Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: SirFinland on February 07, 2014, 08:18:21 AM
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Hi,
I have made a pocket size 60x40 mm and 2mm deep and it is cutting 0.5mm at a time.
But when it's done the right side off the pocket is not like it should be...
I'm using Cut2D
Look at the images....
Thanks!
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To me it looks like you are losing steps in the X axis (as the pic is posed). Is the deepest part of the pocket the correct width? It looks much worse in the upper picture. Did you change the feedrate? What changed in those 2 pockets?
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Looks to me like some kind of formula is active in X direction. Because it comes back to the same location on the left side.
Not much in common with the pockets if they are all supposed to be the same program. Something is real odd looking, that's for sure.
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Looks to me like some kind of formula is active in X direction. Because it comes back to the same location on the left side.
No, it doesn't. It keeps moving farther to the left with each pass, ans since they're deeper, each successive pass makes a full depth cut.
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guess it looked like it did to me, my bad.
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Hi,
I changed a bit on the feedrate an thats why it's different on the other picture, but how can i get it so that it cuts right the hole pocket?
Thanks!!
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Can someone help me...
Thanks
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It looks like your machine is losing steps. This can be caused by many things.
What kind of machine is this?
First thing you should do is go through the entire machine, and make sure everything is perfectly aligned, with no binding. If you still have issues at that point, then reduce your acceleration and velocity setting in motor tuning by 25%-50%.
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It is CNC3040
Thanks for the help I will see if i can do something I'm new with this ;)
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SF, Sure there are some things you can do.
Lube all ways, slides ball or lead screws too.
Then as Gerry said, lessen your velocity and or acceleration.
Find out the micro stepping that your controller is on and see if changing its value doesnt lessen the resonance. This will require some retuning so if you are very new, hold off a bit. Not that it is difficult.
Btw is this all of a sudden? Was there a change in its operation? Or are you new to the machine and experienced these problems right away?Just out of curiousity, what kind of speeds/accels were you running?
Either accel or velocity can cause lost steps depending on their values, so it could be the velocity was fine but the instant accel for its mass caused loss of steps or vice versa.
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It works Okay when I just engrave a word, but when I start to engrave a pocket so its okay on the left side off the pocket but not on the right side.
Settings for my CNC3040T-DJ
35000 MHz
Steps Veloci Acceler Step Pulse DirPuls
X: 400 2000 200 3 1
Y: 400 2000 200 3 1
Z: 400 700 100 3 1
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Is the left side of the pocket at the correct X position or is it further to the left than it is meant to be?
That will be the deciding factor as to your problem, ie if its further left then it is as Gerry and others have said, you are losing steps on X.
Hood
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Its a bit more to the left
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Then it is confirmed you are losing steps or in effect losing them.
You need to check everything that has been mentioned such as any binding on axes and also things like pulleys slack or coupling slack. The slack pulley could account for it as with engraving forces are light, with pocketing forces are higher so pulley slips a bit each time.
Hood
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Okay...
I'm new with this... Can you help me step by step?
It would be great!!!
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I do not know how your X axis is coupled, if it is direct coupled then draw a line with a pen on the motor shaft and screw shaft and the couplings and run a pocket. If after the pocket is complete all the lines still lined up then couplings are not slipping. If you have a belt reduction system do similar.
If the couplings are not slipping then reduce your Velocity and Accel by 50% and test again, see if it runs this time.
Hood
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You also said 35,000 MHz above, what is that referring to? If the kernel then I presume you mean 35,000Hz.
Your motor tuning only requires 13,000Hz so I would suggest you reduce the kernel to 25,000Hz (25KHz)
Hood
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Hi,
I have one off this and two other, because one was broke. Should they all be same?
Can this have something to do with the X axis?
Thanks!
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It doesnt matter whether they are the same or not, what you have to be concerned about is whether it is secured correctly or not. If it is slipping then it would cause the issues you are seeing, so mark a line on either side of the coupling aligning with a mark on the screw and motor shaft at each side and run your pocket again. If the lines still match and the pocket is still out of alignment then you need to look elsewhere for your issue.
Hood
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I am having problems with pockets as well.drew a design in vecrtic aspir was supposed to cut a circle to 51 mm and 4.5 mm deep depth came out fine but circle is only 46 mm dia and should be 51.I have calibrated all the axis and they cut to the right length and z axis raises and lowers to the right heights don't know whats wrong does anyone have any ideas
Regards \Kevin
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attach your code and your xml and maybe the problem can be found.
Hood
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I am having problems with pockets as well.drew a design in vecrtic aspir was supposed to cut a circle to 51 mm and 4.5 mm deep depth came out fine but circle is only 46 mm dia and should be 51.I have calibrated all the axis and they cut to the right length and z axis raises and lowers to the right heights don't know whats wrong does anyone have any ideas
Regards \Kevin
Is your tool diameter correct?
Not being familiar with your CAD/CAM, is your offset correct for the direction of travel? I know in BobCad I usually have 3 choices, to the right, left or on the line. Those would all make a difference in the widths only and not the depth.
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yeah as far i i know it is correct i have three choices
1. outside the line
2 on the line
3 inside the line
mine is set to inside the line
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Try cutting in the opposite direction and see if the size changes. It could very well be machine or tool deflection.
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will give it a try thnx