Overcut to Reduce Undercutting - Explained

[Joe Jones]

I understand exactly what it does, but it is difficult to explain it to others. The "overcut" refers to a .08" kerf forcing itself along a closed path that is narrower that the kerf, for example. Sort of like trying to force a golf ball through a garden hose, a timeless test for choosing a girlfriend! However, that overcut distance is NOT what determines where the torch will stop cutting.

The misnaming of the function "Overcut to reduce Undercutting" refers to the WIDTH of the closed path the torch wedges through. It tells me that even PlasmaCam could not clearly explain what it was doing.

It is in fact "overcutting" that closed path. However, the MIN. and MAX. numbers entered actually refer to the distance between leading quadrant of the kerf and the NODE at the actual end of the path. So you are ACTUALLY setting the amount of UNDERCUT. You are telling the torch how much of the actual path you DO NOT want to cut. The file I uploaded shows this.

When people say, "What numbers do I enter for Minimum and Maximum?" the chart in the file shows what the result will be, based on the kerf width setting and the width of the closed path it is trying to wedge itself through, and where it is in relation to the RANGE established by the MIN. and MAX. values.

To determine where the torch will stop cutting, you enter the two numbers, and this establishes the RANGE where the kerf must make a decision. (represented by the rectangular closed path)

If the closed path is still wide enough for the kerf to fit through inside of the range, it will continue until Condition 1 the width of the closed path is equal to the kerf width.

In this example, the MAX. distance was set to 2 FEET but the .08 kerf STOPPED at 1.960 feet because that distance from the leading quadrant of the kerf to the node at the end of the path fell within the (Min / Max) RANGE when the closed path was exactly .08" wide.

Example in file (Kerf = .08 Min. 1" / Max. 2")

If the closed path is NOT wide enough for the kerf to fit through inside of the range, it will continue until Condition 2 the forward quadrant of the kerf hits the minimum distance from the END of the path.

In this example, the MIN. distance was set to 1 FOOT but the .12 kerf had already spilled over the closed path ("overcut") BEFORE ENTERING THE RANGE, so it continued cutting until it met condition 2; the distance from the leading quadrant of the kerf to the node at the end of the path, which was set to 1 FOOT.

Example in file (Kerf = .12 Min. 1" / Max. 2")

So it really should be called UNDERCUT to prevent OVERCUTTING, because although it IS "overcutting" the closed path on both sides as it follows the closed path, the point where the torch STOPS cutting is set by the distance from the leading quadrant of the kerf to the NODE at the END of the closed path in relation to where that point falls inside of, or outside of the RANGE established by entering the MIN and MAX distances.

If the OVERCUT of the closed path happens, what STOPS the torch from cutting to infinity? Why doesn't it just keep cutting to the NODE at the end of the closed path before reversing direction? It is stopped by a CALCULATION determined by the distance from the forward quadrant of the kerf (The "nose" of the comet) to the NODE at the end of the path, and the decision to STOP cutting is determined by whether the kerf is INSIDE or OUTSIDE of that RANGE at the moment one of two conditions are met.

Study the numbers in the chart to see this. ZOOM IN as some of the dimensions are very small and cannot be seen at the F5 view of the chart.

Joe


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[weldguy]

Man i had to read this 3 times. Don’t own a Pcam so unfamiliar with these settings but impressed it has them and impressed at your understanding of them. I expect that for most cutting thin metal art this setting doesn’t really matter.

[Joe Jones]

I expect that for most cutting thin metal art this setting doesn’t really matter.

The thickness of the metal is not a factor. The paths dictate where the torch will cut through any material, When the paths restrict torch movement, it changes the final product. This feature allows things like cat whiskers to be cut longer, rather than cut short due to narrow closed paths.

Joe

[weldguy]

Still don't get it but I'm not the sharpest tool in the shed. Don't get how this would allow a cat whisker to be cut longer. Figured it was to overcut so if you were cutting thick material there would be no chance of a short un-severed section of material at the beginning of your profile holding your part to the main plate.

[rdj357]

In a sentence or two:

Turning the feature on allows the torch to continue down in an area where it will not fit (because of kerf) and it will overcut into the part. This will reduce the amount of undercutting that would have occurred because the torch wouldn't otherwise fit so the path would not be drawn down in.

[adbuch]

In a sentence or two:

Turning the feature on allows the torch to continue down in an area where it will not fit (because of kerf) and it will overcut into the part. This will reduce the amount of undercutting that would have occurred because the torch wouldn't otherwise fit so the path would not be drawn down in.

Exactly!! Just like it is explained in the Video Manual, and how it actually works - from personal experience.

[weldguy]

That is a simpler way to describe it. I get it now, thanks guys.

[rdj357]

No problem. There is a lot going on behind the scenes and your settings make the changes that were originally pointed out. However, it is a handy tool to use when needed, a bad tool to leave on when you don't need it, and it just works so doesn't require a ton of understanding unless you just like to dig into those things!