Re: [Emc-users] A simple question on I J
Jon Elson wrote on 28/11/2007 04:05: I think the above quoted text should read Only one offset word is required. You definitely can have two. I think with the in-plane only arcs that EMC does, you can't have 3. Some controls allow arcs in arbitrary planes, and you can have an arc move with XYZ and IJK words! I can imagine all sorts of conditions where the plane of the arc is not uniquely defined. Actually, only 180° arcs would be underdefined in a 3D (not plane-bound) arc. That's because a plane is always well defined if three points on that plane are known and are not on a single straight line. So in theory, one could implement plane-free-arcs in EMC with the added error condition of the start and end points defining a line which also contains the center point. (i.e. xstart+2*I=xend, zstart+2*J=yend, zstart+2*k=zend) Regards, sven - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
Hi Matt, I, J and K are not modal as far as I can tell. I get bitten by this one every-once-in-awhile. Dave On Nov 27, 2007, at 10:58 AM, Matthew Glenn Shaver wrote: The interpreter manual says that, in a center format arc move (G2 or G3), only one offset word (I, J, or K, whichever are appropriate to the selected plane). Assuming for example that the XY plane is selected, and only I is specified in a center format arc move block, what Y axis offset value (J) will be used? The last declared J value? Zero? Basically, are I, J, and K modal? Perplexidly, Matt -- --- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
I wasn't quite wordy enough. A proper G3(2) XnnnYnnnInnnJnnn G3XnnnYnnn will get you a missing I,J,K error message D On Nov 27, 2007, at 11:27 AM, Dave Engvall wrote: Hi Matt, I, J and K are not modal as far as I can tell. I get bitten by this one every-once-in-awhile. Dave On Nov 27, 2007, at 10:58 AM, Matthew Glenn Shaver wrote: The interpreter manual says that, in a center format arc move (G2 or G3), only one offset word (I, J, or K, whichever are appropriate to the selected plane). Assuming for example that the XY plane is selected, and only I is specified in a center format arc move block, what Y axis offset value (J) will be used? The last declared J value? Zero? Basically, are I, J, and K modal? Perplexidly, Matt - - --- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- --- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
I believe you don't need the J. All you need are two points on the circle and a line known to contain the center. Take the two points and draw a line through them. Draw a perpendicular line through the midpoint. Where your I line intersects the perpendicular line is your radius center. Now that you mention it, I have have called out both I and J in my programs which I guess is erroneous. I suppose G2/3 uses the first option it sees and ignores the rest? On Tue, 2007-11-27 at 11:27 -0800, Dave Engvall wrote: Hi Matt, I, J and K are not modal as far as I can tell. I get bitten by this one every-once-in-awhile. Dave On Nov 27, 2007, at 10:58 AM, Matthew Glenn Shaver wrote: The interpreter manual says that, in a center format arc move (G2 or G3), only one offset word (I, J, or K, whichever are appropriate to the ... snip -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC lathe Bridgeport mill conversion pending Zubal lathe conversion pending) - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
I can see now that the documentation was unclear about this. I am revising it to add the sentence marked +: I and J are the offsets from the current location (in the X and Y directions, respectively) of the center of the circle. I and J are optional except that at least one of the two must be used. + If only one is specified, the value of the other is taken as 0. It is an error if: ... and similarly for the other planes. Does this clarify emc's behavior for you, or is it still not clear? Jeff - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
Yep! This is what I suspected, but I had to be sure... Thanks a lot for this help! Dave Engvall did some experiments as well and came to the same conclusion. Matt On Tue, 2007-11-27 at 15:40 -0600, Jeff Epler wrote: I can see now that the documentation was unclear about this. I am revising it to add the sentence marked +: I and J are the offsets from the current location (in the X and Y directions, respectively) of the center of the circle. I and J are optional except that at least one of the two must be used. + If only one is specified, the value of the other is taken as 0. It is an error if: ... and similarly for the other planes. Does this clarify emc's behavior for you, or is it still not clear? Jeff - This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse012070mrt/direct/01/ ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
On Tue, 2007-11-27 at 13:28 -0800, Kirk Wallace wrote: I believe you don't need the J. All you need are two points on the circle and a line known to contain the center. Take the two points and draw a line through them. Draw a perpendicular line through the midpoint. Where your I line intersects the perpendicular line is your radius center. Now that you mention it, I have have called out both I and J in my programs which I guess is erroneous. I suppose G2/3 uses the first option it sees and ignores the rest? No, it uses both if supplied, and then checks to make sure start_rad=end_rad and that rad!=0. If either of the two offsets (relevant to the currently selected plane) is not supplied, it is assumed to be zero. Your method on the other hand would (I think) always define a valid arc! Nice idea! I don't know how to put it into practice such that it would fit with the present scheme of doing things, but it's something to think about. Thanks, Matt - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
Hi all, On Nov 27, 2007, at 4:39 PM, Matthew Glenn Shaver wrote: On Tue, 2007-11-27 at 13:28 -0800, Kirk Wallace wrote: I believe you don't need the J. All you need are two points on the circle and a line known to contain the center. Take the two points and draw a line through them. Draw a perpendicular line through the midpoint. Where your I line intersects the perpendicular line is your radius center. Now that you mention it, I have have called out both I and J in my programs which I guess is erroneous. I suppose G2/3 uses the first option it sees and ignores the rest? No, it uses both if supplied, and then checks to make sure start_rad=end_rad and that rad!=0. If either of the two offsets (relevant to the currently selected plane) is not supplied, it is assumed to be zero. Your method on the other hand would (I think) always define a valid arc! As far as I can tell that is true. It may not be the arc you expected but you will get an arc. ;-) Nice idea! I don't know how to put it into practice such that it would fit with the present scheme of doing things, but it's something to think about. Dave Thanks, Matt -- --- SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] A simple question on I J
Matthew Glenn Shaver wrote: The interpreter manual says that, in a center format arc move (G2 or G3), only one offset word (I, J, or K, whichever are appropriate to the selected plane). Assuming for example that the XY plane is selected, and only I is specified in a center format arc move block, what Y axis offset value (J) will be used? The last declared J value? Zero? Basically, are I, J, and K modal? No, I J and K are incremental offsets to the arc center, and are not modal. That would be far more dangerous than having them default to zero if not specified. Some controls interpret them differently depending on whether you are in incremental or absolute coord mode, but the behavior in abs coord mode, which is what most people use most of the time is not modal. it is quite common to have one of the axes in the plane stay the same to the arc center (like when doing a 180 degree arc that comes back to the same X coord, then I would be zero, and the start, center and finish would all lie at the same X cord, and J would be equal to half the difference between the start X and the end X. On EMC, the I,J,K words are signed to indicate the direction from the start point to the arc center. I think the above quoted text should read Only one offset word is required. You definitely can have two. I think with the in-plane only arcs that EMC does, you can't have 3. Some controls allow arcs in arbitrary planes, and you can have an arc move with XYZ and IJK words! I can imagine all sorts of conditions where the plane of the arc is not uniquely defined. Jon - SF.Net email is sponsored by: The Future of Linux Business White Paper from Novell. From the desktop to the data center, Linux is going mainstream. Let it simplify your IT future. http://altfarm.mediaplex.com/ad/ck/8857-50307-18918-4 ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
