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funBart
Dec 18, 2013, 5:02:30 PM12/18/13
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But this is true only for the first layer, not the rest of the layers - right?
You can learn this by looking at the G-code. There is a relationship between Bed Roughness and Z-offset. It is best to run a set of test slices on a small, simple part and see exactly what is happening. Then you will understand far better than we could try to explain.
Hey, 1,200 posts!
PenskeGuy
- Hero Member
- Posts: 1246
- Any Day I Learn Something New Is A Good Day
I always set my Z-offset to half my layer height
As a hard, fast rule, that's way dangerous to recommend to other users. It is assuming that Z-level is set perfectly, which it is most often not. My 3DT an only get so accurate and I fine tune it in KS with Z-offset, because I have near infinite control over the gap setting. I do this by measuring the thickness of a skirt and micro-adjusting from there until I get a good thickness value.
altarke
- Newbie
- Posts: 8
I always set my Z-offset to half my layer height, i.e. for a 0.2mm layer I set Z-offset to -0.1mm
If I am printing with a raft I set Z-offest to -.15 because raft layers are always printed at 0.25mm, more than my 0.25mm nozzle can handle.
But this is true only for the first layer, not the rest of the layers - right?
Dirty Steve
- Full Member
- Posts: 191
I always set my Z-offset to half my layer height, i.e. for a 0.2mm layer I set Z-offset to -0.1mm
If I am printing with a raft I set Z-offest to -.15 because raft layers are always printed at 0.25mm, more than my 0.25mm nozzle can handle.
If I am printing with a raft I set Z-offest to -.15 because raft layers are always printed at 0.25mm, more than my 0.25mm nozzle can handle.
altarke
- Newbie
- Posts: 8
OK so just so I understand this as clearly as I can... when and if I have (at times) problems with first layer not sticking to plate I should enter -.05mm on the PRINTER/ Hardware tab under Z Offset so the head will "force" the first layer to stick to the build bed - BUT only for the first layer! Is this correct?
If it is then it may bring an end to lots of sleepless nights wondering why the prints go bad....
Altarke
If it is then it may bring an end to lots of sleepless nights wondering why the prints go bad....
Altarke
PenskeGuy
- Hero Member
- Posts: 1246
- Any Day I Learn Something New Is A Good Day
I see you point, but I saw this "bed roughness' more like: there are a lot of hills on the plater: so a positive value , or: there are a lot of potholes in the plater, so a negative value to define them.
"Hills" and "Potholes" are relative to an arbitrary datum. The relationship between them stays the same, only the start point of measurement is different. If the hardware Z-level is set to 0 when the nozzle contacts the highest point, all measurements from that point are lower, which is the only way it can be set--otherwise you drive the nozzle into the bed elsewhere. Use KS Z-offset to fine tune the actual gap adjustment, if any, as hardware Z-level (at least on this machine) is a coarse setting compared to what I can obtain with KS Z-offset.
So, Bed Roughness can only be a positive value. It makes the first layer taller and computes the additional extrusion volume needed to compensate for the additional cross section that it needs to fill.
What has always puzzled me is that it really doesn't work as you would think. In order to take care of that which are always "potholes" one must compensate for the added layer elevation by dropping the nozzle back, at least partially, to where it would be if Bed Roughness were at 0 by setting a negative Z-offset that is a percentage of the Bed Roughness value. I don't recommend completely offsetting Bed Roughness additional elevation with an equal negative setting in Z-offset. The bed is rough, so there will be areas that haven't been identified as being at or below the point used to set the hardware Z-level. If I do remove some of the additional elevation, it is only by 25%-50% of the Bed Roughness value in the negative. This makes an increased "squish" in the higher areas, leaves some tolerance for areas that are higher than unexpected, and fills the lower areas; creating a flat plane upon which the remainder of the print will build.
I like that there is the separation of controls with which to fine tune this but new users would be potentially confused by Bed Roughness not making the "vertical autocentering" computation on its own. Perhaps this functionality could be added into the Beginner Settings Level.
