Center Spot Sheetcam Post

If you can sense with a current sensor than you can also sense by voltage as they do have a defined relationship but that is not the real issue here.
From Stefans and Stevens results it seems their machines require a time delay because they did not sense an arc transfer. Steven ended up at 20 seconds. I would think that a 20 second wait between centre pops is not really viable.
I am also guessing that this will be different between machines so I think it will be difficult to find a solution.

I will have a chance to try the experimental spotting late this afternoon. My concern is that it is going to go ahead and pierce the metal, not really create just a dimple. That was the reason for such a short time on the 18g. The cut chart calls out only a 200mS pierce delay for that thickness. When I tested on 0.125" material, I found it only took about 150mS to get a good dimple. I think the cut chart only calls out a 400mS pierce delay for 0.125" material.

I think you are correct in that there is a fault requiring a delay because there was no arc transfer sensed. I'm beginning to think my inelegant solution of just attempting a second pierce at the same location is a decent solution. The second (failed) pierce seems to reset the machine. While this adds a little time, it is better than waiting 20 seconds.

My other thought is to turn down the amperage which would allow for a longer arc on time before the material is actually pierced. The only issue there would be the need to create two g-code files, one to dimple and one to cut. I don't have a serial port on my machine that would allow plasmaC to change the amperage.

Steven

docwelch wrote: The only issue there would be the need to create two g-code files, one to dimple and one to cut. I don't have a serial port on my machine that would allow plasmaC to change the amperage.

Steven

In sheetcam you can move elements onto a different layer and apply a different operation eg spotting on one layer and then cut your part on another layer. eg. Tool change. Can't you do that in Fusion?

Sheetcam also has a setting that determines what range of diameters gets centre punched.

EDIT: I'm still convinced this can be done based on the behaviour I observed when a probe signal generated from my THCAD ohmic probing. Its just that we have not replicated what I saw was happening.

Rod,

Yes, you can set up different operations in Fusion360 CAM. I suppose you could put some a pause/stop between operations so that you could change the current and continue into the next operation. I'm not really sure if that would really be any easier than just setting it up as 2 different g-code files. Either way, you have to be there to change the current setting. I should be able to figure out if changing the current setting changes the behavior later today or in the morning.

I definitely can produce a nice dimple with the short pulse - I just have to either wait for about 20 seconds or "trick" it by pulsing the torch a second time before moving to the next location.

Steven

Steven just looking at the manual for the 45XP. Were you using the marking/gouging setting on your machine?
Page 121 and cut charts on p 138/139 show dwell times for dimpling of 50 ms for air so it must be able to be done on your machine.
Maybe you can ask Hypertherm support how it should be done.

Of course the solution to changing settings is to use the RS485 interface.

Rod,

To use the book settings, you have to actually change the mode of the plasma machine, drop down to 10a, and use a mechanized marking shield with other standard (as opposed to fine cut) consumables. In other words, you have to basically set the system specifically for marking. My hope was to be able to use the machine as it was set up for cutting and not have to go to such lengths just to spot a few holes. I will try putting the machine in the marking/gouging mode to see if it behaves better with the short pulse. I don't think I have the marking shield they call for but I can at least test with a cutting shield.

Having to change the consumables obviously negates any real benefit of a serial (RS485) interface. If I can get it to work with the fine cut consumables and a cutting shield, I might consider a serial interface. It looks like the interface can actually change the mode from cutting to marking/gouging on the 45xp.

Steven