Loss of detail with height control? & Kerf compensation?

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gamble
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Loss of detail with height control? & Kerf compensation?

Post by gamble »

Ever since added height control I have a problem with really small detail. One of my pieces has a thin spot maybe .090 thick. Ever since adding height control it will blow this section out or cut it so thin if i grind the back it will fall apart. Another section is a small eye on an animal. Maybe .20 or .25 in diameter. It will blow this apart as well.
Tried slowing down the cutting process to my normal 120ipm and it still happens. Worst at 250ipm. Tried adding kerf compensation at about .125 and it made a very very little difference but not much.

What is it about height control that would be causing these issues here?

How exactly does kerf compensation work? Say If I made the kerf 1" does that mean the entire part is 1" larger?

I can post some pics later tonight to show you.
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motoguy
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Re: Loss of detail with height control? & Kerf compensation?

Post by motoguy »

Kerf compensation tells it how wide the hole is, made by the plasma arc. This way it knows where to put the center of the torch, so the outside will just touch the line you want cut. If you tell it your kerf width is 1", it thinks your torch cuts a 1" hole, so it will put the center of the torch 1/2" (1/2 the kerf diameter) inside (or outside, depending on your cut type) the line to cut.
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tcaudle
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Re: Loss of detail with height control? & Kerf compensation?

Post by tcaudle »

gamble wrote:Ever since added height control I have a problem with really small detail. One of my pieces has a thin spot maybe .090 thick. Ever since adding height control it will blow this section out or cut it so thin if i grind the back it will fall apart. Another section is a small eye on an animal. Maybe .20 or .25 in diameter. It will blow this apart as well.
Tried slowing down the cutting process to my normal 120ipm and it still happens. Worst at 250ipm. Tried adding kerf compensation at about .125 and it made a very very little difference but not much.

What is it about height control that would be causing these issues here?

How exactly does kerf compensation work? Say If I made the kerf 1" does that mean the entire part is 1" larger?

I can post some pics later tonight to show you.
Height control is based on the arc volts. The arc volts is based on the arc gap (height) AND the federate AND the amount of adjacent material that remains . That last part is a kicker because if you make a really small cut (small object) or get a cut close to another , two things happen: The machine slows down to make the rapid direction changes and the flame "hunts" for metal to cut so the kerf gets wider. Worse, the arc volts start to climb so the THC tries to compensate and dives the torch. The best way is to be able to dynamically (in the cut) turn off the THC so it does not react. If the THC has some form of Anti-dive that can help but cutting with the THC off for that object or close cut would be better. If you got good detail before with no THC then find out how to turn it off in the areas that are causing problems
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