Line Following Circuit

You need a CNC plasma cutter...

http://torchmate.com/

For rough cuts, there are cells that follow a chalk line well. Check for Sick cells.

Need to follow a call line on concrete can you help have no ideal what I am doing

You might get some ideas here:Autonomous Robotics

Not my field. _{My field is in Arkansas, complete with cows.}

Several manufacturers have low cost vision systems that can be (and are) used to follow lines, as long as there is enough contrast. But the other side of this is the ability to have a motion control system for the cutter that is capable of taking that information in and acting on it in a meaningful and accurate manner. What is your budget? I know of a company in canada that has done this with Sick Sensors, but the one I'm thinking of was approximately $250,000 CDN.

The low cost way to do this is to use CAD for your layouts and program a CNC machine to follow the cad drawings. Is there a reason why you can't do that?

Or, digitize the current drawings and convert that into a whachamacallit? DXE No, DFX.

Do they even know what a DXF "file" is?

Yes, I was wondering why the optical following of a manual drawing, not digitaldrawing and cnc output.

Can you tell us more OP?

cnc jim

If you are interested in a CNC cutter instead of a line follower (as suggested by others) have a look at my blog entry "From CAD to FAB" here. Pay especial attention to the EMC2 Software- their preliminary "example" run is exactly what you are talking about- a driver for a laser cutter. I think this would be a whole lot easier to implement than an optical follower- and a lot more repeatable, reliableand less expensive. You would basically need the same cutter head driving mechanism for either the optical or the CNC approach.

Most CNC is done on a relatively small scale- if you are looking for something that can be done on the spot on, say, a construction site, you could implement something with this approach, where you could define the line you want to cut (say, from a digital photo of the mating part) and program the cutter driver on the fly. Scale should not be a problem (note in my blog how easy it was to modify the machine definition to accommodate a part too large for the initial machine definition).

We used such a system in the late 1970s at Mallory Timer; someone drew up cam profiles at something like 30:1, in ink on Mylar, and a tracer mill cut the profile for testing, or the reverse to make a mold. These systems have been obsolete since about the time that the term "CNC" became useful.

Try Googling "tracer mill" +optical (without the underlining) as a starting point. Some of these are still around and available; the output is often via hydraulic cylinders or similar, so that you could use whatever device you wanted as the cutter.

It is now 2012.

Digital drawings and a CNC plasma cutter has to be the easiest and least costly method for repetitive or high fidelity cutting.