How to setup an ohmic sensor

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Re: How to setup an ohmic sensor

Postby asuratman » Sat Jun 22, 2019 2:58 pm

Hi Greolt,
Why not to use plasma cutter without pilot arc ? I know you will need more consumable, but Chinese consumables are cheap. Plasma cutter without pilot arc is a lot cheaper. You will have no problem with high voltage on the ohmic sensor.
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Re: How to setup an ohmic sensor

Postby Greolt » Sat Jun 22, 2019 11:35 pm

I am happy with my Chinese plasma cutter.

This is a hobby for me and the cutter was cheap. If it were not, then I would not have a cutter at all.

I works better than I expected. So far it is reliable and cut quality is acceptable.

My understanding is that cheap cutters without pilot arc use HF drag start and are not suitable for CNC cutting.

More expensive cutters use blow back start. That would be great but I am retired and that is not going to happen.
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Re: How to setup an ohmic sensor

Postby beefy » Sun Jun 23, 2019 2:34 am

asuratman wrote:Hi Greolt,
Why not to use plasma cutter without pilot arc ?

How to you initiate the arc with a drag start (non pilot arc) torch on a CNC table ??

You'd be starting the pierce with the torch touching the material.
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Re: How to setup an ohmic sensor

Postby jcoldon » Tue Jul 02, 2019 5:29 am

ohmic input setup

The probing can be done with G31 code. The G31 code is very simple, what it does is that it touches the probe input and then stops the axis.
In practise a plunge is added to the G31, but that is done usually in a macro with the macro executing the G31 and then a linear plunge motion and then the macro can adjust the Z work coordinate to offset the measured position or it can write a G92 offset or a tool offset, all solutiuons work.

The UCCNC understands the same industry standard programming language (RS274NGC) as Mach3, so Mach3 post processors work.
Also a generic Fanuc post processor usually work, but might need a few small adjustments for mach3 and uccnc.

There are macros built into the UCCNC (M213/M214) to turn the safe probe mode on/off. What the safe probe mode does is it stops the motion if the probe triggers.
So, you could use those macros... or you could input a switch to a separate input which sensor senses if the sensor mount, you could then configure it to an input trigger and e-stop or to an unused axis limit input.
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