npolanosky
Cast Iron
- Joined
- Apr 9, 2016
- Location
- USA, FL
I'm using a KIA SKT21LMS with a Fanuc 0i-TB and I'm trying to solve a couple of remaining issues. I'm not sure if they are postprocessor issues, machine parameter issues, or something else.
1. [EDIT: Using G12.1 polar interpolation, so everything is in IPM]
When interpolating a circle or helix close to X0 (milling out a shallow pocket on the face of a part, for example), the C axis has to turn really fast, and I get alarms like "excess error". If I turn feed rate override down while it's close to center, I can turn it back up later because the degrees/second required for a given feed reduce as you get further from center.
Is there a param I can use to limit the speed it tries to rotate at? I'd rather hit a hard upper limit than get an alarm every time.
I know I can program around this, but it would be better if I can just punch milling toolpaths out of CAM and not worry about it.
[Edit: It could be spindle belt slippage too, causing the encoder to get upset...maybe? I am pretty sure I fixed that and I don't hear the characteristic squeak.]
2. C coordinate direction. My CAM software wants to give C+ and C- values to indicate the direction the chuck should turn, but my lathe seems to only be expecting positive values. If I give it the + and - I get many extra rotations and if I were running a part it would end poorly. If I change all of the -C moves to +C it works fine.
Everything I read online though seems to indicate that the + and - values are the norm, so is there a parameter that someone could have changed at some point to determine how it handles this?
It also seems to behave a little different in radial milling vs face milling with regard to this.
Same thing, I can change my CAM post to match if I have to, but to me it does seem like a good idea to know exactly which way things are going to go and not just hope that the shortest path is the correct one. I dug in the fanuc param manual and searched but did not find anything.
3. Live tool holders- I have VDI40 live tools, and the previous owner must have used them a LOT. They're pretty wobbly. Like .01" of radial slop on each. I tightened up the preload on a radial holder a little to make it acceptable for some loose tolerance hole drilling, but 2/3 of them are no good for radial loads anymore.
Is there any black magic inside or should I be safe to take them apart, clean, replace bearings (with suitable high spec ones, though anything is an improvement right now), lube, and run? I'm tangentially familiar with the principles behind bearing types, grades, preload, spindle design, etc so if I take my time I think I can rebuild them.
It has just occurred to me that the above is assuming they are some sort of ball or roller bearing. If they're plain bearings, I guess I'd have to turn new ones and fit them to the shaft? That would be odd, but I'll have a look-see in a bit or wait for someone here to chime in and concur with or disprove my assumptions.
Thanks in advance! I might add more to this as I think of it tonight.
1. [EDIT: Using G12.1 polar interpolation, so everything is in IPM]
When interpolating a circle or helix close to X0 (milling out a shallow pocket on the face of a part, for example), the C axis has to turn really fast, and I get alarms like "excess error". If I turn feed rate override down while it's close to center, I can turn it back up later because the degrees/second required for a given feed reduce as you get further from center.
Is there a param I can use to limit the speed it tries to rotate at? I'd rather hit a hard upper limit than get an alarm every time.
I know I can program around this, but it would be better if I can just punch milling toolpaths out of CAM and not worry about it.
[Edit: It could be spindle belt slippage too, causing the encoder to get upset...maybe? I am pretty sure I fixed that and I don't hear the characteristic squeak.]
2. C coordinate direction. My CAM software wants to give C+ and C- values to indicate the direction the chuck should turn, but my lathe seems to only be expecting positive values. If I give it the + and - I get many extra rotations and if I were running a part it would end poorly. If I change all of the -C moves to +C it works fine.
Everything I read online though seems to indicate that the + and - values are the norm, so is there a parameter that someone could have changed at some point to determine how it handles this?
It also seems to behave a little different in radial milling vs face milling with regard to this.
Same thing, I can change my CAM post to match if I have to, but to me it does seem like a good idea to know exactly which way things are going to go and not just hope that the shortest path is the correct one. I dug in the fanuc param manual and searched but did not find anything.
3. Live tool holders- I have VDI40 live tools, and the previous owner must have used them a LOT. They're pretty wobbly. Like .01" of radial slop on each. I tightened up the preload on a radial holder a little to make it acceptable for some loose tolerance hole drilling, but 2/3 of them are no good for radial loads anymore.
Is there any black magic inside or should I be safe to take them apart, clean, replace bearings (with suitable high spec ones, though anything is an improvement right now), lube, and run? I'm tangentially familiar with the principles behind bearing types, grades, preload, spindle design, etc so if I take my time I think I can rebuild them.
It has just occurred to me that the above is assuming they are some sort of ball or roller bearing. If they're plain bearings, I guess I'd have to turn new ones and fit them to the shaft? That would be odd, but I'll have a look-see in a bit or wait for someone here to chime in and concur with or disprove my assumptions.
Thanks in advance! I might add more to this as I think of it tonight.
