Arc OK intermitent issues on torch fire

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01 Apr 2021 17:00 #204404 by txtrone

Yep, in fact that’s how mine are wired.


Thanks. I cleaned up the drawing a bit, also made it a bit more indicative of my real world wiring using distribution blocks. The only 'real' change is THCAD 'gnd' moved to TB3-1 and the shield is connected to frame ground. If anyone sees any error, please let me know. I will try Rod's spindle mode for torch on, just need to understand which pins he is using.

Now on to hypersensing wiring. How exactly is the 390k wired in?
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01 Apr 2021 17:47 #204407 by snowgoer540
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01 Apr 2021 19:35 #204418 by rodw
The spindle enable is on TB4-5 and TB4-6
You'd have to check with halshow but there is a single pin to trigger this which ends in something like spinena
If you are using DIN rail terminals you can get blocks designed to mount a relay to but last time I used a DIN rail fuse block and soldered the resistor across the terminals.

oceancontrols.com.au/DIN-Rail-Special-Function-Terminals.html
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01 Apr 2021 20:35 #204426 by txtrone


This schematic is very similiar to the schematic in the the primer, to which I was referring. However, this one has a bit more detail and also an additional resistor. My original question could have been worded better. I was asking how exactly to wire the 390K resistor into the circuit, ie: do I simply solder a wire onto each end and attach them to +IN on THCAD5 and +24V on isolated power supply?

Your drawing clarifies the power rating of the 390k resistor at 1w, which was another question I had, so that is great!

It also has another resistor in the circuit, unlike the schematic in the manual, the 24k 5w. Is this a newer/updated schematic which has not yet been incorporated into the manual?

thx

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01 Apr 2021 20:55 #204428 by snowgoer540


This schematic is very similiar to the schematic in the the primer, to which I was referring. However, this one has a bit more detail and also an additional resistor. My original question could have been worded better. I was asking how exactly to wire the 390K resistor into the circuit, ie: do I simply solder a wire onto each end and attach them to +IN on THCAD5 and +24V on isolated power supply?

Your drawing clarifies the power rating of the 390k resistor at 1w, which was another question I had, so that is great!

It also has another resistor in the circuit, unlike the schematic in the manual, the 24k 5w. Is this a newer/updated schematic which has not yet been incorporated into the manual?

thx


forum.linuxcnc.org/plasmac/38848-hypersensing-questions?start=0

^—— This thread has everything you could ever want to know about the evolution thus far of ohmic sensing using a thcad, at least as it pertains to that diagram.

I can understand your confusion/frustration with the plasma primer. It is definitely out dated in some areas. But that said, none of this is etched in stone. You should be doing your best to understand the process, experiment, and see what works best for you. You will find conflicting advice sometimes because what works on one person’s table, doesn’t work on another. Not everyone here has the same power sources, stepper motors, stepper drivers, servos, etc. about the only commonality we all share is the Mesa hardware (mostly, some still use parallel ports), and Linuxcnc be it with PlasmaC or QtPlasmaC.

There are a lot of good reads in the PlasmaC section alone, I would encourage you to take time to read through the treads and understand how things came to be... A lot of the questions we’ve all had in the beginning have been answered several times over.

That said, the 24k resistor was added as a method to reduce sensitivity of the sensing circuit, especially when used around water tables.

As for how to insert the wires into the connectors, that’s up to you. Some people crimp the ends on them, some people “tin” the ends with solder, etc. I’d do what seems safest and most reliable given your scenario... keep in mind that you are dealing with lethal voltages. Most of the circuits ive seen here totally negate fuses, breakers, etc. So I would consider everything “use at your own risk, your mileage may vary, etc.” Whatever you do, please make sure you do it safely.
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01 Apr 2021 20:56 #204429 by rodw
yes, the diagram was updated by snowgoer following some suggestions by PCW to improve probing reliability on a water table and has not been updated in the primer. I did have one go at it once but the spanish docs triggered an error on the pull request.

The 1 W rating on the 390k resistor is what Snowgoer used. Its not critical. I've only ever used an ordinary 0.5W resistor for any THCAD scaling becasue the current draw is down to micro amps. I do recall getting some clarity around this from PCW at the time but it was 5 years ago so it would be hard to find.

When I added the resistor to mine I had to use 5 x 4.7k 1 W resistors in series as that was all I could buy locally. I soldered them to a board and placed a two terminal strip at each end that I tied together on the board. This made it super easy to wire it in.
www.digikey.com.au/product-detail/en/pho...8/277-1247-ND/260615

But today I would use a modified DIN rail terminal block to carry the correct resistor.
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01 Apr 2021 21:08 - 01 Apr 2021 21:18 #204431 by txtrone

The spindle enable is on TB4-5 and TB4-6You'd have to check with halshow but there is a single pin to trigger this which ends in something like spinena

Does this look correct? Depending on how my hypertherm pm85 reacts, I may need to swap the TB4-5/6 wires around like you stated earlier.

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01 Apr 2021 21:30 #204434 by txtrone

When I added the resistor to mine I had to use 5 x 4.7k 1 W resistors in series as that was all I could buy locally. I soldered them to a board and placed a two terminal strip at each end that I tied together on the board. This made it super easy to wire it in.
www.digikey.com.au/product-detail/en/pho...8/277-1247-ND/260615

But today I would use a modified DIN rail terminal block to carry the correct resistor.


Thanks Rod, sorry I ask the same questions over and over... just trying to get the THC and Hypersensing installed somewhat correct before I fire it all up. I am excited to see the downdraft in action. The smoke test was cool and all, but I am ready to throw a plate on the grill! I haven't cut anything since December.:(

I did install the laser on the Z and integrated with the gantry board, but I am not even going to bother trying to implement that at this point. The laser and VFD control (blower motor) through Plasmac/Mesa are my long game.

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01 Apr 2021 21:56 #204437 by rodw
QTPlasmac supports the laser but I have not played with it on real hardware. Maybe over Easter.. But I don't have enough pins on the gantry to turn it on and off from the GUI :(

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01 Apr 2021 22:04 #204440 by txtrone

QTPlasmac supports the laser but I have not played with it on real hardware. Maybe over Easter.. But I don't have enough pins on the gantry to turn it on and off from the GUI :(


Rod, as your attorney I advise you to install more pins on the gantry.
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