Machsupport Forum
Mach Discussion => General Mach Discussion => Topic started by: Metalclad on November 01, 2011, 11:16:37 PM
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I am a newbie but have managed to put together my first CNC mill. It is running on Mach 3 which I am very impressed with. I have managed to sort out most of the issues thanks to these forums.
I have everything technical working but not having any prior CNC experience I am somewhat confused on the relative motion of my table/ work.
I have viewed all the training videos (more than once) and if my spindle moved instead of my table I am sure that I wouldn't have any problem. In my case, the spindle is fixed and the cutter direction relative to the work is opposite that of the table direction.
Viewed from the front of the mill, when I issue a G0X1 command should the table or the cutting direction of the tool move to the right. same queston for the Y axis.
When I tried to cut the roadrunner sample which is inverted, the only way I could get it to cut was to reference my cutter at the top right. The image appeared upright viewed from the front of the mill.
I understand that the home should be at the bottom left but it this correct for a fixed spindle? I think the home position should be at the top right but this is the opposite of what I understood from the training video.
The key question is are my motors reversed when the table moves to the right for G0X1 and up for G0Y1?
I'm don't think that I have the direction of the motor drives reversed but the real problem is I am not sure where I should establish home position on the mill.
Your help would be appreciated.
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When standing in front of the machine, facing the machine, a positive X will move the tool to the right, or the table to the left. A positive Y move will move the tool away from you, or the table towards you. A positive Z move will move the tool up, or the table down. The home position can be wherever you choose to put it - at any corner, or even in the middle of the travels. It's completely arbitrary.
Regards,
Ray L.
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as far as homing is concerned try to get the "Y" axis to home towards you.
The "Z" axis to home so the tool is as far away from the table as possible.
The "x" at one end of it's travel.
A good guide of tool motion, is to hold your left hand out in front of you and point to the machine with your index finger, then put your thumb up and point your second finger to the right. This is the positive motion of the tool, with your thumb being "Z", your index finger is "Y", and the second finger is "X".
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Thank you very much for the confirmation of motor directions. It turns out that they are as you said they should be so I just have to work out the homing. Presently I do not have any homing switches. Most people say they are the way to go. My x and y axis go home when I hit go to zero in machine co-ordinates but my Z axis doesn't stop where I expect it to.
I'll add a homing switch on the Z axis on the weekend and see how it works.
Thanks again for all your help.
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Home switches are a convenience, not a requirement. I've never had them on any of my machines.
Regards,
Ray L.
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Ray, Just curious, do you ever RefAll?
Hood
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Ray, Just curious, do you ever RefAll?
Hood
Hood,
No, not really. Not sure what that would accomplish, with no reproducible machine zero reference position. I touch off to the part/vise/fixture. I will, someday, install homes/limits, but it just hasn't been a priority. I do have switches on the quill, mostly to protect from damage if it's over-driven, but nothing yet on the other three axes.
Regards,
Ray L.
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Only reason I was asking is sometimes things go crazy for you, TP also has/had that happening and I seem to recall him recently saying he doesnt use Home switches. Probably a wild shot but just wondering if Machine Coords are massive and maybe rolling over or something when things start going weird.
Hood
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Only reason I was asking is sometimes things go crazy for you, TP also has/had that happening and I seem to recall him recently saying he doesnt use Home switches. Probably a wild shot but just wondering if Machine Coords are massive and maybe rolling over or something when things start going weird.
Hood
Hood,
No, my problem is a confirmed bug in Mach3 with the SmoothStepper. For reasons we still don't understand they sometimes "sync" when they shouldn't, which means Mach3 updates its position counters with the values it receives from the SmoothStepper. Unfortunately, these are somehow wrong, and result in the machine zero spontaneously changing mid-program, which should never, never EVER happen. It's a completely random (though, sadly, not all that rare - happened three times in as many minutes yesterday) occurrence. Brian, Greg and I have been trying to nail it down for almost two months now, but no joy.... It's become such a problem for me, I'm in the process of switching over to a KFlop right now.
Regards,
Ray L.
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Heres hoping for your sake its not something in Machs plugin interface that is the issue then. Have never seen any issues myself and I use the SS on all my machines but maybe just dont do the one thing that triggers it.
Hood
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HIYA HOOD, Not the problem here as well. I monitor the Machine coords. I think it is something in the way we use the Macros and Offsets and Subs that triggers the perfect storm. (;-).
I don't think it is SS specific the resetting of offsets is part of the main problem EVEN with a LPT version.
I rareley see it with the plasma machine BUT it is a very simple 2d process(;-). All the other machines were converted over to the dark side and they NEVER act up, NEVER(;-)
(;-) TP
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Was worth a stab in the dark :)
It would be great to find out what the magic combo is.
Hood
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I always keep a EYE out for the storm waters that may cause it. That is the reason for an ODD question sometimes when somone brings up a problem they see(;-).
(;-) TP
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Now just so there is no confusion I run the others on the darkside to prove the hardware is sound. It is a directect plugin and play for me to switch back and forth between them as both are running LPT version.
I believe it has something to do with the G92 problem running TC or Subs. Mach looses track of the Base Corrds in XY.
(;-)TP
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Heres hoping for your sake its not something in Machs plugin interface that is the issue then. Have never seen any issues myself and I use the SS on all my machines but maybe just dont do the one thing that triggers it.
Hood
Well, I think I made some progress today, in narrowing down the "trigger" - this issue has always reared its ugly head during peck drilling cycles. My peck drilling cycles do a rapid down, feed down, dwell, rapid up, repeat as needed. As the hole gets deeper, the RPM, feedrate, and peck depth are reduced. Today I took out the RPM changes and dwells, and successfully drilled over thirty 3" deep holes without a problem - first time I've ever been able to do that many holes in a row. Hopefully this will give Brian or Greg a clue....
Regards,
Ray L.
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Ray are you using a canned cycle or a macro or a sub?
(;-) TP
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Ray are you using a canned cycle or a macro or a sub?
(;-) TP
Terry,
D) None of the above. I have a G-code post-processor that re-writes the G-code with a whole lotta changes. The peck drill cycles are pure G-code, using nothing but G0s, G1s, G4s, and S-words.
Regards,
Ray L.