I've been having problems with probing. It's giving me inconsistent results, usually seems to be over-shooting. What I'm currently doing is a "fast" jog (to quickly get close to the target position), until I see the probe input change, then back off a short distance, and do a second, slow jog until I see the probe input change. But, if I use this for zero-setting, the true zero invariably ends up being off by 0.005-0.010 or so.

I know that Mach3 handles probing (G31) at the driver level, and it will take a single step, and see if the probe input changes. When it sees a change, it notes the axis position, and reports that. So, slight over-shoot becomes harmless, even if you do the probe at a pretty good speed. I don't think I can do exactly that here, but if I read chx->Pos when the probe input changes, will that give me the current axis position?

BTW - I am completely baffled by the Probe.c example code - seems useless to me, and not related to probing at all....

Regards,
Ray L.

Never mind.... Answered my own question. I re-wrote so I capture chx->Dest when the probe input switches, and I'm now getting repeatability of better than 0.001". The amount of overshoot was a surprise, but no longer matters.

Regards,
Ray L.

--- In DynoMotion@yahoogroups.com, "himykabibble" <jagboy@...> wrote:
>
> I've been having problems with probing. It's giving me inconsistent results, usually seems to be over-shooting. What I'm currently doing is a "fast" jog (to quickly get close to the target position), until I see the probe input change, then back off a short distance, and do a second, slow jog until I see the probe input change. But, if I use this for zero-setting, the true zero invariably ends up being off by 0.005-0.010 or so.
>
> I know that Mach3 handles probing (G31) at the driver level, and it will take a single step, and see if the probe input changes. When it sees a change, it notes the axis position, and reports that. So, slight over-shoot becomes harmless, even if you do the probe at a pretty good speed. I don't think I can do exactly that here, but if I read chx->Pos when the probe input changes, will that give me the current axis position?
>
> BTW - I am completely baffled by the Probe.c example code - seems useless to me, and not related to probing at all....
>
> Regards,
> Ray L.
>