G10 L1 and offsets
11 Aug 2017 15:52 #97346
by Roc
G10 L1 and offsets was created by Roc
Hello,
I have a small bench top cnc mill so I don't have any sort of tool changer or any sort of tool holder that allows pre-measuring of tools for a job. By the way this configuration which I imagine is very common for home linuxcnc users, is very painful for tool changes, but not my question. I have been trying to set up so automated probing of tool length as a way to get accurate tool heights on my manual tool changes. I intend to modify the manual tool change procedure to perform the probe automatically after a tool change. I have a nc routine that performs the whole probing operation correctly with one big problem. I can't seem the get the tool offsets working as expected. Basically my routine currently uses the first tool as a reference point. That is effectively the first tool will have a tool height of zero and any subsequent tools will lengths relative the probed position of the first tool. The expectation was that I can then touch off no G54 for instance and all subsequent changes in the tool length would shift the G54 accordingly(when G43 is applied). But for what ever reason I can seem to get this to work as expected. When I change to a tool with a different height and probe it.
The probe sequence works as follows:
G49 Turn off tool length compensation
G28 to saved probe location
G38.2 till probe hit
if (first tool) Ref = #5063 (probe z offset)
G10 L1 P#5400 Ref-#5063 Set the tool length
G43 H0 Turn on tool length compensation
My exception here was that if tool 2 was placed such that it was .25 shorter then the reference tool, the tool offset will be set to -.25 and when he G43 is applied my G54 would shift by .25 thus have zero be at the same location as with the touch off for the reference tool. Just always seems to be off by some amount. I have not debugged enough to determine how much it is off, but is my understanding correct here? Or am I off base some how. Thanks in advance.
I have a small bench top cnc mill so I don't have any sort of tool changer or any sort of tool holder that allows pre-measuring of tools for a job. By the way this configuration which I imagine is very common for home linuxcnc users, is very painful for tool changes, but not my question. I have been trying to set up so automated probing of tool length as a way to get accurate tool heights on my manual tool changes. I intend to modify the manual tool change procedure to perform the probe automatically after a tool change. I have a nc routine that performs the whole probing operation correctly with one big problem. I can't seem the get the tool offsets working as expected. Basically my routine currently uses the first tool as a reference point. That is effectively the first tool will have a tool height of zero and any subsequent tools will lengths relative the probed position of the first tool. The expectation was that I can then touch off no G54 for instance and all subsequent changes in the tool length would shift the G54 accordingly(when G43 is applied). But for what ever reason I can seem to get this to work as expected. When I change to a tool with a different height and probe it.
The probe sequence works as follows:
G49 Turn off tool length compensation
G28 to saved probe location
G38.2 till probe hit
if (first tool) Ref = #5063 (probe z offset)
G10 L1 P#5400 Ref-#5063 Set the tool length
G43 H0 Turn on tool length compensation
My exception here was that if tool 2 was placed such that it was .25 shorter then the reference tool, the tool offset will be set to -.25 and when he G43 is applied my G54 would shift by .25 thus have zero be at the same location as with the touch off for the reference tool. Just always seems to be off by some amount. I have not debugged enough to determine how much it is off, but is my understanding correct here? Or am I off base some how. Thanks in advance.
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14 Aug 2017 16:29 #97471
by andypugh
Replied by andypugh on topic G10 L1 and offsets
You might want G10 L10
This might also require your routine to "know" where the top of the tool sensor is in the current coordinate system.
This might also require your routine to "know" where the top of the tool sensor is in the current coordinate system.
The following user(s) said Thank You: Roc
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15 Aug 2017 03:34 #97490
by Roc
Replied by Roc on topic G10 L1 and offsets
Thanks for the reply. My problem was in fact that it didn't occur to me the the G38 probe results were relative to the active coordinate system(which of course make sense). I was thrown off because my work offset while testing was such that it was only off a few tenths of an inch. I changed my probe routine to convert the coordinates to machine coordinates and things work as expected! Now onto remapping the tool change
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