Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: jcrouch on October 01, 2010, 12:52:40 AM
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I have a fine line automation CNC Machine That I built I have set it up two times. The first times when I measured with a steel rule and used the Settings/set steps per unit I got it close and was able to air carve the road runner.
I then made a dust hood with cut2d and that worked. I then tried my hand with the tutorials for cut2d and made a sign. simple one with year 1982 and that was also close.
I saw the tutorials on zeroing with a PC board and clip and got that to work.
I then worked on tweaking the rollers and taking up some slop I worked with the dial indicator and was able to get real accurate, it surprised me how accurate this thing is.
Then I loaded in the same file from cut2d and everything went to the dumper. When I moved the z axis with the MDI .125. The others where also off. If I restart the mach3 program it was back to where it should be.
Am I saving the g-code with the correct Post Processor?
Mach2/3 Arcs(*.txt)
I did read something about that but I an using (I think) everything the same as before.
Anyone have a clue?
JR
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Could it have something to do with metric and imperial as 0.125 x 25.4 is close to the movement you are seeing.
Hood
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Hood,
I don't know just getting started. I looked at the .pp file and it looks like it can be changed. I removed the (Mach2/3postprocessor) line by putting a + at the start of the line. and I noted N20G00G20G17G20G90G40G49G80 and the next line is N30G70. so
G00 = Rapid positioning
G20 = inches
G17 = XY plane
G20 = inches again
G90 = Absolute distance mode
G40 = Cancel cutting radius compensation
G49 = Cancel tool length offset
G80 = Cancel motion mode
and then on the next line
G70 = inches again
Don't know why all the inches that's all in the header of the post processor file but until I know more I'm not going to remove anything. I did put that other line back in but I don't think it does anything. I guess cute2d want to make sure it's in inches. The pp files are in cute2d but I just don't know enough yet hopping someone has had this happen and can tell us how to fix it. Not even sure if it's cure2d problem or mach3.
JR
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Do the DROs show the 3.3125 or is it just the axis that moves that and the DROs read 0.125?
Hood
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Hood,
The dro doesn't sow it it is just the movement. the dro says .125 but movement is around 3 3/8 inch.
JR
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mmmmmmm thats going to be a hard one to test in simulation as I will have no idea of the distance the axis would move :(
If you want attach your xml and code and I will see if I can find an issue.
Hood
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Hood,
I am using a gecko controller so the 540b.xml
the other two files are files that worked. The roadrunner still does.
I did load the mach3 program and found that it is always (in regard to movement) correct. oops!
I just went to look at something on the machine and when I loaded mach3 got a blank screen.
I have no idea what to do but uninstall and reload. With all that is going on it may be the best thing.
I will weight a while to see what you think
Jim
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Hood
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Hood
last two
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Do you still see the menu bars in Mach? if so go to View and Load Screen and then in the Mach3 folder choose the screenset you have been using.
Will look through your files in a bit.
Hood
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The xml you attached is set as metric units by default, is that correct?
Hood
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In other words, what I am asking is when you first start Mach and if you zero the X DRO and command a G0X1 from MDI does it move 1mm or 1 inch?
Hood
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hood,
I do see menu. I'll go and try that.
And thanks for the help.
JR
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It needs to be inches
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Ok you are set as default units metric and what I suspect is happening is you have set up your steps per unit to move 1 inch when you command a 1 inch move when in fact 1 unit should only move 1mm.
What are your screws pitch and also is there any gearing between motor and screws?
Hood
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Hood
will this tell you anything?
ACME 1/2-10 Single Start Anti-Backlash Nut or
ACME 1/2-10 5 Start Anti-Backlash Nut Don't know which one. How can I tell or does it mater?
JR
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Motors are direct connect. Shaft to shaft.
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Ok as you are already getting 1 inch movement when you command a 1 unit move then really all you need to do is go to config menu and then Default units. Change that to Inch and you should be fine.
The problem you have been getting is you have it set to metric but you have entered the amount of steps per unit to equal a 1 inch move. So when you command a move of 1unit you get 1 inch like you expect. Problem is Mach is thinking its only 1mm so you load the roadrunner and it seems fine but when you load your code it is 25.4 times bigger, the reason is your code has G20 in it telling Mach its inch and for a move of 1 it needs to move 25.4 times the normal unit. The reason the Roadrunner is fine is because there is no G20 in it :)
I suspect your screw is 5 start 1/2 -10 which would mean 2 turns of the motor would move 1 inch so 200 steps x 10 microsteps x 2 turns = 4000 steps per unit.
You have it close to that if I recall but really the number should be 4000 if the screws are accurate.
Hood
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Its actually named Select Native Units and not Default Units like I said.
Hood
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X = 4059
Y = 4118
Z = 4050
I'll check that once I have set to inches.
I was sure that I set it to inches at the start.
What is the best way to set it? Somewhere I read that you have to setup everything if you change it.
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Normally you would need to reset your steps per unit but because you are already getting a 1 inch move when you command a 1 unit move then you will be fine. As said your problem is because Mach thinks the steps per unit you have set are moving it 1mm but its actually moving 1 inch.
So just go to config the Select Native Units change t0 Inch and you will be close.
Suspect really you should have 4000 for each but you can try with your settings first then try at 4000 if they are out a bit.
Hood
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Hood,
That's it. It is now working. I'll get back to it on Monday. The week end goes to the wife she gives me most of the week. Retirement is good if you don't mind the looks I get from her. so, Monday
Now how can I thank you. if I ever get to Scotland I'll buy you a beer or two at the local establishment. and if you get to Rochester, Mi I'll take to the local pub.
Thanks Again
Jim
PS if you have time another day I have questions, man I have questions. 1024.set is the one I used BTW
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The default units in Mach3 is mm. If you don't change it, and set up the machine assuming inches, then MDI and jogging will move the correct amount, but if you run G-code with a G20 in it, it'll move 25.4x too far.