Hi, yeah, what's in a name......as I said I'm very new to CNC as in what's Gcode Mum?.....LOL.....but as I'm expecting delivery eventually of an SVM-0 mill from the Skyfire build thread, I quickly realised that if you want to make parts you gotta have a plan, and that means either generating the G code by Cad/Cam process or probing an original part......the latter can be modelled in any material and then translated to CNC savvy coding when the final design is formalised.

Having looked at the process it boils down to getting enough points of reference for the cutter to move smoothly and generate the profile etc.

I seem to remember in another thread that a probe was made by a Dutch fellow that moved in all directions, up down and sideways, similar to a gymbal motion.... it was a longish spring loaded rod that moved a plate and made contact no matter which way it moved etc.

I think it was a copy or derived from a commercial one so as it was quite simple it probably won't be all that expensive.

I'll have to find out more on how touch probes work....no sense in re-inventing the wheel.

I'm still puzzling over how a probe senses the steep sides of a sphere without deflecting off before recording.

If the probe relies on up pressure to make the "switch" work it will mean there is undue pressure before the probe works and coming down against a sloping face will be a bit iffy.

I looked at the design for an EDM and the way the sensing head retracts immediately the contact was made.

Although in the EDM design it's an electrical contact, having a fine and sensitive switch in the probe could make the contact pressure very slight and give a good indication the moment contact is made.
Ian.