Center Spot Sheetcam Post

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13 Sep 2019 12:24 #145053 by phillc54
Replied by phillc54 on topic 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. :(

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13 Sep 2019 13:05 #145057 by docwelch
Replied by docwelch on topic Center Spot Sheetcam Post
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

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13 Sep 2019 19:54 - 13 Sep 2019 19:59 #145079 by rodw
Replied by rodw on topic Center Spot Sheetcam Post

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.
Last edit: 13 Sep 2019 19:59 by rodw.

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13 Sep 2019 20:31 #145080 by docwelch
Replied by docwelch on topic Center Spot Sheetcam Post
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

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13 Sep 2019 21:15 - 13 Sep 2019 21:16 #145082 by rodw
Replied by rodw on topic Center Spot Sheetcam Post
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.
Last edit: 13 Sep 2019 21:16 by rodw.

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13 Sep 2019 23:03 #145085 by docwelch
Replied by docwelch on topic Center Spot Sheetcam Post
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

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13 Sep 2019 23:48 #145087 by docwelch
Replied by docwelch on topic Center Spot Sheetcam Post
With my 45xp set in marking/gouging mode and turned down to 10 amp as the book says, 50mS torch on time set in PlasmaC, I still have the same issue - the first torch fire works, the second does not, the third one does. I don't have the mechanized marking shield they call for but the other consumables are as called out in the manual.

Next test is Phill's experimental version posted earlier.

Steven
The following user(s) said Thank You: phillc54

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14 Sep 2019 00:48 #145088 by docwelch
Replied by docwelch on topic Center Spot Sheetcam Post
With the plasmac.comp Phill posted earlier:
With torch on time set to 77 (cut volts is 78 and use auto volts is disabled) - the torch never fires. Air flows and the Torch On button briefly lights.
With torch time set to 299 - torch fires every other time (same problem)
With torch time set to 450 - torch fires every other time (same poblem).

I'll try to call Hypertherm next week to see what they recommend.

Steven

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14 Sep 2019 00:58 - 14 Sep 2019 00:59 #145089 by phillc54
Replied by phillc54 on topic Center Spot Sheetcam Post

docwelch wrote: With the plasmac.comp Phill posted earlier:
With torch on time set to 77 (cut volts is 78 and use auto volts is disabled) - the torch never fires. Air flows and the Torch On button briefly lights.

That seems odd, what does the Arc Voltage display?
Last edit: 14 Sep 2019 00:59 by phillc54.

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14 Sep 2019 01:03 #145090 by docwelch
Replied by docwelch on topic Center Spot Sheetcam Post
I think it stayed at 0. I even turned out the lights and there was no flash from the torch on that test.

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