Make Sense (or Not)?

Ron, these metal studs... as in steel studs in a gypsum board wall/partition?

If yes, I don't know of such a device. Metal stud finders don't really tell you where a stud isn't, they tell you where metal (magnetically detectable metal, not necessarily a steel stud) is at behind the wallboard.

A positive detection could be a conduit, rain water leader, air ducting, maybe a metal backer for mounting a grab bar to the wall... It's up to the operator to deduce the likelihood that a positive detection is indeed a framing member.

[edit] I'm starting to believe these are studs/bolts fixed to a parent piece, not wall studs. Tell us more, if you would.

I think OP is Ron Burgundy (a guess)

What are you trying to build?

We can build almost anything you need. All it takes is some research in metal sensing sensors and then calibrate them to the specific return of a specific metal stud. You will need to know the exact dimensions of every metal stud made or at least have an idea of what size and thickness they are.

You are right on it, as far as the scope of what is required; imagine a magnetic field whose output (current or voltage) is varied by a changing induction determined (calibrated) from the resistance total of a programmed stud count. The sense field would be custom and the device should be ODVA (DeviceNet) or Ethernet compatible. The stud specs are established, just seeking a possible source for this type of device as I don't have time to develop myself however resources are not the issue.

So, let's say that you have a job with 1,723 total stud count.

Your magic gizmo comes up with a count of 1,715, or 1,795. Then what?

I may be too dense to get it, but at this time I say,

I doubt there is a COTS solution for the Anonymous posters requirements.

One can be developed with the right amount of funds!

You want to detect metal studs. But do not provide the type of studs. Those placed in cloth or those in a wall?

A count on those placed in items for decoration can be done with imaging.

Now why would any one want the count of studs in a wall. We pay building inspectors to make sure it's done to code. If one was missing it would stand out an inspector would not miss it.

Elaborate on the reason of such a device.

You have a brilliant idea of not only detecting a metal but also determining what it's shape is.

But how to do? Is a problem that needs a further research and experimentation.

Shoot me for being simplistic, but what is to keep someone from looking at the walls before the outer drywall (or whatever) is put in place?

The metal conduit, even wiring/pipe/ac duct/or whatever else is in the wall is a show stopper.

What is your reason for/purpose of this device?

Why are you insisting that it is magnetic? An infra red camera system will distinguish metal studs from a non metal background/foreground, or a visual camera system if the studs can be seen. This is widely used rugged industrial technology, no development work required. Optical recognition systems just need a snapshot of a correct stud array to compare, any discrepancy is immediately flagged. Set up times are now as low as a few minutes so getting a supplier to demonstrate on your application is viable. Cost has dropped rapidly in the last few years and all the communications you need come as standard. Before you approach a supplier work out the lowest speed and lowest resolution that you need as these are the two critical factors that escalate the price.

Just to let you know this is the best comment so far, have you used the camera system? If so, what optical system did you use?

Check sources for object recognition software. Lots on internet hits.

Ron, this is why feedback is useful.

To answer your question, about twelve..... or none. As a consultant engineer I design, specify and oversee the installation of complete systems. When it comes to the detail of what optics to use I consult (pick other peoples brains). Of the systems the I have worked on three were infra red the rest visual. Two of the infra red were used to check for hot spots on printed circuit boards while under test. This shows up faulty components and bad joints. The third checked to see if metal inserts were correctly embedded into a molded plastic automobile tailgate. The visual systems are more varied. Checking that slate is evenly spread with no missed areas on roofing felt as it comes off the production line. Checking that ice cream tubs are filled to the correct level (coming off the line too fast for accurate weighing). This was later modified to also check the ice cream colour after 20,000 tubs left the factory with Raspberry Ripple lids fitted onto tubs of Chocolate ice cream. Checking the orientation of a part on a conveyor so that a robot gripper can be aligned to pick the part up correctly. The optics on all these applications were different so without further information about your application I cannot comment constructively. Orientation of the camera is as important as optics. Looking vertically down onto wheelnut studs fitted into a wheel hub as it passes along a conveyor will tell you if all the studs are fitted. Adding a mirror angled at 45º alongside the conveyor will also give the camera a side view so you can check the height of the studs. Another way of doing this is to shine a light from one side and check the length of the shadows.

Get a round Neodimium magnet and roll it along the wall. Where it sticks, count one stud.

Or, one conduit, one water pipe, one HVAC duct, etc.

True, but studs will only stick for the width of a stud. Conduit and pipe stick in only one place, and HVAC sticks for several inches.

Probably a quantity surveyor problem.

The high street banks weigh coins these days instead of counting them, because it is quicker than counting. Any help?