Path Rules on Circles - Why are they really needed?

[Nacs Fab]

I am a noob on Path Rules and have a question regarding them during hole cuts. When I create a DXF to import into Sheetcam, I always put my holes on a separate layer than all of my inside cuts; in fact, I sometimes put varying inside cuts on separate layers as well so I can better control which one's are cut first and so on. In my sheetcam tools, I have set up basically 3 different tools for 14 gauge for example:

Full speed (200ipm cut)
Reduced speed Holes (60% feedrate 120ipm cut)
zero delay pierce for no offset cutting

By doing it this way, is there any advantage to adding a path rule for circles, if I simply add a second layer for them? Just not at all following the reason for adding a rule other than to turn off THC, but I never have trouble cutting holes with THC on.

This brings up a second question - probably for Tom. If i DO actually want to start using path rules on these, am I unable to use them with my current THC? I believe I cannot use the code snippet for DTHC On/Off using my LCTHC because It would cause a delay in cutting. Could someone explain?

[sphurley]

My "normal" rules for small holes is reduce feedrate and also turn DTHC off to prevent diving. Not sure on the LCTHC.

[tnbndr]

Your method with layers and different tools seems like another way to skin the same cat!!!
If it works don't fix it!!!
In fact probably simpler than path rules as I can see where path rules could conflict with one another.

[mechanicalmongoose20]

I run mine on a separate layer as well to control lead in and out. I run Whatever lead in I need to pierce in the center, perpendicular lead in, 60% feed rate, and DTHC off. This is only on holes smaller than about 1.5" in Dia.

[tcaudle]

I am a noob on Path Rules and have a question regarding them during hole cuts. When I create a DXF to import into Sheetcam, I always put my holes on a separate layer than all of my inside cuts; in fact, I sometimes put varying inside cuts on separate layers as well so I can better control which one's are cut first and so on. In my sheetcam tools, I have set up basically 3 different tools for 14 gauge for example:

Full speed (200ipm cut)
Reduced speed Holes (60% feedrate 120ipm cut)
zero delay pierce for no offset cutting

By doing it this way, is there any advantage to adding a path rule for circles, if I simply add a second layer for them? Just not at all following the reason for adding a rule other than to turn off THC, but I never have trouble cutting holes with THC on.

This brings up a second question - probably for Tom. If i DO actually want to start using path rules on these, am I unable to use them with my current THC? I believe I cannot use the code snippet for DTHC On/Off using my LCTHC because It would cause a delay in cutting. Could someone explain?

The LCTHC has no external enable or disable input. It cannot be enabled or disabled independent of MACH3 THC logic. Turning MACH THC logic on/off via G-code with any M code EXCEPT M10/M11 causes a motion pause even in a rule set. There have been various ways to deal with this that entails using an output with M10/M11 and mapping that to the THC ON/OFF function. Another way is with external logic use the Output to enable /disable a buffer chip that is in the UP and DOWN path. Next model up from the LCTHC (THC302DVP) does have an output tied to the internal THC enable in the unit.