View Full Version : A simple introduction to Vector CAM for other CAD users - by a novice!

Gerald D
06-12-2001, 09:28 AM
For the guys who avoid Vector and have discarded the “freebie” to go back to their regular Turbo-, Auto- Intelli–cads, etc. Try the following exercise under the guise of reducing your dxf file sizes. (A simplistic guide by a novice user, who also discarded Vector a few times)

1. While still in your regular CAD program (TurboCad, AutoCad, etc,) explode everything down to the smallest and simplest line elements.

2. Scale the project to the right size and units. I.e If your Shopbot is set for millimeters, and your finished project is about 500mm wide, make sure that your CAD program shows something that is about 500 units wide.

3. Look for the smallest element in your CAD program – you may find tiny line segments of only 0.0002 inches (.005mm) that may look insignificant. One segment by itself is not important, but a chain of 100 tiny segments becomes important.

4. Decide your overall resolution accuracy. If your work will be inspected with a magnifying glass from 4 inches away, then a resolution of 0.005” (0.13mm) is maybe necessary. But if you are talking about a passing motorist reading a sign from 20’ (6m) away then a ten to twenty times lower resolution is more than sufficient..

5. Now you are ready to make a .dxf for Vector. Remember that Vector works on a white screen and that selected lines turn red or black. So I find it convenient to make all lines in blue for the dxf.

6. When you open Vector, first go File > New > Normal to get a blank white screen first, before you try to open your dxf file.

7. Then go Special > Options > Units > and make sure that the General Accuracy setting is smaller than the smallest element decided in step 3. If you don’t set this parameter correctly, then you will find that Vector maybe ignores some tiny elements in your dxf file.

8. Now go to File > Open , find your dxf file and open it. If you see nothing on the screen, press the V key. You should now see your drawing somewhere on the screen. Be patient with these steps, they are not instantaneous!

9. If your drawing is still tucked away in a corner of the screen, drag the right-angled blue arrows onto your drawing. Press V again. Now your drawing should fill a decent part of the screen.

10. Use the W key to create a zoom box to check if all the fine detail has been imported by Vector. If something has already disappeared by this stage, then there is a problem either in step 7, or your original CAD drawing. The V key always gives the full view and the W key lets you zoom down onto a different area.

11. Move the arrow cursor on to any line segment, hold down the Shift key, and simultaneously press the left mouse button. You should see that a whole row of separate line segments change to red, with a tiny arrowhead in the center of each segment. Normally these red-selected segments will run right around your complex profile. (If you want to un-select, then click the left mouse button anywhere on a blank part of the drawing window)

12. To reduce the number of segments making up a curve (the original aim of this guide), Shift-select a chain as per previous step 11, go to Draw > Splines > Arc Spline. Set the Abs. Error parameter to about the value that you decided in step 4. (the default values in the remaining 2 boxes are okay for a start). Press “Go” and see how the many red arrows change to fewer red arrows – i.e. less segments and a smaller file size, still giving acceptable resolution.

13. Go File > Save and you have a smaller dxf to take back to your regular CAD program.

Those of you who are putting dxf files directly into your Shopbot converters, will appreciate how critical it is to draw each line segment in the right cutting direction and then save them in the right sequence. After doing this exercise above, you should immediately recognize the power of Vector to automatically organize the direction and sequence of line segments.

(For those of you who enjoy moving everything over 96” and then copying everything back in the right sequence (after drawing each element in the right direction as well), I don’t want to spoil your fun . . . . . . ;-))

For me, the power of Vector lies in its CAM capabilities – I design and draft in AutoCad, but to get a project ready for Shopbot, Vector is a very powerful aid.

sheldon dingwall
06-12-2001, 11:52 AM
Good tips Gerald. Regarding point number 3, how (in AutoCAD) do you find the smallest element? Is there a search function or are you limited to manually hunting it down?

Gerald D
06-12-2001, 12:26 PM
Normally manually (remember I'm a novice), but in AutoCAD 2000 LT we can use Tools > Quick Select to find lines under a defined length. I have just done a quick test and searched for lines under .05mm (lots), .01 (quite a few), .005 (4 only) then zoomed in on those and discovered they are .0037mm long.

What I didn't say above, was that there are times that shift-select will not work as per step 11, probably due to small gaps in your original file bigger than the value set in step 7. Since you have already imported the file correctly by this stage, you can increase (coarser/rougher) the General Accuracy value under Special > Options > Units so that Vector becomes "blind" to the small gaps. (This has been mentioned on this board a few times before)

06-12-2001, 02:28 PM
Considering how well you explained those steps I'd say you can't refer to yourself as a 'novice' anymore.