, it's now easy, just remember to save often if you modify.

There are links to manuals and FAQs at the top of the start page. I would recommend you to at least skim those.

Thanks!

I don’t understand what you are saying?  How do I “insert the measured dimensions” while tracing my image?

Thanks again!

Ok, wire then

Let's say for example you had very simple 10" x 10" cardboard square.

Photoing is easy, but the skew and scale are not, as you noticed. Just forget the photo, it is a bad idea.

Start a new drawing, draw that box, 10" x 10".

I am not making a box.  It is a complex shape and the whole point is tracing the image.

I have resolved my issue by using math and the Scale function to adjust the completed line drawing to the correct scale.  This wasn’t hard once ai figure out how to do it,  but the scale function seems odd to me.

How useful is it to arbitrarily scale objects? How often do we want to Double or halve the size of something? Once I got over the clunkiness of the scale interface,  I was able to adjust my dimensions successfully.

Thanks!

The box was an example.

To more complex shapes I prefer polar coordinates, where you give the length and angle of the next line.

Ok,  thanks,  I see that would be possible,  but VERY tedious considering the complexity of the shape and the amount of measuring it would take.

Tracing a photo IS the way to go in this case,  so the software designers might consider making this a bit easier.

I am also not clear on how the document sizing works. I originally set my Document up to use Arch 2 paper as my work will fit nicely on that size of stock.  The document editing window persists in being limitless, which is odd and not helpful in my case.

Thanks again for the fantastic free software! It performs very well on my 2016 Macbook pro.

It might have been easier to scale the imported photo to the wanted size, either during import or afterwards. There is a bug in V 2.1.3, the image seems to be disappeared after scaling, doing an Auto Zoom brings it back. Then you can draw (trace) over the image in the right size from the onset. It's advisable to draw a frame in the document size first. I assume it is the same size as the metal sheet you want to get laser cut.
What do you mean by the document editing window? If you mean the drawing area, yes it is limitless. Arranging on the real paper sheet is done in the printing process, in Print Preview mode. This is not relevant for you, as you don't want to print it, but to send it to a laser cutting service. They need the dxf file.
Generally, if you don't really need to work in inches, everything is easier and less error prone if you work in mm.

It sounds like you have a template of something which needs to fold into a 3D form. Instead of tracing, might I recommend actually modeling the 3D form with another software, like Blender? It is then possible to unwrap it into a net. If the form is complex and the sheet metal has particular bending radiuses or thicknesses to consider, FreeCAD has sheet folding tools which can help.

Wow!

Thanks for the ideas, that sounds very cool and all with free software!  I am not sure I can tackle the learning curve for the three different apps however…

I am enjoying using LibreCAD,  but I am also struggling to do some simple tasks.  For example,  if I want to change the color of one line segment.

Thanks!
Marty


> On Dec 14, 2020, at 2:27 PM, Moult [via LibreCAD] <[hidden email]> wrote:
>
> It sounds like you have a template of something which needs to fold into a 3D form. Instead of tracing, might I recommend actually modeling the 3D form with another software, like Blender? It is then possible to unwrap it into a net. If the form is complex and the sheet metal has particular bending radiuses or thicknesses to consider, FreeCAD has sheet folding tools which can help.
>
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> NAML

"I want to change the color of one line segment"
Tools - Modify - Properties.
If the line segment is a part of a Polyline, you have to use Explode first.

Thanks!  Wow you provide amazing support!

Appreciate the direction.

Actually, it’s attributes, not properties,  but you still pointed me in the right direction!

Depends.
With Properties you can change pen properties, layer and some geometrics of a single entity only, while with Attributes only pen properties and layer but several entities at once.