Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: brianjones00 on February 08, 2021, 11:11:27 PM
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Hello. I am brand new to cnc and mach3. I am trying to cut out my first project that I made in Fusion360. Unfortunately my machine keeps showing the piece in the display mode in the wrong place. A bit of background- when I turn my machine on I hit "ref all home" which brings my z all the way up, and my table all the way to the front of the machine (moving in the neg to get there), and the table all the way to the left (moving in the neg to get there). I have home switches set up to do this. After that, I set my work zero's and than load the g-code. In the attached picture of the display- my spindle is actually sitting directly over the the middle of my work piece- which is not what the display is showing. After several hours of messing with it, I did hit run even though it said I was out of the soft limits on the y. That was a mistake- the table took off moving to the right and away from me (y in the +). Just being too impatient. Luckily I was able to stop it before it crashed.
I did make a Turners cube just using the "circular pocket" wizard and had no problems. After I set my work zeroes, and put the spindle over the center it showed exactly that on the display and cut the g-code flawlessly.
I have been trying to figure this out for the last couple of days and have read so many different posts and watched so many videos that I am more confused than when I started. I also attached the beginning of the g-code that is showing on mach3 when I load it. Not sure it matters but i am trying to cut 1.5 by 3" blade out of a 3 x 5" stock piece. I attached some pics of that as well. Any all help would be immensely helpful- thank you.
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Jog the machine so the pink cross hairs are more to the lower left then press x zero and y zero then press regen toolpath
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Graham, thank you for taking the time to respond to my question. It is greatly appreciated. If I simply move the pink crosshairs I don't understand how that corrects my actual spindle position relative to my work piece (my current problem being that the spindle position is not correct relative to my work piece). Wouldn't that just give me a different work home position, and one that isn't relative to my actual workpiece. I am trying hard to do as much research as possible and improve my understanding- so again thank you.
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The problem is the way you have drawn the part in 360, the XYZ is in the opposite direction to the datum on your machine.
Your cad datum is front left of part. Machines tend to be top right.
Most machine tools home with the table left front and up for the XYZ so you draw in your cad to the left of the X (Red arrow) front of the Y (Green arrow) and Z is top of work on a mill and in most cases bed of machine on a router.
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Ah . . . ok. That is starting to make sense. I need to move my datum to the top right corner of my drawing. Do I have the orientation on the x & y correct in the drawing below? Thanks!!
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Yes the drawing looks good, look up right hand rule for more details.
https://www.autodesk.com/products/fusion-360/blog/cnc-coordinate-system-made-easy/ (https://www.autodesk.com/products/fusion-360/blog/cnc-coordinate-system-made-easy/)
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Unfortunately I still couldn't get this to work. Now my workpiece is incorrectly displaying on the bottom left of my table. In the first picture the pink crosshair is an accurate representation of where my spindle is in reference to my table (in the middle of my x axis, and a little north of the middle of my y axis). However, as you can see in my second picture, the workpiece is directly under my spindle- which is not what the display is showing. I changed the datum in the CAM to the top right corner, and a zeroed my workpiece off the the top right corner as well. Any other suggestions? I would really appreciate your continued help. Thank you.
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Do you have homing switches on your machine?
Is the material in the CAD the same size as the material on the machine?
If the answers are yes then click home all.
Move the centre of the spindle over the back right corner of the material and click 'Zero X' then ' Zero Y'
Touch tool on top of material and click 'Zero Z'
Click Regen Toolpath
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After posting the above, I went back and messed around with my mill some more. I discovered that my table coordinates appear to be reversed. In the attached picture you can see that my display shows my spindle over the bottom right of my table, when in actuality you can see that the spindle is over the top left of my table. Thoughts? How do I fix this?
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If you press MDI and type in G01 G91 X1. F10. and press return the table should move to the left
Then type Y1. and enter and the table should move to the front.
If you are in MM then X25. F100 may be better
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Ok, I am in "reverse".
When I entered the "G01 G91 X1. F10." command my table moved the right, and when I entered "Y1" my table moved to the rear.
(my machine is set in inches)
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you can reverse the direction in homing and limits but you will have to reverse your softlimits too.
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I played with that a little bit last night. It is kind of confusing because the table moves in the opposite direction of the of the onscreen jog controller buttons and arrows on the keyboard (the z makes more sense).
My home switches are set up on the front (near) side of my y axis, and the right side of my x axis (so when reference all home my table moves all the way to the front, and the table all the way to the left). When i switched direction and tried to home my machine- it moved away from my switches. Thoughts? I read a bunch a posts about home offset under config, but I couldn't seem to get that to work either. Thank you.
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it is allways a bit confusing if you view your table.
movements are allways related from your millbit to the workpiece
so if your table moves to the left millbit related to the worpiece is moving to the right.
i try to explane from Keyboard arrow key's
key left -> X- -> table moves to the right -> millbit on workpiece moves to the left
key right -> X+ -> table moves to the left -> millbit on workpiece moves to the right
key down -> Y- -> table moves up -> millbit on workpiece moves down
key up -> Y+ -> table moves down -> millbit on workpiece moves up
for reference normaly is in your case:
for X table is far right (witch is workpiece related left) and
for Y table is far up (witch is workpiece related down)
after ref all your millbit has to be at the left lower Corner of the table
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TPS, thank you. Currently due to the positioning of my home switches, when I "ref all home" my spindle sits above the top right corner of my table. Is there a way I can switch this to the bottom left without having to change the physical location of my home switches on the mill?
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you can try to set Config -> Home and Softlimits -> Home Off.
for X and Y axis to a value that lower left of table is Zero and not negative:
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This image shows the normal home position for a milling machine.
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Thank you for the visual. I am absolutely in the reverse of that (I am in the bottom left corner instead of the top right as shown).
So it appears as though I have 2 issues going on:
1.) My machine is homed incorrectly (due to where I have my home switches placed on the mill)
2.) My x & y axis are not moving in the correct directions (ie. I put Y1 into the MDI and my table moves to the rear instead of to the front)
This is definitely enlightening; as well as melting my brain. I can switch my x & y motor direction, but that will not fix my homing problem. Suggestions? Thanks again to all, this can be very frustrating- and having help makes a huge difference!
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Move the switches or the trigger plates or both will be the best option.
The home position should be about 1" to 2" from the end of travel its not critical, you then set the work area with the soft limits plus and minis from the home position.
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to reverse axis you have the following possibilties:
Config -> Ports&Pins -> Motor Outputs -> Dir low active
Config -> Homing/Limits -> Home Neg.
with a combination of both you should be able to bring everything
moving as expected.