Hi Folks - Newbie Q1 and 2 are in the general section - FYI...

When I am aligning solids in a model, I have found that drawing several lines or other 2D objects with conveniently located snap points make my alignment problems almost disappear. When I export my model to a DXF file, I presume that these 2D objects are embedded in the file along with the 3D solid information. So, maybe someone can confirm that is true - just curious...

If I send my model to a machine shop, I assume that they know how to process out the 2D objects. Does someone know more about the process of the receipt of a DXF file and the conversion of that file to be useful input into the CAM machine - a 3D mill for example. I am sure that there are trivial elements in that process on the CAM end that I do not need to even know about on the model design end, but i suspect that there are quite a number of considerations (some I will learn the hard way) that impact the utility of the DXF file and the end result from the CAM machinery. Some things I might do may require unanticipated attention from the CAM folks...

So, just curious what a ViaCAD 2D/3D user needs to do to make the CAM operation as smooth as possible - starting first with considerations for 2D objects, for example.

A second consideration I am making is whether the order of the model build process has an impact. For example, I tend to model from the Top view first, and then from the Bottom view - does that impact a CAM process directly (I doubt it)? I tend to mix Unions and Subtractions - is it less ambiguous on the CAM end to do all Unions before any Subtractions?

Thanks - Brian

Hi Brian.
I might be able to answer some of your questions as I'm using ViaCad for drawing parts for machining. I also do the Cam bit myself for lathe and milling. If you're talking about milling, then 2D and 3D operations are done differently, so we perhaps need to know a little more about what you want to make. The one thing I can tell you is that the machine shop will not know how you want your part making from just a drawing. For example, a drawing of a 2D rectangle could be machined on the inside to create a pocket (of any realistic depth you specify) or around the outside to create a relief - different things from the same drawing. I hope I'm not telling you things you already know.
I will help you if I can. Cheers, Martin.

Thanks both of you for replying.

To ZeroLengthCurve, I have my 2D objects in a separate layer from the solids. That in itself is good to organize my drawing as I can hide it easily or even delete it entirely if that is necessary. Thanks for that tip!

To blowlamp, my 2D objects are not intended to be machined in any way. They are all "helpers". Some are surface profiles that I extrude, and these remain afterwards. Some are simply lines with a convenient snap point that help me align elements of my model. An extruded rectangle would be a block, and that block is what I would machine. The rectangle is just the surface profile...

The Concept Explorer shows all the surface profiles that I extrude as children of the corresponding solids in the features list, and these profiles are referred again to when I do Addition, Subtraction, Intersection and even Solid Alignment operations on my model. Further, deleting these profiles causes a warning dialog that links will be lost upon their deletion. This leads me to wonder if this information (the 2D surface profiles) may be necessary to retain for some reason.

So, I guess I can narrow this discussion down to a few questions for starters:
- If I export a DXF file to a machine shop, is the 2D surface profile information necessary?
- If I export my "helper" layer in the DXF file to the machine shop, do the 2D helper lines and other 2D shapes cause a problem? Does it hurt to include the Helper layer, or is it essential to eliminate it before export?

Now, the order of modeling operations - the concept explorer presents a rough sequence-wise order for my modeling work - because of the link relationships and object-children containment, it is not exactly the sequence of my own work, but it is often quite close. Does the sequence of my model creation matter to the machinability and cost for my part? Here is one question to consider that is more specific:
- Is it important to do all my building up - all the Extrusions, Solid Adds, Bosses and Chamfers first to create the gross rough form before I do my removals - before I do Subtractions, Intersections, Holes and Fillets?

Sound like Newbie questions, don't they? Sorry for that... I DO certainly appreciate your time and the experience you are sharing.

Thanks - Brian

Brian.
You are aware that Cam is another process before machining aren't you? I ask because you said this "That is probably the case if the CAM process is all done on one machine." and it made me wonder. What I mean is, that you can't just send a drawing (2D or 3D) to the miller and expect it to make it from that, it has to be converted to a language the machine tool understands and this is known as Gcode. Gcode is what the Cam system produces. Have a look here http://www.zen26610.zen.co.uk/overview/level2%202.html for an intro into 2D Cam systems.
Cheers, Martin.