Probe - How does it work?

[robinsoncr@naxs.net]

Hi Everyone,

Exactly how does the 3d Probe work? I understand how the z-axis zeroing plate works. But when probing a wooden object, how does the SB interface with the probe and the object?

I know it's running on a grid but after that....?!

Sorry for my lack of knowledge. This cnc stuff is still new to me.

Chris R.

[artisan]

Chris, if you understand the zero plate, then the probe is sort of similar. Where the zero plate uses current through the grounded Shopbot to open and close a switch by contacting the metal zero plate, the probe simply has spring loaded contacts inside of it that are triggered (opened and closed) by the probe making physical(non-electrical)contact with your material....be it wood, foam, plastic or metal. The point in space (x,y,z) is then recorded. It's simple and efficient and something your robot can do while you're busy elsewhere....or sleeping....D

[robinsoncr@naxs.net]

Darrell,

Gotcha! (Light bulb just lighted up!)

Thanks,

Chris Robinson

[gerald_d]

Is the probe switch also sensitive to a horizontal force on the side of the tip? A sketch of the inner workings would really be appreciated. (I understand there are some some gold-plated contacts in there?)

[artisan]

Gerald, my experience is that the probe has no horizontal contacts.... and rightly so. It would require a more sophisticated apparatus, costing much more than the probe to accurately measure horizontal pressure or pitch from 360 degrees. The software would also be far more involved and in the end largely unnecessary. The real issue is one of resolution. If you take measurements every hundreth of an inch, you'll have a far more accurate picture than if you take a measurement every inch. Of course, your file is gigantic and must be edited. The probe is only part of the answer anyway. Your files will be much cleaner and easier to use if you learn to copy objects into 2 dimensional modes (trace or draw), and then build them yourself in 3D software such as Rhino or Innovate. I understand that sometimes there is no other way....like probing organic shapes.. but it takes nearly as long to edit and clean the files as it does to scan them. The probe seems to work best on objects from 2 square inches to 2 square feet in my personal experience....though far more is possible. So far....at least in my humble experience.... most of the magic happens in the software. The sooner you commit to specific software and learn it... the more powerful your cnc skills become. I currently use Corel Draw, Corel Design, Rhino, Innovate, and Visual Mill.... though MANY other solutions exist.... I hope this helps...laughing... I got a little more involved than I meant to....D

[gerald_d]

Darrel, the reason I asked the question is to confirm that I will not buy it!
Essentially, the probe is thus only a smartly packaged micro-switch, and that is something that I can easily make myself. We have played around with probing some items using tin-foil and a paperclip, and have had the introduction to a lot of what you have just posted. I am under no illusion what probes and probing can do - probably more sceptical than you expect.

[artisan]

I always say..."trust your instincts"....D

[bill.young]

Hi Gerald,

The probe does trigger from horizontal contact, and is used in some of the edge-finding routines where ALL the contacts are horizontal. It's not microswitch based but is basically a spring-loaded mechanical switch that can be triggered in 3 dimensions.

Bill

[gerald_d]

Thanks Bill, I should have remembered the edge finding application. Back to the drawing board . . . . .

[artisan]

Hi Bill...I didn't know that (obviously) ...but I too remember the edge finding routines....back to study....Thanks....D

[artisan]

Bill, now I see....so the probe can also be used as a "2D" tool to trace parts.... I just ran it through the edgefinder routine without a hitch and got a usable "tracing" of a part....which I would still prefer to build to 3D in software. This however makes the probe MUCH more useful as an input device....Thanks again....D