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Author Topic: No reverse run in G41/42  (Read 3492 times)

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Offline Whacko

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No reverse run in G41/42
« on: July 03, 2007, 04:04:04 PM »
Actually this question is more for Art I think. Why is no reverse run in G41/42 allowed? In a plasma system or Oxyfuel system, you would use the reverse run after you lost the cut. That means that the operator would use the "Reverse run" button almost always in a kerf compensated path, i.e. between the G41/42 blocks of GCode. I havent tried to enter a kerf off in the MDI page, I will try it. But I'm still curious as to why the ability to run in reverse between G41/42 is not possible. With CNC controllers like the ESAB, Messer Griesheim, Burny, Wescan Lynx etc. it is possible to run reverse in the G41/42 blocks to the point where the cut was lost, and restart the cut.

It is also possible that I am overlooking something, I seem to have a strong tendency to that!

Best regards,
William
Nothing's impossible
Re: No reverse run in G41/42
« Reply #1 on: July 05, 2007, 12:26:00 PM »
The problem is that when the system is in a feed hold and in comp The movment data is lost and a revers run is not avalable... It could be fixed but would require about 3 weeks of work and we would run the risk off killing the comp code! This is a limitation that will not be fixed in Mach3 but we hope to have it working in Quantum as we know MUCH more about how to setup the data structures in the program :)


Thanks and sorry for the bad news :(
thanks
Brian
Fixing problems one post at a time ;)

www.newfangledsolutions.com
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Offline Whacko

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Re: No reverse run in G41/42
« Reply #2 on: July 05, 2007, 02:11:49 PM »
Thank you for the reply Brian,

I can make provision for the g41/42 codes in the software, i.e. Profile Lab from Cadlink. I am a distributor for them in South Africa. You can choose to have the compensation taken care of in toolpath with no G41/42 code. I have noticed that reverse run is not possible even if you issue a G40 command after you encountered the first G41 or G42 code in the program. I can also implement a step position buffer with my dsPIC controller and overide mach3 and implement a reverse run. Question though, I havent tried it but will Mach3 allow the changes to the xy dro's whilst in a g41/42 block?.  I have gone quite far with my development and I'm tailoring mach3 with my own controller to keep a standard common in the flame cutting and plasma cutting applications. I have built many machines, and I am a Hypertherm OEM bussiness partner in South Africa. Thus I have extensive knowledge on plasma interfacing as well as flame cutting. I have about 25 years experience in this field, and if you need any information when you are doing developments, feel free to contact me. I used Burny and Wescan ltd. controllers in the past, and now the time is drawing near where I'll be drawing the final curtain on them. Burny for instance has a PCbased controller called the Burny phantom at one heck of a price. I can now do everything the burny can except the G41/42 which I will address as I mentioned earlier. They have inherent problems, one being the hardrives don't last long as they are kept spinning for quick access from the kernel, as the system has limited ram, why I don't know, and at the price they're going a few bucks for more ram would increase the life of the hard disk.

I am a systems programmer and done mostly firmware in native code. So the swing to high level programming is a bit painfull, but it is easier than I thought. I'm getting there!

Best regards,
William
Nothing's impossible