Possibly a different approach to manual digitizing?

[Cold Fusion]

Once again, need facilitates creativity. I've got lots of parts that are 2d with lots of holes and odd pockets. This would be a pain to do with point cloud system. Perhaps we could bring the operator into the picture a bit more. If the entire system could be moved by hand, it would definitely improve the quality of the data received because it would only be the necessary points determined by the user.

So here is what I thought of. A free sliding 2 axis frame similar to a tabletop cnc router. The Z axis could be a simple sliding axis with a leadscrew for raising and lowering a stylus. The key to the design is low friction and minimal skew. There are two options for encoders. Linear encoders could be installed along the rails, or rotary encoders could be attached with timing belts.

Now, what I'm confused about is inputting the data into Cad. With this type of system, isn't it possible to get arcs and lines instead of a point cloud system?

Have I completely lost my mind, or does this idea have potential?

[HuFlungDung]

Andrew,
If you do the joining of the points manually, you can probably do a much better job of reconstructing the object. Otherwise, you are likely to end up with a bunch of splines or a mesh to mess with, and most likely you would end up wanting to straighten up and simplify the model anyways.

I like the idea of the 3 axis linear scale idea, in some kind of gantry setup, guided by hand. However, in real life, I wonder if a person would find it too tedious to do?

I wonder what the users' working impressions are, who have used a Microscribe or Faroarm digitiser?

[Cold Fusion]

True. It might be a bit time consuming to operate, but for the hobby guys, that's less of an issue. In any case, the idea is to have something of similar capability but 1/10 the price of the Microscribe.

What is not clear to me is the software end. Is there a program that can take a direct signal from the encoders and reverse interpolate that into a managable format. I know mach2 can control a cloud point type probe, but that's going against the whole idea of this thing.

[DieGuy]

Think spherical coordinates. an encoder on each pivot point and a known length between pivots and you are in business.

[turmite]

Andrew are you using mach software or Desk?? If so why not just program in the envelope and let the machine digitize the part for you. As Hu said far less boring and you can be doing something else while the work is being done????

Mike

[Cold Fusion]

Mach2. Because I'm trying to avoid huge mesh files and wasted time scanning unneeded areas. The parts I need to trace are quite simple, except when you're triangulating every single hole by hand with calipers and parallels... With some sort of hand controlled gantry tracer, I could probably do the whole part in 5 minutes. Here is an example of what I would be doing.

[turmite]

Andrew all you need for that is 2 axis of recording with a accurate and quick way to move your probe up and down. Mach3 or Newfangle has wizards for digitizing but I am not sure it would do that.

Mike

[HenryCNC]

There are a lot of manual CMMs out there... if you could lock your Z axis and then manually push the X-Y axis around (with a touch probe, of course) you have basically the same thing. The software should just sit there are save XYZ points to a file.

Unfortunately, I can't answer the question of collecting coordinates.

You could bring that XYZ text file into any CAD software (I use Rhino) and make a 2D profile with very little trouble.

[vmax549]

Andrew I have posed the same question to the Mach group. I also do a lot of obsolete part replicating. If someone could write a wizard it could be a simple task. Jog over the hole insert probe, mach then does a probe cycle to determine center position and size of hole, move to next hole and repeat. You could also save points on other vertical surfaces. Then Mach would save out the points to be used in a cad/cam program. You can do the same thing manualy if you need to. You just have to do the work and center calculations but it is a lot better than having to draw it out manually. If I could program we would have such a critter. Mach is capable I am not. "MACH 3 DMM" (:~)=TERRY

[JBV]

Why not use a ordinary scanner? Just put the part on the scanner and a ruler, put some cloth over and scan at highest optical resolution...

Then you load the picture into a cad program and scale it correctly by using the ruler as reference. Then its easy to trace the lines and hole locations...

600 dpi = 0.001666" (0,042333 mm) resolution...

[Cold Fusion]

I've tried the scanner approach, but it never works out cleanly. All the scans have a slight shadow on one side, which ruins the image when I convert to grey scale and do a raster/vector conversion.

[greybeard]

If the scanner could lose the shadows..... ?
How about filling all the holes with a contrasting colour wax, then scan ?
John