Using Spotting with Sheetcam

phillc54 wrote:

It may be possible to change spotting a bit by adding a value of -1 to the threshold which would mean start the delay when arc ok is established. If you are interested in this let me know and I will have a look tomorrow. This may be a bit heavy handed for spotting but then again it may suit your machine.

Thats the wrong way to go about it. The correct way that will always work is to wait for AcOK, then kill the torch. I've done it that way with my Everlast and Thermal Dynamics for years until we played with spotting which started becasue of an observation I noticed..

We don't want to make the spot any bigger than it has to be (which the delay after AcOK will cause). Stopping at ArcOK on 16mm steel on my machine almost perforated the sheet (at least 12mm deep anyway.

phillc54 wrote:

Clive wrote:

phillc54 wrote:

I seem to recall similar voltage issues when you were setting your machine up which required using a relay for arc ok. Maybe you machine is not suitable for the way we have spotting set up.

It may be possible to change spotting a bit by adding a value of -1 to the threshold which would mean start the delay when arc ok is established. If you are interested in this let me know and I will have a look tomorrow. This may be a bit heavy handed for spotting but then again it may suit your machine.

Phill I have managed to do what I wanted ie make a back plate to hold a 7i76e all done on the plasma drilling all the holes and cutting it out in one go All I had to do was stick a 3mm drill through each plasma hole

I changed M3 $2 S1 (cut start) to M3 $0 S1 (cut start) through the file

Cool, glad you got your part made.
If you had done it the way you said and set your Pierce Delay to 0 then that would have the same effect as The -1 idea I suggested above.

For the avoidance of doubt I just wanted to (and achieved) blow a hole through the ali at the hole centres so that I could just drill out to the size I wanted. The part was cut out in less than a minute but the learning and setup took me hours. But its all a learning curve.

I am still not sure how to setup up sheetcam yet to work with PlasmaC.. A bullet list of point order would help

Many thanks to Phill and Rod for the patience

phillc54 wrote:

rodw wrote:

Thats the wrong way to go about it. The correct way that will always work is to wait for AcOK, then kill the torch. I've done it that way with my Everlast and Thermal Dynamics for years until we played with spotting which started becasue of an observation I noticed..

We don't want to make the spot any bigger than it has to be (which the delay after AcOK will cause). Stopping at ArcOK on 16mm steel on my machine almost perforated the sheet (at least 12mm deep anyway.

Those two sentences seem to be at odds with each other to me.

Plasmac doesn't wait for Arc OK when spotting and seems to spot well for folk who have reported using it.

I meant if you want to add a -1 mode, to do it that way, not add a delay after ArcOK.
The reason why Plasmac does not wait for ArcOK is because I made you code it and it works perfect form me now at 220 ms.

phillc54 wrote:

rodw wrote:

phillc54 wrote:

rodw wrote:

Thats the wrong way to go about it. The correct way that will always work is to wait for AcOK, then kill the torch. I've done it that way with my Everlast and Thermal Dynamics for years until we played with spotting which started becasue of an observation I noticed..

We don't want to make the spot any bigger than it has to be (which the delay after AcOK will cause). Stopping at ArcOK on 16mm steel on my machine almost perforated the sheet (at least 12mm deep anyway.

Those two sentences seem to be at odds with each other to me.

Plasmac doesn't wait for Arc OK when spotting and seems to spot well for folk who have reported using it.

I meant if you want to add a -1 mode, to do it that way, not add a delay after ArcOK.
The reason why Plasmac does not wait for ArcOK is because I made you code it and it works perfect form me now at 220 ms.

Well your first sentence says to wait for Arc OK...

I think I remember reading about the delay on Plasma Spider.

Yes, probably from Beefy in Melbourne as he pioneered the process with his home built THC. He actually took it a bit further and installed a current sensor in his plasma cutter so he could kill the torch based on the current level.

I still don't get the fine spot from Plasmac I observed when I first emailed you and Stefan about it in August 2019. Then some testers (pre snowgower's reign) that found some issues made it hard on some machines.

I'd also like to experiment with another very cool thing I found out by accident today.
I'd like to suggest Plasmac supports a third tool for plasma centre punching. It will need a pin to set the number of servo cycles the torch stays on after its turned on. So basically, select the tool, do an M3 as if you are spotting a hole and turn the torch off X number of servo cycles later. From what I saw today, at 1 servo cycle, this should make the finest of centre punch holes you've seen, way better than what I have been doing. This would probably be tidier if the scribe is moved to spindle 2.

So onto why we need these features. Centerpunch first. At one stage, my component fired the torch and left the probe enabled. Linuxcnc Immediately turned it off once motion started and Plasmac tried to restart and do it again! Even after several goes, the spot was still tiny! So I think if we can experiment with the length of the pulse up to a few milliseconds, it will give amazing results!

phillc54 wrote:

I didn't quote cause it's getting a bit lengthy but I don't understand what you mean...

That was my original observation I shared when you did the spotting initially. The probe signal turned off the torch immediately it fired becasue of my bug. The result was the tiniest pinprick which I have not replicated with plasmac since... Plasmac is much coarser...