|Home » Forums » CNC » Message||Login|
You are not logged in. Consider these WOODWEB Member advantages:
picture to dxf2/26
i'll preface this with my only experience is with sketch up (and limited at best).
i'd like to be able to take a picture of a profile and convert that to a dxf. file. is there a way to do this, or a program that does this better than others?
i have 100 custom balusters to reproduce. we have one that almost works on our copy lathe, but working off a template would work best. i'm just trying to avoid making the template by hand.
There are many ways to do this. The most technologically adanced is Raster to Vector software as you imply. I've used a few of these over the years with mixed results. The really good ones take some experience to get good at what with various settings to use in various situations.
Much simpler for a one off situation like this is to trace the baluster on a piece of paper and then scan it into the PC. If it is too large for your office printer/fax/scanner type machine then cut it in sections with index marks to bring it back together. You'll have to scale it back to exact size as scanning will skew the size somewhat.....usually slightly smaller in my experience.
Once scanned into the PC you can open the image in your CAD program (in Autocad I paste it into a drawing) and then trace over it with a spline. I trace in red as it is easier to see. Just be sure to have ORTHO turned off or you'll get an ortho influence on the tracing.
The best way I've found to digitize tracings of large items though is with a very large digitizing board. Mine was 44" x 60" and I was able to click a cross-hair puck on the line typically every few inches. You mate the digitizing board to your CAD program and every click of the digitizing puck becomes a point on the spline on screen. Very fast and accurate....and can be used on huge tracings by adding indexing points just like in the office scanner method.
We do this in SU Pro all thr time. Not sure about the free versions. We snap an overhead photo of either thr parts or the templates and import them as BH stated then scale and draw over top of the image.
thanks for your replies.
how to you correctly re-scale once imported?
You can't do it yourself for what he charges.
Using Illustrator or CorelDRAW scaling and converting to dxf is dead easy.
There are a couple of approaches in SU that I use. Both pretty simple.
With either I take an overhead photo of the object/drawing. Step stool, standing if you can fit it in the frame, whatever. I try to be directly overhead to minimize distortion.
I then import this image in to SU (file, import)
Then using your baluster example, you can measure the actual baluster length and width. Draw a rectangle that size and scale the photo so that the baluster fits in that rectangle. The photo will come in as a group.
OR.. often times its easier to draw a rectangle the size of your balluster, make IT a group, then make a copy (hold down CTRL with the move tool) now move the copy onto your imported image which will come in much larger than actual size. Scale to match the image only using the corners of the scale tool (so the ratio of length to width remains constant). Once you have the rectangle over the image you can open the group and begin to add the geometry of the baluster in the image.
When your done you exit the group, and scale the entire group back down to the size of the original rectangle you made again only using the corners to maintain aspect ratio.
Feel free to message me if needed. Its a relatively easy process.
I'll add one more method for doing this that does not require scaling the image.
Mount a laser pointer on your CNC Z-axis. All you have to do is somehow secure it there pointing down.
Then tape your tracing to the CNC table. Move the head until the laser is at the bottom left corner of the tracing and define that as X0,Y0.
Now move the head a couple inches along the tracing and record the co-ordinates of the new location. Then move it further and record the co-ordinates again. Keep doing this all the way around the tracing using greater distances between points on straighter sections and shorter distances on tighter curves.
Then take your list of points and draw them out in your CAD program. Use lines between points on straight sections and a spline with an approx. 1/32" tolerance on the tighter/curved areas.
Before we got the 44" x 60" Calcomp digitizing board this is the method we used to get window templates into the computer. To speed it up we spoke the co-ordinates into a tape recorder. Works great.
That would surely work.
We use a digitizing probe to do the same thing. It takes a while but we can set thr probe intervals and just walk away and the the cnc probe the part. Bad thing is if you set the interval spacing wide it will miss fine detail. And if you set it tight it will capture it all but leave you with vectors that have thousands (or tens of thousands) of points that then have to be cleaned up.
I like your idea for reasonably shaped parts.