I have an OpenBuilds Ox CNC router using an OpenBuilds BlackBox X32 host controller and running OpenBuilds Control software on my Kubuntu 24.04 LTS Linux PC.
I’ve been using an OpenBuilds XYZ probe to set the Z-axis to 0 at the surface of the material to be machined. However, I’m trying to define a job that machines the whole top layer and subsequently use multiple bits for later toolpaths. Since I will no longer have the top surface to put the XYZ probe on top of, it is not usable after the first toolpath.
To solve this, I bought this tool length probe on Amazon. It uses a normally closed (NC) switch. I thought the XYZ probe was NC, too, but it does not work when wired in series, so I think it may be a normally open (NO) probe.
I think I can make this work if I invert the NC logic to NO by using a 2N3904 NPN transistor, so that I can then hook them both up to the same probe port on the BBX32 and then have either one just trigger normally when I tell it to probe.
Prior to trying to hook them both up to the same probe input, I’m trying to make sure I have the tool length probe working correctly first.
Does this look right? Am I even close? Is this a fool’s errand for some other reason?
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Forum Mods: I thought this question made more sense here than the General CNC community, but feel free to move it (if possible).
Most of these I’ve worked with use a pull down mechanism to indicate active using a NO type switch.
Nevertheless all the ones I can think of allow the firmware to be setup for either operation. I’d check the software documentation to see how this is handled.
The GrblHAL firmware does have a setting ($6=0 or $6=1, the latter is what the XYZ probe needs) to invert the probe trigger. I will use that to test this.
However, I’m trying to verify this circuit before I move on to trying to connect the 2 probes together.
True. But that does not answer my question. Remember, the goal is to be able to eventually connect both this normally closed (NC) switch and the XYZ Probe which is normally open (NO). That is why I am asking for help verifying this circuit first. I am not looking for help to connect this switch by itself, I have already verified that works.
That’s not a bad idea, but my workflow has me putting a blank in a pocket of a jig, and not taking it out until it is done. So I would have to remove it to locate the bottom, which doesn’t fit my workflow.
