Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: xray_man on October 31, 2006, 11:33:00 AM
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Hi Guys -- I am just finishing up converting a New Hermes engraver to CNC with the MACH3 controller. I have all my limits and home switches adjusted and working properly but I am having a problem with homing the Z axis (engraver tool bit). I would like to be able to make the Z axis move to a specific position away from the Z Home switch, rather than to have it stop immediately upon actuation of the Home switch. Is that possible in MACH3? Also, could the SEQUENCE of Axes be changed? In other words can I make the system Home first the Z, then the X, then the Y?
Thanks!
Mike
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Hi Mike,
I think you can change the z home by going to Home Off and entering a value. The homeing sequence can also be changed. Let me play with it a minute. In the new version, there is also a safe z set up in config. This may do what you want.
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I think to change the sequence you will have to do this in screen 4. You can change it with VB script ( I know nothing of this ) or have the button perform Gcode moves.
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In the new version, there is also a safe z set up in config.
I tried this, I set the safe z set up as global, allow z moves, work cord., value .250.
It moved the z to .250, moved the x & y to 0, then the z to 0.
This is a nice feature.
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Thanks for your reply!.
In my version of MACH3 (R1.84.001) there is a check box in "Config, Logic" tab, labeled "Use Safe_Z" but I do not see any way to enter specific parameters that define Safe_Z. I also can not find the screen that you show in your post. It must be in a different version of MACH3. Also, it seems that the "Home Off" settings in the Home/Limits tab only affect the DRO value during Homing, but does not change the actual position of the axes. For example, if I put the value 5.00 for the X Home Offset, the axis will stop on the Home switch as usual, but the DRO will indicate a position of +5.00.
I think the Safe_Z function will do what I need but I may have to switch to a different version of the program. Any further assistence would be greatly appreciated.
Thanks again!
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I dont think you can have the Z move off home for a set distance, the way the home works is the axis moves until the switch is hit then it backs off slowly until it comes off the switch, that is your home position. You could use seperate home switch and place it where you want your home to be if it is what you are wanting.
For the homing sequence it should move Z First then Y then X, is this not happening with you or am I misunderstnding.
Hood
EDIT
just noticed the homing and limits page that Brett posted, I have never noticed the "HomeOff" column before so possibly that is what it is for. Unfortunatel I cant test it as I am not at the mill, just have Mach on the home computer and its not easy to actually see what that function does without having physical limits set.
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Yes Hood, that is exactly what happens, at least on mine. I think X-ray's too. The x&y first then the z.
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Brett are you saying your X and Y move together then the Z when homing?
Hood
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Yes.
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Can you go to the operator menu then down to Edit button script, your home button should now flash, click on it and what does the VB say?
Hood
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Actually, my homing sequence is correct. First the Z moves, which makes good sense because you don't want the Z axis to crash into any tooling or work pieces that happen to be in the way when the X/Y begin to move toward Home.
As for the Safe_Z function, I figured out how to enable it and set the offset, but the function works only for "Go To Zero". It does not work for Home. So, I think I'm simply going to reconfigure my Z Home switch to a higher position that would clear anything on the table. That should resolve my problem and it's probably the BEST solution.
Thanks again for everyone's input!
BTW - The MACH3 is an incredible piece of software. I've used very expensive GE/Fanuc CNC controllers over the years and I must say that MACH can do just about everything the Fanuc controller can do at a tiny fraction of the cost. I am totally blown away by its capabilities! I'm a very happy and satisfied customer. ;D
Mike
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Mike
the best thing is Mach is evolving all the time and Art and Brian are on the ball when it comes to ironing out the slight glitches :)
Hood
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Thanks Hood! Yes, I will continue to keep tabs on the updates. I can only imagine how many great new features we will see in the coming years!
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I second Mikes emotions about Mach. It is the bomb.
Hood, mine does move the x&y first, then the z when I hit go to Z. I have z homeing disabled in ports and pins so not sure about the ref. all home button. The Goto Z button is a function = go to Zeros. The VB script edit form operator tab will not open it. Not to concerned as I'm going to load the latest release and a KILLER screen one of my friends made. He is good. I would like to know why though.
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Brett
Is there a reason why you have the Z Homeing disabled? No limits on Z yet?
The Go to Z button does not have VB in it, its just a button with G Code function enabled. The button I was meaning when I said Home button was the reference button.
Hood
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I have Z limits installed. The reason I don't have the Z home enabled is because my knee is so slow. 8 IPM. I will hardley ever move the Z more than 2.00" in a run.
The Goto Z button is a function = go to Zeros.
Well, it is on mine anyway. I tried to put Gcode in and it didn't like it. Was probably my code. Cam package has made me dumb. ;D Do you have a string of code I could try?
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In screen 4 you just click on the Go To Z button and in the G Code box it should have the code, you also have to make sure you have the G Code box checked I think. The code for it is simple even for a dummy like me, its G0 X0 Y0 Z0
Ah yes forgot it was the knee you had as the Z.
Hood
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Yes, I could get it to do that, but when it does they all three move together. When I make the z the first line, the x&y the second I get an error message. And yes, that is screen 3. LOL The alarm says " The code must not be more than one line or end with an <Enter>."
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What is meant to happen is the Z moves to its safe position, the X and Y move to zero then the Z moves to zero. Your problem is likely to be because you dont have your Z Home enabled and therefore dont have the safe Z set up. Might be worth setting up an adjustable home switch for your knee so that you can reference without having to move the whole knee travel.
Hood
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I think it would work fine if I knew how to get more than one line of code to take. I edited my last post.
The alarm says " The code must not be more than one line or end with an <Enter>."
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I dont think you can have more than a single line of code in a button :(
What might work is to make up two buttons on your screen, one with a G0 X0 Y0 and the other G0 Z0, You could then make the Go To Z button a VB button and add code for it to call your buttons in the order you want. I think that should be possible but maybe not, will have to try it out at some point but its getting late and my brains functioning at less than 10% capacity, and 10% of very little is almost zero ;) so it wont be tonight.
Hood
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I understand that. Good night Hood.
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mmmm in the light of day maybe my suggestion wont work, will have to think about it later on.
Hood
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I got it Hood,
I downloaded the latest version of Mach. Used my old screen set. Also downloaded screen 4 to mill PC and used it to change GOTO Z button. I had set it up as Gcode yesterday. Changed it back to function, Go to zeros. Went to config., did the safe Z setup. All is well in the universe. :)
Brett
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:)