Z axis problems

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acourtjester
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Re: Z axis problems

Post by acourtjester »

I have mine wired like this, is setup for NO so when the torch tip touches the metal surface it completes the circuit. To test with switch operations go to the diagnostic page and look at M3 Home box ( right side in the middle) if you touch a wire from the torch tip to the metal surface that box should turn yellow. I check before each time cutting I manually drive the torch down slowly looking at that box to see if the box lights when the torch tip touches the metal surface. I go up/down to be sure and clean off the metal and tip if it does not light. :lol:
You will need to have the correct pins selected in ports and pins for Z home. My floating head switch is wired in series with the other home/limits switches, this is a safety if the ohmic sensor does not work when cutting to stop the torch's downward motion. :?

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fabricator909
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Re: Z axis problems

Post by fabricator909 »

Acourtjester, what ports and pins should be selected? The manual has me confused on the Z home, with the ohmic sensor, that replaces the need to wire the z home inside the actual control box correct? Or does the z home have to be spliced to both?
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Re: Z axis problems

Post by tcaudle »

We are in the motor tuning stages as well, however our Z-axis wants to plunge through the material even once it has it the limit switch on the floating head. We have the switch wired to the ohmic sensor as described in the manual, although the ohmic option is something we will very rarely use IMO because we will be cutting 11ga and up material most of the time. We have tried NO and NC positions on the switch (the manual contradicts itself on switch position). At a loss at the moment on what the problem is, we also tried the G-CODE acourtjester posted, to maybe see if the switch only worked with g code, but it didn't work.[/quote]


If you have the ohmic sensor plugged in It IS your Z home signal Its used for homing and touch off BOTH . Its not htere simply to only on thin material, it IS the method for tocuh off. The Z home mechanical swtich if wired THROUGH the Feather Touch (Ohmic sensor) becomes an E-Stop that is a safety over run. If you want to use it for homing and touch off it has to be wired DIRECTLY to the Z home and the FT-01 plug removed at the input card (Table I/O)

If the mechanical swtich is used as E-stop it HAS to be wired Norammly Closed and the EPO jumper on the input card (blue wire) has to be taken loose or it simply will not work.

There is no LIMIT switch on Z unless you add it and wire it in and set it up. Even then it won't work on a Homing move beacuse LIMITS are ignore. E-Stop is NEVER ignored.
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Re: Z axis problems

Post by fabricator909 »

Thanks Tom, we finally just figured it out, only question is how well does the ohmic sensor from the torch head itself stand up to the abuse of cutting 1" plate on a regular basis?
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Re: Z axis problems

Post by tcaudle »

No more abuse (probably less) than cutting loads of 16g. There is nothing to wear out ...no moving parts. Circuit is potted in epoxy and has protection of up to 1000 VDC at the inputs.
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Re: Z axis problems

Post by fabricator909 »

Ok,
We are up and running for the most part, just figuring out minor details. One big one is getting the feather touch to touch off consistently, cutting an array of 2" tubing end caps out of 11GA P&O, the feathertouch would NOT sense the material quick enough, and would hit the limit on the Z. It did this quite often, with no pattern at all. I'm guessing at least 1 out of 10 cuts it would not sense the material fast enough, IE, it would hit the limit on Z, THEN the light SENSE light would come on, but it is too late at that point. I read Command CNC can use both , the ohmic and Limit switch to pick up the material as a backup, but since we just started running, I'd rather not switch platforms yet.
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Re: Z axis problems

Post by tcaudle »

Probably, the Z is not slowing down at a spot above the material as it should. That "spot" is set by the Plunge Safety Clearance in SheetCAM/Options/Job Options. It shoul dbe at least 1/2" (12mm) and the Rapid Clearance is on that same page and should be higher than the Plunge Safety. It should cause the Z ti visibly slow down as it does a touch off so it does not overrun the Ohmic sensor.
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Re: Z axis problems

Post by fabricator909 »

The feather touch is not sensing the material at all now. Even when jogged manually. I've checked all connections, moved the ground directly to the plate, and nothing.
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Re: Z axis problems

Post by fabricator909 »

Found the problem, for some reason the Ohmic retaining ring was not holding continuity with the shielding cap, yes it was visibly touching. I even measured it with an ohm meter, and resistance was very high, and was not consistent. I eventually soldered the two together to get a good connection. Maybe Jim Colt will chime in on this, not sure the issue between the stainless ring on the ohmic retaining cap and the copper shield. I also used dielectric grease on the connection.
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acourtjester
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Re: Z axis problems

Post by acourtjester »

Great if later you have a problem you know the path to check.
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Re: Z axis problems

Post by tcaudle »

Dialectric does not mean "conductive" its used to describe an insulating layer in a component like a capacitor . Its probably the cause of your non-conduction not the cure. Grease itself is an insulator

Clean off the grease completely and use a solvent to remove the film. The connect then will improve.
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Re: Z axis problems

Post by plain ol Bill »

I have had this problem in the past until I started putting a thin piece of copper sheet between the omnic sensor and the shield ring - solved that problem then.
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