Can anyone tell me what Z home offset does Simplify3D assume exists from levelling the bed?
I'm using a PrintInZ Zebra print bed. They recommend setting a 0.2mm clearance between the nozzle and bed when levelling as the bed is damaged by contact with the hot nozzle. However, my prints never came close to sticking on the bed. By progressively adjusting my Z home offset, I gotten successful prints, but the nozzle was just touching the bed and left a mark.
From this it would appear that Simplfy3D assumes zero clearance between the nozzle and bed at the Z axis home position.
I have been able to work around this by setting a 0.2mm nozzle-bed clearance and a Global G-Code Z-Axis Offset of -0.2mm. The problem is that the G-Code previewer now shows the print as starting 1 or 2 layers below the print bed. Would I be better off setting the Origin Offset for the machine definition?
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CompoundCarl
- Posts: 2005
- Joined: Wed Aug 05, 2015 7:23 am
Re: Levelling Nozzle Clearance
It doesn't assume anything. It only does what you tell it 
First of all, the Z-homing offsets are defined in the firmware. It's the one that actually applies these offsets after homing. The software can also shift all of the gcode coordinates in your file to help print parts at slightly different elevations to quickly adjust for a poorly positioned bed. So it's pretty common to have tiny global gcode z-axis offsets to make these adjustments (which it sounds like you're already using).
And just to be clear, if you set the global z-axis offset to -0.2mm, the nozzle will start 0.2mm CLOSER to the bed, so make sure that's what you are actually hoping for!
First of all, the Z-homing offsets are defined in the firmware. It's the one that actually applies these offsets after homing. The software can also shift all of the gcode coordinates in your file to help print parts at slightly different elevations to quickly adjust for a poorly positioned bed. So it's pretty common to have tiny global gcode z-axis offsets to make these adjustments (which it sounds like you're already using).
And just to be clear, if you set the global z-axis offset to -0.2mm, the nozzle will start 0.2mm CLOSER to the bed, so make sure that's what you are actually hoping for!
Re: Levelling Nozzle Clearance
Ok, so when I run the Bed Levelling Wizard and the instructions say to adjust the bed so that a piece of paper just slips under the nozzle, Simplify3D must be making an assumption somewhere about the thickness of the piece of paper (typically about 0.1mm).
The firmware Z-homing offset sets the zero position relative to the end stop - I am using this offset to account for the additional thickness of the Zebra plate (4.2mm). When I level my plate using the firmware, this is the offset that it uses. Normally, prints do not use the firmware offset unless you explicitly request it using the M132 command (Sailfish).
The firmware Z-homing offset sets the zero position relative to the end stop - I am using this offset to account for the additional thickness of the Zebra plate (4.2mm). When I level my plate using the firmware, this is the offset that it uses. Normally, prints do not use the firmware offset unless you explicitly request it using the M132 command (Sailfish).
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CompoundCarl
- Posts: 2005
- Joined: Wed Aug 05, 2015 7:23 am
Re: Levelling Nozzle Clearance
The offsets I'm talking about are the homing offsets which are always applied after a homing command. Perhaps that's different than the "firmware offsets" you are talking about. Either way, I just wanted to make sure you knew there were other firmware offsets that may influence things.
On the Simplify3D side, the bed leveling wizard doesn't assume the thickness of the paper or whatever you use for leveling. It uses the value that you enter. It's labeled as "Z-height for leveling moves". So if you enter 0.1mm for that, the nozzle will try to position itself exactly 0.1mm above the bed, and of course, if your paper is that thick, then it would perfectly be touching the paper on top of the bed.
On the Simplify3D side, the bed leveling wizard doesn't assume the thickness of the paper or whatever you use for leveling. It uses the value that you enter. It's labeled as "Z-height for leveling moves". So if you enter 0.1mm for that, the nozzle will try to position itself exactly 0.1mm above the bed, and of course, if your paper is that thick, then it would perfectly be touching the paper on top of the bed.
Re: Levelling Nozzle Clearance
OK, yes, I missed the tooltip that explained the Z height.
In the Sailfish firmware, there are Home Offsets which are applied when using the firmware levelling wizard. These offsets can be applied to a print by an M132 command at the start of the G-Code.
In S3D, there is the Origin Offset in the machine definition and the Global G-Code Offset. Just to be confusing, they work in opposite directions - positive Origin Offset = negative Global G-Code Offset. What actually happens is that Origin Offset moves the origin relative to the print bed, and Global G-Code Offset moves the object relative to the origin.
The other difficultly I will have to work around is that the firmware and S3D have different ideas about the Z level for each layer, which will have an affect when I use pause at z level via G-code/firmware and start/stop printing at height via S3D.
I'm getting a better understanding of the inter-relationships and might need to re-think my approach.
In the Sailfish firmware, there are Home Offsets which are applied when using the firmware levelling wizard. These offsets can be applied to a print by an M132 command at the start of the G-Code.
In S3D, there is the Origin Offset in the machine definition and the Global G-Code Offset. Just to be confusing, they work in opposite directions - positive Origin Offset = negative Global G-Code Offset. What actually happens is that Origin Offset moves the origin relative to the print bed, and Global G-Code Offset moves the object relative to the origin.
The other difficultly I will have to work around is that the firmware and S3D have different ideas about the Z level for each layer, which will have an affect when I use pause at z level via G-code/firmware and start/stop printing at height via S3D.
I'm getting a better understanding of the inter-relationships and might need to re-think my approach.
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CompoundCarl
- Posts: 2005
- Joined: Wed Aug 05, 2015 7:23 am
Re: Levelling Nozzle Clearance
The origin offset is used to position the XYZ origin (the location of X=0, Y=0, Z=0) relative to your build plate. You can see the little red/green/blue XYZ indicated in the 3D simplify3d view to see where it is currently located.
The global gcode offsets simply shift all coordinates in your gcode file by that amount.
The global gcode offsets simply shift all coordinates in your gcode file by that amount.
