Initial Height Skip (IHS) not functioning properly

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24 May 2022 19:59 #243720 by Uthayne
I've noticed when cutting that IHS does not seem to work as intended. Sometimes it will skip the probing routine, but most of the time it does not. I believe it has something to do with the state of the THC. Most of my cuts (artwork) are small and the THC never kicks (enabled, but inactive) in due to velocity anti-dive. IHS does not seem to work when moving between these types of cuts. If a cut is larger and has straighter sections where the THC would actually be active, then it seems like IHS settings are considered between the next cut.

Per the QtPlasmac docs, IHS should function as such:
9.20. Initial Height Sense (IHS) SkipIHS may be skipped in one of two different ways:
[list=1]
[*]If the THC is disabled then the IHS skip will occur if the start of the cut is less than [b]Skip IHS[/b] distance from the last successful probe.
[*]If the THC is enabled then the IHS skip will occur if the start of the cut is less than [b]Skip IHS[/b] distance from the end of the last cut.
[/list]
A value of zero for [b]Skip IHS[/b] will disable IHS skipping.Any errors encountered during a cut will disable IHS skipping for the next cut if [b]Skip IHS[/b] is enabled.

If I run a program with the torch disabled (dry run), it will properly IHS based on the distance set on my parameters tab, so I know that this has the ability to work. When I run the same program with torch enabled, it does not IHS.

My test program is a grid of holes. If THC is enabled, then it will not IHS between the holes. As soon as I uncheck the THC enable button, it skips probing between holes. My understanding is that with THC enabled (my default state), it should check the distance between the end of the last cut and the current probe position. Even though the THC is enabled but does not activate due to the velocity anti-dive feature, I feel like IHS should still operate as it does with THC disabled.

Test program and machine configuration are attached. I am currently running QtPlasmac version 1.223.186
Attachments:

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24 May 2022 22:39 #243728 by tommylight
I am not helping, just awoiding confusion:
Initial Height Sense (IHS)
IHS is not "initial height skip", it is "initial height sense".
The following user(s) said Thank You: Uthayne

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24 May 2022 23:51 - 25 May 2022 00:04 #243733 by phillc54
If the THC was not active at the end of a cut then IHS skip in THC mode will not operate, that is a slight documentation error.
This statement:
If the THC is enabled then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the end of the last cut.
Should probably be changed to:
If the THC is enabled and activated then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the end of the last cut.

EDIT:
On further reading, I think this:
If the THC is disabled then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the last successful probe.
Should be changed to :
If the THC is disabled or if THC is enabled and not activated then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the last successful probe.
Last edit: 25 May 2022 00:04 by phillc54.
The following user(s) said Thank You: tommylight, Clive S

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25 May 2022 01:21 - 25 May 2022 01:25 #243742 by Uthayne

If the THC is disabled or if THC is enabled and not activated then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the last successful probe.


This logic makes sense to me. It doesn't currently work this way though, does it? Like you said earlier, if THC is enabled but not active at the end of the cut, IHS skip will not function. It should (in theory) default back to the last successful probe in this case.

Edit: Wow, editing on mobile is a disaster
Last edit: 25 May 2022 01:25 by Uthayne.

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25 May 2022 01:33 #243744 by phillc54

If the THC is disabled or if THC is enabled and not activated then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the last successful probe.


This logic makes sense to me. It doesn't currently work this way though, does it? Like you said earlier, if THC is enabled but not active at the end of the cut, IHS skip will not function. It should (in theory) default back to the last successful probe in this case.

So long as you have a large enough Skip IHS distance it will work.

Edit: Wow, editing on mobile is a disaster

Yeah, it is bad enough on a PC, I rarely reply on a mobile and if I do it is usually without quotes.

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25 May 2022 01:46 #243745 by Uthayne
Running the test program attached to the first post with a Skip IHS Distance = 3 (inches) does not prevent it from probing every single time. The grid pattern is 0.150" diameter holes 0.300" on center (pierce location delta). The hole pattern is only 1.05" x 1.20" in size so they should all be within the 3.00" IHS Skip distance

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25 May 2022 02:12 #243748 by phillc54
Hmm, it works fine here (on a sim).
It works down to a Skip IHS value of 0.4.
 

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25 May 2022 02:45 #243751 by Uthayne
It's confusing because it works as intended if I do not enable the torch. It probes the first hole and then finishes the remainder without probing (THC Enabled, not active obviously because of no torch voltage).

When I enable the torch and actually cut it probes each time. There are no errors while cutting which would disable IHS skip.

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25 May 2022 04:11 #243756 by phillc54

It's confusing because it works as intended if I do not enable the torch. It probes the first hole and then finishes the remainder without probing (THC Enabled, not active obviously because of no torch voltage).

When I enable the torch and actually cut it probes each time. There are no errors while cutting which would disable IHS skip.

That is odd because it probably wouldn't reach full velocity on those holes, THC would not be activated, then it should fall back to:
If the THC is disabled or if THC is enabled and not activated then the IHS skip will occur if the start of the cut is less than Skip IHS distance from the last successful probe.

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25 May 2022 04:25 #243757 by Uthayne
My thoughts exactly

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