Height Map - Substantial z-offset after setting z-offset
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@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
I lowered it another 0.89mm to get it touching the wrench and set that in my
G31for my Z offset.Got you.
The Duet docs use the term "Z Trigger Height" thus my lack of understanding of the term "offset".
But it sounds like you have found the correct value for use in G31.
Using a 4 point test can give misleading results.
Are you using the center of the bed for your XY reference point when doing your G30?
Frederick
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@fcwilt said in Height Map - Substantial z-offset after setting z-offset:
Are you using the center of the bed for your XY reference point when doing your G30?
Frederick
In my zhome_config.g file, I am just using G30 after I centre the bed, so I believe that I am and when I kick off a G29, it does start at the centre fist.
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@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
@fcwilt said in Height Map - Substantial z-offset after setting z-offset:
Are you using the center of the bed for your XY reference point when doing your G30?
Frederick
In my zhome_config.g file, I am just using G30 after I centre the bed, so I believe that I am and when I kick off a G29, it does start at the centre fist.
OK here is how a 4 point grid can be misleading.
Imaging the bed rises or falls from the center to the edges in both X and Y.
When you set the Z=0 Datum in the center of the bed but don't probe near the center of the bed but just the near the edges you can get a picture like yours because all of the probed points are above/below the Z=0 Datum.
Try a 9 point grid which will include a probed point near the center of the bed and I think you will see what I mean.
Frederick
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@fcwilt Yeah, I was stating to think my probe points are probably too far in the corners which is why I get the big low hanging gaps.
I upped the points to 3 and started to a similar result:
And then went to 5 points and started seeing the old mesh I used to have, which is slanted on one side:
I read another post from a frustated BLT user who said he needed to manually move one of his z-rods to get it set right and I've just dont that and am seeing the slant start to get better...
But I also think that I may want to control my two z motors seperately to get better levelling as right now they only seen as one motor in the config and that may help my slant become more even.
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So just read up and I can't do MBL on my 4 bed screws AND my 2 Z rod screws, so I won't be able to help adjust the slant I've been seeing
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@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
So just read up and I can't do MBL on my 4 bed screws AND my 2 Z rod screws, so I won't be able to help adjust the slant I've been seeing
If you configure things so ABL can be used with your two steppers you can cannot use the MBL assistant.
But you can use G29 to help you adjust the 4 bed screws - thought it takes a bit of practice.
What you do is create 4 point height maps and based on what you see when you view the height map (or read out from the points of the height map) you adjust 3 of the 4 screws, more of less by trial-and-error, until you are happy with the results.
I've done this in the past and it works pretty well.
Frederick
Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6
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@infidelprops
Though your bed looks pretty level already.
I put off trying out ABL because it meant a good deal of work modifying my printer but I finally did it.
It's really nice to let the firmware do the work.
Did I post the link to my quick-and-dirty video of it working?
Frederick
Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6
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@fcwilt Yeah - I've got G32 mapped to my bed screws and I adjust accordingly... and then I run a G29 to get the mesh once I level the 4 points...
I've seen that sometimes this can have the opposite effect and I end up running a smaller G29 probe point, adjust the screws and once happy, run the 20 point probe.
Mesh has gotten much better throughout the day, huge thank you for all the help mate.
Of topic question... if I wanted to purchase a new bed plate which is more level, where would I go about looking for one?
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@fcwilt said in Height Map - Substantial z-offset after setting z-offset:
@infidelprops
Though your bed looks pretty level already.
I put off trying out ABL because it meant a good deal of work modifying my printer but I finally did it.
It's really nice to let the firmware do the work.
Did I post the link to my quick-and-dirty video of it working?
Frederick
No, and would love to watch it!
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And this is my mesh now... I'd still like to get it better, but don't know what else to do
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@infidelprops said in [Height Map - Substantial z-offset after setting z-offset]>
No, and would love to watch it!
You will notice that when making this conversion I decided to also try using belts instead of lead screws for the Z axis.
I like it so much any future printers are going to use belts.
Here is the video:
Printers: a E3D MS/TC setup and a RatRig Hybrid. Using Duet 3 hardware running 3.4.6
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@fcwilt Thanks, I'll watch it shortly!
I just tried a bed level print and some really weird behaviour....
On the 3/4 of the bed, the files skirt starts to print, but on the back left and left side, it doesn't print at all.. and comparing it to my mesh, those sides are low, not high, which would be causing it to not extrude since it's to close to the print bed.
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@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
And this is my mesh now... I'd still like to get it better, but don't know what else to do
That's really pretty good.
I would guess that it might just be an accurate reflection of your bed.
Cast aluminum tool plate is the material of choice but even that can require the skills of a machinist.
One site for tool plate lists the material as being flat within 0.015" but that works out to appx 0.4 mm - which isn't that great - given print heights of 0.1 and up.
I've fitted 3 of my 4 printers with tool plate. Two of the pieces were better than spec and I'm quite pleased.
The last one is within spec but not what I hoped for.
There are some places that will mill/grind a plate flatter than 0.4mm.
Here is one that has reached out to me in the past.
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@fcwilt said in Height Map - Substantial z-offset after setting z-offset:
@infidelprops said in [Height Map - Substantial z-offset after setting z-offset]>
No, and would love to watch it!
You will notice that when making this conversion I decided to also try using belts instead of lead screws for the Z axis.
I like it so much any future printers are going to use belts.
Here is the video:
Wow... your bed tilts on 3 axis?? That's mad and awesome at the same time
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@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
On the 3/4 of the bed, the files skirt starts to print, but on the back left and left side, it doesn't print at all.. and comparing it to my mesh, those sides are low, not high, which would be causing it to not extrude since it's to close to the print bed.
Yeah - I see that myself - and it has led some folks to suggest that there is a "bug" in the firmware.
Now I've verified that the firmware is turning the Z steppers as the XY position changes but I have not taken the time to verify that at each grid point the Z adjustment is correct.
It's on my list to do - someday - when I have something called "free time" - which I have heard of but have yet to see.
Frederick
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@fcwilt said in Height Map - Substantial z-offset after setting z-offset:
@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
On the 3/4 of the bed, the files skirt starts to print, but on the back left and left side, it doesn't print at all.. and comparing it to my mesh, those sides are low, not high, which would be causing it to not extrude since it's to close to the print bed.
Yeah - I see that myself - and it has led some folks to suggest that there is a "bug" in the firmware.
Is that just on skirts, or with prints as well? Going to try a smaller size and see how it goes
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@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
Yeah - I see that myself - and it has led some folks to suggest that there is a "bug" in the firmware.
Is that just on skirts, or with prints as well? Going to try a smaller size and see how it goes
Prints as well but since most of my printing only uses about half the bed I get the printing done that I need to get done.
Someday I'm going try to determine why the whole bed is still a problem.
Frederick
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@fcwilt Interesting... I used to be able to print around the whole bed.
I just made it 25% smaller and same problem.. even noticed first layer issues... front side was good, right side was a bit high, back side was waay to high, left side didn't print. -
@infidelprops said in Height Map - Substantial z-offset after setting z-offset:
@fcwilt Interesting... I used to be able to print around the whole bed.
I just made it 25% smaller and same problem.. even noticed first layer issues... front side was good, right side was a bit high, back side was waay to high, left side didn't print.Have you tried it without enabling mesh bed compensation?
Frederick
