Cam/Cad DXF units question

[WarrenW]

I have a question again on the units of a DXF file. Didn't someone say there are no actual units such as inches or mm for a DXF file? Its just how your software selects to view it? So if my software says a line is from 0,0 to 20,20 and I select inches for the units in a viewing software, its going to show that line as 20 inches?

In my app I am writing I am drawing lines using pixels. So a letter may be 150 pixels tall. When I save it as a DXF and then view it in a program like SheetCam and select Inches as the units, the letter is HUGE! It shows it as 150 inches tall.

So do I need to scale down the line lengths if I want it to be in inches? And if a letter is showing 150 inches tall based on the pixels, I need to divide every line by atleast 10 or more. And if I want to make it be measured in MM then I would hardly divide it at all.

Did I answer my own questions? My brain is so tired from working on this all day!

Warren

[ger21]

What I'd do is figure out how tall the largest letter drawn is in pixels. Then give the user a box for height. Then just divide the requested height by the pixel height to get the actual height.

[WarrenW]

For testing I divided each number by 10 and it reduced it down to 14 inches. Now I just need to determine what number to divide by to match the ruler setting for both Inches and MM.

Gerry, I'll send you a copy when its done. It may not be as fancy as some of the other software but for my first cnc application I think its coming along okay. After this version I may work on a carving type application similar to vcarve and others.

Warren