« Last Edit: November 28, 2013, 02:50:59 PM by PenskeGuy »
funbart
- Sr. Member
- Posts: 307
Flat is flat. There is no such thing as flatter than flat, which is what a negative number would be.
I see you point, but I saw this "bed roughness' more like: there are a lot of hills on the plater: so a positive value , or: there are a lot of potholes in the plater, so a negative value to define them. But I assume you are right; certainly easier to remember ;-)
Makerbot Replicator 1 dual
Minimalistic Mk8 replacement by Emmett
Sailfish Firmware
Kisslicer Pro 1.1.0 Alpha
Minimalistic Mk8 replacement by Emmett
Sailfish Firmware
Kisslicer Pro 1.1.0 Alpha
PenskeGuy
- Hero Member
- Posts: 1246
- Any Day I Learn Something New Is A Good Day
On the Printer // Hardware tab, set the bed roughness to 0.05 or 0.1mm or so, it results in a fatter extrusion for the first layer (I'm 90% sure it has to be a positive value to get more extrusion;-)).
Flat is flat. There is no such thing as flatter than flat, which is what a negative number would be.
(And / Or) On the Printer // Hardware tab, set the Z offset to -0.05 or -0.1mm resulting in pressing the first extrusion layer harder on the build plate. (Same: I'm 90% sure it has to be a negative value to get the plate a little closer to the nozzle, so more pressure).
Yes. Negative values in Z-offset bring the bed closer to the nozzle; positive results in more space between the two.
funbart
- Sr. Member
- Posts: 307
Hi, I don't know how you adjust the flow rate for the first layer, or by manually adjusting it in the Gcode?
Anyway, to help it stick I can think of the following (assuming you know already the temp to use in general for the HPB and extruder, very much dependent of the use of PLA or ABS).).
As far I know these settings are applying to either first layer, whether it's a raft or the object itself.
Anyway, to help it stick I can think of the following (assuming you know already the temp to use in general for the HPB and extruder, very much dependent of the use of PLA or ABS).).
As far I know these settings are applying to either first layer, whether it's a raft or the object itself.
- On the Printer // Speed tab, set the first layer speed low (I have 20mm/s)
- On the Printer // Hardware tab, set the bed roughness to 0.05 or 0.1mm or so, it results in a fatter extrusion for the first layer (I'm 90% sure it has to be a positive value to get more extrusion;-)).
- (And / Or) On the Printer // Hardware tab, set the Z offset to -0.05 or -0.1mm resulting in pressing the first extrusion layer harder on the build plate. (Same: I'm 90% sure it has to be a negative value to get the plate a little closer to the nozzle, so more pressure).
« Last Edit: November 27, 2013, 01:49:01 PM by funbart »
Makerbot Replicator 1 dual
Minimalistic Mk8 replacement by Emmett
Sailfish Firmware
Kisslicer Pro 1.1.0 Alpha
Minimalistic Mk8 replacement by Emmett
Sailfish Firmware
Kisslicer Pro 1.1.0 Alpha
magicmodel
- Newbie
- Posts: 7
- We build anything (within reason)
Hi Kiss fans,
I have been experiencing a lot of adhesion problems of late on the first layer (less grid)
But have been getting the dreaded curling even though my bed is flat and at a good temp.
Since discovered that adjusting the flow rate to 70-80 for the first layer seems to prevent this from happening.
Trouble is I have to stick around to change it back to 100 in Repetier.
Does anyone know of any setting within Kiss that allows you to include this operation in the gcode?
Many thanks,
Magicmodel
3DPrinting Never Sleeps
I have been experiencing a lot of adhesion problems of late on the first layer (less grid)
But have been getting the dreaded curling even though my bed is flat and at a good temp.
Since discovered that adjusting the flow rate to 70-80 for the first layer seems to prevent this from happening.
Trouble is I have to stick around to change it back to 100 in Repetier.
Does anyone know of any setting within Kiss that allows you to include this operation in the gcode?
Many thanks,
Magicmodel
3DPrinting Never Sleeps
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