Parametric Programming

[widgitmaster]

What Is Parametric Programming?

[tlhbear55]

it is using macro var. . if the part dimentions change but are similer like length could be from 1.0000 to 1.5000 and anywhere betwen an a dia or hole 1.0 to 1.5 insteed of writing seperat programs just change the vareables there could be a lot more dim. involved i have some vary intense ones for impellers for compressers for lathes

[pcroxford]

Do you mean parametric Modelling?
Parametric Modelling is a technique qhich involves sketching a crossection, constraining the dimensions of the sketch and then extruding, lofting or revolving the sketch around an axis to create a solid. This is the basic difference between a 2d software (autocad, microstation) and a 3D modeller (Inventor, Unigraphics, Catia, Solidworks)

[widgitmaster]

A machinist friend was trying to discribe how he was using G codes to access math and logic functions like goto loops stored in his machine, I was under the impression all M & G codes were either hand coded or computer generated, I didn't know there were functions or subroutines stored on chips!

The only programming I have ever done was basic & QuickBasic, but Microsoft runed them for everybody!

I have never heard of parametric modeling tho...

I guess what I really wanted to know was, is it available in BobCAD & BobART?
Eric

[Dan the Tech]

Parametric programming, in general, is the ability to use variables in a line of G code programming. This would be used for a family of parts, or situations that are used repeatedly in different parts. Let’s say you drill holes in a wheel. You change a few variables and you can change the number of holes and the diameter of the bolt hole pattern. Everything else would remain the same… depths, tools, setup, and so fourth. This concept is also available for solids creation in BobCad. Anything that is created with the same steps, can be recorded and a variable applied to the hard data. These are called scripts.

[stupidog]

To find a lot of info on parametric programming, go to www.cncci.com. This is the Mike Lynch site. I bought his book on parametric programming for CNC machines and touch probes and found it to be a great reference.

[tjones]

Fanuc calls this macro programing. Using variables and math functions is a great way to save program space and make a routine flexible for multi application use. I do this type programming on a 5 axis Jungner cnc tool and cutter grinder. I can use many math and trig functions for locating and machining(grinding). It can also be used for error checking of code and for machine subroutines like pecking or for a variable size hole, elipse, rectangle.etc.

This is also a great way to pocket on mills with low memory capacity. Input a variable for length,width,depth,corner radii, depth of cut per pass,etc. Input cutter diameter and calculate offset for those few machines that don't have cutter comp.

As you see with this type programming it makes little things faster and less likely to create operator errors. But it can also be used to do extream calculations for very difficult jobs like flute grinding. Although most machines like the Junger have special software to handle these things there are always specialty needs that go beyond the software limits.

In BobCad Cam software this is called scripting and can be used in drawing and NC output. It can use pop up windows to ask for input and then generate a part on the cad then generate then NC code ofr output. Very usefull for speeding up every day tasks.

[dcencer]

Any adjustable dimension in a CAD model is a parameter. When you edit a model to change one dimesion you are adjusting a parameter. ProE, Solidworks and the like create parametric models. Parametric based modeling is good because it allows the user to make extensive changes quickly by changing one number. Whereas 2D wireframe CAD models do not allow you to do that. That's partly why ProE, Solidworks and the likes are the standard.

The same concept is extended to using variables, scripts and calculating per formulas as applied to model creation. In a parametric model, I can enter in a value for a 'base' or 'master' variable, and the program can calculate all the dimensions of a part based on that numberper pre-entered formulas, and generate the complete model automatically.

So if I make windows for a living, I can make a parametric model of a type of window with several parts, most of which are dependent on the basic height and width of the window. I can open my CAD program file and simply enter in the basic height and width of the finished window, and the program can draw all of the part drawings to the right size, as well as the assembly drawing, BOM, etc.