1 Topic by msummers (edited by msummers 2013-08-06 04:15:33)

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Topic: Z-offset tab doesn't actually offset the Z axis during print

Hello community, I'm hoping you can help me figure out how to get my Solidoodle 3 up and running.

I have spent many hours trying to calibrate the SD3 and I just haven't had any luck. It will consistently fail to stick to the platter, particularly for the first few seconds of the print. I followed all the guides I could find, cleaned my platter with acetone and alcohol, and spent hours messing around with the Z-offset tab. I can watch the extruder laying down the ABS, and I can visually see that the ABS is not pressing up against the platter. So I'm pretty sure its a Z-offset problem.

I must not understand how that Z-offset tab works. It seems to have no effect whatsoever during a print. It does affect where the "home" position is, as when I hit the Z axis home with the tab at the extremes, the extruder can be way above the platter, or even below it. However during print it seems to get no closer than what I would eyeball estimate to be a third of a mm. I can use the offset tab to get it higher, but no closer.

What am I missing?

2 Reply by MolecularConcept

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Re: Z-offset tab doesn't actually offset the Z axis during print

the z offset tab is only going to effect it when it homes. its just a screw that hits the limit switch and tells it where to stop where home is.   after it starts printing turning the screw wont have any effect till it tries to home again.

you could make some thumbscrews and those changes will be immediate.

3 Reply by ronsii

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Re: Z-offset tab doesn't actually offset the Z axis during print

If you have it start a print and it is printing too high then move the ztab screw up (unscrew it) and the next print WILL be that much(how much you moved the screw) closer to the bed.

4 Reply by msummers (edited by msummers 2013-08-06 15:08:19)

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Re: Z-offset tab doesn't actually offset the Z axis during print

Thanks for the replies guys.

MolecularConcept wrote:

the z offset tab is only going to effect it when it homes. its just a screw that hits the limit switch and tells it where to stop where home is.   after it starts printing turning the screw wont have any effect till it tries to home again.

you could make some thumbscrews and those changes will be immediate.

That sounds like what I'm seeing, so hopefully that means I'm not crazy. It sounds like you are saying it resets the calibration of the extruder / print head every time it goes "home"? So I need to hit the "home" button after changing the z-offset screw, and then it will take effect? I thought I tried that, but after a few hours all the things I tried just kind of ran together. I will make sure to give it a shot.

To be clear: every time I change the z-offset screw I am just hitting the "kill" button to stop the print job, then hitting run job again. Should I be doing something else to make sure it changes the z-offset?

ronsii wrote:

If you have it start a print and it is printing too high then move the ztab screw up (unscrew it) and the next print WILL be that much(how much you moved the screw) closer to the bed.

Thats what I tried while following the videos on the Solidoodle website and elsewhere. I observed that raising the screw would not make the extruder get any closer to the platter, even taken to the extremes. I wonder if there is some setting I am missing, where it "goes home" before a print or something.

5 Reply by MolecularConcept

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Re: Z-offset tab doesn't actually offset the Z axis during print

it dosent reset the calibration of the extruder.... lol

all that screw does is, it actuates a LIMIT SWITCH and tells the machine to stop moving then it goes and does it again slowly  to more accurately  find the home position. nothing to do with the extruder.   Any changes made to that screw wont take effect till you try to find the home position again either by starting a new print or pressing the home buttons.

it is quite a nightmare trying to get the bed level and the right distance from the bed to the extruder nozzle. pretty much a constant game of cat and mouse.

6 Reply by msummers

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Re: Z-offset tab doesn't actually offset the Z axis during print

MolecularConcept wrote:

it dosent reset the calibration of the extruder.... lol

all that screw does is, it actuates a LIMIT SWITCH and tells the machine to stop moving then it goes and does it again slowly  to more accurately  find the home position. nothing to do with the extruder.   Any changes made to that screw wont take effect till you try to find the home position again either by starting a new print or pressing the home buttons.

it is quite a nightmare trying to get the bed level and the right distance from the bed to the extruder nozzle. pretty much a constant game of cat and mouse.

Ok, so if I understand what you are saying: if I need the extruder nozzle closer to the print bed, I should be adjusting the 3 screws in the print bed, not the one in the back of the chassis that they call the z-offset tab in the videos? Is that correct?

Thanks for the help.

7 Reply by cckens

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Re: Z-offset tab doesn't actually offset the Z axis during print

z-tab screw is a coarse adjustment, the 3 bed screws are fine adjustments, so, yeah, that's right.  Use the Z-tab to get close, then use the bed screws to make it better.  If your screws are too tight/loose, screw them to about the middle level, then z-tab close, and try fine tuning with the screws.  It takes a bit of getting used to, but you'll find that it gets easier every time you do it.

8 Reply by msummers

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Re: Z-offset tab doesn't actually offset the Z axis during print

cckens wrote:

z-tab screw is a coarse adjustment, the 3 bed screws are fine adjustments, so, yeah, that's right.  Use the Z-tab to get close, then use the bed screws to make it better.  If your screws are too tight/loose, screw them to about the middle level, then z-tab close, and try fine tuning with the screws.  It takes a bit of getting used to, but you'll find that it gets easier every time you do it.

Ok, I think I am set. I did the adjustment again using the bed screws and using a thinner business card for my reference when leveling the bed and adjusting the extruder distance. Now it is working much better.

I also had a second problem where it would stop feeding the filament after a few seconds of printing. I think it was trying to print too fast and getting clogged, as when I changed the "Feedrate" under "Speed Multiply" down to 25 it worked fine. Now I just need to find the right setting where it isn't so slow, yet keeps feeding.