Help please. Dip switches and mach 3 settings

[Radu_Andrei]

Oh, and another thing.
It is not an issue the alignment of material on the cnc spoilboard, when you run a profiling cut at the end, and throw away the remaining wood, but how about when a client comes to you with a finished piece of wood, and he want a 3mm edge all around the work. Gave this example as it is extremly visible a missalignment of this nature. How do you approach this?

[Radu_Andrei]

This last 2 questions are secondary to what happened today. While I was doing a job in 2 cuts, a roughing and a fininshing cut, on both of them, in one or two points, the z axis decided to go upwards and cut in thin air.
This was about 5mm or more in the air. Like it was cutting for 2-3 hours without a problem and then sudently, raise the z axis 3-5 mm above and continue cutting.
I could say to the client: it is cubism, but he.ll not buy it as it looks very weird.
I managed to fix it by rewinding the g code, , restart from an approximate gcode line, rezero the z axis and continue cutting, but that.s no fix.

Any ideas, or links that detail this or a similar problem?

[cropwell]

There is a possibility of a broken wire or loose connection. You should check the DIR pulse connections, but it is more likely that you have a break in one of the connecting wires to the Z motor. This is what I had.

[Radu_Andrei]

Hi Rob.
I.ll check that. Thank you.
Today at the end of a job, during the profiling toolpath, the limit switches kept triggering. I assume because they are very cheap lever type switches and don.t go well with dust and vibration.
I.m considering replacing all of them with someting better, especially for homing, as aparently I got a couple of milimeters of error today, as the lever got bent more and more.
Any recommendations?

[Clive S]

Today at the end of a job, during the profiling toolpath, the limit switches kept triggering. I assume because they are very cheap lever type switches and don.t go well with dust and vibration.

Or noise as in emf getting in to the system

[cropwell]

I use inductive proximity sensors for home switching, but a micro-switch for limit like this

The inductive sensor triggers off the aluminium of the gantry, but the micro-switch is tripped by a plastic wedge, which allows me to adjust the trip point.

Separate pictures as I can not move the gantry at the moment as I am installing a new mains switch panel for the computers and CNC.

There is one lesson I learned early on - do not have the proximity switch triggered by movement axially toward the switch, once you crush the end it is f***ed (rendered inoperative permanently), make the movement across the face of the switch. If you mount the switch on the gantry, you will only need one switch to sense at both ends of travel, by putting metal targets (preferably ferrous) at the appropriate places.

[Radu_Andrei]

It was an apx 5 hour cut. The switches went mad only in the last 10 min profiling cut. In fact I could not finish it, so I cut the work on the tablesaw.
I assume a noise issue would be persistent all the time, but who knows. I was lucky I was watching it and had pressed the estop quickly, as after a trigger, pressing reset, restarting the spindle and pressing cycle start (which in this case should continue the cut from where it stopped), well, after that, the cutter went straight through the work in a perpendicular direction, no idea where it was planning to go, messing up fortunately, only 3mm on one edge, which I managed to sand and fix.
I.ll do on monday some experiments, to see if it was just for that cut, or was just the starting point of triggers, check the connections and all.
It very well may be noise, but at this moment, my personal opinion is that the limits used as homing, due to the rough contact with the metal components and dust, malfunctioned. The levers are already bent, and I did get some differennt homing refferences. Might be a a loose connection, as Rob said, which causes some noise and all kind of trouble. MIght be somthing else. Who knows.
Anyway, any recommendation about homing switches types?

[Radu_Andrei]

*once you crush the end it is f***ed (rendered inoperative permanently)* - the switch or the cnc?

[Radu_Andrei]

Hi again.
Shortly after the the 3 weeks old conversation, I received 3 inductive switches, which I.ll install next week.
I like Rob.s approach of also keeping some mechanical switches in place next to the homing ones, but I.m somewhat unsure what.s the best way to wire all this.
I.ve only got 5 pins on the Bob, one being used for the probe. So 4 pins for the remaining Estop, 6 mechanical limit switches (2 for each axis), 3 inductive homing switches (3wires).

So for example (let.s say P15 is the probe)
1. Combine all limits and estop in let.s say P10 and have P11,12,13 for x,y,z home switches.
2. Combine all limits in P10 and all homes in P11, Estop in either P12 or 13
3. Combine the limits and home of each axis in one pin

So what the best wiring option and why?

[cropwell]

First , what inductive switches have you got? Keep Estop separate! All your limit switches can go in series to one pin using Com and NC on the switch, then you can put a push-to-make switch across the lot so you can jog off your limits when you hit them (otherwise you have to toggle and jog, then toggle again) . All your homes can go to one pin using diode routing if needed.
So I have just described option 2.

Homing works by moving an axis to trigger the home switch and then backing off to where the switch is not triggered, so it it quite OK to use the same i/o pin.